Dissertation Hardcopy (My Version)

University of Brighton
Formula Student
Final Year Project
Christopher Blackman
XE 337
Supervised by:
Dr Nicolas Miché, Dr Steven Begg and Dr Khizer Saeed
20/04/2015
Final year report submitted in partial fulfilment of the requirements for
the degree of Bsc Honours in Mechanical & Manufacturing Engineering (Top-up)

Final Year Project XE337 Christopher Blackman
2
Disclaimer
I hereby certify that the attached report is my own work except where otherwise indicated.
I have identified my sources of information; in particular I have put in quotation marks any
passages that have been quoted word-for-word, and identified their origins.
Print CHRISTOPHER BLACKMAN
Signed Christopher Blackman
Date 20th
April 2015

3
Electronic copy of dissertation
Please find included an electronic copy of this Final Year Formula Student Project dissertation.

4
Abstract
The findings of this report conclude that from the research and evaluation of existing Final Drive
systems, employed by the teams that currently enter the Formula Student Event an effective Final
Drive system in the form of a chain and sprocket set up has been derived. Through further critical
evaluations and designs in compliance with the technical regulations laid out by the Institute of
Mechanical Engineers (IMECHE). Along with requirements of other areas such as the gear ratios
and the differential which directly relate to the Final Drive package.
The findings also further concluded that the design can either be manufactured internally or provide
an option for the parts to be manufactured outside of the university. The conclusions also state that
the final designs may be subject to minor alterations for positioning purposes when the assembly
stages take place.

5
Contents
Disclaimer Page 2
Electronic copy of dissertation Page 3
Abstract Page 4
Introduction Page 7
Project Management
1.1 Overall project management Page 8
1.2 Individual project management Page 10
Research
1.3 Formula Student Technical Regulations 2015 - 2016 Page 12
1.4 Initial research Page 14
1.5 Evaluation from 2014 Formula Student entries Page 17
1.6 Single 520 Chain Page 18
1.7 Spur Gear Page 19
1.8 Helical Gear Page 20
1.9 Final Drive decision matrix Page 21
Research Conclusions Page 24
Design
1.10 Initial design ideas Page 26
1.11 Design ideas decision matrix Page 27
1.12 Information from other team members Page 29
1.13 Design calculations Page 30
1.14 Final design Page 32
1.15 Shatter Guard design Page 33

6
Conclusion Page 34
Appendices Page 35
Bibliography Page 49

7
Introduction
The information documented in this report is based upon the Formula Student race car event
conducted by the Institute of Mechanical Engineers (IMECHE), looking at the Final Drive section
of the car.
Objectives:
Due to the size of this project the tasks were divided into seven different work packages. The area
that I was assigned to was the drivetrain package with the responsibility of the development of the
Final Drive system. So my individual objective is as follows:
 Individual objective is to: Evaluate, develop and if possible produce an effective and
efficient Final Drive system that will be combined with other components to produce a
complete, effective drivetrain package which will be used on the university’s Formula
Student Car.
Limitations:
The limitations that I have encountered on this project are that the designs are constrained by the
Formula Student Technical Regulations 2015 – 2016.
Other limitations have been through the process of how my design will operate in relation to the
other components that it will be assembled to or work in conjunction with.
Document Summary:
This document covers the initial research into the Final Drive system. By evaluating the systems
used by the current entries, taking the recommendations of the research, to develop initial designs
and further evaluate the final design that will be taken forward to the manufacturing and assembly
stages of the project.

8
Project Management
1.1 Overall project management
Throughout the duration of this project the management schedule was controlled by the use
of Gantt charts and a weekly progress log.
The initial Gantt chart that was included in the project proposal (Appendix A) for our work
package was only used as a reference point for our group. Upon feedback for improvements
of our Gantt chart we informed the supervisors that we were in the process of deriving
individual Gantt charts tailored to our individual tasks and requirements for this project.
Individual Project Gantt charts can be found in the appendices, Appendix A - D.
The use of the progress log was split into two sections. These two sections consisted of a
work packages feedback session and an individual feedback session with the assigned
project supervisors.
The whole team session consisted of all seven work packages involved in the project with a
different team member being nominated as the team’s project lead. The leads were
responsible for the feedback of their group’s progress to the other project teams each week,
by highlighting their current progress and where their team will be heading in the future.
The responsibility involved in the progress log was to ensure that the documentation was up
to date. This was then fed back to the other members on the project and questions that arose
either from the supervisor or the other work packages were answered.
As stated, the project lead rotated at every weekly review session and it was my
responsibility to be project lead on five occasions throughout the duration this project.
During this session after all feedback has been given, the opportunity arose to communicate
with the other teams freely to either obtain a better understanding of their progress for
personal knowledge, or to obtain information which would be relevant to their particular
part of the project.

9
The session was also the opportunity to speak with our assigned supervisor, Dr Khizer
Saeed, about our current progress and problems that we may have encountered. This
meeting also highlighted the tasks that our supervisor wished to see the following week to
keep the project focused and on track with our completion deadlines.

