1. 1
Chapter 1
1.1 Introduction
A scissor lift or mechanism is a device used to extend or position a platform by mechanical
means. The term “scissor” comes from the mechanic which has folding supports in crises cross
“X” pattern. The extension or displacement motion is achieved by the application of force to one
or more supports, resulting in an elongation of the cross pattern. The force applied to extend the
scissors mechanism may by hydraulic, pneumatic or mechanical (via a lead screw or rack and
pinion system).
The need for the use of lift is very paramount and it runs across labs, workshops, factories,
residential/commercial buildings to repair street lights, fixing of bill boards, electric bulbs etc.
expanded and less-efficient, the engineers may run into one or more problems when in use.
The name of scissors lift originated from the ability of the device to open (expand) and close
(contract) just like a scissors. Considering the need for this kind of mechanism, estimating as
well the cost of expanding energy more that result gotten as well the maintenance etc. it is better
to adopt this design concept to the production of the machine.
The initial idea of design considered was the design of a single hydraulic ram for heavy duty
vehicles and putting it underneath, but this has limitations as to the height and stability, and
someone will be beneath controlling it. It was rather found out that; there is a possibility of the
individual ascending/descending, to be controlling the device himself. Therefore further research
was made to see how to achieve this aim.
Before this time scissors lift existing use mechanical or hydraulic system powered by batteries
for its operations. Several challenges were encountered in this very design. Some amongst many
include; low efficiency, risk of having the batteries discharged during an emergency, extended
time of operation, dependent operation, as well as maintenance cost. It is the consideration of
these factors that initiated the idea of producing this hydraulically powered scissors lift with
independent operator. The idea is geared towards producing a scissors lift using one hydraulic
ram placed across flat, in between two cross frames and powered by a pump connected to a

2. 2
motor wheel may be powered by a pump generator. Also, the individual ascending / descending
is still the same person controlling it. I.e. the control station will be located on the top frame.
A scissors lift is attached to a piece of equipment having a work station known as scissors lift
table that houses the pump, the reservoir, the generator, control valves and connections and the
motor. A scissors lift does not go as high as a boom lift; it sacrifices heights for a large work
station. Where more height is needed, a boom lift can be used.
1.2 Statement of the Problem
A problem remains a problem until a solution is proffered. With the limitations encountered in
the use of ropes, ladders, scaffold and mechanical scissors lifts in getting to elevated height such
as the amount of load to be carried, conformability, time consumption, much energy expended
etc. the idea of a Pneumatic scissors lift which will overcome the above stated limitations is used.
1.3 Scope of the Study
The design and construction of the Pneumatic scissors lift is to lift up to a height of .3m and
carrying capacity of less than 10kg (10 kilograms) with the available engineering materials.
However, there is for academic purpose, a similar project for general carrying – capacity with a
selection of better engineering materials.
1.4 Importance / Significance of the Study
The design and construction of a hydraulic scissors lift is to lift a worker together with the
working equipment comfortably and safely to a required working height not easily accessible. It
may be used without a necessary external assistance or assistance from a second party due to the
concept of the design. This project will be an important engineering tool or device used in
maintenance jobs. Changing the streets light, painting of high buildings and walls around the
school environment.
1.5 Aims/Objectives of the Study
The project is aimed at designing and constructing a hydraulically powered scissors lift to lift
and lowers worker and his working equipment with ease and in the most economical way. The
lift is expected to work with minimal technical challenges and greater comfort due to its wide

3. 3
range of application. The device can easily be handled to the site to be used with a tow-van and
then powered by Pneumatic equipment’s. Between the heights of lift (i.e. the maximum height)
the device can be used in any height within this range and can be descend immediately in case of
emergency, and can be operated independent of a second party.

