Proj Report Final

8/8/2019 Proj Report Final

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PROJECT SYNOPSIS

The HCV dynamometer is a unique machine which is used for the testingof different materials used in different types of brakes, and thereby evaluatingtheir various properties. The brakes tested on this machine are those used for heavy commercial vehicles like trucks, buses etc.

This dynamometer is designed to test both, disc and drum, types of brakes and that too of different sizes. This facility makes the dynamometer quiteversatile from application point of view. It covers several parameters for thetesting. To mention a few, braking torque, friction characteristics, temperatureetc. are measured and evaluated on this dynamometer.

Various driving conditions of the vehicles can be simulated by means of the inertia flywheels provided in the machine. These inertia flywheels are themost vital elements used for simulation of vehicle conditions. There are in-all 8flywheels on this machine and all these are of different sizes. All these flywheelsare detachable. i.e. they can be engaged or disengaged as per requirementindividually.

As mentioned earlier, driving conditions of the vehicle are simulated interms of different values of inertia. A vehicle at high speed, vehicle at full load,vehicle on a slope, vehicle parked etc. are the various vehicle conditions that can

be simulated on this dynamometer. A special facility provided on thisdynamometer is that of the wet conditions testing.

The operation of the dynamometer and the data retrieving system iscompletely computer controlled. Special software is developed and used for thecomplete operation of the dynamometer.

The driving unit is a 170 kW D.C. motor. The purpose behind using D.C.motor is that it has a very high starting torque. It also possesses a wide range of speed variations which is very essential for the simulation of various speedingconditions of the vehicle.

Various tests that can be performed on this dynamometer are the staticfriction test, parking brake test, partial load test and full load test. All the dataretrieved from the tests is stored in the computer for further comparison purpose.


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Sr.no. Topic Pageno.

1 Introduction1.1) Brakes1.2) Friction Materials1.3) Brake testing methods

1

2 Inertia Simulation2.1)introduction2.2) System Inertia And Removable Inertia

9

3 Driving Unit3.1)Introduction3.2)Why D.C. Drive3.3) Speed Control Methods

17

4 Tailstock End4.1) Constructional Features4.2) Brake Mounting Arrangement

22

5 Design calculations5.1) Optimum design5.2) Material selection of shaft5.3) Shaft design5.4) Inertia disc calculations5.5) Drawings

29

6 Dynamic balancing 497 Data Acquisition System 558 Standards for brake testing 629 Optional Features

9.1) Wet test9.2) Static Friction Test

65

10 Conclusion 6811 Bibliography 69

INDEX


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INTRODUCTION

Safety is the primary impetus behind advanced brake testing technology.According to studies, brake system defects are the single largest cause of automobile defectrelated accidents

The evidence is now in to suggest that vehicle defects, particularly brake systemdefects, are an avoidable cause of many automobile accidents. Even if braketests result in only a one percent reduction in vehicle accidents, annual savingswould include 460 fewer deaths, 34,000 fewer injuries.

The brake testing dynamometer developed provides a quick go/no-go check of a vehicle's braking ability, offers a diagnosis of the braking system, help a shopmerchandise its brake services and provide a safer vehicle for the car owner.

The general braking system in a 4-wheeled vehicle:


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General problems faced with a braking system

Leaky wheel cylinder or caliper piston

Seized wheel cylinder or caliper piston

Worn lining

Worn or scored drum or rotor

Defective brake hardware

Out of round drum/out of parallel rotor

Defective proportioning valve


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Brake fade

Stuck parking brake cable

Low fluid level

Defective master cylinder

Brake Testing Methods

A variety of brake testing methods are used today, offering varying levels of accuracy and reliability.

Road Test

Road testing is one of the most popular methods for checking vehicle brakingcapability. In a road test, the technician simply drives the vehicle, applies thebrakes, and observes the results. This test can be performed on public streets,on the service facility's parking lot, or as a vehicle is driven into the service bay.

Visual Inspection


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The visual inspection is currently the most common method of brake testing usedtoday and is the method most often used by. This quick stop and pull-a-wheelmethod of testing typically specifies that one or two wheels are examined. Italone cannot verify brake system operation. Seldom performed by itself, the pull-a-wheel inspection is generally accompanied with a quick stop road test.

Plate Tester Method

With a plate brake testing system, either two or four steel plates are installed onthe shop floor, with a display console alongside. (Four plates allow all four wheels to be tested simultaneously; two plates test one axle at a time.)

During testing, a technician drives a vehicle onto the plates at four-to-eight mphand then applies the brakes. Working with a computer, force transducers in the

plate assemblies measure the braking forces, calculate the results, and displaythem on a panel or a CRT.

