‫بسم هللا الرحمن الرحيم‬
University of Khartoum
Faculty of Engineering
Mechanical Engineering Department
Electrical Car Jack
A thesis submitted in partial fulfillment of the requirements for the degree of
B.Sc. in Mechanical Engineering
Presented by:
Osman Adil Osman
Ehab Murtada El-tijane
Supervised by:
Dr. Obai Younis Taha
August 2015
Dedication
I am dedicating this to those who had the major role in the success of this project
and my academic life as a whole. Those who provided the needed support through
all the obstacles I have faced. I proudly dedicate this to my father, who taught me
that the best kind of knowledge to have is that which is learned for its own sake. It
is also dedicated to my mother, who taught me that even the largest task can be
accomplished if it is done one step at a time.
I am also dedicating this to my colleagues and professors, and those who even
had the slightest role in the completion of this work.
I
Acknowledgement
I would like to express my very great appreciation to Dr. Obai Younis Taha for
his valuable and constructive suggestions during the planning and development of
this project. His willingness to give his time through the whole year so generously
has been very much appreciated.
I am also very much thankful to Dr. Mudawi Ibrahim Adam for providing all
needed facilities, Materials and support to meet my project requirements.
I would also like to thank my dear friend Eng. Mohammed Hamza Gasim who
provided insight and expertise that greatly assisted the research and improved the
manuscript.
II
‫الملخص‬
‫حاالت الطوارئ على الطرق الجانبية مثل انثقاب أو ارتخاء اإلطارات ‪ ،‬مشكلة تحدث عادة للسيارات‪.‬‬
‫الرافعات المرفقة مع السيارات تستخدم الميزة الميكانيكية للسماح لالنسان لرفع السيارة بالقوة اليدوية ‪ ،‬يحلل‬
‫هذا البحث تعديل الرافعة الحالية من خالل دمج محرك صغير في الرافعة من اجل جعل رفع الحمل اسهل‬
‫لالستخدام في حالت الطوارئ عن طريق اشتخدام قوة بطارية السيارة (‪ 12‬فولت) ‪،‬و تم استخدام التروس‬
‫لنقل الحركة و لزيادة نسبة السرعة‪.‬‬
‫أهمية الغرض من هذا العمل هو تعديل رافعة السيارة المرفقة من أجل جعل العملية أسهل وأكثر أمنا وأكثر‬
‫اعتمادا من أجل توفير الطاقة الداخلية للفرد والحد من المخاطر الصحية و مشاكل آالم الظهر وخاصة‬
‫المشاكل المرتبطة بالعمل في وضعية حرجة مثل القرفصاء لفترة طويلة من الزمن‪.‬‬
‫‪III‬‬
Abstract
Side road emergency like tire puncher, is a problem commonly observed in cars.
Conventional car jacks uses mechanical advantage to allow a human to lift a
vehicle by manual force. This paper analyzes the modification of the current toggle
jack by incorporating an electric DC motor in the screw in order to make load
lifting easier for emergency use with using power of car battery (12 Volts), Gear
ratio is used to increase the lifting speed.
The significance and purpose of this work is to modify the existing car jack in
order to make the operation easier, safer and more reliable in order to save
individual internal energy and reduce health risks especially back ache problems
associated with doing work in a bent or squatting position for a long period of
time.
Fabrication work has been done using with milling, drilling, grinding, and
welding machine. The developed car jack is tested on car. Implementation of
design will solve problem associated with ergonomics.
IV
Table of contents
Dedication ................................................................................................................. I
Acknowledgement ................................................................................................... II
‫ الملخص‬.......................................................................................................................III
Abstract .................................................................................................................. IV
Table of contents ....................................................................................................... V
List of figures ........................................................................................................VIII
List of tables ............................................................................................................ IX
CHAPTER ONE ........................................................................................................1
INTRODUCTION .....................................................................................................1
1.1 Introduction ........................................................................................................1
1.2 Objective and goals: ...........................................................................................2
1.3 Methodology: ......................................................................................................2
1.4 Results expected: ................................................................................................3
1.5 Restrictions to the project: ................................................................................3
CHAPTER TWO .......................................................................................................4
LITERATURE REVIEW ..........................................................................................4
2.1 Jack Definition: ..................................................................................................4
2.2 Historical Background: .....................................................................................4
2.2.1 Scissor carjack: .............................................................................................................................. 4
2.2.2 Bottle car jack: ............................................................................................................................... 5
2.2.3 Hydraulic bottle carjack: .............................................................................................................. 6
2.2.4 Trolley carjack: .............................................................................................................................. 6
2.2.5 Pneumatic carjack: ........................................................................................................................ 7
2.2.6 Electrical Carjack: ......................................................................................................................... 8
2.3 Theory: ................................................................................................................8
2.3.1 Motor: ............................................................................................................................................. 9
2.3.1.1 Motor construction: ....................................................................................................................... 9
V
2.3.1.2 Stepper motor: ......................................................................................................................... 11
2.3.2 Gears: ............................................................................................................................................ 11
2.3.2.1 Spur gears: .................................................................................................................................. 12
2.3.2.3 Bevel gears: ................................................................................................................................. 12
2.3.3 Power screws: ............................................................................................................................... 13
2.3.3.1 Types of Screw Threads used for Power Screws: ....................................................................... 14
2.3.3.1.1 Square thread: .......................................................................................................................... 14
2.3.3.1.2 Acme or trapezoidal thread: ..................................................................................................... 14
2.3.3.1.3 Buttress thread: ........................................................................................................................ 15
2.3.4 Bearing:......................................................................................................................................... 15
2.3.4.1 Ball and roller bearings: .............................................................................................................. 16
2.3.5 Cigarette lighter receptacle: ........................................................................................................ 16
2.3.6 Push button remote control: ....................................................................................................... 17
CHAPTER THREE..................................................................................................19
DESIGN ...................................................................................................................19
3.1 Torque required to raise load by the power screw:......................................19
3.2 Calculations: .....................................................................................................21
3.3 Motor selection: ................................................................................................23
3.4 Gears design: ....................................................................................................24
3.5 Shafts design: ....................................................................................................26
3.5.1 Shafts with twisting moment only: ............................................................................................. 27
3.1.2 Shafts subjected to bending moment only: ................................................................................ 29
CHAPTER FOUR ....................................................................................................31
FABRICATION .......................................................................................................31
4.1 Components: .....................................................................................................31
4.1.1 Bottle car jack: ............................................................................................................................. 31
4.1.2 Gears: ............................................................................................................................................ 31
4.1.3 Motor: ........................................................................................................................................... 35
4.1.4 Base and side members: .............................................................................................................. 35
4.1.5 Bearing:......................................................................................................................................... 36
4.1.6 Bearing housing: .......................................................................................................................... 37
