Screw jack project_1

R
INSTITUTE OF TECHNOLOGY
COLLEGE OF ENGINEERING
Department of Mechanical
Engineering
Project Titel: Screw jack design
Name…. Ebrahim Ayelegn
ID-No……CESR/0259/09
Submission Date…...10/08/2011EC
Submitted-To. Mr.Abebe Asmamawu
Machine design project 1

Acknowledgement
First of all, I would like to thanks ALLAH that have given me the opportunity to complete my
“Project Screw Jack” (PSJ). Alhamdulillah, His Willingness has made it possible for me as the
author to complete the PSJ in time. I worked hard in completing this project within a semester.
I would like to take this opportunity to give my special thanks to our instructor Mr. Abebe
Asmamawu for guiding this project at every stage with clarity, spending much time to discuss
and help with this project, and that priceless gift of getting things done by sharing his valuable
ideas as well as share his knowledge. And Mr. Abebe Asmamawu for the great guidance that he
has given all the information, procedures and reference books.
I would also like to thank to all Madda Walabu University lecturers especially Mr. Abebe
Asmamawu Next we would like to acknowledge our classmates for their encouragement,
understanding and support throughout the entire project being with us.
Finally we would like to thank the almighty ALLAH for the successful completion of our first
project.

Notations
 p=Pitch of screw thread (mm)
 n=Number of threads in contact with screwed spindle
 l=Lead of screw thread (mm)
 t=Thickness of screw
 d=Nominal diameter of screw (mm)
 Core diameter of screw (mm)
 Mean diameter of screw (mm)
 Θ Friction angle (degree)
 α Helix angle of screw (degree)
 W=Load (kg)
 N=Normal reaction (newton)
 Μ Coefficient of friction
 P=Effort (newton)
 T=Torque
 μ Efficiency (%)
 The force the jack exerts on the load.
 The rotational force exerted on the handle of the jack
 r-the length of the jack handle
 BS=British standards
 Pure compression stress
 Cross sectional area of the screw shaft
 ( ) Maximum principal stress
 Maximum shear stress
 J=Polar moments
 Bearing pressure on the nut
 Thickness of nut collar
 h=Height of the nut
 Outer diameter of nut collar
 Outside diameter of nut collar
 Tearing strength of the nut
 Crushing strength of the nut
 Shearing stress on the screw
 Shearing stress on the nut
 Diameter of head on top of screw
 τ Shearing stress of nut collar
 Diameter of pin
 T=Total torque to which the handle is subjected
 Torque required to rotate the screw
 Torque required to overcome friction

 T=Total torque subjected to handle
 Yield stress
 L=Length of the handle
 D=Diameter of handle
 M=Bending moment
 H=The height of head
 Bending stress
 Effective length of screw
 Lift of screw
 Buckling or Critical load
 E Young’s modulus or modulus of elasticity
 I=Moment of inertia of the cross section.
 Diameter of body at the top
 Thickness of body
 Thickness of base
 Inner Diameter at the bottom
 Outer Diameter at the bottom
 Height of the body

Abstract
This technical paper presents design, and analysis of screw car jack. A screw jack
serves to give mechanical advantage by changing rotational force to linear force thus allowing
one to lift a load and support it at a given height. The aim of the project was to come up with
a design procedure for a simple screw jack. This technical paper is divided into various
sections that describe classification and parts of the screw jack and selection of materials.
A factor of safety of 5 and above should be used in this design to reduce high chances of failure
due to dynamic loadings and impact loadings. Dynamics loading is as a result of external
interferences such as whirl wind, earth tremors and external forces while impact loading is
such as load is applied suddenly with a short time and results into high stresses which can
cause failure hence these calls for a high factor of safety
Car jack is a device used to lift up the cars while changing the tires during an
emergency. Car jacks are available at the market has some disadvantages such as
requiring more energy to operate, are not suitable for women and cannot be used on the
uneven surface. The purpose of this project is to modify the design of the existing car
jack in terms of its functionality and also human factors considerations.
The scopes of research were on the designing 1.65 ton maximum lifting capacity of car jack by
using optimization concept. To optimize the existing design, the hand lifter has been replaced by
the use of pedal lever as it can reduce energy usage. In addition, ergonomic factors are also taken
into consideration in order to reduce and simplify how to use a car jack. The best concept had
been selected using the weighted rating method; next step was to determine the part and
component that can be modified by arrange the part into chunks and clustering with the
component according to the function or system. From this step, it can be determined which
component can be reduced or modified. Then the configuration design was analyzed according
the function factor and critical issue so that the design that had been
implementing was according to the specification and customer requirement. The last
step for this project was parametric design. In this topic, the new project concept will be
calculated to obtain the required force and compared with the theoretical calculation in
the table of human factor.

Contents
Acknowledgement.......................................................................................................................ii
Notations ..................................................................................................................................... v
Abstract .....................................................................................................................................vii
CHAPTER ONE............................................................................................................................. 2
1. INTRODUCTION................................................................................................................... 2
1.1 Background of screw car jack ........................................................................................... 2
1.2 Overview of the screw car jack ......................................................................................... 5
1.3 Applications....................................................................................................................... 6
1.4 Advantage and Disadvantages........................................................................................... 6
1.5 Components of screw car jack........................................................................................... 6
2 PROBLEM STATEMENT ...................................................................................................... 6
3 OBJECTIVE OF THE DESIGN.............................................................................................. 7
3.1 General objective............................................................................................................... 7
3.2 Specific objective. ............................................................................................................. 7
4 SCOPE AND LIMITATION ................................................................................................... 7
4.1 Scope ................................................................................................................................. 7
4.2 Limitation .......................................................................................................................... 7
1.5 METHODOLOGY................................................................................................................ 8
CHAPTER TWO ............................................................................................................................ 9
LITRATURE REVIEW .............................................................................................................. 9
2.1 Introduction to literature reviews about design of screw car jack..................................... 9
2.2 Illustrations of literature reviews about design of screw jacks.......................................... 9
CHAPTER THEREE.................................................................................................................... 11
3.1 DETAIL DESIGN AND ANALYSIS ................................................................................ 12
3.1.1 Overall specification of the project .............................................................................. 12
3.1.2 Force analysis ............................................................................................................... 13
3.1.3 Geometrical analysis..................................................................................................... 13
3.1.4 Material selection ......................................................................................................... 14
3.2 Design of Screw jack parts.................................................................................................. 18
3.2.1 Design of Screw spindle................................................................................................... 18

