Bolero Brake System

Mahindra institute of learming excellence, Nasik

Brake system - Bolero

Brake equipment's specification

Servo : LSC 65 (9”)Boost ratio : 5 : 1TMC Dia : 15/16”

Front SystemCaliper Assembly : Collete II.Size : C 57Pad grade : Apache 522/12(Black) [ Asbestos free ]

Rear system :Size : Dia 280 x 50Lining grade : Apc 108 crown contact asbestos freeWheel cylinder : Dia 25.40 mm

Typical braking system

Installation layout of bolero brake system

Working principle of brake booster

Brake released condition

Diaphragm

N.R.V

Out putrod

Vaccum

Vacuum

Diaphragm

N.R.V

Out putrod

Vacuum

Air

Brake applied condition

Type : As/asSize : Dia 15/16 InchNominal Stroke Length : 30 mmSplit Ratio : 60 : 40Reservoir : Close CoupledCircuit : H Split primary to frontPipe Tightening Torque : 16.00/10.00nm

Tandem master cylinder

Exploded view of servo - Tandem master cylinder assembly

Master cylinder : Generates hydraulic pressure to applyon the disc and / or drum brakes.

Disc [ Rotor ]: Transmit the stopping force from the discbrake caliper to the road wheel.

Disc brake caliper : Provides stopping force at the wheelby clamping the disc pads against the disc / rotor.

Booster: Provides power assistance to reduce the amountof brake pedal effort required by the driver.

Drum brake : Provides stopping force at the road wheel,by pushing the brake shoes against the inner diameter ofthe brake drum.

Function of main parts

Function of a sealing ringA] Works as seal.B] It helps for piston return.

Working of Caliper

Ventilated Rotor

Friction Pad With Back Plate

Brake Oil

Seal

Housing

Dust Cover

Bleed Screw

Inlet Hole

Caliper seal working principle ( Recuperation )

Piston Seal Relaxed

Piston on releasedcondition

Housing

Piston Seal Distorted

Piston on brakeapplied condition

Housing

Piston Seal Distorted

Piston movementsduring pad wear

Housing

Piston Seal Relaxed

Auto adjustment

after pad wear

Housing

CaliperType : Colette II.Size : 57mmFinish : Zinc plating with yellow passivation.Pad grade : Apache 522/12 (black colour)

[Asbestos free.]Disc : 281 mm diameter

21 mm thicknessLimit 19 mm

Torque data : Bleed screw 7 to 10 NMPin bolt 22 to 32 NM.

Exploded view of caliper Assembly - Bolero

Anti rattle clip and caliper grease

• Ensure to replace anti rattle clip whenever pads arereplaced

• Apply grease ( red rubber) over sliding pin whilereplacing pad.

REAR DRUM BRAKE

Exploded view of rear brake assembly - Bolero

Rear brake

Type : HNSS ( hydraulic non servo sliding shoe )

Size : Dia 280 x 50 mm

Operating clearance between lining & brake drum: 0.3 mm - 0.9mm

Lining grade : Apache 522/12[Asbestos free]

Wheel cylinder type : Double acting - cast iron

Wheel cylinder bore : 25.4 mm

Nashik Models VehServo Assy TMC Assy Valve

Clutch MC assy

Clutch Sc Assy

Model Identification Type SizeWC Size Type Size

WC Size Size Size

CL 340 Classic Kdv Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 1''Alumnium GP valve

Commander 750 Hard top Nsk HLSS 11x2'' 1'' HNSS 11x2'' 1'' 1'' Flange Mtd NA

Marshal DI Royale Nsk HLSS 11x2'' 1'' HNSS 11x2'' 1'' 1'' Flange Mtd NA

ARMY Kdv Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 1''Alumnium GP valve

Single Cab Kdv Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 1''Alumnium

Single Cab Export Kdv Caliper C57 522/12 HNSS 11x2'' 1''

Double Cab Kdv Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 7/8 Cast iron