10
1.2 Individual project management
Individual project management was monitored through a specifically derived Gantt chart
for my section of the drivetrain work package. This Gantt chart was accessible for my
fellow team members to review throughout the project.
This not only outlined my own objectives for the project, but it also combined the tasks
which had to be completed as a team, such as the progress review presentation and the
poster display.
Throughout this project my Gantt chart undertook amendments on numerous occasions.
These amendments included factoring in additional tasks as the project progressed and the
alteration to the existing tasks to ensure continual progression. Any extra available time
was to be factored in on tasks that could be considered a problem and delay the progress of
the project. These amendments can be seen in the appendices (Appendix B - D).
During the project, one task was highlighted as a concern as it was started a week later than
the Gantt chart allowed. The task in question was the initial development of conceptual
designs. This issue was recorded onto our progress log and my Gantt chart was amended
accordingly. The setback for this task was a direct result of the accessibility to the
computers on which the relevant Computer Aided Design software "Solidworks" was
installed. Once access was gained to the computers this issue was resolved and did not
develop into a further problem causing delay to the remainder of the project.
The change in the Gantt chart for this task can be found in the appendices (Appendix B -
C).
Improvements to the project management:
An area for improvement would be the communication within our own team. Although we
delivered the group tasks and produced our individual projects, combining them to make an
effective drivetrain system for the Formula Student project, there were times that the
communication lapsed.

11
The areas where this lapsed were in the preparation of tasks such as the poster and
presentation reviews. Another area was in obtaining the required information, giving the
other members sufficient time to collate the information so that they could pass it on, rather
than having to rush to prevent the team’s objective from falling behind.
Others areas for improvement come down to effective time planning as there were minor
delays in obtaining information from other work packages. This impacted on the progress
for the design of the differential which in turn delayed my progress for the Final Drive.
The area where this impacted most was on the completion of my final design. Whilst
waiting for the other work packages to be completed, I made design assumptions which
were amended where necessary.
One area on the project management that worked well was the use of the progress log. This
had to be reported to the supervisors with other work packages involved in the project, as
this helped to keep the project focused and on track to achieve our own objectives. This log
also helped to bring the different work packages together so there was more involvement
across the whole project and not just in certain areas.
Minor monitoring improvements could have been made to our work packages to ensure that
the logs were completed and up to date as we approached the end of the project.

12
Research
1.3 Formula Student Technical Regulations 2015 - 2016 [1]
(Part T General Technical Requirements, Article 8 - Transmission and Drive)
The most important stage that had to be addressed in this type of project were the regulations that
had to be complied with in order to produce an effective and competitive car.
By using the supplied reference document on the Formula Student Technical Regulations 2015-
2016, I conducted a search of the regulations to determine those that had the most relevance to the
Final Drive system.
This search leads me to Article 8 Transmission and Drive
The points from this section of the regulations are listed below, they detail what parameters must be
adhered to when the design and manufacturing stages take place.
 T8.3 Transmission and Drive - Any transmission and drivetrain may be used.
 T8.4 Drive Train Shields and Guards T8.4.1 Exposed high-speed Final Drivetrain
equipment such as Continuously Variable Transmissions (CVTs), sprockets, gears,
pulleys, torque converters, clutches, belt drives, clutch drives and electric motors,
must be fitted with scatter shields in case of failure. The Final Drivetrain shield must
cover the chain or belt from the drive sprocket to the driven sprocket/chain
wheel/belt or pulley. The Final Drivetrain shield must start and end parallel to the
lowest point of the chain wheel/belt/pulley. (See figure below) Body panels or other
existing covers are not acceptable unless constructed from approved materials per
T8.4.3 or T8.4.4.
 NOTE: If equipped, the engine drive sprocket cover may be used as part of the scatter
shield system.
 Comment: Scatter shields are intended to contain drivetrain parts which might separate from
the car.
 T8.4.2 Perforated material may not be used for the construction of scatter shields.

13
 T8.4.3 Chain Drive - Scatter shields for chains must be made of at least 2.66 mm (0.105
inch) steel (no alternatives are allowed), and have a minimum width equal to three
(3) times the width of the chain..The guard must be centred on the centre line of the
chain and remain aligned with the chain under all conditions.
 T8.4.4 Non-metallic Belt Drive - Scatter shields for belts must be made from at least 3.0 mm
(0.120 inch) Aluminium Alloy 6061-T6, and have a minimum width that is equal to
1.7 times the width of the belt. The guard must be centred on the centre line of the
belt and remain aligned with the belt under all conditions.
 T8.4.5 Attachment Fasteners - All fasteners attaching scatter shields and guards must be a
minimum 6mm Metric Grade 8.8 (1/4 inch SAE Grade 5) or stronger.
 T8.4.6 Finger Guards – Finger guards are required to cover any drivetrain parts that spin
while the car is stationary with the engine running. Finger guards may be made of
lighter material, sufficient to resist finger forces. Mesh or perforated material may
be used but must prevent the passage of a 12 mm (1/2 inch) diameter object through
the guard.
 Comment: Finger guards are intended to prevent finger intrusion into rotating equipment while
the vehicle is at rest
This image was included in the regulations to illustrate how the shatter guard must cover the
sprockets on the system and what reference points it is taken from.