3.2.1.1 Considering Screw spindle under compressive......................................................... 18
3.2.1.2 Considering torsional shear stress for screw spindle................................................. 19
3.2.1.3 Considering Maximum principal stress..................................................................... 21
3.2.1.4 Considering maximum shear stress ........................................................................... 21
3.2.2 Design of nut.................................................................................................................... 22
3.2.2.1 Considering Height of the Nut................................................................................... 22
3.2.2.2 Stresses in the Screw and Nut.................................................................................... 24
3.2.2.3 The outer diameter of Nut ......................................................................................... 24
3.2.2.4The outside diameter of Collar ................................................................................... 25
3.2.2.5 Thickness of the Nut Collar....................................................................................... 25
3.2.3 Design for Head and Cup................................................................................................. 26
3.2.3.1 Dimensions of Diameter of Head on Top of Screw and for the Cup .................. 26
3.2.3.2 Torque Required to Overcome Friction..................................................................... 27
3.2.3.3 Total Torque Subjected to the Handle....................................................................... 27
3.2.3.4 Diameter of Handle/Lever......................................................................................... 28
3.2.3.5 Height of Head........................................................................................................... 29
3.2.3.6 Design Check against Instability/Buckling ............................................................... 30
3.2.4 Design of body ................................................................................................................. 31
3.2.4.1 Efficiency of the Screw Jack ..................................................................................... 33
CHAPTRE FOUR......................................................................................................................... 35
4.1 RESULT AND DISCUSSION............................................................................................ 35
4.1.1Result............................................................................................................................. 35
4.1.2 Discussion..................................................................................................................... 35
4.2 CONCLUSION AND RECOMMENDATION.................................................................. 36
4.2.1 Conclusion.................................................................................................................... 36
4.2.2 Recommendation.......................................................................................................... 36
4.3 PART AND ASSEMBLY DRAWING .............................................................................. 36
4.3.1 Part drawings of screw car jack.................................................................................... 36
4.3.2 Assembly drawing of screw car jack............................................................................ 38
APPENDICES........................................................................................................................... 52

List of figures and table
List of figures
Figure 1Scissor Jack------------------------------------------------------------------------------------------ 3
Figure 2 House Jack------------------------------------------------------------------------------------------ 4
Figure 3 Bottle Jack ------------------------------------------------------------------------------------------ 4
Figure 4 Hydraulic Jack ------------------------------------------------------------------------------------- 5
Figure 5 Schematic diagram of screw jack---------------------------------------------------------------12
Figure 6 section of screw spindle--------------------------------------------------------------------------19
Figure 7 screw jack ------------------------------------------------------------------------------------------20
Figure 8 development of screw-----------------------------------------------------------------------------20
Figure 9 section of nut collar 1 ----------------------------------------------------------------------------25
Figure 10 section of pin -------------------------------------------------------------------------------------26
Figure 11 section of cup-------------------------------------------------------------------------------------27
Figure 12 section of lever -----------------------------------------------------------------------------------28
Figure 13 section of lever - diameter----------------------------------------------------------------------29
Figure 14 section of screw head---------------------------------------------------------------------------29
Figure 15 body (or) frame of screw car jack-------------------------------------------------------------33
Figure 16 A 2-D representation of body or frame screw car jack ------------------------------------36
Figure 17 A 2-D representation of cup of screw car jack----------------------------------------------37
Figure 18 A 2-D representation of handle of screw car jack ------------------------------------------37
Figure 19 A 2-D representation of nut with collar of screw car jack --------------------------------37
Figure 20 A 2-D representation of screw rod (spindle) of screw car jack---------------------------38
Figure 21 Assembly drawing of screw car jack----------------------------------------------------------38
List of Table
Table 1 Overall specifications of the project................................................................................ 12
Table 2 Mechanical Properties of Cast iron – Appendix a .......................................................... 16
Table 3 Mechanical Properties of Plain carbon steel – Appendix B............................................ 16
Table 4 Safe Bearing Pressures for Power screws – Appendix.................................................... 17
Table 5 Mechanical Properties of Plain carbon steel – Appendix............................................... 17
Table 6 Mechanical Properties of Plain carbon steel – Appendix B............................................ 17
Table 7 Safe bearing pressures for power screws ........................................................................ 22
Table 8 Maximal Isometric Force by General European Working Population for Whole Body
Work in a Standing Posture.......................................................................................................... 28
Table 9 Result And Discussion ..................................................................................................... 35

CHAPTER ONE
1. INTRODUCTION
1.1 Background of screw car jack
Screw type mechanical jacks were very common for jeeps and trucks of World War II vintage.
For example, the World War II jeeps (Wally’s MB and Ford GPW) were issued the "Jack,
Automobile, Screw type, Capacity 1 1/2 ton", Ordnance part number 41-J-66. This jacks,
and similar jacks for trucks, were activated by using the lug wrench as a handle for the jack's
ratchet action to of the jack. The 41-J-66 jack was carried in the jeep's tool compartment. Screw
type jack's continued in use for small capacity requirements due to low cost of production raise
or lower it. Before the invention of weight lifting device such as screw jack, hydraulic jack,
crane, etc., the early man apply a crude way of lifting objects to great heights through the use of
ropes and rollers, which was mostly applied in the construction area, where, it was used to raise
mortar (cement, sand & water). [1]
The virtues of using a screw as a machine, essentially an inclined plane wound round a cylinder,
was first demonstrated by Archimedes in 200BC with his device used for pumping water.
There is evidence of the use of screws in the Ancient Roman world but it was the great
Leonardo da Vinci, in the late 1400s, who first demonstrated the use of a screw jack for lifting
loads. Leonardo’s design used a threaded worm gear, supported on bearings, that rotated by
the turning of a worm shaft to drive a lifting screw to move the load - instantly recognizable as
the principle we use today. We can’t be sure of the intended application of his invention, but
it seems to have been relegated to the history books, along with the helicopter and tank, for
3 almost four centuries.
It is not until the late 1800s that we have evidence of the product being developed further. With
the industrial revolution of the late 18th and 19th centuries came the first use of screws in
machine tools, via English inventors such as John Wilkinson and Henry Causley The most
notable inventor in mechanical engineering from the early 1800s was undoubtedly the
mechanical genius Joseph Whitworth, who recognized the need for precision had become as
important in industry as the provision of power .A screw jack that has a built-in motor is now
referred to as a linear actuator but is essentially still a screw jack.
Today, screw jacks can be linked mechanically or electronically and with the advances in
motion-control, loads can be positioned to within microns. Improvements in gear technology
together with the addition of precision ball screws and roller screws mean the applications for
screw jacks today are endless and a real alternative to hydraulics in terms of duty cycles and
speed at a time when industry demands cleaner, quieter and more reliable solutions. Car jacks
usually use mechanical advantage to allow a human to lift a vehicle by manual force alone. The
use of screws in the Ancient Roman world but it was the great Leonardo Vinci, in the late 1400s,
who first demonstrated the use of a screw jack for lifting loads. Leonardo’s design used threaded