4.1.7 Push Button remote unit: ............................................................................................................ 37
VI
4.2 Material used:...................................................................................................38
4.2.1 Steel: .............................................................................................................................................. 38
4.2.1.1 Yield strength: ............................................................................................................................. 39
4.2.1.2 Toughness: .................................................................................................................................. 39
4.2.1.3 Ductility: ..................................................................................................................................... 39
4.2.1.4 Weldability.................................................................................................................................. 40
4.2.1.5 Durability: ................................................................................................................................... 40
CHAPTER FIVE......................................................................................................42
Conclusion ...............................................................................................................42
5.1 Conclusion: .......................................................................................................42
5.1.1 Methdology: .................................................................................................................................. 42
5.1.2 Restrictions: .................................................................................................................................. 42
5.1.3 The obtained results are: ............................................................................................................. 42
5.1.4 Design tables:................................................................................................................................ 43
References ...............................................................................................................45
Appendix .................................................................................................................46
Physical constants of materials ............................................................................................................... 46
ASTM minimum tensile and yield strengths for some hot rolled (HR) and cold drawn (CD) steels ..... 47
Bearing tables.......................................................................................................................................... 48
Gear 3D ................................................................................................................................................... 49
Pinion 3D ................................................................................................................................................ 49
Gear 2D ................................................................................................................................................... 50
Pinion 2D ................................................................................................................................................ 50
VII
List of figures
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
(2.1) Scissor carjack ....................................................................................................................... 5
(2.2) Bottle carjack......................................................................................................................... 5
(2.3) Hydraulic bottle carjack ....................................................................................................... 6
(2.4) Trolley carjack ...................................................................................................................... 7
(2.5) Pneumatic carjack................................................................................................................. 7
(2.6) Electrical carjack .................................................................................................................. 8
(2.7) Spur gear.............................................................................................................................. 12
(2.8) Bevel gear ............................................................................................................................. 13
(2.9) Square thread ...................................................................................................................... 14
(2.10) Acme thread ...................................................................................................................... 15
(2.11) Buttress thread .................................................................................................................. 15
(2.12) Ball and roller bearing ...................................................................................................... 16
(2.13) Receptacle plug.................................................................................................................. 17
(2.14) Push button remote ........................................................................................................... 18
(3.1) Force resultant .................................................................................................................... 19
(3.2) DC motor ............................................................................................................................. 23
(3.3) Bottle carjack gears ............................................................................................................ 24
(3.4) Torsion in shafts .................................................................................................................. 28
( 3.5) Modes of torsional failure.................................................................................................. 29
(4.1) Steel shaft ............................................................................................................................. 32
(4.2) Sawing machine ................................................................................................................... 32
(4.3) Lathe machine ..................................................................................................................... 33
(4.4) Milling machine ................................................................................................................... 33
(4.5) Module ................................................................................................................................. 34
(4.6) Gears .................................................................................................................................... 34
(4.7) Motor shaft and the motor after mounting the gear on it ............................................... 35
(4.8) Base and side members ....................................................................................................... 36
(4.9) Bearing ................................................................................................................................. 36
(4.10) Bearing house .................................................................................................................... 37
(4.11) Remote control Relays ...................................................................................................... 38
(4.12) The diagram shows the strain diagram for the steel. ..................................................... 38
(4.13) The figure shows the stress-strain behavior of the steel. ............................................... 40
VIII
List of tables
Table
Table
Table
Table
Table
(3.1) Carjack power screw dimensions ........................................................................................ 21
(5.1) Manufactured components .................................................................................................. 43
(5.2) Gears characteristics ............................................................................................................ 43
(5.3) Carjack characteristics ........................................................................................................ 43
(5.4) Components price.……………………………………………………….……….............................................44
IX
CHAPTER ONE
INTRODUCTION
1.1 Introduction
The word ‘design’ comes from the Latin word ‘designare’, which means to designate or mark
out. Design can be taken to mean all the processes of conception, invention, visualization,
calculation, refinement and specification of details that determine the form of a product. Design
generally begins with either a need or requirement or, alternatively, an idea. It ends with a set of
drawings or computer representations and other information that enables a product to be
manufactured and utilized. [1]
Design of machine elements is an integral part of the larger and more general field of mechanical
design.
Designers and design engineers create devices or systems to satisfy specific needs. Mechanical
devices typically involve parts that transmit power and accomplish specific patterns of motion.
Mechanical systems are composed of several mechanical devices. [2]
The Subject Machine Design is the creation of new and better machines and improving the
existing ones. A new or better machine is one which is more economical in the overall cost of
production and operation. The process of design is a long and time consuming one. From the study
of existing ideas, a new idea has to be conceived. The idea is then studied keeping in mind its
commercial success and given shape and form in the form of drawings. In the preparation of these
drawings, care must be taken of the availability of resources in money, in men and in materials
required for the successful completion of the new idea into an actual reality. In designing a machine
component, it is necessary to have a good knowledge of many subjects such as Mathematics,
Engineering Mechanic, Strength of Materials, Theory of Mechanics, Workshop process and
Engineering Drawing. [3]
1
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 car jack (manually operated) that is still included as
standard equipment with most new cars. These days, a car jack is an important tool to have in our
vehicle due to unknown upcoming event such as flat tire in our journey.
Working near a vehicle that is supported by a car jack can be fatal. A lot of people have been
crushed and killed by a vehicle while they were working under it.
1.2 Objective and goals:
In order to fulfill the needs of a present car jack, some improvement must be made based on
the problems statement:

To design a car jack that is safe, reliable and able to raise and lower the height level.

To develop a car jack that is powered by internal car power and fully automated with a
button system.
1.3 Methodology:

Preliminary survey to determine which type of car jack is preferred.

Determining the number of components which are going to be bought and which are going
to be manufactured.

Application of SOLIDWORK software for providing a detailed 2D and 3D drawings,
material selection and simulation for the car jack.

Manufacturing all needed components at the workshop.

Testing the project so is to check it.
2
1.4 Results expected:

Design an electrical car jack with the least amount of components at the least cost

Design an electrical car jack that works in efficient way.
1.5 Restrictions to the project:

Financial support to buy motor,

Financial support to manufacture the different parts and

Difficulty of designing the electrical circuits.
3
CHAPTER TWO
LITERATURE REVIEW
2.1 Jack Definition:
A jack is a mechanical device used as a lifting device to lift heavy loads or apply great forces.
A mechanical jack employs a screw thread for lifting heavy equipment. The most common form
is a car jack, floor jack or garage jack which lifts vehicles so that maintenance can be performed.
Mechanical jacks are usually rated for a maximum lifting capacity (for example, 1.5 tons or 3
tons). More powerful jacks use hydraulic power to provide more lift over greater distances and
can be rated for many tons of load. [4]
2.2 Historical Background:
2.2.1 Scissor carjack:
Scissor car jacks usually use mechanical advantage to allow a human to lift a vehicle by
manual force alone using long, self-locking jack screws to raise the vehicle. Although these jacks
are simply designed, they are considered so sturdy and dependable that car manufacturers often
include them with new cars, according to Floor Automotive Jacks.
The centrally located jack screw raises and lowers the scissor-shaped jack using either a tire
iron or a specially designed tool. These jacks vary in size and weight-bearing capabilities, so care
should be taken when purchasing one. [4]
4
Figure (2.1) Scissor carjack
2.2.2 Bottle car jack:
This type consists of a power screw that converts the rotary motion to a linear motion.
This type of jack is extremely versatile, and can not only help lift vehicles, but can also aid in
pushing vehicles around. These jacks are compact in size, but are designed and built for
performance.
Lifting capacities range from heavy duty 1 ton bottle jack up to 30 ton bottle jack. [4]
Figure (2.2) Bottle carjack
5
2.2.3 Hydraulic bottle carjack:
This type of automotive jack uses hydraulics to provide enough pressure to lift a vehicle
weighing up to several tons. Most hydraulic jacks have a cylinder, top, base, plunger and pump
filled with oil. Using the plunger builds oil pressure, which is controlled by valves, and performs
the lifting and lowering actions. These jacks are rated according to how much weight they can
safely lift without failing. Olive-Drab reports lower end hydraulic jacks can lift up to 3 tons
without problem. [5]
Figure (2.3) Hydraulic bottle carjack
2.2.4 Trolley carjack:
A trolley jack is any type of wheeled hydraulic floor jack that can be moved easily. Depending
on the size and weight of a vehicle, standard trolley jacks can lift weights ranging from 2 to 4
tons. While some models feature manual braking controls, others have brakes that lock
automatically when the jack is being used. Unlike other jacks that may slip or disengage unless
on a firm surface, a trolley jack can be safely used on gravel or dirt and will lift the vehicle
higher. [5]
6
Figure (2.4) Trolley carjack
2.2.5 Pneumatic carjack:
A pneumatic jack is a hydraulic jack that is actuated by compressed air - for example, air from
a compressor - instead of human work. This eliminates the need for the user to actuate the
hydraulic mechanism, saving effort and potentially increasing speed. Sometimes, such jacks are
also able to be operated by the normal hydraulic actuation method, thereby retaining
functionality, even if a source of compressed air is not available.
Hydraulic jacks, on the other hand, use liquid to affect motion. Both types of jacks are
available to consumers; however, hydraulic jacks are more popular for a number of reasons, and
pneumatic jacks are less readily available due to the drawbacks of pneumatic mechanics. This
doesn’t mean that a pneumatic jack is a bad choice, but rather that a comparison between the two
products is time well spent. [5]
Figure (2.5) Pneumatic carjack
7
2.2.6 Electrical Carjack:
An electric car jack is device that plugs into the 12V lighter or power socket on your car. It is
used in place of a manual jack if you need to change a tire or raise your car to work on the
undercarriage.
An electric car jack uses a motor to raise your vehicle. As the jack's motor runs, the jack turns,
raises and lifts the car. An electric jack creates less force per turn than a manual jack, but it turns
at a much faster rate.
Most electric car jacks have a 12-foot power cord to place the jack at any corner of the car, and
will raise a 1-ton vehicle up to 14 inches. [4]
Figure (2.6) Electrical carjack
2.3 Theory:
The mechanism of the ELECTRICAL CARJACK is to make the jack drops and rises by the
use of motor and spur gears.
There will be two gears, one will be mounted on the motor shaft and the other one will be
mounted on the rotary part of the jack.
The motor and the jack will be fixed in a metal base in a way that the two gears are in mesh
perfectly, when the motor rotate clockwise, the gears will rotate and transmit motion and the jack
will raise up and when the motor rotates anti-clockwise the jack will drop down.
8
Many components should be used, such as:

Motor.

Gears.

Power Screw.

Bearing.

Cigarette lighter receptacle.

