PATEL GROUP OF INSTITUTIONS, INDORE
Rajiv Gandhi Proudyogiki Vishwavidyalaya Bhopal (M.P.)
Project report on -
AUTOMATIC HYDRAULIC JACK Submitted to the Rajiv Gandhi Technical University (RGTU) In Partial Fulfillment of the Requirements For the Award of the Degree of Bachelor of Engineering (B.E.)
(2011-12)
Submitted To:
Submitted By:
Mr. Mukesh Sharma
Arpit Verma
HOD, Department of Mechanical Engineering
0828ME081006
CERTIFICATE OF ORIGINALITY
Session 2011-12
This is to certify that the project report entitled “Automatic Hydraulic Jack” submitted to Patel College of Science & Technology, Indore in partial fulfillment of the requirement for the award of degree of Bachelor of Engineering (B.E.) is original work carried out by Arpit Verma with Enrollment No. 0828ME081006 under my guidance. The matter embodied in this project is genuine work done by the student and has not been submitted whether to this university or to any other university institute for the fulfillment of the requirement of any course of study.
Internal Examiner:
External Examiner:
Mr. Mukesh Sharma (Head of Department)
……………………
Guided by:
Project maker:
Mr. Mukesh Sharma
Arpit Verma (0828ME081006)
ACKNOWLEDGEMENT
I tried my best to learn by means of this project. However, it would not have been possible without the kind support and help of many individuals. I would like to extend my sincere thanks to
SINGH AUTO PARTS, INDORE KHANUJA AUTO ELECTRIC, INDORE M.H. DISPOSAL HOUSE , INDORE GOSIA ENGINEERING WORKS, INDORE CULCUTTA METALS, INDORE MARUTI DISPOSAL HOUSE, INDORE BABLU GERMAN WELDER, INDORE INDORE EARTH MOVERS, INDORE P.J. AGENCIES, INDORE
I am highly indebted to Mr. MUKESH SHARMA, for their guidance and constant supervision as well as for providing necessary information regarding the project and also for their support in completing the project. I also thanks my project guide and team members who have spared their valuable time for discussions and suggestions on the critical aspects of this report. I am grateful to my family who has patiently supported me during my studies for Bachelor of Engineering in Mechanical Engineering.
ABSTRACT Since pre-historic times mankind has been using tools to improve the quality of life and work efficiency. A revolutionary change has taken place in the field of Fluid Power Technology in past few decades. Due to sophistication of hydraulics and allied fields of power and higher accuracy in speed, force and position control. Efforts have been made to include the latest possible trends in the field of hydraulics and allied control areas to keep the ever changing state of the technology in hydraulics. Now a day more stress is given to luxury, comfort and safety as much as possible
with
money
and
technology
available
with
the
mankind.
In that way to reduce the human effort this project is been made. That is a case of lifting an automobile with a jack, with less physical efforts. And I am using oil, hence the jack as a means of power transmissions. Hydraulic systems are now extensively used in almost all the engineering fields in varied applications. So I tried to grab the opportunity. Energy can neither be created nor be destroyed but it can be transformed from one form to another. I reduced the physical efforts of human and provided alternate source of energy by taking the power from automobile battery to operate the jack. This project works on the mechanism of converting rotary motion of the motor into reciprocating motion of the hydraulic ram with the help of oil pump. Important thing is that the power is available at any instant and anyone can withdraw easily, without any hazard. This project is applicable for emergency jack for automobiles, Lifting jack in service centers or garages and even can be used for other commercial purpose at home or any other place. Realizing that the engineers are more concerned with the applications than with theory, I woven the subject-matter with this practical application in engineering and achieved the objective.