worm gear, supported on bearings, that rotated by the turning of a worm shaft to drive a lifting
screw to move the load - instantly recognizable as the principle we use today [2]
1.1.1 Types of jacks
Jacks are of mainly two types- mechanical and hydraulic. They vary in size depending
on the load that they are used to lift
1.1.1.1 Mechanical Jacks
A mechanical jack is a device which lifts heavy equipment. The most common form
is a car jack, floor jack or garage jack which lifts vehicles so that maintenance can be
performed. Car jacks usually use mechanical advantage to allow a human to lift a vehicle
by manual force alone. More powerful jacks use hydraulic power to provide more lift over
greater distances. Mechanical jacks are usually rated for maximum lifting capacity. There
are several types of mechanical jacks: scissor jack, floor jack, scaffolds, bottle jack etc.
 Scissor Jacks
Scissors jacks are also mechanical and have been in use at least since the 1930s. A scissor jack
is a device constructed with a cross-hatch mechanism, much like a scissor, to lift up a vehicle
for repair or storage. It typically works in just a vertical manner. The jack opens and folds
closed, applying pressure to the bottom supports along the crossed pattern to move the lift
Figure 1Scissor Jack
 House jack
A house jack, also called a screw jack, is a mechanical device primarily used to lift
buildings from their foundations for repairs or relocation. A series of jacks is used and then
wood cribbing temporarily supports the structure. This process is repeated until the desired
height is reached. The house jack can be used for jacking carrying beams that have settled or
for installing new structural beams.

Figure 2 House Jack
 Bottle (cylindrical) jack
A bottle jack or whiskey jack is a jack which resembles a bottle in shape, having a
cylindrical body and a neck. Within is a vertical lifting ram with a support pad of some kind
fixed to the top. The jack may be hydraulic or work by screw action. In the hydraulic version
the hydraulic ram emerges from the body vertically by hydraulic pressure provided by a pump
either on the baseplate or at a remote location via a pressure hose.
Figure 3 Bottle Jack
1.1.1.2 Hydraulic Jacks
Hydraulic jacks are typically used for shop work, rather than as an emergency jack to
be carried with the vehicle. Use of jacks not designed for a specific vehicle requires more than
the usual care in selecting ground conditions, the jacking point on a vehicle, and to ensure
stability when the jack is extended. Hydraulic jacks are often used to lift elevators in low and
medium rise buildings

Figure 4 Hydraulic Jack
1.2 Overview of the screw car jack
A jack is mechanical device used to lift heavy loads or apply great forces. Jacks employ a
screw thread or hydraulic cylinder to apply very high linear forces. A mechanical jack is a device
which lifts heavy equipment more powerful jacks use hydraulic power to provide more lift over
greater distance. The mechanical advantage is the factor by which a mechanism multiplies the
force or torque applied to it. An automotive jack is a device used to raise all or part of a vehicle
into the air in order to facilitate repairs. Most people are familiar with the basic auto jack that
was still included as standard equipment with most new cars. These days, fewer people than ever
have had to use a car jack. This is due to the continuing improvements in modern tires that have
made “getting a flat” rare. Even so, people who like to rotate their tires themselves or who may
install snow tires before the winter and remove them in the spring need to use a jack to perform
the job.
A jackscrew is a type of jack that is operated by turning a lead screw. In the form of a screw jack
it is commonly used to lift moderately heavy weights, such as vehicles. More commonly it is
used as an adjustable support for heavy loads, such as the foundations of houses, or large
vehicles. These can support a heavy load, but not lift it. The power screws (also known as
translation screws) are used to convert rotary motion into translator motion. For example, in the
case of the lead screw of lathe, the rotary motion is available but the tool has to be advanced in
the direction of the cut against the cutting resistance of the material. In case of screw jack, a
small force applied in the horizontal plane is used to raise or lower a large load. Power screws
are also used in vices, testing machines, presses, etc. In most of the power screws; the nut has
axial motion against the resisting axial force while the screw rotates in its bearings. In some
screws, the screw rotates and moves axially against the resisting force while the nut is stationary
and in others the nut rotates while the screw moves axially with no rotation

1.3 Applications
The main applications of screw jack are as follows:
 To raise the load, e.g. screw-jack,
 To obtain accurate motion in machining operations, e.g. lead-screw of lathe,
 To clamp a work piece, e.g. vice, and
 To load a specimen, e.g. universal testing machine.
1.4 Advantage and Disadvantages
1.4.1Advantages
Screw jacks lift or raise the moderate heavy weights against gravity and uses very small
handle force that can be applied manually. Generally screw jacks have the following advantages:
 They are self-locking.
 They are simple to design.
 They are large load carrying capacity.
 The manufacturing of screw jack is easy without requiring specialized machinery.
 Screw jacks give smooth and noiseless service without any maintenance.
 There are only a few parts in screw jack. This reduces cost and increases reliability.
 They can lift moderately loads like cars with very less force.
1.4.2 Disadvantages
The major disadvantage of the screw jack is that chances of dropping, tipping or slipping of
the load are high, they should always be lubricated, and they cannot be used to lift or support
very heavy loads and can cause serious accidents hence the device is termed as not safe fail.
1.5 Components of screw car jack
Screw jack has the following parts:
 Body (Frame)
 Screw rod (spindle)
 Nut and collar for nut
 Handle (Tommy bar)
 Cup
 Set screw
 Washer
2 PROBLEM STATEMENT
The purpose of the Jake is to lift the weight of 1.65 ton vehicle. The minimum of the maximum
lifting height of the Jake are 170mm and 265mm respectively. The type of Jake used to lift the
vehicle is Jack screw design to the whole component of the Jake.