14
1.4 Initial research
The initial stage of this project's research, after the focus on the Formula Student technical
regulations, was to investigate what the Final Drive system is. This was done to obtain a sufficient
understanding of this area and enable an effective delivery of the system for its required purpose.
The following statements were found when researching into the Final Drive system which looks at
the general overview and the types of drive that exist:
 Straight Axel Drive
 Pinion Gear Drive
 Planetary Gear Drive
General overview of Final Drive system:
Power is transferred from the differential to the final work point. This power is passed through the
Final Drive.
On wheeled machines the Final Drive provides the final reduction in speed and increases the torque
used to drive the wheels. The location of the Final Drive can be found mounted near the rear driving
wheels on most machines.
With machines that have no driving wheels the Final Drive system carries the power through to
tiller tines by means of reducing the speed along with reducing the stress in the transmission and
other power-train components.

15
Straight Axel Drive Systems
The Straight Axel Drive contains a rigid shaft connected to the differential by splines and supported
on the other end by a tapered bearing or roller bearing. The drive wheels receive their power from
the differential. For each revolution of the differential the axel shaft and wheels make one
revolution.
If a machines final work point uses implements such as tines, blades or an auger instead of drive
wheels the shaft will connect directly to the implement. Straight Axel Drives are simple in
construction and relatively easy to maintain and repair.
[2]

16
Pinion Gear Drive systems
In Pinion Gear drive systems, the power is transferred to the drive wheels through pinion gears
connected directly to a differential.
The pinion gears then mesh to a larger Final Drive gear that drives the axel.
A pinion gear will be completely enclosed within a differential case.
[3]
Planetary Gear Drive
Planetary Gear Drive systems are more compact than the
Pinion Gear Drive system.
Planetary gear drives are very strong and durable because they
spread the applied load over several gears.
The power is then transmitted from the differential through a
final drive shaft to the sun gear.
As the sun gear turns it meshes with the planet pinion gears.
These are held in place by a planet pinion carrier which is
attached to the rear axle shaft. As the sun gear and planet pinions turn they turn the carrier and the
rear axle shaft.
[4]

17
1.5 Evaluation from 2014 Formula Student entries
In order to determine the best Final Drive mechanism an evaluation of the type of mechanism used
on previous Formula Student entries was necessary.
The Formula Student 2014 event programme, [5] which was sourced from the race car engineering
website, contained all the key information on the Class One and Class Two entries. This proved to
be helpful in determining the best design to carry forward.
The evaluation table of the different drive mechanisms can be found in the appendices (Appendix
E).
The results of the evaluation of the 123 overall entries split across the Class One and Class Two
divisions are as follows:
Overall Conclusions:
The overall conclusions from the evaluation table showed that from the 123 entries across both
divisions, seven of the entries used a combination of either chain and gear systems or used two
different types of gearing for the Final Drive.
The most common Final Drive system that was used throughout the teams in this event was that of
the Single 520 Chain. With the gearing systems that were used, the most common format was that
of a Spur Gear followed by the Planetary Gear system.
Class 1 Entries:
From the entries in this division, one team who used the Single 520 Chain for their Final Drive
combined this with the use of a Planetary Gear system. As for the gear systems used three teams
used a combination of the Spur Gear and the Planetary Gear.
Class 2 Entries:
One of the entries that used a Helical Gear combined this with the use of a Planetary Gear.

18
1.6 Single 520 Chain
Following the research evaluation of the different drive mechanisms used by the Formula Student
Entries in the 2014 event the most popular mechanism was the Single 520 Chain.
After conducting research into the Single 520 Chain, I found information on the Vortex 520 steel
sprocket chain kit. [6] So the design criteria for this product was used as a reference and is listed
below:
Vortex Front Sprocket 520: This is made from the highest quality steel and is case
hardened and on most applications has drilled
lightening holes.
Vortex Rear Steel Sprocket 520: The rear sprocket is laser cut from carbon steel with
the aim to provide extended chain wheel life over an
aluminium manufactured sprocket.
The rear sprocket is electroplated satin black to help
against corrosion resistance. The sprockets teeth are
hardened for increase durability and deeply cupped for
weight reduction. The application is both applicable
for street and race usage.
D.I.D 520 ZVMX Series X-Ring Gold Chain (100 Links):
This particular type of chain has increased rigidity which provides for a better power transfer and
greater resistance towards stretching under workloads. The design and overall improved
performance of the chain means that it meets the requirements for machines bigger than 1000cc.
The average tensile strength of this particular chain
in 8,745 Pounds. In relation to the product weight,
for every 100 links it weighs 3.59 pounds. The
master link is a rivet style design.
[7]