Push Button remote control unit.
2.3.1 Motor:
An electric motor is an electric machine that converts electrical energy into mechanical energy.
In normal motoring mode, most electric motors operate through the interaction between an
electric motor's magnetic field and winding currents to generate force within the motor. In
certain applications, such as in the transportation industry with traction motors, electric motors
can operate in both motoring and generating or braking modes to also produce electrical energy
from mechanical energy.
Electric motors can be powered by direct current (DC) sources, such as from batteries, motor
vehicles or rectifiers, or by alternating current (AC) sources, such as from the power grid,
inverters or generators.
2.3.1.1 Motor construction:
A- Rotor:
In an electric motor, the moving part is the rotor which turns the shaft to deliver the mechanical
power. The rotor usually has conductors laid into it, which carry currents that interact with the
magnetic field of the stator to generate the forces that turn the shaft. However, some rotors carry
permanent magnets, and the stator holds the conductors.
9
B- Stator:
The stationary part is the stator, usually has either windings or permanent magnets.
C- Air gap:
In between the rotor and stator is the air gap. The air gap has important effects, and is generally
as small as possible, as a large gap has a strong negative effect on the performance of an electric
motor.
D- Windings:
Windings are wires that laid in coils, usually wrapped around a laminated soft iron magnetic
core to form magnetic poles when energized with current.
Electric machines come in two basic magnet field pole configurations: salient-pole machine
and nonsalient-pole machine. In the salient-pole machine, the pole's magnetic field is produced
by a winding wound around the pole below the pole face. In the nonsalient-pole, or distributed
field, or round-rotor, machine, the winding is distributed in pole face slots. A shaded-pole motor
has a winding around part of the pole that delays the phase of the magnetic field for that pole.
Some motors have conductors, which consist of thicker metal, such as bars or sheets of metal,
usually copper, although sometimes aluminum is used. These are usually powered by
electromagnetic.
E- Commutator:
A commutator is a mechanism used to switch the input of certain AC and DC machines
consisting of slip ring segments insulated from each other and from the electric motor's shaft.
The motor's armature current is supplied through the stationary brushes in contact with the
revolving commutator, which causes required current reversal and applies power to the machine
in an optimal manner as the rotor rotates from pole to pole. In absence of such current reversal,
the motor would brake to a stop. In light of significant advances in the past few decades due to
improved technologies in electronic controller, sensor less control, induction motor, and
permanent magnet motor fields, electro-mechanically commutated motors are increasingly being
displaced by externally commutated. [6]
10
2.3.1.2 Stepper motor:
Stepper motors are a type of motor frequently used when precise rotations are required. In a
stepper motor, an internal rotor containing PMs or a magnetically soft rotor with salient poles is
controlled by a set of external magnets that are switched electronically. A stepper motor may
also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is
energized in turn, the rotor aligns itself with the magnetic field produced by the energized field
winding. Unlike a synchronous motor, in its application, the stepper motor may not rotate
continuously; instead, it "steps" -starts and then quickly stops again- from one position to the
next as field windings are energized and de-energized in sequence. Depending on the sequence,
the rotor may turn forwards or backwards and it may change direction, stop, speed up or slow
down arbitrarily at any time.
Simple stepper motor drivers entirely energize or entirely de-energize the field windings,
leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can
proportionally control the power to the field windings, allowing the rotors to position between
the cog points and thereby rotate extremely smoothly.
This mode of operation is often called micro stepping. Computer controlled stepper motors are
one of the most versatile forms of positioning systems, particularly when part of a digital servocontrolled system. [7]
2.3.2 Gears:
A gear or cogwheel is a rotating machine part having cut teeth, or cogs, which mesh with
another toothed part to transmit torque, in most cases with teeth on the one gear being of
identical shape, and often also with that shape on the other gear. Two or more gears working in a
sequence (train) are called a gear train or, in many cases, a transmission; such gear arrangements
can produce a mechanical advantage through a gear ratio and thus may be considered a simple
machine. Geared devices can change the speed, torque, and direction of a power source. The
most common situation is for a gear to mesh with another gear; however, a gear can also mesh
with a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.
An advantage of gears is that the teeth of a gear prevent slippage.
11
When two gears mesh, and one gear is bigger than the other (even though the size of the teeth
must match), a mechanical advantage is produced, with the rotational speeds and the torques of
the two gears differing in an inverse relationship.
In transmissions with multiple gear ratios—such as bicycles, motorcycles, and cars—the term
gear, as in first gear, refers to a gear ratio rather than an actual physical gear. The term describes
similar devices, even when the gear ratio is continuous rather than discrete, or when the device
does not actually contain gears, as in a continuously variable transmission. [3]
2.3.2.1 Spur gears:
Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk
with the teeth projecting radially, and although they are not straight-sided in form (they are
usually of special form to achieve constant drive ratio, mainly involute), the edge of each tooth is
straight and aligned parallel to the axis of rotation. These gears can be meshed together correctly
only if they are fitted to parallel shafts. [3]
Figure (2.7) Spur gear
2.3.2.3 Bevel gears:
A bevel gear is shaped like a right circular cone with most of its tip cut off. When two bevel
gears mesh, their imaginary vertices must occupy the same point. Their shaft axes also intersect
at this point, forming an arbitrary non-straight angle between the shafts. The angle between the
shafts can be anything except zero or 180 degrees. Bevel gears with equal numbers of teeth and