LIST OF FIGURES Figure-1, Pascal’s law Figure- 2, Principal of hydraulic press Figure- 3, Hydraulic Press Figure- 4, Hydraulic Brakes Figure- 5, Hydraulic Intensifier Figure- 6, Hydraulic Jack Figure- 7, Hydraulic Jack Figure- 8, Air Hydraulic Jack Figure- 9, Bottle Hydraulic Jack (Exploded View) Figure- 10, Bottle Hydraulic Jack Figure- 11, Hydraulic floor Jack Figure- 12, Strand Hydraulic Jack Figure- 13, Toe Jack Figure- 14, Trailer hydraulic Cylinder Jack Figure- 15, Pneumatic Jack Figure- 16, Hydraulic Cylinder Designed For Jack Figure- 17, Hydraulic Cylinder Designed For Jack (Expoled View) Figure- 18, Working of Rotary Vane Pump Figure- 19, Parts of Rotary Vane Pump Figure- 20, Control Unit Assembly Figure- 21, Relief Valve Figure- 22, Gear Assembly for Power Transmission Figure- 23, Circuit Diagram Figure- 24, Jack Picture 1 Figure- 25, Jack Picture 2
TABLE OF CONTENT 1.
INTRODUCTION
3-6
1.1 HYDRAULIC 1.2 HYDRAULIC BASICS
HYDRAULICS PRESSURE FORCE PASCAL’S LAW FLOW VELOCITY FLOW RATE VISCOSITY
2. BASIC SYSTEMS/DEVICES
7-19
2.1 HYDRAULIC PRESS 2.2 HYDRAULIC BRAKES 2.3 HYDRAULIC INTENSIFIER 2.4 HYDRAULIC JACK 2.5 TYPES OF HYDRAULIC JACK
AIR HYDRAULIC TRUCK JACK BOTTLE JACK HYDRAULIC FLOOR JACK STRAND HYDRAULIC JACK TOE JACK TRAILER HYDRAULIC CYLINDER JACK PNEUMATIC JACK
3. CONSTRUCTION AND WORKING OF JACK 3.1 HYDRAULIC CYLINDER
1
20-40
CONSTRUCTION AND WORKING OF CYLINDER CYLINDER SPECIFICATION DESIGN CONSIDERATION
3.2 HYDRAULIC PUMP
ROTARY VANE PUMP CONSTRUCTION AND WORKING OF PUMP PUMP SPECIFICATION ADVANTAGES AND DISADVANTAGES VANE PUMP APPLICATION OF VANE PUMP
3.2 CONTROL UNIT CONSTRUCTION AND WORKING 3.3 OIL RESERVOIR 3.4 DC MOTOR 3.5 POWER TRANSMISSION 3.6 INSTALLATION
BASE PLATE CONNECTION PIPES PUMP AND MOTOR MOUNTING CONTROL UNIT MOUNTING
3.7 ELECTRICAL CONNECTION 3.8 WORKING OF JACK 3.9 MAINTENENCE OF JACK 3.10 SAFETY PRECAUTIONS
4. CONCLUSION
41
5. BIBLOGRAPHY
42 2
1. INTRODUCTION 1.1 HYDRAULICS Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through most science and engineering disciplines, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry, pumps, turbines, hydropower, computational fluid dynamics, flow measurement, river channel behavior and erosion.
1.2 HYDRAULIC BASICS PRESSURE Pressure is force exerted against a specific area (force per unit area) expressed in psi (pounds per square inch), Bar or Pascal. Pressure can cause an expansion, or resistance to compression, of a fluid that is being squeezed. A fluid is any liquid or gas (vapor). An example of pressure is the air (gas) that fills an automobile tyre. As a tyre is inflated, more air is squeezed into it than it can hold. The air inside a tyre resists the squeezing by pushing outward on the casing of the tyre. The outward push of the air is pressure. Equal pressure throughout a confined area is a characteristic of any pressurized fluid. For example, in an inflated tyre, the outward push of the air is uniform throughout. If it were not, a tyre would be pushed into odd shapes because of its elasticity.