Inertia dynamometer testing method

Various driving conditions of the vehicles can be simulated by means of theinertia flywheels provided in the machine. These inertia flywheels are the mostvital elements used for simulation of vehicle conditions. There are in-all 8flywheels on this machine and all these are of different sizes. All these flywheels

are detachable. i.e. they can be engaged or disengaged as per requirementindividually. This dynamometer is designed to test both, disc and drum, types of brakes and that too of different sizes. This facility makes the dynamometer quiteversatile from application point of view. It covers several parameters for thetesting. To mention a few, braking torque, friction characteristics, temperatureetc. are measured and evaluated on this dynamometer.

The operation of the dynamometer and the data retrieving system iscompletely computer controlled. Special software is developed and used for thecomplete operation of the dynamometer.


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DRIVING UNIT

Types of drives:A.C. DriveD.C. Drive

Drive used here: D.C. Motor


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Why DC motor is used here?

This dynamometer uses dc motor because the speed-torque relationship can bevaried to almost any useful form -- for both dc motor and regenerationapplications in either direction of rotation. Continuous operation of dc motors iscommonly available over a speed range of 8:1. Infinite range (smooth controldown to zero speed) for short durations or reduced load is also common.

Dc motors are often applied where they momentarily deliver three or more timestheir rated torque. In emergency situations, dc motors can supply over five timesrated torque without stalling (power supply permitting).

Dynamic braking (dc motor-generated energy is fed to a resistor grid) or regenerative braking (dc motor-generated energy is fed back into the dc motor supply) can be obtained with dc motors on applications requiring quick stops,thus eliminating the need for, or reducing the size of, a mechanical brake.

Dc motors feature a speed, which can be controlled smoothly down to zero,immediately followed by acceleration in the opposite direction -- without power circuit switching. And dc motors respond quickly to changes in control signalsdue to the dc motor's high ratio of torque to inertia.

Speed control:


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There are two ways to adjust the speed of a wound-field dc motor. Combinationsof the two are sometimes used to adjust the speed of a dc motor.

Shunt-field control:

Reel drives require this kind of control. The dc motor's material is wound on areel at constant linear speed and constant strip tension, regardless of diameter.

Control is obtained by weakening the shunt-field current of the dc motor toincrease speed and to reduce output torque for a given armature current. Sincethe rating of a dc motor is determined by heating, the maximum permissiblearmature current is approximately constant over the speed range. This meansthat at rated current, the dc motor's output torque varies inversely with speed,and the dc motor has constant-horsepower capability over its speed range.

Dc motors offer a solution, which is good for only obtaining speeds greater thanthe base speed. A momentary speed reduction below the dc motor's base speedcan be obtained by overexciting the field, but prolonged over excitation overheatsthe dc motor. Also, magnetic saturation in the dc motor permits only a smallreduction in speed for a substantial increase in field voltage.

Dc motors have a maximum standard speed range by field control is 3:1, and thisoccurs only at low base speeds. Special dc motors have greater speed ranges,but if the dc motor's speed range is much greater than 3:1, some other controlmethod is used for at least part of the range.

Armature-voltage Control:

In this method, shunt-field current is maintained constant from a separate sourcewhile the voltage applied to the armature is varied. Dc motors feature a speed,

which is proportional to the counter emf. This is equal to the applied voltageminus the armature circuit IR drop. At rated current, the torque remains constantregardless of the dc motor speed (since the magnetic flux is constant) and,therefore, the dc motor has constant torque capability over its speed range.Horsepower varies directly with speed. Actually, as the speed of a self-ventilatedmotor is lowered, it loses ventilation and cannot be loaded with quite as mucharmature current without exceeding the rated temperature rise.


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Speed range:

If field control is to be used, and a large speed range is required, the base speedmust be proportionately lower and the motor size must be larger. If speed rangeis much over 3:1, armature voltage control should be considered for at least partof the range. Very wide dynamic speed range can be obtained with armaturevoltage control. However, below about 60% of base speed, the motor should bederated or used for only short periods.

Speed variation with torque:

Applications requiring constant speed at all torque demands should use a shunt-wound dc motor. If speed change with load must be minimized, a dc motor regulator, such as one employing feedback from a tachometer, must be used.

When the dc motor speed must decrease as the load increases, compound or series-wound dc motors may be used. Or, a dc motor power supply with adrooping volt-ampere curve could be used with a shunt-wound dc motor.

Reversing:

This operation affects power supply and control, and may affect the dc motor's

brush adjustment, if the dc motor cannot be stopped for switching before reverseoperation. In this case, compound and stabilizing dc motor windings should notbe used, and a suitable armature-voltage control system should supply power tothe dc motor.

Duty cycle:


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Direct current motors are seldom used on drives that run continuously at onespeed and load. Motor size needed may be determined by either the peak torquerequirement or heating.