shaft axes at 90 degrees are called mitre gears.
Spiral bevel gears can be manufactured as Gleason types (circular arc with non-constant tooth
depth), Oerlikon and Curvex types (circular arc with constant tooth depth), Klingelnberg CycloPalloid (Epicycloide with constant tooth depth) or Klingelnberg Palloid. Spiral bevel gears have
12
the same advantages and disadvantages relative to their straight-cut cousins as helical gears do to
spur gears. Straight bevel gears are generally used only at speeds below 5 m/s (1000 ft/min), or,
for small gears, 1000 r.p.m. [3]
Figure (2.8) Bevel gear
2.3.3 Power screws:
The power screws are used to convert rotary motion into linear 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. [3]
13
2.3.3.1 Types of Screw Threads used for Power Screws:
2.3.3.1.1 Square thread:
A square thread, as shown in Fig (2.9), is adapted for the transmission of power in either
direction. This thread results in maximum efficiency and minimum radial or bursting pressure on
the nut. It is difficult to cut with taps and dies. It is usually cut on a lathe with a single point tool
and it cannot be easily compensated for wear. The square threads are employed in screw jacks,
presses and clamping devices. [3]
Figure (2.9) Square thread
2.3.3.1.2 Acme or trapezoidal thread:
An acme or trapezoidal thread, as shown in Fig (2.10), is a modification of square thread. The
slight slope given to its sides lowers the efficiency slightly than square thread and it also
introduce some bursting pressure on the nut, but increases its area in shear. It is used where a
split nut is required and where provision is made to take up wear as in the lead screw of a lathe.
Wear may be taken up by means of an adjustable split nut. An acme thread may be cut by means
of dies and hence it is more easily manufactured than square thread. [3]
14
Figure (2.10) Acme thread
2.3.3.1.3 Buttress thread:
A buttress thread, as shown in Fig (2.11), is used when large forces act along the screw axis in
one direction only. This thread combines the higher efficiency of square thread and the ease of
cutting and the adaptability to a split nut of acme thread. It is stronger than other threads because
of greater thickness at the base of the thread. The buttress thread has limited use for power
transmission. It is employed as the thread for light jack screws and vices. [3]
Figure (2.11) Buttress thread
2.3.4 Bearing:
The purpose of a bearing is to support a load while permitting relative motion between two
elements of a machine. The most common type of bearing supports a rotating shaft, resisting
purely radial loads or a combination of radial and axial (thrust) loads. Some bearings are
designed to carry only thrust loads. Most bearings are used in applications involving rotation, but
some are used in linear motion applications.
15
2.3.4.1 Ball and roller bearings:
The ball and roller bearings consist of an inner race which is mounted on the shaft or journal
and an outer race which is carried by the housing or casing. In between the inner and outer race,
there are balls or rollers as shown in Fig (2.12).
A number of balls or rollers are used and these are held at proper distances by retainers so that
they do not touch each other. The retainers are thin strips and is usually in two parts which are
assembled after the balls have been properly spaced. The ball bearings are used for light loads
and the roller bearings are used for heavier loads. [3]
Figure (2.12) Ball and roller bearing
2.3.5 Cigarette lighter receptacle:
The cigarette lighter receptacle in an automobile was initially designed to power an electrically
heated cigarette lighter, but became a DC connector to supply electrical power for portable
accessories used in or near an automobile. While the cigarette lighter receptacle is a common
feature of automobiles and trucks, as a DC power connector it has the disadvantages of
bulkiness, relatively low current rating, and poor contact reliability.
Examples of devices that can be operated from a cigarette lighter receptacle include lights,
fans, beverage heating devices, and small motorized tools such as air compressors for inflating
tires. Many portable electronic devices such as music players or mobile telephones use a
cigarette lighter receptacle to recharge their internal batteries or to directly operate from the
vehicle electrical system. Adapters for electronic devices may change voltage to be compatible
16
with the supplied device. Devices that require alternating-current mains electricity can be
operated with a plug-in inverter.
Currently, automobiles may provide several 12 V receptacles that are intended only to operate
electrical accessories, and which cannot used with a cigarette lighter. Car manufacturers may
offer a cigarette lighter only as an optional extra-cost accessory. Usually, only one 12 V
receptacle near the driver will be able to accommodate an actual cigarette lighter, with other
receptacles designated as "12 V auxiliary power outlets" which are not physically able to power a
lighter.
Receptacle Plugs often include a pilot light LED indicator to indicate that electrical power is
connected. Optionally, the plug may be equipped with an internal fuse for electrical safety,
usually rated at 15 amps or less. In some designs, the tip of the plug may be unscrewed to reveal
a cylindrical glass fuse; other variants may use a newer blade-type fuse inserted into the side or
back of the plug.
In the 12-volt cigarette lighter receptacles the receptacle inside diameter: 21.41 - 21.51 mm
(median 21.455 mm) and the plug body diameter: 21.13 - 21.33 mm (median 21.18 mm). [8]
Figure (2.13) Receptacle plug
2.3.6 Push button remote control:
A push-button is a simple switch mechanism for controlling some aspect of a machine or a
process. Buttons are typically made out of hard material, usually plastic or metal. The surface is
usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or
pushed. Buttons are most often biased switches, though even many un-biased buttons (due to
their physical nature) require a spring to return to their un-pushed state.
17
Pushbuttons are often color-coded to associate them with their function so that the operator
will not push the wrong button in error. Commonly used colors are red for stopping the machine
or process and green for starting the machine or process.
Switches with the "push-to-make" mechanism are a type of push button electrical switch that
operates by the switch making contact with the electronic system when the button is pressed and
breaks the current process when the button is released. [9]
Figure (2.14) Push button remote
18
CHAPTER THREE
DESIGN