19
1.7 Spur Gear
Following the Single 520 Chain the more commonly used gear system was the Spur Gear. When
research was conducted into the Spur Gear the results were as follows:
From all the gearing systems the Spur Gear is the most common type that is used today. The gear is
mounted on parallel shafts and the gears themselves have straightened teeth. The teeth are
straightened because it allows for design simplicity and efficiency on low power and speed
applications.
In selected scenarios many of these gears will be used at any one time to create larger gear
reductions.
Due to the design simplicity of this gear it can be found in many applications such as washing
machines and electric screwdrivers but not many will be applied in cars.
The reason why this type of gear will rarely be found applied in cars is because the gear generates
too much noise when in operation. The increased noise level is a created every time the gear teeth
engage one another.
Alongside the noise level, the levels of stress applied though the gear teeth also increases, making
this design an inappropriate system to use in car applications.
A way to reduce the noise and stress levels within this gear system is to us a Helical Gear. The
Helical Gear system is commonly applied and located within cars.
[8]

20
1.8 Helical Gear
As mentioned on the previous page the Helical Gear is the type of gear system that will be
commonly found applied in car transmissions.
The reason why this preferred gearing system is used in cars is because of the reduced noise levels
and the difference in the way the stresses are applied to the gear.
The reason for the differences in the stress and noise levels compared against the Spur Gear is
because on the Helical Gear the teeth are design and manufactured at an angle, this helps when the
two gears engage each other as the initial point of contact is made at one end of the gear and then
gradually spread across the remainder until both of the teeth are fully engaged making an overall
smoother quieter operation. Unlike the Spur Gear in which full contact is made across the gear
immediately applying higher stress levels.
The angled teeth on this gear design create a thrust load when they mesh to each other. Any devices
that use the Helical Gear system contain bearings which are capable of supporting the applied thrust
load. Another key advantage to the gear’s teeth is that if the angle of the teeth is correct they can be
mounted onto perpendicular shafts adjusting their rotational angle by 90 degrees.
This gear can be found in applications where the requirements for the power and speed are higher to
allow for a smoother operation such as car gearboxes and machine tools.
[9]

21
1.9 Final Drive decision matrix
This decision matrix was used to evaluate the three popular Final Drive mechanisms that were
derived from the 2014 Formula Student entries (See page 40 and Appendix F respectively).
The three popular Final Drive mechanisms’ that are used in the matrix are:
1. Single 520 Chain
2. Spur Gear
3. Helical Gear
Detailed information on these three Final Drive designs can be found on pages 18 - 20.
The scoring for the decision matrix is based upon a one to five scale with the lowest overall score
being determined to be the most effective. The scoring criteria can be seen below:
1) Very Low: Designs that scored this are considered to be the best against the relevant
criteria
2) Low: This score is given to designs to which have potential to be the best but have
some factors making the design slightly complex.
3) Average: Designs that score this are considered to be neither the best nor
the worst, although in order to be the best modifications may be
required to the design on other surrounding parts.
4) High: This is scored on designs that are beginning to have an overall
effect towards the cars performance (Such as weight or the
complexity of their design).
5) Very High: This score reflects that the design against the relevant
criteria is to complex or has major implications towards the cars
performance and handling.

22
The criteria which was used in the decision matrix to determine the most effective Final Drive
system was based upon:
 Formula Student regulation requirements
 Design effecting the performance & handling of the car
The criteria listed below was used to evaluate the three Final Drive mechanisms against each other:
1) Design Simplicity: How easy is the manufacture and
assembly of the drive system.
2) Accessibility for Maintenance: Is the design easily accessible for
maintenance requirements.
3) Efficiency: How efficient is the drive mechanism.
4) Is the use of a Shatter Guard required: This is a Formula Student regulation
for chain/belt driven mechanisms.
5) Does the mechanism require to be enclosed in a housing:
This is applicable to designs that are gear
based, as they are required to be enclosed in
housing as they use lubricants such as oil.
6) Is the drive design going to have an effect on the weight of the car:
This will be subject to the chosen design as the
car wants to be a light as possible for speed.
From reviewing the Decision Matrix (Appendix F) it is clear to see that the Final Drive method
which scored the lowest (10 points) and subsequently will be continued with to produce a Final
Drive design is the Single 520 Chain.

23
The Spur Gear was the next with a score of 17. The Helical Gear had the overall highest score of
20.
The areas in the matrix where the two gear driven methods scored the highest were in the following:
1) Accessibility for maintenance
2) Does the mechanism require to be enclosed in a housing
3) Is the design going to have an effect on the weight of the car
The listed criteria where the two gear driven systems scored highly in the matrix was because they
would have to be enclosed into a housing unit making difficult access for quick maintenance
purposes.
The factor of the gears having to be enclosed in a housing unit then adds to the cars weight. This
additional weight of the gears would affect the overall weight distribution of the car and
subsequently have a damaging impact upon the handling and performance during testing and race
conditions.
Although the Spur Gear design scored well on its simplicity and efficiency, it was in the above
criteria that raised the score making it inadequate at this current time.
When looking into the simplicity and efficiently of the Helical Gear it scored an average mark as a
result of the teeth being at a slight angle. In order for the effective operation of this gear the angle
has to be manufactured correctly.
Although the decision matrix proved that the Single 520 chain method was the most effective at this
present time, it may be possible in future Formula Student events for the university’s car to run a
gear driven system once sufficient data has been gathered about its reliability and the track and
racing conditions.