4. 4
Chapter 2
2.1 Review of Related Literature
Man’s quest for improvement has never been satisfied. The drive towards better and greater
scientific and technological outcome has made the world dynamic. Before now, several scientist
and engineers have done a lot of work as regards the scissors lift in general. A review of some of
that work gives the design and construction of a hydraulic scissors lift a platform.
2.2 Upright Scissors Lift
In Selma California, there is a manufacturer of aerial platforms by name “UPRIGHT”, this world
– wide company was founded in 1946, and now it manufactures and distributes its product.
According to Wikipedia article, upright was founded by an engineer, Walkce Johnson who
created and sold the first platform which was called a “scissors lift” due to the steel cross
bricking that supported the platform giving it the product name “magic carpet”. The magic carpet
was able to provide instant revenue for the young company due to its quick popularity among its
companies.
Wikipedia further explained that the company constructed innovating and by early 1930s their
product included the X – series scissors lift. By 1986, they had introduced their first sigma arm
lift, model SL20. In 1990, they improved upon their product line by introducing the sigma arm
speed level. This feature continued to be unique to be upright product and allow self-leveling of
the platform on rough terrains
Upright introduced an equal innovative family of boom lift in 1990s. In 1995 they produced their
first trailer mounted boom. The 8P37 (known as AS38) in 1996. This truly innovated company
has left their mark with the other products including compact scissors design and modular alloy
bridging, as well as expanding the versatility of instant span towers with aircraft docking and
faced system, you will find upright products, especially the scissors lift, as standard equipment
for a variety of application it is now a visual application in numerous fields and locations.
2.4 Mechanical Scissors Lift: The mechanical scissors lift is used for lifting materials especially
on construction sites. This is one of the most recent advancement on scissors lift. There, the lift

5. 5
utilizes a belt drive system connected to a load screw which constructs the “X” pattern on
tightening and expands it on loosening. The lead screw actually does the work, since the applied
force from the wheel is converted to linear motion of the lift by help of the lead screw. This can
be used to lift the working and equipment to a height.
A general knowledge however, regarding screws will reveal the loss due to friction in the screw
threats. Therefore, the efficiency of this device is low due to losses in friction. Also, the power
needed to drive the machine is manual, and much energy is expanded to achieve a desired result.
Its suitability however, cannot be overemphasized as it can be used in almost every part of the
country whether there is availability of electricity or not.
2.5 Pneumatic Scissors Lift
Scissors lifts has developed overtime and at each stage of its development, critical problems are
solved.
The Pneumatic type, but this time, the load screw is replaced by a Pneumatic Actuator by a
double acting cylinder and on air compressor. One outstanding feature about this design
however. It is independent operation and increased efficiency. Fluid power is one of the greater
forms of power where small input results in a very large output. This scissors lift can be handled
by one person to a place of use. The lift does not lifting immediately, the operator’s climbs on
the platform and switches open the solenoid valve thereby leading to an upward extension. When
the required height is reached the circuit is closed, and lifting stops the control panel or station is
located on the top frame. When work is done, the scissors lift is folded by pneumatic means and
handled back to the point of collection.
2.6 Principle of Operation of Pneumatic Lift
Extension and contraction: A scissors lift is a type of platform that can usually only move
vertically. The mechanism to achieve this is the use of linked, folding supports in a criss-cross
“X” pattern, known as a scissors mechanism. The upward motion is achieved by the application
of pressure to the outer side of the lowest set of supports, elongating the crossing pattern and
propelling the work platform vertically. The platform may also have extending “bridge” to allow
closer access to the work area, because of the inherent limits of vertical – only movement. The

6. 6
contraction of the scissor action can be hydraulic, pneumatic or mechanical (via a lead screw or
rack and pinion system), but in this case, it is hydraulic. Depending on the power system
employed on the lift; it may require no power to enter “desert” mode, but rather a simple release
of hydraulic or pneumatic pressure. This is the main reason that these methods of powering the
lift is preferred, as it allows a fail – safe option of returning the platform to the ground by release
of a manual valve.