Peak torque :

The peak torque that a dc motor delivers is limited by that load at whichdamaging commutation begins. Dc motor brush and commutator damagedepends on sparking severity and duration. Therefore, the dc motor's peaktorque depends on the duration and frequency of occurrence of the overload. Dcmotor peak torque is often limited by the maximum current that the power supplycan deliver.

Dc motors can commutate greater loads at low speed without damage. NEMAstandards specify that machines powered by dc motors must deliver at least150% rated current for 1 min at any speed within rated range, but most dc motors

do much better.Heating:

Dc motor temperature is a function of ventilation and electrical/mechanicallosses in the machine. Some dc motors feature losses, such as core, shunt-field,and brush-friction losses, which are independent of load, but vary with speed andexcitation.

The best method to predict a given dc motor's operating temperature is to usethermal capability curves available from the dc motor manufacturer. If curves are

not available, dc motor temperature can be estimated by the power-loss method.This method requires a total losses versus load curve or an efficiency curve.

For each portion of the duty cycle, power loss is obtained and multiplied by theduration of that portion of the cycle. The summation of these products divided bythe total cycle time gives the dc motor's average power loss. The ratio of thisvalue to the power loss at the motor rating is multiplied by the dc motor's ratedtemperature rise to give the approximate temperature rise of the dc motor whenoperated on that duty cycle.

Specifications of motor used in the dynamometer

Power: 170 kW

Speed Range: 0 2500 rpm.

0 600 rpm at constant torque.


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600 2500 rpm at constant power.

INERTIA SIMULATION

Inertia , or in this case rotational inertia is an intrinsic property of all physicalobjects which have mass and are rotated about an axis. It takes torque toincrease (or decrease) the RPM of a rotating object. The amount of torquerequired is the product of the inertia and the rate of angular acceleration .

T = I x aWhere T = torque

I = moment of inertia a = angular acceleration
http://popup%28%27inertia_def.html%27%29/http://popup%28%27torque_def.html%27%29/http://popup%28%27ang_acc_def.html%27%29/http://popup%28%27inertia_def.html%27%29/http://popup%28%27torque_def.html%27%29/http://popup%28%27ang_acc_def.html%27%29/


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As soon as the RPM is stabilized, however, it requires less torque to maintainthat RPM. Only enough torque to offset the parasitic losses is required at thatpoint.

When a motor is bolted to a dynamometer, the motor and dynamometer rotating

elements are connected together and represent the sum of all the rotatingmasses. This sum can be thought of as a single mass with a specific moment of inertia which does not change throughout the testing procedure. Because of thisrotational inertia, torque is required to accelerate the motor, even if thedynamometer is unloaded. A typical dynamometer which measures torque froma lever arm attached to the stator housing cannot sense this inertial or "reactive"torque because of the way it is mechanically connected. Our advanced "reactiontorque" measurement system can.

If an motor is performing a sweep test where the RPM is continuously increasing,then some of the torque the motor is producing is consumed by accelerating the

rotating elements ( T = I x a ). Because of this, a conventional dynamometer willread a torque lower than the actual motor torque while the motor is accelerating.Some commercial data acquisition systems "adjust" this reading to show whatthe motor torque would be if the motor were being held at a constant speed. Theabove equation shows that the adjustment amount is directly related to how fastthe motor is accelerating and the total inertia of the rotating elements.

What is inertia simulation? Whenever it is desired to test a vehicle for its braking parameters, it is notpossible to make a real time test. The biggest force that the brake encounterswith is the inertia force. Now this inertia force can be generated in thedynamometer by using certain mechanical and electrical arrangements. Theprocedure of doing so is called inertia simulation. All the vehicle inertia effectscan be simulated in one single dynamometer.
http://popup%28%27losses_def.html%27%29/http://popup%28%27losses_def.html%27%29/


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How it is done?The dynamometer incorporates a shaft on the end of which the brake to be

tested is to be mounted. This shaft is driven by a powerful d.c. shunt motor. But just the motor is incapable of generating sufficient amount of inertia required for testing. Hence inertia discs or flywheels are used. There are in all 8 flywheels onthe shaft. All these flywheels are removable ones. They are engaged to the shaftby means of 4 fixed discs. Various combinations of the flywheel engagementsequals various inertia simulations. Various inertia simulations equals varioustypes of tests to be performed on brake. The fixed discs are keyed to the mainshaft and depending on the amount of inertia required, the number of discs areengaged with these fixed discs. Several combinations of these disc engagementsare possible. These removable discs are engaged with the fixed discs by meansof nuts and bolts. The engagement and disengagement of these discs is donepneumatically.

Implementation of Inertia SimulationThe most apparent way to simulate inertia is to match the torque that should bepresent in a given braking situation and use torque feedback to the motor controller to maintain the proper amount of torque. This type of control requires a torque cell toprovide feedback to the controller on the shaft torque. The general layout is shownbelow.