3 OBJECTIVE OF THE DESIGN
3.1 General objective.
The general objective of this project is to design screw jack with the details drawing
3.2 Specific objective.
Design and considering the following part
Parts to be designed
 To be designed Screwed spindle having square threaded screws,
 To be designed Nut and collar for nut,
 To be designed Head at the top of the screwed spindle for handle,
 To be designed Cup at the top of head for the load,
 To be designed Body of the screw jack.
Forces to be considered
 To be considered Load applied
 To be considered Compressive stress
 To be considered Torques
 To be considered Shear stress
 To be considered Bending stress
4 SCOPE AND LIMITATION
4.1 Scope
This project is about the designing and fabricating the car jack. The types of car jack that we
were used in this project were hydraulic car jack as it is more reliable and easy to operate. In
order to develop new concept of the car jack design. The scopes of project were on the designing
1.65 ton maximum lifting capacity of car jack by using optimization concept. For optimizing the
human power, the concepts that will be used in this product were replacing the long arm with the
leg pad. By this, the mechanical advantage while lifting can be reducing. Therefore, the
deformation, von stress misses, and the factor of safety of pedal lever will be analyzed using the
Finite Element Analysis Software. From our analysis, we will propose the best concept of the car
jack in terms of friendly user.
4.2 Limitation
In the design of screw car jack we have faced so many limitations including:
 Lack of resource i.e. computer access, Mat lab, and other software’
 Lack of experience

1.5 METHODOLOGY
This section of the report includes guideline system to achieve our objectives, for solving the
problem which is stated in statement of the problem; with specific component such as phases,
tasks, methods, techniques and tool.
Result and discussion
Stress analysis
Need or aim
Synthesize
Size and form
determination
Literature review
Geometry analysis
Conclusion
Material selection
Force analysis
Recommendation
Detail drawing

CHAPTER TWO
LITRATURE REVIEW
2.1 Introduction to literature reviews about design of screw car jack
In this section project papers are discussed related to the present work. Published
papers are highlight in this section. The main purpose of this literature review is to get
information about the project from the reference books, magazines, journals, technical papers
and web sites. In this chapter the discussion will be made base on all the sources. After going
through various literatures on pressure vessel supports some of the selected papers are cited
below and which are considered as basis for developing structural analysis methodology for
screw car jack.
2.2 Illustrations of literature reviews about design of screw jacks
“Experimental Investigation of the Performance of a Laboratory Screw Jack’ and concluded it
has been established that the relationship between the load and efficiency, and between the load
and effort applied is linear and was also discovered that decrease in load means decrease in effort
and decrease in load causes increase in efficiency [3]
In this paper a lifting device is a system that allows small force (effort) to overcome a large
force or load. There are practically hundreds of uses for lift tables in manufacturing, warehousing
and distribution facilities. The addition of this device (lift table) makes job faster, safer and
easier. Some typical applications include; machine feeding and off-loading, product assembly,
inspection quality control repair, feeding and offloading conveyor levels. The commonest
method for operating a scissors lift is the use of a power screw [4]
The manually operated screw jack lift is a device that makes use of a horizontally placed power
screw to overcome large load through less effort applied on the power screw. One of the most
important factors of lift platform is its stability. Knowing that stability is a source of concern for
a lift platform, its positioning should be on a flat surface and the load should be place or
concentrated at the center of gravity of the table. Other constraint to be considered is the
deflection of the unit. Deflection in the lift can be defined as the resulting change in elevation of
all parts of a screw jack lift assembly, typically measured from the floor to the top of the
platform deck, whenever load is applied to or removed from the lift. [5]
Safety requirement for industrial scissor lifts states that “All industrial screw jack lift will deflect
under load”. The Shop standard goes on to outline the maximum allowable deflection base on
platform size and number of scissor mechanism within the lift design. Screw jack lift deflection
becomes more critical in material handling applications where the lift must interface with
adjoining, fixed elevations, especially when transferring rolling load.
In these cases, it is important that any difference in elevation between adjoining surfaces during
material transfer be minimize or if not totally eliminated. Before attempting to discuss how to

limit scissor lift deflection, it is important to understand the contributing factors to a lift total
deflection. An open or raised scissor acts very much like a spring would apply a load and it
compresses, remove a load and it expands. Such component within the screw jack lift has the
potential to store or release energy when loaded and unloaded (and therefore deflects).
There are application specific characteristics that may promote deflection, understanding these
root causes helps to pin-point and apply effective measures to limit them. Leg deflection due to
bending is as a result of stress which is driven by the total weight supported by the legs, scissor
leg length, and available leg cross section. The longer the scissors leg length, the more difficult it
is to control the bending under load other important component is the platform structure.
Platform bending will increase as the load center of gravity move away from the center
(unevenly distributed load) or at an edge (eccentric loading) of the platform. Also as the scissor
open during rising of the lift, the rollers could roll back towards the platform hinges and create
an increasingly unsupported overhung portion of the platform assembly. Increase platform
strength via increase support structure material height does improve resistance to deflection, but
also contributes to an increase collapsed height of the lift. The lift base frame is usually placed
on the floor and may not experience deflection. For cases where the scissor lift is mounted to an
elevated or portable frame, the potential for deflection increases. To effectively resist deflection,
the base frame must be rigidly supported from beneath to support the point loading created by
the two scissor leg hinges. [6]

CHAPTER THEREE
3.1 DETAIL DESIGN AND ANALYSIS
3.1.1 Overall specification of the project
Design of screw car jack
Parameter Value Unit
Lift Weight 1.65 Ton
Maximum lifting height 265 Mm
Minimum lifting height 170 Mm
Table 1 Overall specifications of the project
Figure 5 Schematic diagram of screw jack

3.1.2 Force analysis
The force analysis consideration is based on the assumption of the screw jack load by vertically
symmetrically. And In force analysis title we have seen on how to calculate the different
dimension of mechanical jackscrew with the necessary calculated since the dimension is
necessary to calculate the force analyses on the mechanical screw jack.
Given data
Lift Weight =1.65 ton
But
So
Therefor maximum mass
Force ( ) where ⁄
3.1.3 Geometrical analysis
Geometrical analysis deals with the determination of the overall dimensions of the part the
maximum and minimum lifting height. The maximum lifting height, =265mm and the
minimum lifting height, =170mm
Then to make the screw jack type from it must be deign with minimum lifting height length so
depend on this changed height is given by
= -
=265mm-170mm=95mm
=95mm
Capacity load =1.65×1000×9.81=16186.5N=16KN
 Capacity load=16KN
 Maximum lifting height=265mm
 Minimum lifting height=170mm

3.1.4 Material selection
3.1.4.1 Introduction
Material selection is an important process in design processes. Selecting materials is a process
that is design-led in that the material selection process uses the design requirements as the input
so as to come up with materials that have the desired properties for the part to be designed to
function well
3.1.4.2 Engineering Materials for Components
The common engineering materials used in making machine components include;
 Cast iron,
 Steel (all types of steel),
 Copper and its alloys,
 Aluminum and its alloys,
 Plastics.
Therefore, the right materials for the design of the screw jack parts should be selected. Selection
requires one to consider the following factors which give the best material fit for the design job:
 Specific strength and mass.
It is preferable to select a material of high yield stress with ability to carry external load
without failure and low density in order to realize a screw shaft of high strength and low
mass. Therefore, the material selection process should aim to maximize the quantity
termed as the specific strength.
 Resistance to abrasive wear.
Most of engineering materials in contact with one another are subjected to surface wear
due to relative motion. It is therefore desirable to select a material from the candidate
materials with low wear rate or capacity to resist abrasive wear at the thread surfaces.
 Resistance to buckling.
Heavy loads may cause the screw to buckle once the critical load is exceeded. It is
preferable to select a material with high resistance to buckling of the screw, that is,
excellent elasticity and deflection behavior in response to application of an external load.
 Availability, Cost and Affordability.
It is also preferable to choose a material with the highest affordability rating. Relative cost
of the materials is used in finding or calculating the affordable rates.