7. 7
Chapter 3
3.1 Material selection and Properties
Material selection plays a very important role in machine design. For example, the cost of
materials in any machine is a good determinant of the cost of the machine. More than the cost is
the fact that materials are always a very decisive factor for a good design. The choice of the
particular material for the machine depends on the particular purpose and the material for the
machine depends on the particular purpose and the mode of operation of the machine
components. Also, it depends on the expected mode of failure of the components.
Engineering materials are mainly classified as:
1. Metal and their alloys, such as iron, steel, copper, aluminum etc.
2. Non-metals such as glass, rubber, plastic etc. metals are further classified as ferrous
metals and non-ferrous metals.
Ferrous metals are those metals which have iron as their main constituent, such as cast iron,
wrought iron and steels.
Non-ferrous metals are those which have a metal other than iron as their main constituent, such
as copper, aluminum, brass, tin, zinc etc.
For the purpose of this project, based on the particular working conditions machine component
were designed for only the ferrous metals have been considered.
Also, certain mechanical properties of metals have greatly influenced our decisions.
These properties include:
Strength: it is the ability of a material to resist the externally applied force without break down
or yielding the internal resistance offered without break down or yielding the internally applied
force is called stress.
Stiffness: it is the ability of a material to resist deformation under stress. Elasticity: it is the
property of a material to regain its original shape after deformation when the external forces are
removed.

8. 8
Plasticity: it is property of a material which retains the deformation produced under load,
permanently.
Ductility: a very important property of the material enabling it to be drawn into wire with the
application of a tensile force. A ductile material is both strong and plastic. Ductile materials
commonly used in engineering practical (in order of diminishing ductility) are mold steel,
copper, aluminum, nickel, zinc tin and lead.
Malleability: it is a special case of ductility which permits materials to be rolled or hammered
into thin sheets. A malleable material is plastic but not 80 essentially strong. Examples include;
lead soft steel, wrought iron, wrought iron, copper and aluminum in order of diminishing
malleability.
Toughness: it is the property of a material to resist fracture due to high impact loads like
hammer blows, when heated. This property decreases.
Brittleness: it is the properties of a material opposite to ductility, it is the property of breaking of
a material with little permanent deformation when subjected to tensile load, brittle materials snap
off without giving any sensible elongation. Cast iron is a brittle material.
Hardness it embraces difference properties such as resistance to water, scratching, deformation
and machinability etc. it also measure of the ability of a metal to cut another metal.
3.2 Analysis of mechanical property requirement of essential machine components
It is necessary to evaluate the particular type of forces imposed on components with a view to
determining the exact mechanical properties and necessary material for each equipment. A very
brief analysis of each component follows thus:
1. Scissors arms
2. Pneumatic cylinder
3. Top plat form
4. Base plat form

9. 9
5. Wheels
Scissors Arms: this component is subjected to buckling load and bending load tending to break
or cause bending of the components. Hence it’s based on strength, stiffness, plasticity and
hardness. A recommended material is stainless steel.
Pneumatic Cylinder: This component is considered as a strut with both ends pinned. It is
subjected to direct compressive force which imposes a bending stress which may cause buckling
of the component. It is also subjected to internal compressive pressure which generates
circumferential and longitudinal stresses all around the wall thickness. Hence necessary material
property must include strength, ductility, toughness and hardness. The recommended material is
mild steel.
Top Platform: this component is subjected to the weight of the workman and his equipment,
hence strength is required, the frame of the plat form is mild steel and the base is wood.
Base Platform: this component is subjected to the weight of the top plat form and the scissors
arms. It is also responsible for the stability of the whole assembly, therefore strength. Hardness
and stiffness are needed mechanical properties. Mild steel is used.
Wheels: the wheels are position at the base part of the scissors lift and enable the lift to move
from one place to the other without necessary employment of external equipment like car.
3.3 Choice of stainless steel and mild steel
Stainless Steel: these are steel with high rust and corrosion resistance to meet specific
application requirements. They also have high strength and toughness.
It is an alloy of iron with about 11% chromium and other metals like nickel, molybdenum etc.
the properties of rust and corrosion resistance, toughness and strength, aesthetics and how
coefficient of friction were considered to meet all requirements and the choice of stainless steel
for the scissors members.
Mild Steel contains 0.05 to 0.3 percent carbons it has for almost all purpose replaced wrought
iron, its greater strength giving it under viable advantages. Mild steel can be rolled, wielded and
down. It can even be cast, though not very successfully. Among its application are plates for ship

10. 10
building, bicycle frame tubes, mesh work, bolts, nuts, studs etc. solid and hollow constructional
sections, sheet metal parts and steel castings such as flywheels and locomotive wheel centers.