3.1 Torque required to raise load by the power screw:
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 as shown in
Fig (3.1).
Figure (3.1) Force resultant
Where:
p = Pitch of the screw,
d = Mean diameter of the screw,
α = Helix angle
P = Effort applied at the circumference of the screw to lift the load,
W = Load to be lifted, and
μ = Coefficient of friction, between the screw and nut
μ = tan φ, where φ is the friction angle.
19
From the geometry of the Fig (3.1) (a), we find that:
Tan α = p / π d
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 as shown in Fig (3.1) (b).
Since the load is being lifted, therefore the force of friction (F = μ.RN ) will act downwards.
All the forces acting on the body are shown in Fig (3.1) (b).
Resolving the forces along the plane:
P cos α = W sin α + F = W sin α + μ.RN ... (i)
And resolving the forces perpendicular to the plane:
RN = P sin α + W cos α ... (ii)
Substituting this value of RN in equation (i), we have:
P cos α = W sin α + μ (P sin α + W cos α)
= W sin α + μ P sin α + μW cos α
Or P cos α – μ P sin α = W sin α + μW cos α
Or P (cos α – μ sin α) = W (sin α + μ cos α)
∴P=Wx
(Sin α + μ Cos α)
(Cos α−μ Sin α)
Substituting the value of μ = tan φ in the above equation, we get:
P=Wx
(Sin α + tanφ Cos α)
(Cos α−tanφ Sin α)
Multiplying the numerator and denominator by cos φ, we have:
P=Wx
(Sin α Cosφ +Sin φ Cos α)
(Cos α Cosφ−Sinφ Sin φ)
20
=Wx
Sin(α+φ)
Cos(α+φ)
= W x tan (α + φ)
∴ Torque required to overcome friction between the screw and nut:
𝑑
𝑑
2
2
T = P x = W x tan (α+φ) x
[3]
3.2 Calculations:
By dismantling the carjack the following dimensions were aquired:
Table (3.1) Carjack power screw dimensions
Pitch = 3 mm
Dp (mean diameter) = 30 – (pitch/2) = 30 – 1.5 = 28.5 mm
Lead = 3 mm
μ (coefficient of friction) = 0.15
Power factor = 1.2
tan 𝛾 = p / π d = (3/𝜋 𝑥 28.5)
< 𝛾 = 1.919
W (assumed load) = 750 kg
750 x 9.81 = 7357.5 N
21
Torque =
=
𝑊×𝑑𝑝 ×(𝜇𝑐𝑜𝑠𝛾+𝑠𝑖𝑛𝛾)
2(𝑐𝑜𝑠𝛾−𝜇𝑠𝑖𝑛𝛾)
7357.5×28.5×(0.15×cos(1.919)+sin(1.919))
2×1000×(cos(1.919)−0.15sin(1.919))
= 19.336 N.m
Maximum lift = 23 cm = 0.23 mm
Assumed lifting time = 75 seconds = 1.25 minute
N=
N=
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑙𝑖𝑓𝑡
𝑃𝑖𝑡𝑐ℎ
76.667
1.25
𝜔=
=
0.23
0.003
= 76.667 Revolutions per 1.25 minutes
= 61.333 rpm
2 𝜋×𝑁
60
=
2 𝜋×61.333
60
= 6.422 rad/sec
Power = Torque X 𝜔 X Power factor = 19.336 X 6.422 = 124.175 watt
22
3.3 Motor selection:
The motor is from the junk yard and it is from used bus wiper motor. From the manufacturer
and calculated value for the torque, it supplied 25 Nm torque which is high enough and suitable
for the project. Specification of motor obtained from label on motor:
1. Trademark: LEILI
2. Part no: ZD1733
3. Use: Wiper
4. Type: DC motor
5. Motor: Brush
6. Power: 130 Watt
7. Speed: 75 Rpm
8. Voltage: 12 V
9. Material: Carbon metal
Figure (3.2) DC motor
23
3.4 Gears design:
First the carjack were dismantled to know the reduction ratio.
Figure (3.3) Bottle carjack gears
From Fig (3.3) we found that:
Pinion teeth= 12 teeth,
And the teeth on the driven gear = 27 teeth.
Reduction ratio =
𝑇𝑒𝑒𝑡ℎ 𝑜𝑛 𝑡ℎ𝑒 𝑑𝑟𝑖𝑣𝑒𝑛 𝑔𝑒𝑎𝑟
𝑇𝑒𝑒𝑡ℎ 𝑜𝑛 𝑡ℎ𝑒 𝑑𝑟𝑖𝑣𝑒𝑟 𝑔𝑒𝑎𝑟
27
=
= 2.25
12
Final speed × reduction ratio = speed on the second shaft.
61.33334 × 2.25 = 140 Rpm
We know that the first shaft speed = the motor speed = 75 rpm
To gain 140 rpm at the second shaft a 1.95 increasing ratio were needed must increase the first,
so the following set were designed:
24
First the module and the number of teeth were assumed to be:
Module = 1.25
Number of teeth= 27 teeth
D = 34 mm
b = 4*3.14*1.25= 15.70 mm, taken = 16 mm
Material C1020(K) used.
Tension stress = 455 Mpa
𝜎d =
𝑇𝑒𝑛𝑠𝑖𝑜𝑛 𝑠𝑡𝑟𝑒𝑠𝑠
𝑆𝑎𝑓𝑡𝑒𝑦 𝑓𝑎𝑐𝑡𝑜𝑟
=
455
2
= 227.5 Mpa
 Lewis static check:
𝐹𝑠 = 𝜎𝑑 ∗ 𝑏 ∗ 𝑚 ∗ 𝑦
Y=0.348
𝐹𝑠 = 227.5 × 16 × 1.25 × 0.348 = 1583.4 N
𝐹𝑡 = 𝑃/𝑣
P = 130 watt
V=
2𝜋 ×𝑁×𝐷
60×2
=
2𝜋 ×60×34
60×2
= 0.13 m/s
𝐹𝑡 = 130/0.13 = 1000 N
𝐹𝑠/𝐹𝑡=1.58 (𝑠𝑎𝑓𝑒)
25
 Lewis dynamic check:
𝐹𝑤 = 𝐾∗𝑄∗𝑏∗𝑑
K=1.807 Mpa
Q=
2×𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑖𝑜
1+𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑖𝑜
4
= = 1.333
3
𝐹𝑤 = 1.807 × 1.322 × 16 × 34 = 1299.53 N
𝐹𝑑 = 𝐶𝑉∗𝐹𝑡
𝐶𝑉 =
6+𝑉
6
𝐶𝑉 = 1.022
𝐹𝑑 = 1.022 × 1000 = 1022 N
𝐹𝑤/𝐹𝑑 = 1.27 (𝑠𝑎𝑓𝑒)
3.5 Shafts design:
In designing shafts in the basis of strength there are three classifications:
1- Shafts subjected to twisting moment or torque only,
2- Shafts subjected to bending moment only and
3- Shaft subjected to the axial load in addition to bending moment. [2]
We considered only the first and the second classifications.
26
3.5.1 Shafts with twisting moment only:
When the shaft is subjected to twisting moment only the diameter can be obtained using the
torsion equation:
𝑇
𝐽
𝜏
=
𝑟
T = Twisting moment acting upon shaft,
J = Polar moment of inertia of the shaft about the axis of rotation,
𝜏 = Torsional shear stress and
r = d/2 , (d: Shaft diameter )
𝜋
J= 32 𝑑 4
𝑇
𝜋 4
𝑑
32
=
𝜏
𝑑/2
𝜋
∴ T= 16 × 𝜏 × 𝑑 3
In case of hollow shaft:
𝜋
J = 32(𝑑𝑜4 − 𝑑𝑖4 )
r=
𝑑𝑜
2
𝑇
𝜏
=
𝜋 4
𝑑𝑜
(𝑑 − 𝑑𝑖4 )
32 𝑜
2
𝜋
4
𝑑
∴ T = 16 × 𝜏 × 𝑑𝑜3 × (1 − ( 𝑑𝑜 ) )
𝑖
27
Twisting moment T may be obtained by using the following relation:
P=
2×𝜋×𝑁×𝑇
60
𝑃×60
T = 2×𝜋×𝑁
P = Power transmitted and
N = speed of shaft ( rpm)
Figure (3.4)
Fig (3.4) (a). Shows the initial conditions of the shaft before loading.
Fig (3.4) (b) Shows the initial location of point A and B.
Fig (3.4) (c) Shows the final location of point A and B.
After loading to torsional moment point A moves to A' as shown point B is fixed. [10]
28
Figure (3.5) Modes of torsional failure
3.1.2 Shafts subjected to bending moment only:
When shaft is subjected to bending moment only the maximum stress (tensile or compressive)
is given by the bending equation:
𝑀 𝜎𝑏
=
𝐼
𝑌
M = bending moment.
𝐼 = moment of inertia of cross-sectional Area of the shaft about the axis of rotation.
𝜎𝑏 = bending stress, and
Y = Distance from neutral axis to the outer most fiber.
We know that for the round solid shaft, moment of inertia:
29
𝜋
I = 64 × 𝑑 4
𝑑
Y=2
𝑀
𝜋
× 𝑑4
64
=
𝜎𝑏
𝑑
2
𝜋
M = 32 × 𝜎𝑏 × 𝑑 3
For hollow shaft:
𝜋
I = 64 × (𝑑𝑜4 − 𝑑𝑖4 )
30
CHAPTER FOUR
FABRICATION
4.1 Components:
4.1.1 Bottle car jack:
We used the bottle car jack because of the following reasons:
1- It’s extremely versatile,
2- Compatible,
3- Small in size,
4- Safe and reliable,
5- Good in performance,
6- And it’s very good at heavy duties.
4.1.2 Gears:
Two gears were made to give the rotating movement of the car jack, they are made of steel.
The pinion has 52 teeth and it was fitted on the motor shaft and used as a driver, and the gear
has 27 teeth and it was fitted on the car jack.
A steel shaft were taken from LAMBDA WORKSHOP within 50 mm diameter and 200 mm
length as shown in Fig (4.1).
31
Figure (4.1) Steel shaft