Therefore, the availability of the material and the cost of processing the material into the finished
product need to be taken into account and considered as supporting information when making the
final choice of the material.
 Heat transmission properties.
As we know there always a relative motion between screw and nut, which cause a friction
that generates heat which can cause change in the mechanical properties of the material.
 Other relevant properties include; resistance to corrosion, electrical and mechanical
properties, heat transmission properties etc.
3.1.4.3 Steps for Selection of Materials for Components
Selection of materials in engineering design involves the following steps
 Translation of design requirements into specifications for a material.
 Screening out those materials that do not meet the specifications in order to leave only
the viable candidates.
 Ranking of the surviving materials to identify those that have the greatest potential.
 Using supporting information to finally arrive at the choice of material to be used
The first three steps involve mathematical analysis, use of various charts and graphs of specific
property such as specific strength, wear resistance, buckling resistance and affordability. The
materials are compared, ranked as per the indices of merit and available supporting information
is used to reach the final decision.
In this project, information from case studies on previous designs of similar products is used in
material selection for the screw jack components/parts. However, other factors such as
availability of the candidate materials, purchase price of the candidate materials, manufacturing
processes and properties, forms and sizes in which the materials are available are also considered
3.1.4.4 Components and their Specific Materials Selected
The goal of material selection is to come up with an appropriate material that best meets the
design requirements. The approach is to identify the connection between functional requirements
and the material properties so as to help us reduce the number of candidate materials from which
to select from. The following are components and materials required in the design of a power
screw (screw jack):
Frame (Body)
The frame of the screw jack has complex shape. It’s subjected to compressive stress. For this
reason, Grey cast iron of grade FG220( )as a material is selected for the frame.
This is also evident from the case study on previous design of the same product (Nyanja’s, 18
December, 2006). Cast iron is cheap and it can give any complex shape without involving costly

machining operations. Cast iron has higher compressive strength compared to steel. Therefore, it
is technically and economically advantageous to use cast iron for the frame. The purpose of the
frame is to support the screw jack and enable it to withstand compressive load exerted on it.
Mechanical properties British standard Specification
Tensile strength ( ) 220
Compressive strength ( ) 766
Shear strength ( ) 284
Endurance limit ( ) 96
Young’s modules ( ) 89-114
Modules of rigidity ( ) 36-45
Hardness number ( ) 196
Table 2 Mechanical Properties of Cast iron – Appendix a
Screw
The screw is subjected to torsional moment, compressive force and bending moment. The screw
profile is square type because of its higher efficiency and self-locking but not compared to
trapezoidal threads. Square threads are usually turned on lathes using a single point cutting tool
also square threads are weak at the root and this leads to use of free cutting steel. Screws are
usually made of steel where great resistance to weather or corrosion is required. Most fasteners
close to 90% use carbon steel because steel has excellent workability, offers abroad range of
attainable combinations of strength properties and it is less expensive. Medium plain carbon steel
can be heat treated for the purpose of improving properties such as hardness, strength (tensile
and yield), the desired results are therefore obtained (Fasteners, 2005). This leads to the use of
plain carbon steels
Material British
Standard
Production
in process
Max
section
size,( )
Yield
strength
( )
Tensile
strength
( )
Elongation
n%
Hardness
number
( )
0.30C 080M30 Hardened
&Tempered
63 385 550-
570
13 152-207
Table 3 Mechanical Properties of Plain carbon steel – Appendix B
Nut
There exists a relative motion between the screw and the nut which causes friction, friction in
turn causes wear of the material used for screw and nut. Therefore, it requires one of the two
members to be softer. A suitable material for the nut is therefore phosphor bronze which is a
copper alloy with small percentage of lead and has the following advantages;
 Good corrosion resistance.
 Low coefficient of friction.
 High tensile strength.

Bronze has 0.2% phosphor to increase tensile strength and the yield stresses may be taken as;
tension = 125MPa, compression = 150MPa, yield stress in shear = 105MPa with safe bearing
pressure of 15MPa, ultimate tensile strength is 190MPa and a coefficient of friction of 0.1.
Type of power
screw
Screw material Nut material Beaning
pressure
( )
Rubbing speed
( )
Screw jack Steel Bronze 11-17 3
Table 4 Safe Bearing Pressures for Power screws – Appendix
Handle
The handle is subjected to bending moments so plain carbon steel of BS 080M30 with yield
strength of 385MPa can also be used. It has the same mechanical properties and process as in
Table 4
Materia
l
British
Standar
d
Production
in process
Max
section
size,
( )
Yield
strengt
h
( )
Tensile
strengt
h
( )
Elongatio
n
n%
Hardnes
s number
( )
&Tempere
d
63 385 550-570 13 152-207
Table 5 Mechanical Properties of Plain carbon steel – Appendix
Cup
Shape of cup is complex and thus requires casting process. It also has the same properties as in
Table3. Taking graphite flakes cast iron with an ultimate tensile strength of 200MPa. The
graphite flakes improve the ability to resist compressive load.
Set Screw and Lock nut + Washer
The purpose of the set screw is to resist motion of nut with screw. The lock nut + washer on the
other hand are used to provide uniform force by enlarging the area under the action of the force.
We can use plain carbon steel for both and they have the same manufacturing process and
properties as in Table 5
Materia
l
British
Standar
d
Production
in process
Max
section
size,
( )
Yield
strengt
h
( )
Tensile
strengt
h
( )
Elongatio
n
n%
Hardnes
s number
( )
&Tempere
d
63 385 550-570 13 152-207
Table 6 Mechanical Properties of Plain carbon steel – Appendix B