P = F/A
3
Units of pressure : MKS Units – Kgf/m2 and Kgf/cm2 SI Units
– Newton/m2 and N/mm2
N/mm2 is known as Pascal and represented by Pa. Other commonly used units of pressure are psi(pound per square inch) and bar. 1 Pascal (N/m2) = 10-5 Bar = 145.04×10−6 psi
FORCE The force is an external agent which produces or tends to produce change in the state of rest, motion, shape or size of an object and is expressed in Newton. It is a vector quantity. The Newton is the SI unit for force
An example of force is to raise a body, to displace a body from one place to the other, to stop a moving body etc. The relationship of force, pressure, and area is as follows:
F = P.A
Where, F = force P = Pressure in psi A = Area
4
PASCAL’S LAW Blaise Pascal formulated the basic law of hydraulics in the mid 17th century. He discovered that pressure exerted on a fluid acts equally in all directions. His law states that pressure in a confined fluid is transmitted undiminished in every direction and acts with equal force on equal areas and at right angles to a container's walls.
According to this law, “In a closed liquid the pressure applied at any part is equally transmitted in all directions and in the same amount”.
Or “If a liquid is in equilibrium then the pressure in every part of it is equal.” i.e.
P1= P2
Figure-1 Pascal’s law
F/A = f/a
F = fA/a 5
FLOW Flow is the movement of a hydraulic fluid caused by a difference in the pressure at two points. In a hydraulic system, flow is usually produced by the action of a hydraulic pump - a device used to continuously push the hydraulic fluid. The two ways of measuring flow are velocity and flow rate. VELOCITY Velocity is the average speed at which a fluid's particles move past a given point, measured in m/s. Velocity is an important consideration in sizing the hydraulic lines that carry a fluid between the components. FLOW RATE Flow rate is the measure of how much volume of a liquid passes a point in a given time, measured in Liter per minute (LPM).
Flow rate
determines the speed at which a load moves and therefore, is important when considering power.
VISCOSITY Viscosity is defined as the property of a fluid which offers resistance to movement of one layer of fluid over another adjacent layer of fluid.
Units of Viscosity: MKS Units – Kgf-sec / m2 CGS Units – dyne-sec/cm2 SI Units
– Newton-sec/m2
6
2. BASIC SYSTEM / DEVICES 2.1 HYDRAULIC PRESS Another useful application of the force magnifying action of liquid pressure is the hydraulic jack or hydraulic press Figure-2.
The pressure exerted by the force on the small piston on the left of the diagram is transmitted through the liquid. This means that large objects can be lifted by the cylinder on the right or large forces can be exerted on object held beneath the top plate as shown by the hydraulic press in Figure 2.
Figure-2 Principal of hydraulic press
7
Figure-3 Hydraulic Press 8
APPICATIONS Hydraulic presses are commonly used for forging of metal parts. Some of the largest in the world were built by the Heavy Press Program.
2.2 HYDRAULIC BRAKES Automotive brake systems are complex hydraulic circuits. In a hydraulic brake system, the master cylinder serves as the main fluid pump and moves the liquid through the system. The lines used to carry the liquid may be pipes, hoses, or a network of internal bores or passages in a single housing, such as those found in a master cylinder. Valves are used to regulate hydraulic pressure and direct the flow of the liquid. The output device is the unit that uses the pressurized liquid to do work. In the case of a brake system, the output devices are brake drum wheel cylinders and disc brake calipers.
Figure-4
Hydraulic Brakes
9
2.3 HYDRAULIC INTENSIFIER A hydraulic
intensifier is
a
hydraulic
machine
for
transforming hydraulic power at low pressure into a reduced volume at higher pressure. Such a machine may be constructed by mechanically connecting two pistons, each working in a separate cylinder of a different diameter. As the pistons are mechanically linked, their force and stroke length are the same. If the diameters are different, the hydraulic pressure in each cylinder will vary in the same ratio as their areas: the smaller piston giving rise to a higher pressure. As the pressure is inversely proportional to the area, it will be inversely proportional to the square of the diameter.