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Standards for brake testing

There are several standards used for brake testing. These standards areissued by world renowned organizations like SAE, JASO, ECE-R90 etc.


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BEEP using SAE J2430

CTA-FMVSS 121 static torque capacityDrum-in-hat PerformanceDry Friction Clutch Durability

Dry Friction Clutch PerformanceDTV Generation and Correction

ECE R90 Type Approval Categories M, N and O

FMVSS 105 & 135 Simulations

FMVSS 121D-RP628 Qualification

ISO 11157-ECE R13 Performance

JASO C406 Passenger Car Brake Performance

JASO C407 Truck and Bus Brake Performance

JASO C419 Caliper Durability

SAE J2115 Commercial Vehicles Performance and Wear

SAE J2521 Noise Squeal Matrix

SAE J2522 AK-Master

SAE J2681 Friction Behavior AssessmentStructural Integrity

SAE J2707-JASO C427 Wear

1. According to Regulation 13, the performance of brake systems should be inline with the tests required for the approval of new brake pads at source. Theassessment is made to make sure that brake pads meet standards of approval.


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2. Also, brake pads made for the open spare parts market must pass thefollowing performance tests:

2.1 Speed sensitivity test.This tests the difference in braking performance (deceleration) of the pads at

different speeds (65, 100, 135 kmph). Deceleration differences of up to +/- 15% of the results obtained from tests on the lowest speed are allowed.

2.2 Compressibility test.To avoid excessive pressure on the brake pedal, the compressibility of the frictionmaterial must not go beyond the following limits: * Comp

* Compressibility in cold conditions: less than 2% at room temperature..* Compressibility in hot conditions: less than 5% at 500C.

2.3 Adherence.Adherence between the friction material and backing plate should at least have thesame value as the Newton cut test 250 per square centimeter of the friction materialshape.

3. Markings and packaging

In order to identify approved brake pads easily, both they and their packagingmust comply with regulation 90 in terms of the information that should appear onthe break pad itself and its packaging. The specifications are as follows:

3.1. On the brake pad:- The test approved stamp for the corresponding brake pad.- Manufacture date, month and year at least.- Composition and type of brake lining.

3.2. On the packaging:- Each axis set must come in a sealed package to prevent tampering.- The name of the manufacturer, the composition and type of replacement brake

pad, the vehicles for which it has been approved, and the approved stamp mustappear on packaging.

4. Manufacturing approval

If deemed necessary, the body responsible for approving the product can assessthe producers quality control methods. The inspector can take random samplesfrom the producer for laboratory testing. Inspections authorized by the approved


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body should normally take place once a year.

In the case of negative inspection results, the approval given to that type of brakepad in accordance with the Regulation will be withdrawn.

Slip ring thermocouple


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Apart from torque and speed, temperature measurement is also equallyimportant in the procedure of brake testing. This parameter comes into pictureevery time the brake is applied. The braking material has certain operatingtemperature limits which should not be crossed. Else it will result in jamming of the brake due to high temperature. Whenever brakes are applied at high speed,

the braking element becomes almost red hot. So it becomes of vital importanceto determine the operating temperature limits of the braking system.

The best way of measuring these temperatures is that of thermocouples. Ithas got a good range of temperatures. But the question arises of the mounting of the thermocouple. Because it requires contact to be maintained with the subject.But the problem arises when the subject is in rotary motion as in this case.

As a solution to this problem, slip-ring thermocouples are used in thisapplication. These thermocouples can maintain constant contact with the rotatingbrake.

The slip ring is as shown above

The low noise thermocouple slip-ring assembly is ideal for transmission of lowlevel emf's where it is necessary to attach thermocouples to rotating parts. It canbe used with any thermocouple calibration. Its low noise design introduces a totalsignal error of less than five micro volts at rotational speeds up to 2000 rpm.

The thermocouple used is Chromel-Alumel thermocouple


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The output leads consist of plain copper wires; no compensation is included.The slip-ring assembly will transfer the true microvolt signal coming from arotating assembly.

Assembly

The assembly of the slip ring and the thermocouple is as shown in the figurebelow.

This low noise thermocouple slip-ring assembly is ideal for transmission of low level emf where it is necessary to attach thermocouples to rotating parts. Itcan be used with any thermocouple calibration. Its low noise design introduces atotal signal error of less than five microvolt at rotational speeds up to 2000 rpm.

Torque measurement

What is torque?

It's a measure of the forces that cause an object to rotate. Reaction torque is theforce acting on the object that's not free to rotate. An example is a screwdriver applying torque to a rusted screw.


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between the driver motor, or driven load, and ground. An added benefit is thatsuch an installation is not limited in RPM by the torque sensor.