11. 11
Chapter 4
4.1 Design Theory and Calculation
In this section all design concepts developed are discussed and based on evaluation criteria and
process developed, and a final here modified to further enhance the functionality of the design.
Considerations made during the design and fabrication of a acting cylinder is as follows:
a. Functionality of the design
b. Manufacturability Economic availability. I.e. General cost of materials and fabrication
techniques employed.
4.2 Design Theory
In this theory, mathematical relationships are developed for the various parameters necessary for
the implementation of this design and arranged in sections below corresponding to the sequence
of their implementation.
Most lifting devices are powered by either electricity, pneumatic or mechanical means. Although
these methods are efficient and satisfactory, they exists lot of limitations and complexity of
design of such lifts as well as high cost of electricity, maintenance and repairs does not allow
these lifts to exist in common places.
4.3 Cylinder Selection
The hydraulic cylinder (or the hydraulic actuator) is a mechanical actuator that is used to give a
unidirectional stroke. It has many applications, notably in engineering.
4.3.1 Single Acting Cylinders
Single acting cylinders use hydraulic oil for a power stroke in one direction only. The return
stroke is affected by a mechanical in one direction only. The return stroke is affected by a
mechanical spring located inside the cylinder. For single acting cylinders with no spring, some
external acting force on the piston rod causes its return.

12. 12
Fig: Single acting cylinder
4.3.2 Double Acting Cylinders
Double acting cylinder uses compressed air or hydraulic fluid to pour both the forward and
return strokes. This makes them ideal for bushing and pulling and pulling within the same
application they are suitable for full stroke working only at slow speed which results in gentle
contact at the ends of stroke.
Fig: Double acting cylinder
Pressure supplied to the pneumatic cylinder:
Design of scissor lifter with force applied from the side
𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 ( 𝑃) =
𝐹𝑜𝑟𝑐𝑒 (𝐹)
𝐴𝑟𝑒𝑎 (𝐴)
Where
𝐹 =
𝑊 + 𝑊𝑓
2 tan 𝜃
𝜃 = Angle between the scissors and the horizontal

13. 13
F = Force needed to hold the scissors lift
W = the weight of the payload and platform
𝑊𝑓 = combine weight of the two scissors arms and frames
Weight of the arm = mass of the scissors arm × acceleration due to gravity.
Fig: Pneumatics cylinder pressure force
Forces Equilibrium equations,
∑ 𝐹𝑦 = 0
𝑃 sin 𝜃 = (𝑊 +
𝑊𝑓
2
)
Here 𝑃 =
𝑊+𝑊 𝑓
2 sin 𝜃
……… (1)
Where 𝑊𝑓= Total frame weight
Now from the Figure ∑ 𝐹𝑥 = 0
𝐹 = 𝑃 cos 𝜃…………………. (2)
Now equation (1) put in equation (2),
𝐹 =
𝑊+𝑊 𝑓
2 sin 𝜃
∗ cos 𝜃

14. 14
=
𝑊+𝑊 𝑓
2 sin 𝜃∗
1
cos 𝜃
𝐹 =
𝑊+𝑊 𝑓(𝑇𝑜𝑡𝑎𝑙 𝑤𝑒𝑖𝑔ℎ𝑡)
2 tan 𝜃
…… (3)
𝐹 =
𝑊𝑡(𝑇𝑜𝑡𝑎𝑙 𝑤𝑒𝑖𝑔ℎ𝑡)
2 tan 𝜃
This is the final equation of cylinder to how much force is required
Note:
In the equation (3), Total weight (𝑊𝑡) = Mass be put on lift+ Mass of top and base frame+ Mass
of each frame.
For a Scissor lifter force required to lift the load is depend on
 Angle of link with horizontal
 Mounting of cylinder on the links
4.4. Design equations for scissor lifter:
For a scissor lifter that has straight, equal-length arms, i.e. the distance from the horizontal
hydraulic-arm-attachment point to the scissor-joints is the same as the distance from that scissor-
joint to the top load platform attachment.