The working volume of the intensifier is limited by the stroke of the piston. This in turn limits the amount of work that may be done by one stroke of the intensifier. These are not reciprocating machines (i.e. continually running multi-stroke machines) and so their entire work must be carried out by a single stroke. This limits their usefulness somewhat, to machines that can accomplish their task within a single stroke. They are often used where a powerful hydraulic jack is required, but there is insufficient space to fit the cylinder size that would normally be required, for the lifting force necessary and with the available system pressure. Using an intensifier, mounted outside the jack, allows a higher pressure to be obtained and thus a smaller cylinder used for the same lift force. Intensifiers are also used as part of machines such as hydraulic presses, where a higher pressure is required and a suitable supply is already available. Some small intensifiers have been constructed with a stepped piston. This is a double-ended piston, of two different diameters, each end working in a different cylinder. This construction is simple and compact, requiring an overall length little more than twice the stroke. It is also still necessary to provide two seals, one for each piston, and to vent the area between 10
them. A leak of pressure into the volume between the pistons would transform the machine into an effective single piston with equal area on each side, thus defeating the intensifier effect. A mechanically compact and popular form of intensifier is the concentric cylinder form, as illustrated. In this design, one piston and cylinder are reversed: instead of the large diameter piston driving a smaller piston, it instead drives a smaller moving cylinder that fits over a fixed piston. This design is compact, and again may be made in little over twice the stroke. It has the great advantage though that there is no "piston rod" and the effective distance between the two pistons is short, thus permitting a much lighter construction without risk of bending or jamming.
Figure-5, Hydraulic Intensifier 11
2.4 HYDRAULIC JACK Hydraulic jacks are device used to lift the loads. Hydraulic jacks are used for shop works, lifting vehicles, lifting houses from their foundation. Hydraulic jacks are often used to lift elevators in low and medium rise buildings.
A hydraulic jack uses a fluid, which is incompressible, that is forced into a cylinder by a pump plunger. Oil is used since it is self lubricating and stable. When the plunger pulls back, it draws oil out of the reservoir through a suction check valve into the pump chamber. When the plunger moves forward, it pushes the oil through a discharge check valve into the cylinder. The suction valve ball is within the chamber and opens with each draw of the plunger. The discharge valve ball is outside the chamber and opens when the oil is pushed into the cylinder. At this point the suction ball within the chamber is forced shut and oil pressure builds in the cylinder.
Hydraulic jack is a device used lifting a jack to automobile, heavy machines. Thus, a hydraulic jack is a mechanical arrangement that uses the power of fluids (hydraulic - study of mechanical property of fluids) to lift really heavy objects and we are using oil, hence the jack as a means of power transmissions.
Figure-6 Hydraulic Jack 12
Figure-7 Hydraulic Jack
13
2.5 TYPES OF HYDRAULIC JACK (1) AIR HYDRAULIC JACK Basically jack climb up on the jack rod (Part of the lifting trestle) with the desired pressure, to lift up the load. Its action is same as a monkey that climbs a trunk tree; i.e., first it holds up on to the trunk with its legs and lunges upwards, then it holds on to the trunk with its hands and lifts its legs up. At any time, either its hands or legs have a grip on the trunk, which prevents it from falling down.
In the same manner, air hydraulic jack, air hydraulic bottle jack and jack is provided with two pairs of jaws, a lower pair of jaws and an upper pair of jaws for an excellent grip. During lifting, both the pairs are “locked”. In this position the jack can only move upwards. At the time of lifting, the lower pair of jaws grips the trestle rod while the jack lifts up. After completing the full stroke, the upper pair of jaws grips the trestle rod, however, the base of the jack moves upward. During the process of lowering, any one of the pairs is always locked.
Lightweight and build for heavy-duty use. The quick-lift mechanism allows a substantially shortened ram lifting time without load. A flow control valve prevents sudden falls of the ram. Featured a specially processed air pump for low noice.The built-in safety valve prevent use beyond rated the rated capacity or lifting limit.