Types of measurements of torque sensors

Torque sensors fall into two categories of measurement; reaction torque androtational torque. Reaction torque sensors convert the torque applied to afixed sensor into a useable measurement signal. Examples of reaction torqueapplications include automotive brake testing, dynamometer testing, and bearingfriction and lubrication studies. Rotational, or rotary, torque sensors typicallymeasure the torque generated by rotating devices such as electric motors,automotive engines, transmissions, pumps, and compressors. The torque sensor that has been incorporated in this dynamometer is of the flange type reactiontorque sensor.

Flange type torque sensor


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Reaction torque sensors of the flange type are machined from a single piece of rigid steel that is instrumented with strain gauges in a Wheatstone bridge circuit.They have no moving parts and are typically flange mounted into a fixed position.

These torque sensors utilize strain gages that are configured in a Wheatstonebridge as their primary sensing element. The resistance value of the strain gageschanges when torsional load is applied to the sensing structure and

consequently, any voltage through the bridge circuit will be varied. TheWheatstone bridge requires a regulated DC voltage excitation that is commonlyprovided by a strain gage signal conditioner. The resultant output signal from thetorque sensor is typically expressed in units of millivolt per volt of excitation. Thismillivolt signal then varies proportionately to the applied torque. The strain gagesignal conditioner provides zero and span adjustments to scale its 0 to 5V DCanalog output to be proportional to any desired input.range. Additional features of the signal conditioner may include a digital display and alarm set point limits.Reaction torque sensors are provided with an electrical connector, and cableassemblies are necessary to interface this connection to the strain gage signalconditioner. Two types of cable are commonly available, and their use is

dependent upon signal transmission distance. Cable assemblies may beselected with a terminating connector, which makes it easier to connect to astrain gage signal conditioner, or with a pigtail termination that allows connectionto screw terminal connections on other styles of strain gagesignal conditioners.

OPTIMUM DESIGN

Optimum design of a mechanical element is the selection of material and thevalues for independent geometrical parameters with the explicit objective of


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either minimizing a most significant undesirable effect or maximizing a mostsignificant functional requirement making certain inn a design procedure that amechanical element satisfies other functional requirements and that other undesirable effects are kept within tolerable limits.

The optimum design is carried out on the basis of most significant quantity to beoptimized. Therefore the objective in the optimum design might be to maximizeone of the quantities like: Power transmitting capacity, load carrying capacity,energy storing capacity ,etc; or to minimize one of the quantitieslike:cost,weight,deflection etc.

OBJECTIVE OF OPTIMUM DESIGN

For any design problems, a large number of solutions are available which fulfillthe performance, cost, safety and robustness requirements .In the present daysof competition, it is very important to select the best available design solutions.

The optimization techniques provide the tool for selecting the best designsolutions from the feasible solutions. An optimum design is the best attainablesolution to the design problem within the given constraints. The optimum designtargets a single parameter for optimizing i.e. maximizing or minimizing whilefulfilling the other requirements.

CLASSIFICATION OF DESIGN EQUATIONS

1. Primary Design Equations (P.D.E)2. Subsidary Design Equations (S.D.E)3. Limit Equations (L.E)

1. Primary Design Equations (P.D.E):In the optimum design of the mechanical element, the primary design equation isthe most important which expresses the most significant functional requirementto be maximized or the most significant undesirable element to be minimized.The primary design equation expresses the quantity upon which the particular optimum design is based. It is designated by P.D.E.

2. Subsidary Design Equations (S.D.E)In the optimum design of mechanical element the design equation other that theprimary design equation are known as subsidary design equations. Thesubsidary design equation expresses either functional requirements or undesirable effects .Subsidary design equations are expressed by S.D.E.


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3. Limit Equations (L.E)In optimum design the satisfactory ranges are available for the values of certainparameters these ranges are expressed mathematically by equations known as

limit equations .The limit Equations are designated as L.E

Optimum design of main shaft

The main shaft is one of the most important parts of the brake testingdynamometer. It has to carry the load of 8 inertia discs and 4 fixed discs.In addition to this it is also subjected to torsion.


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A large number of materials are available for manufacturing shafts but wewill have to select the material such that it results in minimum cost andmaximum strength.

If we use a material with very high ultimate strength the amount of materialrequired will be less but cost of such materials is also high.If we use lowcost materials with low values of strength then more material will berequired.

Thus we need to strike a balance between cost and strength. For this weuse the approach of optimum design .

The various materials used for manufacturing shafts are as follows:

MATERIAL Syt(N/mm 2) Sut(N/mm 2) COST(Rs/kg)

40Cr1Mo28 600 720 63

40Ni2Cr1Mo28 800 1150 63

31Ni3Cr65Mo55 687 883 65

40Mn2S12 - 600 50

17Mn1Cr95 - 800 55

Out of these materials we will select the material which will give us minimumcost provided it satisfies all functional requirements.