15. 15
Free body diagram of scissor lifter:
Fig (1) Fig (2)
Statics equations for scissor lifter:
From figure (1)
We take counter clock wise is a positive moment, Moment about the point B
From A point
∑ 𝑀 𝐵(↑ +) = 0
−
𝑊
2
× 2𝐿 × cos 𝜃 + 𝐹𝑦 × 𝐿 cos 𝜃 + 𝐹𝑥 × 𝐿 × sin 𝜃 = 0 ………….. (1)
From point E
∑ 𝐹𝑥(→ +) = 0
𝐹𝑥 − 𝑅 𝑥1
= 0 ……………………. (2)
From point B

16. 16
∑ 𝐹𝑦(↑ +) = 0
−
𝑊
2
+ 𝐹𝑦 − 𝑅 𝑦1
= 0 ……………… (3)
From the figure (2)
The point D
∑ 𝑀 𝐶(↑ +) = 0
−
𝑊
2
× 2𝐿 × cos 𝜃 − 𝐹𝑦 × 𝐿 cos 𝜃 + 𝐹𝑥 × 𝐿 × sin 𝜃 = 0 ……………………….. (4)
Point E
∑ 𝐹𝑥(→ +) = 0
−𝐹𝑥 + 𝑅 𝑥2
= 0 ………………………. (5)
Point C
∑ 𝐹𝑦(↑ +) = 0
−
𝑊
2
− 𝐹𝑦 + 𝑅 𝑦2
= 0 ………………………… (6)
Here,
Six equations (1), (2), (3), (4), (5) and (6), these are unknown equations. We know all forces sum
is equal to zero, so we can now equilibrium all these equations.
Point A at a center load,
𝐹𝑦 × 𝐿 cos 𝜃 = 𝐹𝑥 × 𝐿 × sin 𝜃 ×
𝑊
2
× 2𝐿 × cos 𝜃
𝐹𝑦 × 𝐿 cos 𝜃 = 𝐹𝑥 × 𝐿 × sin 𝜃 − 𝑊 × 𝐿 × cos 𝜃
𝐹𝑦 =
𝐹𝑥×𝐿×sin 𝜃−𝑊×𝐿×cos 𝜃
𝐿×cos 𝜃
𝐹𝑦 =
𝐹𝑥×sin 𝜃−𝑊×cos 𝜃
cos 𝜃

17. 17
𝐹𝑦 = 𝐹𝑥 tan 𝜃 − 𝑊 ……………………………… (a)
Point D,
−
𝑊
2
× 2𝐿 × cos 𝜃 − 𝐹𝑦 × 𝐿 cos 𝜃 + 𝐹𝑥 × 𝐿 × sin 𝜃 = 0
𝐹𝑥 =
𝑊
tan 𝜃
−
𝐹𝑦
tan 𝜃
……………………………… (b)
Now equation (a) and (b) is substitution,
𝐹𝑥 =
𝑊
tan 𝜃
−
𝐹𝑥 𝑡𝑎𝑛 𝜃−𝑊
tan 𝜃
𝐹𝑥 =
𝑊
tan 𝜃
+
𝑊
tan 𝜃
+ 𝐹𝑥
𝐹𝑥 =
2𝑊
tan 𝜃
+ 𝐹𝑥 …………………………………… (c)
Equation (c) means; horizontal load by the actuator, which moves horizontally forward and
backward. So equation (c) we can. .. (in center load)
𝐹𝑥 =
𝑊
tan 𝜃
Now,
If −𝑅 𝑥1
+ 𝐹𝑦 = 0 (point E)
And 𝑅 𝑥1
= 𝐹𝑥 (point B)
Again,
𝑅 𝑥2
+ 𝐹𝑥 = 0 (Point E)
And 𝑅 𝑥2
= 𝐹𝑥
So the equation is,
𝐹𝑥 =𝑅 𝑥1
= 𝑅 𝑥2
=
𝑊
tan 𝜃
Now again,