14
Figure-8 Air Hydraulic Jack
(2) BOTTLE JACK In a bottle jack the piston is vertical and directly supports a bearing pad that contacts the object being lifted. With a single action piston the lift is somewhat less than twice the collapsed height of the jack, making it suitable only for vehicles with a relatively high clearance. For lifting structures such as houses the hydraulic interconnection of multiple vertical jacks through valves enables the even distribution of forces while enabling close control of the lift.
15
Figure-9 Bottle Hydraulic Jack (Exploded View)
Figure-10 Bottle Hydraulic Jack
16
(3) HYDRAULIC FLOOR JACK In a floor jack (aka 'trolley jack') a horizontal piston pushes on the short end of a bellcrank, with the long arm providing the vertical motion to a lifting pad, kept horizontal with a horizontal linkage. Floor jacks usually include castors and wheels, allowing compensation for the arc taken by the lifting pad. This mechanism provides a low profile when collapsed, for easy maneuvering underneath the vehicle, while allowing considerable extension.
Figure-11 Hydraulic floor Jack
17
(4) STRAND HYDRAULIC JACK
Figure-12 Strand Hydraulic Jack
(5) TOE JACK
Figure-13 Toe Jack
18
(6) TRAILER HYDRAULIC CYLINDER JACK
Figure-14 Trailer hydraulic Cylinder Jack
(7) PNEUMATIC JACK 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.
Figure-15 Pneumatic Jack
19
3. CONSTRUCTION AND WORKING OF JACK 3.1 HYDRAULIC CYLINDER A hydraulic actuator receives pressure energy and converts it to mechanical force and motion. An actuator can be linear or rotary. A linear actuator gives force and motion outputs in a straight line. It is more commonly called a cylinder but is also referred to as a ram, reciprocating motor, or linear motor. A rotary actuator produces torque and rotating motion. It is more commonly called a hydraulic motor or motor.
Cylinders are linear actuators which convert fluid power into mechanical power. They are also known as JACKS or RAMS. Hydraulic cylinders are used at high pressures and produce large forces and precise movement. For this reason they are constructed of strong materials such as steel and designed to withstand large forces.
Figure-16 Hydraulic Cylinder Designed For Jack
20
CONSTRUCTION AND WORKING OF CYLINDER The cylinder fabricated for the jack have a sleeve in which the piston reciprocates while operation. The cylinder material is cast iron and welded with an iron base plate. The plate is gas welded below the hollow cast iron cylinder. There is an opening for oil in the base of cylinder.
A cast iron head cover is designed for covering the cylinder from upper end. The piston have an oil rubber ring to seal the fluid in cylinder while operation. The piston rod is fitted with the piston and screw nut on other end. The head cover is locked with the help of circlip lock. A hole is made in the head cover to release air from the upper hollow portion of cylinder while reciprocating motion.
When fluid (oil) pushed by the pump into the cylinder from the inlet opening given below, it pushes the piston up in the cylinder and thus linear motion is obtained by displacement of piston in the cylinder.
CYLINDER SPECIFICATION Cylinder internal diameter :
76mm
Cylinder outer diameter
94 mm
:
Stroke
:
116.5 mm
Volume of cylinder
:
528.22 ml
Base plate diameter
:
115 mm
Piston length
:
15 mm
21
DESIGN CONSIDERATION Lifting capacity
:
1000kg
Pump max pressure
:
22 bar @ 1000 rpm 224337.56 kgf/m2
W=PxA
1000 = 224337.56 x 3.14 x r2
r = .0376 m = 37.67 mm
Therefore Diameter,
r x 2 = 75.35 mm
(Approx 76 mm considered)
22
Figure-17 Hydraulic Cylinder Designed For Jack(Expoled View)
23
3.2 HYDRAULIC PUMP Hydraulic pumps convert mechanical energy from a prime mover (engine or electric motor) into hydraulic (pressure) energy. The pressure energy is used then to operate an actuator. Pumps push on a hydraulic fluid and create flow. A rotary vane pump is used in the jack to create the pressure difference in fluid medium.