Primary design equation: (PDE)

Since we have to minimize the cost, the PDE will beas follows;


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Cm = .A.L * c = c...d 2.L/4

Where, Cm Cost of shaft Density of material

L Length of shaftc Cost per unit mass of material

But we know that;

max = 16T / d 3

Subsidary Design Equation: (SDE)

Now we need to eliminate the parameterd from the PDE to get the subsidarydesign equation (SDE).

d = {16T/ *(1/ max )} 1/3

Limit equations :

According to ASME code,

max 0.3S yt

or

0.18S ut--- (Whichever is smaller)

Substituting the SDE in PDE;

Cm = c...L/4{16T/ *(1/ max )}2/3

For minimum value of Cm, max should be placed at its maximum value fromthe limiting equations.


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Case (1): If 0.3Syt < 0.18Sut

Cm = c...L/4{16T/ *(1/ 0.3Syt)} 2/3

Case (2): If 0.18Sut < 0.3Syt

Cm = c...L/4{16T/ *(1/ 0.18Sut)} 2/3

Therefore;

Cm c * (1/ 0.3Syt) 2/3 --------------- (case1)

And

Cm c * (1/ 0.18Sut) 2/3 --------------- (case2)

Result table


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MATERIAL Syt(N/mm 2) Sut(N/mm 2) COST(Rs/kg)

c/( 0.3Syt) 2/3 or c/( 0.18Sut) 2/3

40Cr1Mo28 600 720 63 2.46

40Ni2Cr1Mo28 800 1150 63 1.80

31Ni3Cr65Mo55

687 883 65 2.21

40Mn2S12 - 600 50 2.20

17Mn1Cr95 - 800 55 2.002

As the ratio of c/ (0.18Sut) 2/3 is minimum for the material 40Ni2Cr1Mo28;using this material will lead to least cost of the shaft for same strength. Thusthe objective of the optimum is achieved here by minimizing the cost of theshaft and still meeting all technical requirements.

ASSEMBLY

A) Tail Stock Assembly .


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Tail Stock assembly is required to mount the brake assembly (Completeassly i.e. Brake Drum mounted on hub assly and brake assly) is mountedon the tailstock shaft by a set of adapters. The tailstock shaft issupported on two Spherical Roller Bearings and is connected to the loadcell (2 ton) through a lever (leverage of 275 mm) for brake torque

measurement.

The thermocouples are to be fixed in the brake linings and on Drum inner diameter respectively and in turn are connected to the temperaturetransmitters in the control panel. Tail- stock assembly can be moved onthe LM rails with the help of screw and nut arrangement driven by anHand Wheel.

The tailstock shaft is aligned with inertia shaft within 0.15 mm. Clamping of housing is done by a lever & screw. (4 Nos.) The Limit switches areprovided to switch off the motor after reaching the stroke in Forward /

Reverse direction. The tailstock is moved forward to engage the brakedrum bolts in the drum adapter mounted on the inertia shaft. Then thetailstock is to be clamped in position by tightening the levers of clampingscrews.

B) Inertia Shaft & Wheel Assembly

The drive to the Test Brake is provided by means of a DC motor, which isconnected to the inertia shaft assembly. The motor is rigidly secured to thebase frame and doweled in position. The Basic load for Test brake isprovided in the form of Inertia wheels through the Inertia shaft. The assly

is consists of following:On the left hand side face of the shaft, an adapter flange is located in aface key of the shaft and fixed with the shaft by 4 Nos. of M12x60 Hex.Bolts & washers. On the right hand side of the shaft is connected to theDC Motor by a Full flexible Gear coupling (Nu-Teck - GC104) thro keys onmain shaft & motor shaft.

Inertia shaft is supported on Spherical roller bearings on both sides inrobust fabricated bearing blocks in two halves. The bearing blocks arelocated on the base frame on tennon and clamped by M12 Cap screws &dowelled also.The bearings (SKF 23022CCK) are fitted on the inertia shaft with thehelp of adapter sleeve (H322) and lock nut with washer (KM22+MB22).The bearings are lubricated with Kluber make high temperature grease.

A fixed inertia discs (4 nos.) are permanently fixed with the hub on shaftlocated between the two supporting bearings.


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Inertia Discs on Fixed Disc-1:

On LH side of fixed disc-1 movable Inertia disc of 8 kg-m-s 2 is mounted onshaft. The disc has a taper to ensure proper location on the taper diameter of the hub. It can be engaged / disengaged with the fixed disc. In engaged

condition this Inertia disc is located on the taper portion of the hub of theshaft. Two locating bushes are fixed to the Inertia disc and they arelocated in the bore on the fixed disc. After engaging the inertia disc has tobe bolted with fixed disc by 4 Nos. of M12X50 Cap screws.