18. 18
Point A,
𝐹𝑦 = 𝐹𝑥 tan 𝜃 − 𝑊
Point D,
𝐹𝑥 =
𝑊
tan 𝜃
−
𝐹𝑦
tan 𝜃
Find
𝐹𝑦 = −𝑊 + (
𝑊
tan 𝜃
−
𝐹𝑦
tan 𝜃
) × tan 𝜃
𝐹𝑦 = −𝐹𝑦
𝐹𝑦 = 0
For calculating upward directions
Point E, −
𝑊
2
− 𝐹𝑦 + 𝑅 𝑦2
= 0
𝑊
2
= 𝑅 𝑦2
Point C, −
𝑊
2
+ 𝐹𝑦 − 𝑅 𝑦1
= 0
𝑊
2
= 𝑅 𝑦1
In conclusion
𝑅 𝑥1
= 𝑅 𝑥2
=
𝑊
tan 𝜃
, 𝐹𝑥 =
𝑊
tan 𝜃
𝑅 𝑦1
= 𝑅 𝑦2
=
𝑊
2
𝐹𝑦 = 0
For a scissor lifter, that has straight; equal length arms i.e. the distance from the horizontal ram
attachment point to the scissor joint is the same as the distance from that scissor joints to the load
platform attachment.

19. 19
4.5 Dimensions of scissor lifter
Lift Extension
- At maximum extension, an “X” arrangement of the lift moves 0.3 m = 300 mm.
- Total number of tiers of scissors (combined) =
- Thus, total height of extension = 2 × 0.3 = .6 m.
- Length of base = 1400mm
- Width of base = 800mm
- Height of base from ground = 500mm
- At maximum extension, Angle of inclination = 40
Bearings (Two small to lower base and Two Large to upper base)
- Number of ball bearings = 4
- Internal diameter of small bearings = 30mm
- External diameter of small bearings = 50mm
- Internal diameter of large bearings = 30mm
- External diameter of large bearings = 15mm
- Pivot pin diameter = 28 mm
(Connected to the bearing in the arms)
Platform
- Total height of platform = 1400mm.
- Total height of platform = 800mm
- Permissible load on plat form + platform weight = 10+10 (kg) = 20 kg

20. 20
Jointed Members
- Thickness of rectangular pipe = 2mm
- Thickness of angle bar = 3mm.
Scissors Arm
The material used for the scissors arms (members), is stainless steel(we used iron).
With the density and the dimensions of the scissors arms known, the mass can be
calculated using the relationship.
Density (p) = Mass (M)/Volume (V), kg cube m
Mass = p.v
Density of stainless steel = 7900kg/m3
(Iron density = 7874 kg/m-cube)
Area (cross sectional area) = A1 – A2
A1 = Outer cross sectional area arm
A2 = Inner cross sectional area arm
A1 = Height × breadth = h × b
A2 = (h – t)(b – t)
Where h = scissors arm height
b = breadth
t = thickness of material.
Volume (v) = area × length
V = AL (m3
)

21. 21
Chapter 5
5.1 Construction Operation and Tools uses
In the design and construction of the Pneumatic scissors lift, the procedures followed to achieve
a positive result are laid down in the preceding text. But first, a look at the operations and tools
involved.
Operations
1. Marking out
2. Cutting
3. Drilling
4. Joining (welding and bolt and nut)
Tools
1. Engineers rule
2. Scriber
3. Hack saw
4. Hand file
5. Drilling machine
6. Welding machine
7. Pliers
8. spanner
9. Try square
10. Electric grinder