Armada Regular Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 1''Alumnium

Marshal 4W Drive Nsk HLSS 11x2'' 1'' HNSS 11x2'' 1'' 6'' 1''Alumnium

Armada Grand Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 1''Alumnium

Marshal 2W NGCS axle HLSS 11x2'' 1'' HNSS 11x2'' 1'' 6'' 1''Alumnium

Savari 8 seater Nsk Caliper C57 522/12 HNSS 11x2'' 1'' 9" 7/8 Cast iron

Bolero Nsk Caliper C57 522/12 HNSS 11x2'' 1'' 9'' 15/16" Al GP valve 19.05 22.22

Bolero ST Nsk Caliper C57 522/12 HNSS 11x2'' 1'' 9"

Bolero DI Nsk Caliper C57 522/12 HNSS 11x2'' 1'' 7"

M&M Brake System Matrix

Front Brake Rear Brake

Bolero Longer Chassis Nsk Caliper C57 522/12 9" 1" Al

Bolero Camper (L C ) Nsk Caliper C57 522/12 9" 1" Al

Bolero Export Nsk Caliper C57 522/12 HNSS 11x2'' 1'' 9"

Maxx Conquer Nsk HLSS 11x2'' 1'' HNSS 11x2'' 1'' 7"

Maxx Fiestara Nsk Caliper C57 522/12 HNSS 11x2'' 1'' 9"

Scorpio Nsk KBX KBX KBX KBX KBX KBX KBX KBX 19.05 22.22

Commander Soft Top Kdv HLSS 11x2'' 1'' HNSS 11x2'' 1'' 1'' Side mtd

540/CL500/550 Kdv HLSS 11x2'' 1'' HNSS 11x2'' 1'' 7/8'' Side mtd

NC640DP Kdv HNSS 11x2'' HNSS 11x2'' 7/8'' Side mtd

550XDP Kdv Caliper C57 522/12 HNSS 11x2'' 1'' 6'' 1''Alumnium GP valve 19.05 22.22

550 DP Kdv HLSS 11x2'' 1'' HNSS 11x2'' 1'' 7/8'' Flange mtd

Tourister/Mouka Zbd HAS 11x2'' 1.12" HAS 11x2" 1" 9" 1''Alumnium RV ratio 2.78:1 Spring rate 6.80Nm

SR.No. MODEL PREVIOUS EXISTING FUTURE

1 Maxx 6" Servo Type 28 booster B R 2.2

7" Servo LSC booster B R 3.15

2 Maxx IFS 9" Servo Type 65 booster B R 5

9" Servo LSC 65 booster B R 5

3 Bolero 9" Servo Type 65 booster B R 5

9" Servo LSC 65 booster B R 5

4 Camper 9" servo Type 38 booster B R 3.85

9" servo LSC booster B R 3.85

5 Savari

6" Servo Type 28 booster B R 2.2TMC Dia 22.2mm (cast iron)

9" servo LSC booster B R 3.85 TMC Dia 25.4 Aluminium

6 Marshal 6" Servo Type 28 booster B R 2.2

7" Servo LSC booster B R 3.15

7 Single cab6"Servo Type 28 booster B R 2.2

9" Servo LSCbooster B R 3.15

8 Double cab

6" Servo Type 28 booster B R 2.2 TMC Dia 22.2 cast iron

9" servo LSC booster B R 3.85 TMC Dia 25.4 Aluminium

BOOSTER DETAILS ON M& M

Bleeding

• Bleeding is removal of air from the system.• Ensure to bleed the system perfectly.• Always use the recommended brake fluid for bleeding the

system.• Pedal sponginess is the indication of improper bleeding.• Bleeding has to be done whenever hydraulic brake circuit

is opened.• The bleeding sequence with front disc brake is:

Front leftFront rightRear leftRear right.

Brake care

• Always exercise cleanliness when handling any part ofthe hydraulic system.

• Use cloth for cleaning the brake components.• Use separate containers for brake fluid while dispensing

out brake bleeding.• Use transparent bleed pipe and bottle while bleeding.• Replace the shoe return springs whenever lined shoes

are replaced.• Use same grade of brake lining on both sides of the

brake.• Check the brake pedal feel before taking the vehicles for

testing.