On RH side of fixed disc-1 movable Inertia disc of 8 kg-m-s 2 is mounted onshaft. The disc has a taper to ensure proper location on the taper diameter of the hub. It can be engaged / disengaged with the fixed disc. In engagedcondition this Inertia disc is located on the taper portion of the hub of theshaft. Two locating bushes are fixed to the Inertia disc and they arelocated in the bore on the fixed disc. After engaging the inertia disc has to

be bolted with fixed disc by 4 Nos. of M12X50 Cap screws.


On LH side of fixed disc-2 movable Inertia disc of 4 kg-m-s 2 is mounted onshaft. The disc has a taper to ensure proper location on the taper diameter of the hub. It can be engaged / disengaged with the fixed disc. In engagedcondition this Inertia disc is located on the taper portion of the hub of theshaft. Two locating bushes are fixed to the Inertia disc and they are

located in the bore on the fixed disc. After engaging the inertia disc has tobe bolted with fixed disc by 4 Nos. of M12X70 Cap screws.

On RH side of fixed disc-2 movable Inertia disc of 2 kg-m-s 2 is mounted onshaft. The disc has a taper to ensure proper location on the taper diameter of the hub. It can be engaged / disengaged with the fixed disc. In engagedcondition this Inertia disc is located on the taper portion of the hub of theshaft. Two locating bushes are fixed to the Inertia disc and they arelocated in the bore on the fixed disc. After engaging the inertia disc has tobe bolted with fixed disc by 4 Nos. of M12X50 Cap screws.


On LH side of fixed disc-3 movable Inertia disc of 0.125 kg-m-s 2 ismounted on shaft. The disc has a taper to ensure proper location on thetaper diameter of the hub. It can be engaged / disengaged with the fixeddisc. In engaged condition this Inertia disc is located on the taper portionof the hub of the shaft. Two locating bushes are fixed to the Inertia disc


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and they are located in the bore on the fixed disc. After engaging theinertia disc has to be bolted with fixed disc by 4 Nos. of M12X50 Capscrews.

On RH side of fixed disc-3 movable Inertia disc of 0.25 kg-m-s 2 is mounted

on shaft. The disc has a taper to ensure proper location on the taper diameter of the hub. It can be engaged / disengaged with the fixed disc. Inengaged condition this Inertia disc is located on the taper portion of thehub of the shaft. Two locating bushes are fixed to the Inertia disc and theyare located in the bore on the fixed disc. After engaging the inertia dischas to be bolted with fixed disc by 4 Nos. of M12X70 Cap screws.


On LH side of fixed disc-4 movable Inertia disc of 0.5 kg-m-s 2 is mountedon shaft. The disc has a taper to ensure proper location on the taper

diameter of the hub. It can be engaged / disengaged with the fixed disc. Inengaged condition this Inertia disc is located on the taper portion of thehub of the shaft. Two locating bushes are fixed to the Inertia disc and theyare located in the bore on the fixed disc. After engaging the inertia dischas to be bolted with fixed disc by 4 Nos. of M12X50 Cap screws.

On RH side of fixed disc-4 movable Inertia disc of 1 kg-m-s 2 is mounted onshaft. The disc has a taper to ensure proper location on the taper diameter of the hub. It can be engaged / disengaged with the fixed disc. In engagedcondition this Inertia disc is located on the taper portion of the hub of theshaft. Two locating bushes are fixed to the Inertia disc and they are

located in the bore on the fixed disc. After engaging the inertia disc has tobe bolted with fixed disc by 4 Nos. of M12X70 Cap screws.

Each inertia disc is provided with proximity switch to sense the engagedposition of that disc. From the signal of proximity switches, the actualconnected inertia is found out and if it is not matching with the requiredinertia, the test will not start.

Inertia Disc engagement / Disengagement Mechanism:

On the shaft there are total four fixed Inertia discs and one fixed adapter flange and Eight Movable Inertia discs, which can be engaged /disengaged as per the requirements.


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Each inertia disc is provided with clamping blocks (2 nos) on front & rear side of the disc. Each clamping block is located in the slots of the inertiadisc by locating pins fixed in the clamping blocks. Then the clamping blockis fixed with the inertia disc with 2 Nos. of M8X55 cap screws & thenresting on the Linear Motion slides

On both sides of inertia disc linear motion slides are mounted on rails,which are fixed to the base frame. Disc Clamping blocks are mounted onthe Linear Motion slides by screw for bringing the disc in parking condition.