24
Research conclusions
From the research carried out on the Final Drive mechanism it was evident (as represented in the
evaluation table Appendix E) that a Single 520 Chain driven mechanism was ultimately the
preferred choice amongst the teams from the 2014 event.
The most popular gear driven method that was chosen was that of a Spur Gear.
Upon further review of each drive method it was found that, for the Spur Gear:
 Although this gear is used for its simplicity of design there is a considerable amount of
stress loads that pass through the gear when in operation combined with the generation of
significant amounts of noise. Whilst reviewing this gear the information listed above
showed that it is better used on lower powered applications, which then directed me onto the
Helical Gear for drive mechanisms.
 Investigation into the Helical Gear has highlighted that this is the preferred option for Final
Drive mechanisms as this can be found in almost all car transmissions. Compared against
the Spur Gear the Helical Gear has angled cut teeth to provide for a smoother and quieter
operation, creating a thrust load when they mesh together. This in turn reduces the amount
of stress applied through the gear when in operation.
The review on the Single 520 Chain highlighted that, by using this method, it allows for better
performance and product life due to the manufacturing methods relating to how the sprockets and
the chain are developed, thereby making this the preferred option for the majority of the teams to
use in the Formula Student event.
Moving on from the research, the Final Drive method which will be carried forward is that of a
chain driven mechanism for several reasons:
1. This is the university's first attempt at this prestigious racing event and the reliability is
currently a high risk factor, so a drive mechanism which is easily accessible is by far the
most effective and safest approach as any problems can be fixed quickly without having to
dismantle big sections of the car wasting valuable time in the pits.

25
2. The use of a gear driven mechanism may be a possibility in future events when the
reliability of the team’s car has improved. Using gear driven systems means that they have
to be enclosed into a casing making it harder to gain access to them in the event of a
problem, leading to either retirement or wasting valuable time in the pits trying to rectify
any problems.

26
Design
1.10 Initial design ideas
With each of these design ideas they show a variety of mounting points. This variation was used as
a test to see how the positioning would work. The final total number of mounting points would be
confirmed prior to the final design being drawn up.
The same will apply for the number of teeth on the gear which will be set once the final gear ratio
has been determined.
Design 1 (Appendix G)
The first conceptual design for the gear uses a top flat tooth. By using the top flat tooth design it
allows for stability in the gear teeth and a wider surface area that will come into contact with the
chain when in operation.
Design 2 (Appendix H)
The design of this gear uses pointed teeth. The pointed tooth design is an improved version of
design 1 by using pointed teeth which are design to grip and prevent the chain from slipping when
in operation.
Design 3 (Appendix I )
This design uses a combination of designs 1 and 2. By using the flat base for increased strength on
the gear teeth with the pointed top on the tooth to help catch and grip the chain better when the
system is in operation.
Design 4 (Appendix J)
This uses a curled teeth design with the aim of catching the teeth better when the system is in
operation. Another advantage of using the curled teeth on this design is to prevent the chain from
slipping off the gear as it rotates.
A set back to this design is that if the angle of the teeth is not correct then the chain won't release at
the required time and can cause serious damage to the rest of the car.

27
1.11 Design ideas decision matrix
Now the four initial conceptual designs have been derived the next stage is to determine which
concept is overall the most suitable to continue forward to the end of the project. To determine the
best concept the use of a decision matrix was necessary and the criteria and results from the matrix
can be found below with the matrix table located in the appendices (Appendix K on page 45).
The scoring is, again like the previous matrix, based upon a 1 - 5 system. Further details for this
scoring system can be found under sub heading 1.9 Final Drive decision matrix on page 21.
The criteria for this decision matrix is listed below:
1. Will the design of the gear teeth grip the chain: Will the teeth on the
gear grip the chain
sufficiently for the most
effective performance.
2. Is the design of the gear teeth practical: Is the gear teeth design
used appropriate to its
required application.
3. Is the overall design of the gear practical: Does the gear design
full fill its required purpose.
4. Are the mounting holes required: The mounting holes for the
Sprockets may not be required
as this is dependent upon the
differential design that will be
used