ROTARY VANE PUMP A rotary vane pump is a positive-displacement pump that consists of vanes mounted to a rotor that rotates inside of a cavity. In some cases these vanes can be variable length and/or tensioned to maintain contact with the walls as the pump rotates.
In a vane-type pump, a slotted rotor splined to a drive shaft rotates between closely fitted side plates that are inside of an elliptical- or circularshaped ring. Polished, hardened vanes slide in and out of the rotor slots and follow the ring contour by centrifugal force. Pumping chambers are formed between succeeding vanes, carrying oil from the inlet to the outlet. A partial vacuum is created at the inlet as the space between vanes increases. The oil is squeezed out at the outlet as the pumping chamber’s size decreases.
Because the normal wear points in a vane pump are the vane tips and a ring’s surface, the vanes and ring are specially hardened and ground. A vane pump is the only design that has automatic wear compensation built in. As wear occurs, the vanes simply slide farther out of the rotor slots and continue to follow a ring’s contour. Thus efficiency remains high throughout the life of the pump.
24
CONSTRUCTION AND WORKING OF PUMP A slotted rotor is eccentrically supported in a cycloidal cam. The rotor is located close to the wall of the cam so a crescent-shaped cavity is formed. The rotor is sealed into the cam by two side plates. Vanes or blades fit within the slots of the impeller. As the rotor rotates (yellow arrow) and fluid enters the pump, centrifugal force, hydraulic pressure, and/or push rods push the vanes to the walls of the housing. The tight seal among the vanes, rotor, cam, and side plate is the key to the good suction characteristics common to the vane pumping principle. The housing and cam force fluid into the pumping chamber through holes in the cam (small red arrow on the bottom of the pump). Fluid enters the pockets created by the vanes, rotor, cam, and side plate. As the rotor continues around, the vanes sweep the fluid to the opposite side of the crescent where it is squeezed through discharge holes of the cam as the vane approaches the point of the crescent (small red arrow on the side of the pump). Fluid then exits the discharge port.
Figure-18 Working of Rotary Vane Pump
25
Figure-19 Parts of Rotary Vane Pump
PUMP SPECIFICATION Type
:
Rotary vane pump
No. of blades
:
10
Body Material
:
Aluminium
Max. Pressure
:
25 bar at 1000 rpm
Max. Flow
:
10 Lpm (liter per min) at 1000 rpm
Rotation
:
Clockwise
ADVANTAGES AND DISADVANTAGES OF VANE PUMP
ADVANTAGES : Handles thin liquids at relatively higher pressures. Compensates for wear through vane extension. Sometimes preferred for solvents, LPG. 26
Can run dry for short periods. Can have one seal or stuffing box. Develops good vacuum.
DISADVANTAGES : Can have two stuffing boxes. Complex housing and many parts. Not suitable for high pressures. Not suitable for high viscosity. Not good with abrasives.
APPLICATIONS OF VANE PUMP Aerosol and Propellants. Aviation Service - Fuel Transfer, Deicing. Auto Industry - Fuels, Lubes, Refrigeration Coolants. Bulk Transfer of LPG and NH3. LPG Cylinder Filling. Alcohols. Refrigeration - Freons, Ammonia. Solvents. Aqueous solutions. 3.3 CONTROL UNIT Control unit controls the direction of flow and pressure of the fluid in the system. It is a major part of the system, the control unit reliefs the excess pressure and stops the stock of oil filled the cylinder to return back. Control unit provides manual and automatic control on the pressure and flow of oil in the system. Weather it is from pump to cylinder or cylinder to tank 27
CONSTRUCTION AND WORKING OF CONTROL UNIT The control unit for the jack is fabricated on an aluminium block. Relief valve, release valve(Manual Shut off valve) and delivery valves(By pass valve) are fitted in the control unit. The assembly of control unit is shown in the figure 20. Connections are made with the help of steels pipes, rubber hose and banjo bolts. When high pressure fluid enters the control unit it passes through the delivery valve which acts as a one way valve allows oil to flow from pump to cylinder and restrict the opposite flow of oil from cylinder to pump. There is a relief valve fitted between the main gallery and flow gallery the excess pressure during the operation is drained in the reservoir by the relief valve. There is a return valve fitted between the delivery and flow lines. This return valve(On-Off valve) is manually operated valve used to drain the stock of the cylinder.