Inertia disc engagement procedure:

a) Open the inertia guard doors.b) Bring the match mark of the fix disc in front of the operator.c) Remove the parking levers of the parked inertia disc blocks.d) Now place the Inertia disc-shifting lever in the clamp block and

locate the vertical pin of the lever in the elongated hole of theshifting block on both sides of the inertia disc.e) Forward both the levers simultaneously to engage the inertia disc

with the fixed disc by engaging the locating bushes in the holes of fixed disc bushes and bring it to the engaged condition.

f) Place and tighten two inertia disc fixing cap screws.g) Loosen the vertical cap screw of the clamp block on both sides.h) Remove clamp block fixing cap screws M12x100 from the both

sides of the inertia disc.i) Move the runner block with clamp block assembly manually to

parking position and fixed it.

j) Rotate the inertia disc by 90 degrees to bring the inertia disclocating bush fixing screw to the front of the operator and tightenthird cap screw.

k) Rotate the inertia disc by 180 degree to bring the inertia disclocating bush fixing screw to the front of the operator and tightenfourth cap screw. Ensure that all four cap screws are tightenedproperly.

l) Close the inertia guard doors.

Inertia disc disengagement procedure:

a) Open the inertia guard doors.

b) Bring the match mark on the inertia discs in front of the operator byrotating the inertia discs manually. Rotate the disc by 90 degree to


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bring the inertia disc locating bush fixing screw to the front of theoperator & remove the cap screw.

c) Rotate the inertia disc by 180 degree to bring the inertia disclocating bush fixing screw to the front of the operator and remove

cap screw.

d) Again bring the match mark on the inertia discs in front of theoperator by rotating the inertia discs manually by 90 degree.

e) Move the runner blocks with clamping blocks on the rail by hand atthe centre of the disc.

f) Mount the clamping blocks on both sides of Inertia disc, which is tobe disengaged. Locate the clamp blocks in the slots of disc andsecure with the inertia disc by M12 cap screws.

g) Tighten the vertical cap screw of the clamping blocks by aboutfifteen to twenty degrees on both sides of disc simultaneously andequally so that the Inertia disc load is just transferred to the runner blocks.

h) Remove remaining two fixing cap screws.

i) Place all the removed fixing cap screws in the holes on the baseplate provided for parking the fixing bolts.

j) Now place the Inertia disc by shifting the block both sides of theinertia disc.

k) Shift both the blocks simultaneously to disengage the inertia discand bring it to the parking place.

l) Engage the parking blocks in the stopper block slot on both thesides of inertia disc.

m) Close the inertia guard doors.

C) Blower and Ducting Assembly

Blower & Ducting assembly consists of the following:

In this system, a Exhaust cum Cooling blower of 1500 m 3/ min at 2820rpm is providing the cool air to the brake. For Fresh air from atmosphere


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suction damper is provided. The blower is mounted on foundation outsidethe shop floor. The blower is provided with an AC variable frequency driveto run the blower at various speeds. User can select the required air velocity in KMPH during configuring the test schedule, with the help of variable frequency drive will be automatically maintained the selected air

velocity during the testing.

The blower is mounted on movable trolley along with nitrogen cooling,water supply arrangement, water gauge arrangement etc. The ducting for cool air supply runs from the blower discharge to the side of the brakelocation & exhaust air runs away from the bottom of the brake location tothe suction of the blower. Suitable wire mesh is provided at the suctionside of the blower. Blower speed is adjusted with help of Variablefrequency drive. Variable frequency drive is located near drive motor.Water collecting tray is provided at the bottom side inside the base frameto avoid any solid objects falling in grounded pipes. Water/ Oil can be

taken out away by connecting pipe to the tray. The grill is provided on thedischarge side of blower duct in base frame.

D) Door Assembly

Doors are mounted on the base frame with lift of hinges for easy removal.Doors enable the access for parking brake assembly, static friction testassembly etc.

E) Inertia Guard Assembly

The inertia section is covered with guard consisting of tubular frame andtwo swing type doors on each side. The frame is fixed with base framewith the help of the screws. The fixed frames and the swing doors arefilled with quire foam to dampen the noise level. The doors are supportedon the frames by hinges and are to be operated manually. The gassprings provided for the doors for help in reducing the effort required tooperate the guard cover.

F) Leveling Screw Foundation Bolt AsslyLeveling screws of M16x40 (14 Nos.) are given for leveling the machine.

G) Stiction Test Assly


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Static Coefficient of friction has to be checked for Car Brake.

Setup :

a) Engage the Tailstock with brake assly to the adapter mounted on

inertia shaft, in case if it is disengaged with inertia shaft clamp the tailstock.b) Locate & Fix the Lever on the Adaptors flat portion and secure it with

screws & washers.c) Connect the other end of lever to the rod end of pneumatic cylinder

mounted on the bracket and secure it with pins & nuts.

Documents

Proj Report Final