28
From reviewing the conceptual four designs in the decision matrix it is clear to see that the best
design to continue the project with is design three.
On closer inspection of the decision matrix we can see that the third design was scored as the
overall best design as it was determined to be the clear winner at gripping the chain along with the
practically of the gear teeth themselves. The overall practically of the gear was considered to be
average in the matrix as the design is subject to amendments.
These amendments are constrained to two factors which are:
1. The Number of teeth the gear will have. – This will be determined through the Gear Ratio as
the number of teeth on the front sprocket determines the number of the teeth on the rear.
(See page 29 for the table showing the number of teeth required for the gear.)
2. The number of mounting holes on the sprocket – This will be determined by the type of
differential that will be used. (See page 29 for the information relating to the type of
differential used on this project.)
The two conceptual designs which scored the highest were designs two and four. Although it was
reflected in the matrix that the concept of design four would grip the chain better, because of the
curled teeth it was determined that this could also hinder the release of the chain from the gear as it
rotates. Also in relation to the complexity of this design concept the manufacturing would take
longer. This would be as a direct result of the shape of the teeth, as the angles would have to be
correct in order for it to function fully.
It was also considered that design two would grip the chain sufficiently because of the point on the
tip of the teeth.
Reviewing conceptual design one, this scored the highest points on the design of the teeth and their
practically as the chain could be seen not to grip the teeth to allow for an efficient and effective
operation of the components.
With the remaining criteria looking at the practicality and mounting holes, all the designs scored the
average rating. The reasons behind this average rating was because whichever design would be
taken foreword would be subject to a redesign of the number of teeth once the gear ratio's have been
finalised and the number of mounting holes once the differential has been chosen.

29
1.12 Information from other team members
Following the four initial conceptual designs before a final design could be constructed certain
information is required from other team members. The required information consists of the Gear
Ratio which will determine the number of teeth for the Final Drive sprockets.
The other piece of required information was how many mounting holes the sprocket is required to
have so that it will join to the differential.
The design assumptions below will be made for my final design until the exact parameters have
been confirmed:
 Number of teeth:
This assumption has to be based upon the chosen Gear
Ratio so the number of teeth for the front sprocket will
range from 11 - 16 and for the rear sprocket the range will
be from 45 up to 55.
(As shown in the table opposite.)
 Mounting holes on the sprocket to connect to the differential:
The mounting holes for the sprocket are also dependent upon another factor, in this case its reliant
on the differential setting used. Although the final number is still to be confirmed the assumption
can be made that the minimal required mounting holes will be 2.
After my fellow team members had concluded their results the final parameters for my design is as
follows:
Number of teeth on sprocket:
 As the desired Gear Ratio has been determined as 3.4375:1, which means the
number of teeth for the sprockets are as follows, 16 teeth on the front sprocket and
55 teeth on the rear sprocket.
Mounting holes to connect sprocket to differential:
 The differential that was used is a Drexler differential package. This package
requires the sprocket to have twelve mounting points.
Front Sprocket Rear Sprocket
11 45
12 46
13 47
14 49
15 51
16 55

30
1.13 Design calculations
Following the supplied information of the derived gear ratio and the number of teeth for each of the
sprockets some simple calculations were done to determine the basic dimensions. By using a
website that calculates the sprocket dimensions and chain requirements the following was derived.
Basic Sprocket Dimension:
By entering the number of teeth on the sprocket the calculations determined the chain pitch and the
diameter of the sprockets.
 Chain Pitch = 0.625
 Number of teeth 16 (Front sprocket) = Ø 81.372 mm
 Number of teeth 55 (Rear sprocket) = Ø 278.075 mm
Distance between sprockets centre to centre:
This was calculated by entering the number of teeth on the front and rear sprockets and the number
of links that the chain will have. An assumption was made that 100 links would be used for the
chain this assumption may change during the assembly of the package.
 Front Sprocket 16 teeth
 Rear Sprocket 55 teeth
 Number of Links 100
 Distance centre to centre = 502 mm
Chain Length:
This is a simple calculation done by entering the number of links that the chain will have.
 Number of links 100
 Chain Length = 1587.5 mm

31
The conclusions that can be taken from these calculations are:
 Front Sprocket (16 teeth) Ø 81.372 mm
 Rear Sprocket (55 teeth) Ø 278.075 mm
 Distance centre to centre 502 mm
 Number of Links 100
 Chain Length 1587.5 mm
In the appendices (Appendix L) is a table with the above calculations and velocity ratios for the
chosen sprocket package. The table also shows a set of calculations for a sprocket package that uses
a 14 tooth front sprocket and a 49 tooth rear sprocket. This new package was considered as it gives
the car improved performance. Although this package improves the performance, the selected
engine which will be used for this car is already supplied with a front sprocket of 16 teeth hence
why the above package was chosen.
The new package could be developed to replace this chosen one on the car at future events.
The link to the website for the calculations can be found listed in the bibliography. [10] [11]