22. 22
5.2 Methodology of pneumatic scissor lifter
Base Platform
The material used for this purpose is Mild steel angle bar. (3×3 inch) thickness 3mm. this used
because the base frame is responsible for the stability of the platform. The basic dimensions were
marked out using on Eng.’s rule and scriber and then cut with the use of hack saw after being
welded firmly clamped to the vice. They are then joined together by welding to give the base
frame.
Scissors Arms
These include the members that are arranged in a cross-cross ‘X’ pattern and whose construction
is responsible for lifting the platform and extension and lowering of the platform. It is usually
made up of pipes with rectangular cross-section and high resistance to bending. The material is
stainless steel for corrosion and rust resistance to give high strength.
After marking out, they were cut to the required sizes holes of appropriate diameter were drilled
at both ends and the middle of each member. Hollow pins of external diameter corresponding to
the drilled holes we then fit into holes and welded in order to strengthen the position then joined
together to give the “X” pattern using bolts and nuts. The scissors arms were brazed to increase
the strength and bending resistance.

23. 23
Top Platform
The material used for the construction of this component is mild steel angle bar for the frame and
timber for the base of the platform. The angle bar is cut into the required sizes and welded to
form a rigid platform. The timber was equally into the required dimensions, drilled at the edges
and fastened using bolt and nut to secure it in position at the base of the platform.
Solenoid valve
A solenoid valve is an electromechanical controlled valve. The valve features a solenoid, which
is an electric coil with a movable ferromagnetic core in its Centre. This core is called the
plunger. In rest position, the plunger closes off a small orifice. Ah electric current through the
coil creates a magnetic field. The magnetic field exerts a force on the plunger. As result the
plunger is pulled toward the Centre of the coil so that the orifice opens. This is the basic
principle that is used to open and close solenoid valves. “A solenoid valve is an
electromechanical actuated valve to control the flow of liquids and gases.”
This valve model is 4V210-08
And pressure capacity is .15-.8 MPa

24. 24
Circuit Function of solenoid valve:
Solenoids valves are used to close, dose, distribute or mix the flow of gas or liquid in a pipe. The
specific purpose of a solenoid valve is expressed by its circuit function. A 2/2 way valve has two
ports (inlet and outlet) and two positions (open and closed). A 2/2 way valve can be normally
closed or normally open. A 3/2 way valve has three ports and two positions and can therefore
switch between two circuits. 3/2 way valve can be have different functions such as normally
closed, normally open, diverting or universal. More ports or combinations of valve in a single
construction are possible. The circuit function of a valve is symbolized in two rectangular boxes
for the de-energized state (right side) and energized state (left side). The arrows in the box show
the flow direction between the valve ports. The examples show a 2/2 way Normally open (NO)
valve, a 2/2 way Normally closed (NC) valve and a 3/2 way Normally Closed valve.
Double acting cylinder
Double acting cylinder uses compressed air or hydraulic fluid to pour both the forward and
return strokes. This makes them ideal for pushing and pulling and pulling within the same
application they are suitable for full stroke working only at slow speed which results in gentle
contact at the ends of stroke. In this cylinder have two ports, one port uses as an inlet and other
port as an outlet. Show in figure. This cylinder stroke length is 250 mm and bore is 25 mm.

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Air Compressor
An air compressor is a device that converts power into potential energy stored in pressurized air(
i.e. compressed air). By one of several methods, an air compressor forces more and more air into
a storage tank increasing the pressure. When the tank pressure reaches its upper limit the air
compressor shuts off. The compressed air, then is held in the tank until called into use. The
energy contained in the compressed air can be used for a variety of applications, utilizing the
kinetic energy of the air as it is released and the tank depressurizes. When tank pressure reaches
its lower limit, the air compressor turns on again and re-pressurizes the tank.
In this project we use the Low-pressure air compressors (LPACs), which have a discharge
pressure of 150 psi or less. This type of air compressor has rotary screw compressor.
A Rotary-screw compressor is a type of gas compressor that uses a rotary-type positive
displacement mechanism. They are commonly used to replace piston compressors where large
volumes of high-pressure air are needed, either for large industrial applications or to operate
high-power air tools such as jackhammers. The gas compression process of a rotary screw is a
continuous sweeping motion, so there is very little pulsation or surging of flow, as occurs with
piston compressors and those types of compressor uses in automobile air compression. The
compressor has 12v and 15 A current needed.