28
30
3.4 OIL RESERVOIR There is a plastic tank fitted in the jack of 700ml volume. The total oil required in the jack is 600ml. There are two openings in the tank one is connected to the inlet of the pump and another is connected to the return flow from the control unit. The connections are made with the help of rubber and steel pipes. There is a cap on the top of the tank for refilling it. Tank is mounted with the help of thin metal sheet in the jack. Hydraulic oil of 46 grade is used in the jack. As the pump used is vane pump so the oil of low viscosity as grade 46 is used.
3.5 DC MOTOR Motor is a device which converts electrical energy into mechanical energy. A DC Motor is used in the jack to rotate the pump .DC motor is used because the current available at vehicle battery is DC current. Motor have to terminals positive and negative. Negative terminal of the motor is itself the body of motor.
Motor Specification :
Type
:
Permanent magnet DC motor
Power input
: 12 volt DC
Power output
: 0.4KW = 0.5 H.P
Rotation
: Clockwise
31
3.6 POWER TRANSMISSION
In this jack power is transmitted with the help of gears.
Figure-22
Gears are generally used for one of four different reasons: To reverse the direction of rotation To increase or decrease the speed of rotation To move rotational motion to a different axis To keep the rotation of two axis synchronized
32
Power is transmitted from the motor to pump, the gear fitted on the motor spline is the driver gear and the gear fitted to the pump shaft is the driven gear. The driver gear have 24 teeths while the driven gear have 68 teeths.
If two gears are in mesh, then the product of speed and teeth is conserved Therefore
S1 x T1 = S2 x T1
Here T = Number of Teeths S = Speed or Rpm
Thus, Driver gear teeths (T1) = 24 Driven gear teeths(T2) = 68 24 x S1 = 68 x S2
S1 / S2 = 2.833
The ratio of rpm of the driver to the driven gear is 2.833
33
3.7 INSTALLATION BASE PLATE All the components are mounted with the help of bolts in an aluminium plate this plate is the base plate. Base plate size –
254mm x 203mm x 10mm (L x B x t)
CONNECTION PIPES Steel pipes of 8 mm diameter are used for connection between pump and control unit. Return and inlet pipes are rubber pipes. The cylinder and the control unit is connected with a flexible hydraulic hose pipe. This hose pipe have maximum working pressure capacity of 40 Mpa.
PUMP AND MOTOR MOUNTING Pump and motor are mounted on the base plate with the help of three vertical mounting plates. These mounting plates are aluminium plates. Pump and motor are mounted such that in order to provide the proper mating of gears used to transmit the power. A small tolerance is provided between the gears in order to avoid the interference of teeth and noise. COUNTROL UNIT MOUNTING Control unit is mounted in the base plate at the delivery side of the pump with the help of a bolt. The control unit is connected with the tank as return flow with the help of rubber pipe and also connected with the outlet of the pump with the help of steel pipe. 3.8 ELECTRICAL CONNECTION Electric connections are made with two terminal wires as positive and negative terminals. Positive terminal wire is an insulated copper wire of thickness 5 mm and 15 feet length. This wire has a battery clip on one end 34
which is to be connected at the positive terminal of the battery of the vehicle. A starter switch is fitted for on off operation of the jack. Negative terminal wire is also a copper wire of thickness 5mm and length 3 feet. This wire is small in length and also have a clip on one end. This negative terminal wire is connected with jack body as earth and while operation it is connected to the vehicle body acting as a negative terminal.