3.2 Design of Screw jack parts
3.2.1 Design of Screw spindle
The screw is subjected to torsional moment, compressive force and bending moment.
The screw profile is square type because of its higher efficiency and self-locking but not
compared to trapezoidal threads. Square threads are usually turned on lathes using a single
point cutting tool also square threads are weak at the root and this leads to use of free cutting
steel. Screws are usually made of steel where great resistance to weather or corrosion is
required. Most fasteners close to 90% use carbon steel because steel has excellent workability,
offers abroad range of attainable combinations of strength properties and it is less expensive.
Medium plain carbon steel can be heat treated for the purpose of improving properties such as
hardness, strength (tensile and yield), the desired results are therefore obtained. This leads to
the use of plain carbon steels (i.e. 0.30C).
Material specification selected for the screw spindle is plain carbon steel to British
Standard specification BS 970 080M30, Hardened and Tempered, whose properties are as
shown in Appendix B and the material yield strength is 700.
3.2.1.1 Considering Screw spindle under compressive
We consider the compression to get core diameter due to the compression is resisting area.
Let Α=Resisting Area.
=Core diameter of the screw.
W = Capacity load. Α= × ( ) 2
Since the screw is under compression, therefore load (W),
W= × × ( ) 2
......................................... (1)
√ ……….................…………………... (2)
Taking factor of safety f. s =5
√ …………………………………..…... (3)
=√

For square threads of fine series, the following dimensions of screw are selected from Appendix
D (Gupta, 2005) hence,
The core diameter =12mm, =14mm and pitch p=l=2mm
Figure 6 section of screw spindle
3.2.1.2 Considering torsional shear stress for screw spindle
We know that torque required to rotate the screw is the same torque required to lift the load
which is given by;
T1= P× =
[ ( )]
………………………..…... (4)
We know that =
( )
=
( )
= 13mm
And
tan = = = 0.04897 α=tan =2.8
Assuming coefficient of friction between screw and nut,
μ=tan =0.1 β=tan =5.71
A screw will be self-locking if the friction angle is greater than helix angle or coefficient of
friction is greater than tangent of helix angle i.e. μor tan >tan
The torque required to raise a load by means of square threaded screw may be determined by
considering a screw jack as shown in Figure below, the load to be raised or lowered is placed
on the head of the square threaded rod which is rotated by the application of an effort at the
end of lever for lifting or lowering the load.

Figure 7 screw jack
A little consideration will show that if one complete turn of a screw thread be imagined to be
unwound, from the body of the screw and developed, it will form an inclined plane.
Figure 8 development of screw
Since the principle, on which a screw jack works is similar to that of an inclined plane, therefore
the force applied on the circumference of a screw jack may be considered to be horizontal.

∴ Torque required to rotate the screw in the nut, we know that torque required to rotate the screw
is the same torque required to lift the load which is given by;
T1 = P× = w×tan( ) = w×* +× ……………..…... (5)
T1=
[ ( )]
= 15.72Nm
Now compressive stress due to axial load,
= =
( )
………………………………..…... (6)
=
( )
Since the screw is subjected to a twisting moment, therefore torsional shear stress is induced.
This is obtained by considering the minimum cross-section of the screw. We know that Shear
stress due to torque transmitted by the screw:
τ ( )
…………………………………..…... (7)
τ ( )
3.2.1.3 Considering Maximum principal stress
∴Maximum principal stress (tensile or compressive),
( )= ×[ √( ) ]…………………………………..…... (8)
( )= ×[ √( ) ( ) ]
( )
The design value of = = 140MPa
3.2.1.4 Considering maximum shear stress
When the screw is subjected to both direct stress and torsional shear stress, then the design
must be based on maximum shear stress theory, according to which maximum shear stress on
the minor diameter section.

= ×√( ) …………………………………..…... (9)
×√( ) ( )
= 85.25Mpa
The design value of τ = = 90Mpa
Check: These maximum shear and compressive stresses are less than the permissible stresses;
hence the spindle or shaft is safe
3.2.2 Design of nut
There exists a relative motion between the screw and the nut which causes friction, friction in
turn causes wear of the material used for screw and nut. Therefore, it requires one of the two
members to be softer. A suitable material for the nut is therefore phosphor bronze which is a
copper alloy with small percentage of lead and has the following advantages;
 Good corrosion resistance
 Low coefficient of friction.
 High tensile strength.
From 6.3 Appendixes C: Safe Bearing Pressure for Power Screws [ ]
Type of power
Screw
Screw material Nut material Bearing
pressure
Rubbing speed
Screw jack Steel Bronze 11−17Mpa 3m/s
Table 7 Safe bearing pressures for power screws
3.2.2.1 Considering Height of the Nut
The screw and nut are in match there is a chance of rubbing due to there is an area which resists.
Resists area (A) = A = ×( − )
A= ( − )
A=40.84mm2
Let n= Number of threads in contact with the screwed spindle,

h = Height of nut = n × p
t = Thickness of screw = =
Assume that the load is distributed uniformly over the cross-sectional area of nut.
In order to reduce wear of the screw and nut, the bearing pressure on the thread surfaces must
be within limits. In the design of power screws, the bearing pressure depends upon the materials
of the screw and nut, relative velocity between the nut and screw and the nature of lubrication.
Assuming that the load is uniformly distributed over the threads in contact, the bearing pressure
∴ bearing strength of nut
W = A × n × → n =
Material specification for the nut is phosphor bronze which has tensile stress = 150MPa,
compressive stress = 125MPa, shear stress = 105MPa, safe bearing pressure not exceed 17MPa
and a coefficient of friction of 0.12 Assuming the load is uniformly distributed over the entire
cross section of the nut and substituting for the known values we get the number of threads in
contact,
[( ) ( )]
…………………………………..…... (10)
17×
[[ ) ( )]]
17×
n=23.1 say n=23 threads
So we can find the height of the nut
=n × p
=23 × 2=46mm
Check: For a safe nut height ≤ 4 =48mm (Gupta, 2005)

3.2.2.2 Stresses in the Screw and Nut
Now, let us check the stresses induced in the screw and nut. The threads of the screw at the
core or root diameter and the threads of the nut at the major diameter may shear due to the axial
load. Assuming that the load is uniformly distributed over the threads in contact,
Shear stress in the screw is as follows;
( )= …………………………………..…... (11)
( )
Shear stress in the nut is as follows;
( )= …………………………………..…... (12)
( )
The given value of
Since these stresses are within permissible limit, therefore design for nut is safe.
3.2.2.3 The outer diameter of Nut
Let
 Outer diameter of nut,
 Outside diameter for nut collar, and
 = Thickness of nut collar.
Outer diameter is found by considering the tearing strength of the nut.
[( ) ( )]
…………………………………..…... (13)
Where tearing strength of the nut = tensile stress
Then we get as follows;

[( ) − ( )]
3.2.2.4The outside diameter of Collar
Outside diameter is found by considering the crushing strength of the nut collar.
[( ) ( )]
…………………………………..…... (14)
Where crushing strength of the nut = compressive stress
Then we get as follows;
[( ) − ( )]
Figure 9 section of nut collar 1
3.2.2.5 Thickness of the Nut Collar