32
1.14 Final design
Taking the above information relating to the number of teeth and mounting points, along with the
design calculations, a final design for the rear sprocket has been created in Solidworks (Appendix
M). The front sprocket does not require a design as this was already included on the engine
purchased for the car.
As shown in the final design (Appendix M) there are 12 mounting points which will be used to
connect the sprocket to the differential package during the assembly. The rear sprocket has 55 teeth
as constrained by the final gear ratio of 3.4375:1. Also shown are 7 cut outs which have been
incorporated to help reduced the overall weight of the sprocket but also to keep sufficient strength
in the component when in it is in operation.
This design can now be carried forward to the manufacturing stages on this project.
At the manufacturing stage there is a decision as to whether to manufacture the component in house
or to purchased it externally. The preferred option would be for the component to be manufactured
in house as the required facilities are present, thus saving cost and time on the production and
delivery if it was purchased elsewhere.
The next stage is to decide from what material the sprocket will be made. By following the
information listed in the report on the Single 520 Chain (Page 18) it shows that the sprocket has
been made from carbon steel over aluminium in order to provide extended chain wheel life. From
using the carbon steel, the sprockets are then electroplated to prevent corrosion and the teeth are
hardened to increase durability.
Carbon steel would be a suitable material to use as it is cheap to purchase and easy to machine but
the extra processes required to protect the component make it a long manufacturing process. An
alternative material that could be used is carbon fibre. Although carbon fibre is more expensive to
purchase it the most preferred material to be used in racing as it is lighter in weight, stronger and
more durable. This means it holds a higher resistance under impact and against corrosion. The
overall manufacturing process is quicker as the material doesn't have to be plated and treated as in
the case of carbon steel.
By manufacturing the sprocket this will result in the Single 520 Chain being the only part of the
Final Drive package that will be purchased.

33
1.15 Shatter Guard design
The design of the Shatter Guard for the sprockets is constrained by the Formula Student Technical
Regulations 2015-2016.
The most relevant section is listed below with all the overall points from this section of the
regulations listed under heading 1.3 Formula Student Regulations Pages 12 & 13.
The design of the Shatter Guard that must be used with the chain driven system is constrained in
design by the requirement below:
Chain Drive - Scatter shields for chains must be made
of at least 2.66 mm (0.105 inch) steel (no alternatives
are allowed), and have a minimum width equal to
three (3) times the width of the chain. The guard must
be centred on the centre line of the chain and remain
aligned with the chain under all conditions.
[12]
Following the design of the Shatter Guard the next stage was to figure out how this will be attached
to the car. This will be done by the use of three brackets.
Two of the brackets will be positioned on the top of the guard at the rear of the suspension and the
third bracket will be attached to the Shatter Guard underneath so that all areas of the guard are
secured to reduce the amount of vibration that will be imposed on the component.
In manufacturing, at the point where these brackets will connect to the chassis, they will have to be
rolled so that more of the bracket comes into contact with the chassis to improve stability of the
shatter guard.
The drawings of the Shatter Guard and the supporting brackets can be found in the appendices
(Appendix N).
The areas where the bracket will attach to the chassis of the car can be seen in the appendices
(Appendix O) with the proposed area for attachment highlighted by red boxes.

34
Conclusion
The conclusions which can be drawn from this report on the Formula Student project, focusing on
the Final Drive system, is that analysis has been conducted into the type of systems that current
Formula Student teams apply on their cars. This has been evaluated to derive the best system to use
along with factoring in the reliability and performance issues that are faced by the university's team
upon entering the event for the first time.
Based on the above research an effective and efficient Final Drive system has been designed which
will be applied to the car once the manufacturing is complete.
The final design that has been produced, following the conclusions drawn from the research and
decision matrices, have been constrained by other factors on the race car such as the gear ratios, the
differential used and the Formula Student Technical Regulations. The constraint imposed by the
technical regulations means that as the chain and sprocket system has been applied a Shatter Guard
would also be required.
This reports also recommends that it may be possible to use a Final Drive system operated by gears
for future events once the reliability has been tested and sufficient data has been collated on the
track conditions and then simulating how the gear system will stand up to the event requirements.
The other recommendation is that the manufacturing is completed in house to reduce costs and
production times imposed through purchasing the product. The use of carbon fibre material for the
sprocket instead of carbon steel has also be suggested because of the materials lightweight and
strength.
Also mentioned is the use of another sprocket package that could be used to replace the chosen one
at a future events. The alternative uses a 14 tooth front sprocket and 49 tooth rear sprocket to
improve the speed of the car. (This data can be found in the appendices Appendix L page 45.)

35
Appendices
Appendix A Initial Gantt Chart Page 36
Appendix B Gantt Chart version 1 Page 37
Appendix C Gantt Chart version 2 Page 38
Appendix D Gantt Chart version 3 Page 39
Appendix E Evaluation table of 2014 Formula Student entries Page 40
Appendix F Final Drive decision matrix Page 40
Appendix G Sprocket drawing 1 Page 41
Appendix H Sprocket drawing 2 Page 42
Appendix I Sprocket drawing 3 Page 43
Appendix J Sprocket drawing 4 Page 44
Appendix K Design ideas decision matrix Page 45
Appendix L Design calculations table Page 45
Appendix M Final sprocket design Page 46
Appendix N Shatter Guard with supporting brackets Page 47
Appendix O Photo's of the current chassis Page 48