3.9 WORKING OF JACK The cylinder of the jack is placed according to the lifting position of the vehicle. After that terminal wires are connected according to polarity, positive terminal wire is connected to the positive terminal of the battery with the help of battery clip, while negative terminal is connected to the vehicle body at any point near to the jack. Now after connections jack is ready to lift the load or vehicle. When the starter switch is pushed. The motor starts rotating the pump. Thus pump pushes the high pressure fluid into the control unit. This fluid passes through the delivery valve and moves to the cylinder with the help of flexible hydraulic hose. As soon as oil goes into the cylinder the piston in the cylinder starts moving up . Pump sucks the oil from tank and delivers it to the cylinder. The jack starts lifting the load and stops after completion of stroke of the piston. Now after releasing the switch the vehicle remain raised, as the return flow of oil is stopped by the delivery valve fitted in the control unit. The relief valve reliefs the pressure if the load is exceeding the maximum lifting capacity and also if switch is not released after completion of stroke.
Now to lower down the load on jack the oil filled in the cylinder which tends to keep the vehicle lifted is released with the help of release valve. The oil filled in the cylinder is drained in the tank and the load comes down slowly. In this way the oil circulates from cylinder to tank and tank to cylinder during operation. A block diagram of jack is shown in the figure. 35
36
3.10 MAINTENANCE When the jack is not in use, keep the cylinder piston fully retracted. Store the jack on its base and in a well protected area where it will not be exposed to corrosive vapors, abrasive dust, or any other harmful elements.
Visually inspect the jack before each use. Take corrective action if any of the following problems are found:
Cracked or damaged housing. Excessive wear, bending, or other damage. Loose hardware. Leaking hydraulic fluid. Scored or damaged piston rod. 3.11 SAFETY PRECAUTIONS
Inspect the jack before each use; do not use the jack if it is damaged, altered, or in poor condition. To prevent tipping, set up the jack on a hard, level surface. The load must not exceed the rated lifting capacity of the jack. Lift only dead weight. Center the load on the jack saddle, because off-center loads can damage the seals and cause hydraulic failure. Use the jack for lifting purposes only. This jack is designed to LIFT loads, not support loads. Immediately support a lifted load with jack stands. Use only approved hydraulic fluid, such as 32, 46, 68 Grade Hydraulic Oil or equivalent. 39
These warnings cannot cover every situation, so have safety foremost in our mind when setting up a job.
40
4. CONCLUSION This project as a working hydraulic jack performed well and according to the design it is working with its full capacity of lifting 1000kg load. The model is working fine as expected during design. We all worked in a team to get these positive results. We machined the components by own and got help from others to fabricate the components like control unit, cylinder, Base plate, mountings etc. We thought creatively throughout the project and solved every problem occurred regarding to project. We used all of our knowledge which we gained in our engineering curriculum. We used knowledge of Hydraulics, Machining, CAD, and Power Transmission with gears etc. Overall we are proud of what we have produced. Before we began this project we don’t have much experience with hydraulic machines, metal cutting and power transmission. Overall we have gained a huge set of skills in areas in which we think will be essential to us further down the line. And finally it’s a team work whatever we achieved.
41
BIBLIOGRAPHY
S. No.
Title
Book/Website
Author’s Name
Publisher
Year
Page No.
1.
Hydraulic Basics
Hydraulics
Moline-Illinois
Deere and Company Service Publications
1997
1.1
2.
Hydraulic Press
-
-
2012
3.
Hydraulic Brakes
Peter Verdone
PeterVerdone.com
2012
4.
Hydraulic Intensifier
Dr. R.K. Bansal
Laxmi Publications
2009
5.
Hydraulic Jack
-
-
-
6.
Types of Hydraulic Jack
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-
-
7.
Hydraulic Cylinder (Introduction)
Hydraulics
Moline-Illinois
Deere and Company Service Publications
1997
8.
Hydraulic Pump
Hydraulics, www.pumpschool.com/ principles
Moline-Illinois
Deere and Company Service Publications
1997
http://www.schoolphysi cs.co.uk The basic Hydraulic System Theory Fluid Mechanics Wikipedia.org/wiki /jack_(device) Wikipedia.org/wiki /jack_(device)
1044 4.1 3.1