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5.3 MODEL AND DESIGN OF COMPONENTS
 Designing the lower and top base
Top base length is 54 inch, breath is 34 inch, and height is 1.2 inch. Top base and lower base has
same measurements.
 Scissor Arms
Scissor arm is made by the iron which has rectangular hollow bar. Its dimensions show in below.
Actually we don’t find mild steel that reason we made this arm by the iron bar. Scissor arms
have three holes, and its diameter 30mm, length of the arms 54in, height is 54mm, thickness is 5,
Holes diameter is 30 mm. All eight arms have similar measurements, only different holes size.

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 Double acting Cylinders
Bore is 25 mm and stroke length is 250 mm.
5.4 ASSEMBLY THE COMPONENTS OF PNEUMATIC SCISSOR LIFTER
The scissors assemblage was mounted on the base frame with one end hinged and the other fitted
with roller (bearing) to produce the needed motion of rolling along the rail to cause lifting and
lowering of the scissors lift.
The scissors arm connected to the platform is also connected with one end hinged and the other
fitted with roller to effect extension and contraction of the lit. The hydraulic cylinder is
connected to the first arm of the scissors lift with both ends hinged. This cylinder provides the
force needed to lift the load on the platform.
The force is as a result of the pressure of the hydraulic supplied to the cylinder by the pump from
the reservoir. The lift is fitted with wheels to aid mobility from one location to another.
Painting of the entire unit is done to improve it aesthetics and increase the corrosion and
resistance to rust.

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Fig: Practical view
Fig: Model designing

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5.5 Ideal Cost Analysis of Materials
No. of
Items
Material description Quantity Required Unit Cost Final Cost
1 Rectangular hollow frame 8 50 400
2 Angle bar 8 (4 small and 4
large)
60 560
3 Ball bearing 4 130 520
4 Silver pipe and solid 1 kg 430 430
5 Solenoid valve 1 480 480
6 Pneumatic cylinder 1 355 355
7 Air compressor 1 1260 1160
8 AC to DC converter 1 760 760
9 Others 2500
Total 7165

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6. Conclusion
The design and fabrication of a portable work platform elevated by a pneumatic cylinder was
carried out meeting the required design standards. The portable work platform is operated by
hydraulic cylinder which is operated by a motor. The scissor lift can be design for high load also
if a suitable high capacity hydraulic cylinder is used. The Pneumatic scissor lift is simple in use
and does not require routine maintenance. It can also lift heavier loads. The main constraint of
this device is its high initial cost, but has a low operating cost. The shearing tool should be heat
treated to have high strength. Savings resulting from the use of this device will make it pay for
itself with in short period of time and it can be a great companion in any engineering industry
dealing with rusted and unused metals.

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7. Recommendation
This device affords plenty of scope for modifications for further improvements and operational
efficiency, which should make it commercially available and attractive. Hence, its wide
application in industries, hydraulic pressure system, for lifting of vehicle in garages, maintenance
of huge machines, and for staking purpose. Thus, it is recommended for the engineering industry
and for commercial production.

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8. Reference
GUPTA S.C (2006). Fluid mechanics and hydraulic machines.
Pearson Education India, 2006. P.p 1296
RAJPUT R.K (2010). Strength of materials (mechanics of solids).
S.Chand and Company LTD; 2010. P.p (928-941, 2-3, 590-592, 264-265).
HENRY W. SASLACH JR. and ROWLAND W. ARMSTRONG (2005). Deformatble bodies
and their material behaviour.
John Wiley and Sons inc. P.p (105-212).
KHURMI R.S and GUPTA J.K (2006). Machine design. Fourteenth edition.
P.p (40-45).