The thickness of nut collar is found by considering the shearing strength of the nut collar
w = 𝛑× × ×𝛕
…………………………………..…... (15)
Shearing strength of nut collar =
Therefore
3.2.3 Design for Head and Cup
3.2.3.1 Dimensions of Diameter of Head on Top of Screw and for the Cup
Assuming
mm mm
The head is provided with two holes at the right angles to receive the handle for rotating the
screw. The seat for the cup is made equal to the diameter of head, i.e. 25mm and it is given
chamfer at the top. The cup prevents the load from rotating. The cup is fitted to the head with
a pin of diameter approximately [ ]
The pin should remain loose fit in the cup.
Figure 10 section of pin

Take length of pin to be 4mm.
Other dimensions for the cup may be taken as follows:
 Height of cup = 35mm
 Thickness of cup = 10mm
 Fillet radii = 5mm
 Diameter at the top of the cup = Diameter of the head = 80mm
Figure 11 section of cup
3.2.3.2 Torque Required to Overcome Friction
We know that by assuming uniform pressure condition torque required to overcome friction is
given as follows;
*
( ) ( )
( ) ( )
+…………………………………..…... (16)
Where
Diameter of head = 25mm
Diameter of pin = 6mm
Substituting for the known values we get;
[
( ) − ( )
( ) − ( )
]
3.2.3.3 Total Torque Subjected to the Handle
Total torque to which the handle is subjected is given by
+

Activity Professional use Domestic use
Pushing 200N( ) 119N( )
Pushing 145N( ) 96N( )
Table 8 Maximal Isometric Force by General European Working Population for Whole Body Work in a Standing
Posture
Therefore taking the force of 96N in domestic use [ ]then the length of the
handle required is
L =
L =
The length of the handle may be fixed by giving some allowance for gripping 70mm.
Therefore, the length of the handle/lever is 381mm.
Figure 12 section of lever
3.2.3.4 Diameter of Handle/Lever
A little consideration will show that an excessive force applied at the end of lever will cause
bending. Considering bending effect, the maximum bending moment on the handle,
M = force applied × length of lever
M = 96N×0.38m
M =36.48Nm
Let D= Diameter of the handle.
Assuming that the material of the handle is same as that of screw, therefore taking bending
stress
The diameter of the handle/lever may be obtained by considering bending effects. We know
that bending moment;

M = ( ) …………………………………..…... (17)
D = √
D = √
D =13.84mm = 14mm
Figure 13 section of lever - diameter
3.2.3.5 Height of Head
The height of head is usually taken as twice the diameter of handle.
Therefore
H = 2×D…………………………………..…... (18)
H = 2×14
H = 28mm
Figure 14 section of screw head

3.2.3.6 Design Check against Instability/Buckling
We know that the effective length for the buckling of screw,
=
= + …………………………………..…... (19)
=265+
=273mm
When the axial load is compressive and the unsupported length of the screw between the load
and the nut is short. But when the screw is axially loaded in compression and the unsupported
length of the screw between the load and the nut is too great, and then the design must be based
on
column theory assuming suitable end conditions. When the screw reaches the maximum lift, it
can be regarded as strut whose lower end is fixed and the load end is free. Therefore, buckling
or critical load for this given condition. In such cases, the cross-sectional area corresponding
to core diameter may be obtained by using Rankin-Gordon formula or J.B. Johnson’s formula.
According to this,
[ − ( ) ]…………………………………..…... (20)
Where
Yield stress = = 385Mpa
C = End fixity coefficient. The screw is considered to be strut with lower end
fixed and load end free. Therefore C = 0.25
k = the radius of gyration = √ = 0.25 =0.003m
I = Moment of inertia of the cross section
The buckling load as obtained by the above expression and must be higher than the load at which
the screw is designed. Substituting for the known values:

[ − ( ) ]
( ) [ − ( ) ]
70,327.77N
Where
W = 16,186.5N
, hence there is no chance for the screw to buckle.
3.2.4 Design of body
Most of the frames are in conical shape and hollow internally to accommodate both the nut and
screw assembly. The frame works to ensure that the screw jack is safe and has a complete rest on
the ground. The purpose of the frame is to support the screw jack and enable it to withstand
compressive load exerted on it.
The frame is a bit complex and thus requires casting as a manufacturing process. For this
reason, grey cast iron as a material is selected for the frame. This is also evident from the case
study on previous design of the same product. Cast iron is cheap and it can give any complex
shape without involving costly machining operations. Cast iron has higher compressive
strength compared to steel. Therefore, it is technically and economically advantageous to use
cast iron for the frame. Graphite flakes cast iron with an ultimate tensile strength of 220MPa is
considered suitable for the design of the frame. The graphite flakes improve the ability to resist
compressive load.
The dimension of the body may be fixed and given as in shown in the figure above
1. Diameter of the body at the top,
2. Thickness of the body,

3. Inside diameter at the bottom,
4. Outer diameter at the bottom,
5. Thickness of base,
6. Height of the Body
Height of the body = Min lift + height of nut + extra 10mm
Finally, the body is tapered in order to achieve stability of the jack
Let us now find out the efficiency of the screw jack. We know that the torque required
rotating
the screw with no friction,
tan

Figure 15 body (or) frame of screw car jack
3.2.4.1 Efficiency of the Screw Jack
The efficiency of square threaded screws may be defined as the ratio between the ideal efforts
(i.e. the effort required to move the load, neglecting friction) to the actual effort (i.e. the effort
required to move the load taking friction into account), if the screw friction and collar friction
is taken into account, then
∴ Efficiency of the screw jack,
η=
η=
But tan …………………………………..…... (21)
5.15Nm
And T= 29.835Nm
Therefore
η= = = 17.26%

3.2.4.2 Maximum Efficiency of a Square Threaded Screw
If there would have been no friction between the screw and the nut, then ∅ will be equal to zero.
The value of effort necessary to raise the load will then be given by the equation,
tan
tan( )
Efficiency, = ( ) ( )
This shows that the efficiency of a screw jack, is independent of the load raised
( )
sin( )−sin
sin( ) sin
…………………………………..…... (22)
The efficiency given by equation will be maximum when sin( )is maximum
sin( )
− sin
sin
%
−sin
sin
×100%
%
Since tan Therefore sin
In the above expression for efficiency, only the screw friction is considered. However, in
practical case it is impossible so we have considered the screw friction and collar (nut) friction
is taken into account, therefore in our design case η= = 17.26%
3.2.4.3 Efficiency vs. Helix Angle
The efficiency of a square threaded screw depends upon the helix angle α and the friction
angle β. The variation of efficiency of a square threaded screw for raising the load with the
helix angle α is shown in Figure below. We see that the efficiency of a square threaded screw
increases rapidly up to helix angle of 20°, after which the increase in efficiency is slow. The
efficiency is maximum for helix angle between 40 to 45°.
When the helix angle further increases say 70°, the efficiency drops. This is due to the fact that
the normal thread force becomes large and thus the force of friction and the work of friction
become large as compared with the useful work. This results in low efficiency.