36
Appendix A Initial Gantt Chart

37
Appendix B Gantt Chart version 1

38
Appendix C Gantt Chart version 2

39
Appendix D Gantt Chart version 3

40
Appendix E Evaluation table of 2014 Formula Student entries
Type of Drive
Mechanism
Class1 Class 2 Total
Single 520 Chain 50 (1) 5 55 (1)
Single 428 Chain 5 1 6
Single 425 Chain 1 - 1
Single 420 Chain 1 - 1
Spur Gears 6 (3) - 6
Planetary Gears 4 (4) 1 (1) 5 (5)
Epicycle Gears 1 - 1
Helical Gears 1 1(1) 2 (1)
Other 18 12 30
N/A 2 1 3
123 (7)
 The rows that have a number enclosed within the brackets means that it's combined
with another mechanism.
 The rows with a dash in them represent a 0.
Appendix F Final Drive decision matrix
Scored from 1-5 with 1 being the better score (the lower the total score the better)
Final
Drive
Methods
against
Design
Criteria
Design
Simplicity
Accessibility
for
maintenance
Efficiency Is the use of
a shatter
guard
required
Does the
mechanism
require to
be enclosed
in a housing
Is the design
going to have
an effect of
the weight of
the car
Total
Single 520
Chain
1 1 1 5 1 1 10
Spur Gear 1 5 1 1 5 4 17
Helical
Gear
3 5 2 1 5 4 20

41
Appendix G Sprocket drawing 1

42
Appendix H Sprocket drawing 2

43
Appendix I Sprocket drawing 3

44
Appendix J Sprocket drawing 4

45
Appendix K Design ideas decision matrix
Scored from 1-5 with 1 being the better score (the lower the total score the better)
Appendix L Design calculation table
Designs
against
criteria
Will the design of
the gear teeth
grip the chain
Is the design of
the gear teeth
practical
Is the overall
design of the gear
practical
Are the mounting
holes required
Total
Design 1 4 4 3 3 14
Design 2 3 3 3 3 15
Design 3 2 2 3 3 10
Design 4 3 3 3 3 15
Information for Existing
Front & Rear Sprocket
Package
Information for
New Front & Rear
Sprocket Package
Number of Teeth on front Sprocket 16 14
Number of Teeth on Rear Sprocket 55 49
Final Drive Ratio
(Front Sprocket: Rear Sprocket) 3.4375:1 3.5:1
Distance between Sprockets
(Centre to Centre) 502.30mm 743.69mm
Diameter (Ø) of Front Sprocket 81.372mm 71.341
Diameter (Ø) of Rear Sprocket 278.075mm
247.775mm
Chain Pitch
0.625
No of Links
100
Chain Length
1587.5mm
Velocity Ratio
1:0.29 1:0.28

46
Appendix M Final sprocket design

47
Appendix N Shatter Guard with supporting brackets

48
Appendix O
These photos’s are of the current chassis of the university’s car.
The arrow on this image represents the
position of the front sprocket and the
area covered by the red box shows
where one of the three supporting
brackets for the shatter guard will be
positioned.
The arrow on this image represents
the position of the front sprocket
and the area covered by the red box
shows where the other two
supporting brackets for the shatter
guard will be positioned.
The arrow on this image represents
the position of the front sprocket and
the area covered by the red boxes
shows where all of the supporting
brackets will be positioned.

49
Bibliography
[1] SAE International Formula Student Technical Regulations 2015 -2016
Part T General Technical Requirements, Article 8 Power train Pages 62 / 63
[2] Straight Axel Drive Image
http://maybach300c.blogspot.co.uk/2012/09/rigid-and-semi-rigid-crank-axle.html
[3] Pinion Gear Image
http://goldwingdocs.com/Images/HowTo/RearWheel/RearWheel98.jpg
[4] Planetary Gear Image
http://www.china-reducers.com/planetary-gearboxes-china-made.jpg
[5] The Formula Student 2014 event programme
http://www.racecar-engineering.com/formulastudent
[6] Single 520 Chain Information
http://www.motosport.com/vortex-520-steel-sprocket-chain-kit
[7] Single 520 Chain Image
http://www.mopartsracing.com/parts/ram/chain.gif
[8] Spur Gear Image
http://cf.ydcdn.net/1.0.1.30/images/main/spur%20gear.jpg
[9] Helical Gear Image
http://s.hswstatic.com/gif/gear-helical2.jpg
[10] Design Calculation Information
http://www.f650gs.crossroadz.com.au/Calc-Chain.html

50
[11] Design Calculation Conversion
http://www.metric-conversions.org/length/inches-to-millimeters.htm
[12] Shatter Guard Image
SAE International Formula Student Technical Regulations 2015 - 2016
Part T General Technical Requirements, Article 8 Power train Page 62

Dissertation Hardcopy (My Version)

Recommended

Recommended

More Related Content

What's hot

What's hot (18)

Viewers also liked

Viewers also liked (6)

Similar to Dissertation Hardcopy (My Version)

Similar to Dissertation Hardcopy (My Version) (20)

Dissertation Hardcopy (My Version)