The shaft were cut to the required dimensions using an electrical sawing machine as shown in
Fig (4.2).
Figure (4.2) Sawing machine
After cutting the shaft into two pieces for the two gears, the pieces were taken to the lathe
machine as shown in Fig (4.3), to acquire the needed diameters for every piece.
32
Figure (4.3) Lathe machine
After acquiring the right diameters for the two pieces they were taken to the milling machine as
shown in Fig (4.4) to make the gears using module of 1.25 mm/tooth as shown in Fig (4.5).
Figure (4.4) Milling machine
33
Figure (4.5) Module
After all these operations the gear as shown in Fig (4.6) (A), and the pinion as shown in Fig
(4.6) (B), were acquired.
(A)
(B)
Figure (4.6) Gears
34
4.1.3 Motor:
The motor used is a bus wiper motor, we made a little hole in the motor shaft then mounted the
gear on the shaft and fixed it using a small pin.
Fig (4.7) (A) shows the motor shaft and Fig (4.7) (B) the motor after mounting the gear on it.
(A)
(B)
Figure (4.7) Motor shaft and the motor after mounting the gear on it
4.1.4 Base and side members:
A steel plate within 150 mm width, 300 mm length and 5 mm thickness were used as a base for
the car jack as shown in Fig (4.8) (A).
Two steel plates within 130 mm length, 40 mm width and 5 mm thickness were used as side
members to hold the base and the motor together as shown in Fig (4.8) (B).
35
(A)
(B)
Figure (4.8) Base and side members
4.1.5 Bearing:
A 6207 bearing was selected to fit in 35mm steel shaft, inner rotates with the shaft and the
outter race is fixed in the housing as shown in Fig (4.9).
Figure (4.9) Bearing
36
4.1.6 Bearing housing:
Bearing housing were made of steel within diameter of 70 mm and 10 mm thickness as shown
in Fig (4.10) (A). The bearing fits in 47 mm groove in the housing as shown in Fig (4.10) (B).
(A)
(B)
Figure (4.10) Bearing housing
4.1.7 Push Button remote unit:
Two switches were designed with the "push-to-make" mechanism which makes contact with
the electronic system when the button is pressed and breaks the current process when the button
is released.
With the help of four relay circuits we were able to make the motor rotates in both ways,
clockwise and anti-clockwise by flipping the supply inputs to it as it shown in Fig (4.11).
37
Figure (4.11) Remote control Relays
4.2 Material used:
4.2.1 Steel:
Steel was used for making gears, base, side member and the bearing housing.
The properties of structural steel result from both its chemical composition and its method of
manufacture, including processing during fabrication. Product standards define the limits for
composition, quality and performance and these limits are used or presumed by structural
designers.
Figure (4.12) Strain diagram for the steel
38
The properties that need to be considered by designers when specifying steel construction
products are:
4.2.1.1 Yield strength:
Yield strength is the most common property that the designer will need, as it is the basis used
for most of the rules given in design codes. In European Standards for structural carbon steels
(including weathering steel ), the primary designation relates to the yield strength, e.g. S275 steel
is a structural steel with a specified minimum yield strength of 275 N/mm².
The product standards also specify the permitted range of values for the ultimate tensile
strength (UTS). The minimum UTS is relevant to some aspects of design.
4.2.1.2 Toughness:
It is in the nature of all materials to contain some imperfections. In steel these imperfections
take the form of very small cracks. If the steel is insufficiently tough, the 'crack' can propagate
rapidly, without plastic deformation and result in a 'brittle fracture'. The risk of brittle fracture
increases with thickness, tensile stress, and stress raisers and at colder temperatures.
The toughness of steel and its ability to resist brittle fracture are dependent on a number of
factors that should be considered at the specification stage. A convenient measure of toughness is
the Charpy V-notch impact test - see image on the right. This test measures the impact energy
required to break a small-notched specimen, at a specified temperature, by a single impact blow
from a pendulum.
4.2.1.3 Ductility:
Ductility is a measure of the degree to which a material can strain or elongate between the
onset of yield and eventual fracture under tensile loading as demonstrated in the figure below.
The designer relies on ductility for a number of aspects of design, including redistribution of
stress at the ultimate limit state, bolt group design, reduced risk of fatigue crack propagation and
in the fabrication processes of welding, bending and straightening.
39
Figure (4.13) Stress-strain behavior of the steel
4.2.1.4 Weldability
All structural steels are essentially weldable. However, welding involves locally melting the
steel, which subsequently cools. The cooling can be quite fast because the surrounding material,
e.g. the beam, offers a large 'heat sink' and the weld (and the heat introduced) is usually
relatively small. This can lead to hardening of the 'heat affected zone' (HAZ) and to reduced
toughness. The greater the thickness of material, the greater the reduction of toughness.
The susceptibility to embrittlement also depends on the alloying elements principally, but not
exclusively, the carbon content. This susceptibility can be expressed as the 'Carbon Equivalent
Value' (CEV), and the various product standards for carbon steels standard give expressions for
determining this value.
4.2.1.5 Durability:
A further important property is that of corrosion prevention. Although special corrosion
resistant steels are available, these are not normally used in building construction. The exception
to this is weathering steel.
The most common means of providing corrosion protection to construction steel is by painting
or galvanizing. The type and degree of coating protection required depends on the degree of
40
exposure, location, design life, etc. In many cases, under internal dry situations no corrosion
protection coatings are required other than appropriate fire protection.
Other mechanical properties of structural steel that are important to the designer include:
- Modulus of elasticity, E = 210,000 N/mm²
- Shear modulus, G = E/[2(1 + ν)] N/mm², often taken as 81,000 N/mm²
- Poisson's ratio, ν = 0.3
- Coefficient of thermal expansion, α = 12 x 10-6/°C (in the ambient temperature range). [11]
41
CHAPTER FIVE
Conclusion
5.1 Conclusion:
The objective of this project was to Design and manufacture an electrical car jack works
through the cigarrete lighter receptacle power output with a button system to raise and lower the
car height level.
5.1.1 Methodology:

Preliminary survey to determine which type of car jack is preferred.

Determining the number of components which are going to be bought and which are
going to be manufactured.

Application of SOLIDWORK software for providing a detailed 2D and 3D drawings,
material selection and simulation for the car jack.

Manufacturing all needed components at the workshop.

Testing the project so as to check it.
5.1.2 Restrictions:

Financial support to buy motors,

Financial support to manufacture the different parts and

Difficulty of designing the electrical circuits.
5.1.3 The obtained results are:

Designed and manufactured an electrical car jack with the least amount of components at
the least cost

Designed and manufactured an electrical car jack that works in efficient way.
42
5.1.4 Design tables:
Manufactured components:
Table (5.1) Manufactured components
Part
Length
Width
Thickness
Outer-
Inner-
diameter
diameter
Base
300mm
150mm
5mm
___
___
Side
140mm
40mm
5mm
___
___
___
___
10mm
70mm
47mm
members
Bearing
housing
Gears:
Table (5.2) Gears characteristics
Part
Material
Module
No. of teeth
Pinion
Steel
1.25
52
Gear
Steel
1.25
27
Carjack characteristics:
Table (5.3) Carjack characteristics
Min.
Max.
Height
Height
190mm
420mm
Weight
8 kg
Length
300mm
Width
150mm
Lifting
Power
time
needed
65 Sec.
130 watt
Components price:
43
Table (5.4) Components price
Unit
Cost/unit (SDG)
Shaft
10
Bearing
60
Bottle car-jack
150
DC Motor
100
2 Push buttons
10
4 relays
15
Remote case
10
Receptacle plug
25
Electrical wire (3m)
5
Total cost
450
44
References
1. Child, Peter R. N. Mechanical Design [2nd Edition], Butterworth-Heinemann (April 1, 2004).
2. Mott, Robert L. Machine Elements in Mechanical Design [4th Edition], Prentice Hall (July 26,
2003).
3. Khurmi, R. S. and Gupta J. K. Machine Design [1st Edition] Eurasia Publishing House
(2005).
4. Jacks Wikipedia [Online] [Cited: May 22, 2015.] https://en.wikipedia.org/wiki/Jack
5. Types of jacks ehow [Online] [Cited: May 22, 2015.]
http://www.ehow.com/list_7261433_types-car-jacks.html
6. Motor. Wikipedia [Online] [Cited: May 22, 2014.] http://en.wikipedia.org/wiki/Motor.
7. Stepping Motor. Wikipedia [Online] (Cited:July 11, 2015)
http://wiki.wikepedia.com/Stepping_Motor.
8.Cigarrete lighter receptacle Wikipedia [Online] (Cited:July 11, 2015)
https://en.wikipedia.org/wiki/Cigarette_lighter_receptacle
9.Push button Wikipedia [Online] (Cited:July 11, 2015) https://en.wikipedia.org/wiki/Pushbutton
10. Hassanain, Nadir Mohammed. Strength of Materials Lectures, UofK (November, 2010).
11. Steel Material Properties Steel Constructions [Online] (Cited: July 20, 2015)
http://www.steelconstruction.info/Steel_material_properties.
45
Appendix
Physical constants of materials
46
ASTM minimum tensile and yield strengths for some hot rolled (HR) and cold drawn (CD) steels
47
Bearing tables
48
Gear 3D
Pinion 3D
49
Gear 2D
Pinion 2D
50