CHAPTRE FOUR
4.1 RESULT AND DISCUSSION
4.1.1Result
Components Parameter Values
Screw spindle Core diameter 12mm
Outside diameter 14mm
Mean diameter 13mm
Torque 15.72×
Max compressive stress ( ) 156.8Mpa
Max shear stress 85.25Mpa
Nut Height h 46mm
Thickness of nut collar 9mm
Outer diameter of nut 30mm
Outside diameter for nut collar 42mm
Shear stress in screw 18.66Mpa
Shear stress in nut 16Mpa
Handel and cup Diameter of the head 25mm
Diameter of pin 6mm
Torque 14.115×
Length of the handle L 310mm
Max bending moment M 36.48×
Diameter of the handle D 14mm
Height of head H 28mm
Body or frame Diameter of the body at the top 63mm
Thickness of the body 4mm
Inside diameter at the bottom 95mm
Outside diameter at the bottom 166mm
Thickness of base 18mm
Height of the body 160mm
Torque 5.15×
Table 9 Result and Discussion
4.1.2 Discussion
From the above result we understand that the allowable stresses are greater than the stresses
gotten by calculation in the design and analysis part of our project. This means that the design
of screw jack is safe.

4.2 CONCLUSION AND RECOMMENDATION
4.2.1 Conclusion
The screw car jack is successfully designed so that it withstands all the mechanical stresses
acting on it. The screw car jack is analyzed under various conditions of operation. The stresses in
above-mentioned conditions are found out and thickness of various parts is selected such that the
stresses produced in each member are within the maximum allowable range. All the selected
have been successfully verified and hence the design of screw jack is safe.
4.2.2 Recommendation
From the project, we concentrated on design of a simple mechanical screw jack where the nut is
fixed in a cast iron frame and remains stationary while the spindle is being rotated by the lever.
This design can only work for light loads hence when a screw jack is needed for heavy load
application a different design is required where the nut is rotated as the spindles moves. Long
lifts should be avoided since they can cause serious overheating and generate a large amount of
heat. It should therefore be used under ambient temperatures with the use of the required
lubricants. Design and manufacturer’s instructions such as speed, load capacity and
recommended temperatures must be followed to avoid accidents. Always keep the mating
surfaces clean after use and check for wear and damage on the surfaces. We therefore
recommend design of a screw jack for the heavy loads.
4.3 PART AND ASSEMBLY DRAWING
4.3.1 Part drawings of screw car jack
Part drawing is a type of drawing which deals about drawing of the individual
components of a given machine
Figure 16 A 2-D representation of body or frame screw car jack

Figure 17 A 2-D representation of cup of screw car jack
Figure 18 A 2-D representation of handle (Tommy bar) of screw car jack
Figure 19 A 2-D representation of nut with collar of screw car jack

Figure 20 A 2-D representation of screw rod (spindle) of screw car jack
4.3.2 Assembly drawing of screw car jack
An assembly drawing is one which represents various parts of the machine in their
working position. These drawings are classified as design assembly drawings, working
assembly drawings, sub assembly drawings, installation assembly drawings, etc. An assembly
drawing made at the design stage while developing a machine is known as design assembly
drawing. It is made to a larger scale so that the required changes or modifications may be
thought of by the designer, keeping in view both the functional requirement and aesthetic
appearance. Working assembly drawings are normally made for simple machines, comprising
small number of parts. Each part is completely dimensioned to facilitate easy fabrication.
Figure 21 Assembly drawing of screw car jack

REFERENCE
1) Collection, J., 2015. hubpages.com › Autos › Automobile History. [Online] retrieved 10
June 2017 from https://www.history of screw jacks.com.
2) Gupta, R. K. &. J., 2005. Theory of Machines. Revised Edition ed. Punjab, India: S.
Chand and Company. Stephen Tambari , Petaba Lemii, Kanee Sorbari ,Nzidee lelesi,
“Experimental
3) Investigation of the Performance of a Laboratory Screw Jack”, IOSR Journal of
Mechanical and Civil Engineering (IOSR-JMCE), Volume 12, Issue 4.
4) J.J. Ferreira, M. B. M. G., 2004. Review of the risks associated with pushing and pulling
heavy loads. First ed. Sheffield: Health and safety Laboratory.
5) Michael-Adel, 2008 Material Selection for a Manual Winch Rope Drum. Volume 1.
6) ANSI MH29.1 screw jack Design for Use in the Automotive Industry New Jersey, 2004
7) Kempster, M. H. A., 1984. Engineering Design III. London: Hodder and Stoughton Ltd.
8) Nisbet, R. G. B. &. J. K., 2015. Shigley's Mechanical Engineering design. Tenth Ed. New
York: McGraw-Hill.
9) Prof. F.M. Oduori, E. D. O., 2016. Material Selection for a Manual Winch Rope Drum.
Volume 1.
10) Bhandari, V. B., 2010. Design of Machine Elements. Third Edition Ed. New Delhi: Tata
McGraw-Hill Education.
11) Ashby, M. F., 2005. Material Selection in Mechanical Design. 3rd Ed. New York:
Pergamum Press
12) Fasteners, C. o., 2005. Technical Reference Guide. Ninth Edition ed. Winona, Minnesota:
Fastenal Industrial & Construction Supplies.
13) Marshek, R. C. J. &. K. M. Fundamental of Machine Design Components. Fifth Edition.

APPENDICES
Appendix A: Mechanical Properties of Cast Iron (Nyanja’s, 18 December, 2006)
Mechanical
properties
Grade designation(British standard )
150 180 220 260 300 350 400
Tensile
strength
( )
150 180 220 260 300 350 400
Compressive
strength
( )
587 663 766 868 970 1097 1225
Shear
strength
( )
176 222 284 346 407 484 562
Endurance
limit ( )
71 82 96 111 125 143 161
Young’s
modules
( )
71-96 70-104 86-114 100-135 110-135 124-147 137-160
Modules of
elasticity
( )
29-40 32-42 36-45 43-51 43-51 48-55 53-58
Hardness
( )
160 176 196 236 236 261 286

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