Brake care

• DO NOT USE WATER FOR CLEANING THE BRAKECYLINDER BORES !

• DO NOT USE PETROL OR KEROSENE TO CLEAN THEPARTS

• DO NOT UES EVEN THE OLD BRAKE FLUID FORCLEANING .

• WHICH MEANS YOU CAN USE ONLY ----NEW BRAKEFLUID.

• Don’t handle rubber seals or internal parts with greasyhand.

• Don’t use cotton waste for cleaning, since the threads ofcotton waste may likely to block the ports and holes of thecomponent.

• Don’t use drained brake fluid for topping up. Bleed brakefluid will have air bubbles.

• Don’t allow the lining to wear upto metal.• Don’t use emery paper for removing stains and rusty

patches from cylinder bore surface. Use brasso polish,clean with cloth for removing stains and rusty patcheswith brake fluid and wipe out with clean cloth.

NoteAlways use genuine spares.

• Don’t use sharp tools for pushing the piston out ofcylinder, use wooden stick or hylem rod for removing thepiston out of the cylinder. Sharp tools like screw drivermay likely to spoil the bore finish.

• Don’t skim the brake drum beyond the recommendedoversize.

Normal conditions

Following conditions are considered normal and not indicatethat the brake master cylinder is in need of service.• Pedal effort on the modern braking system is not very

hard as in the past. Light pedal effort complaint should be compared with the pedal effort of another vehicle of the

same model and year of manufacture.• During brake application fluid level goes down in the

reservoir and reverts back to normal level when the pedal is released.

• The fluid level in the reservoir will fall depending upon thewear of friction material in calipers as well as in rearbrakes. reservoir need topping up with fresh brake fluidwhen the fluid level warning indicator glows continuouslyon the dash board.

• If the fluid level fall off is very high with a change in thebrake pedal feel, there could be a leak in the system whichshould be identified and rectified immediately.

Following conditions are considered abnormal and indicatethat the brake master cylinder is in need of service.• The brake pedal goes down fast. This could be caused by

an external or internal leak.• Brake pedal low or spongy -

Fluid level very low in master cylinder and there could beair in the system.

• Slight brake binding -If the reservoir cap vent hole is clogged the brake couldstart binding slightly apart from other general causes ofbrake binding.

Abnormal conditions

• Brake pedal effort is excessive - This could be due to insufficient vacuum coming to

booster, obstruction in pedal cross shaft and linkages. Ifthe brakes are binding that could also result in hard pedal.

• The rear brake locks up during light pedal force - Low tyre pressure, distorted brake shoes.• Brake pedal effort is erratic -

Mal functioning of booster, improper installation of brakeshoes, high piston knock in calipers on high speedturnings.

Sl.No Problems Test Brief Description Ref. Value1 Pull, Vibration,

PulsationTo determine if concern is in front or rear braking system

First use foot brake and then parking brake. If the condition (I.e. pull, vibration, pulsation) occurs only on operation of the parking brake, the concern is in the rear brake system. If the condition occurs when the foot brake is depressed, the concern i

2 Brake pull or drift Check pressure control valve ( Proportionating valve)

Install pressure gauge in the left hand front and right hand rear bleed nipples

1000 psi front 680 - 750 psi rear

3 Brake light always on

Brake warning lamp check

Remove the brake master cylinder reservoir filler cap. Allow the float to rest at its lowest point. If the brake warning indicator illuminates, the wiring/ switch is O.K. If the fluid level is below the minimum level brake light will continuously glow.

1. Brake judder.

2. Erratic brake pedal travel.

5 Hard brake Booster vacuum test Install pressure gauge on the brake booster hose end. Check the reading.

Should read more than 40.5Xpa (12in-Hg)

1. Position the dial gauge so that it contacts the disc face 10mm. (0.4inch) from the outer edge.2. Rotate the disc and absorve reading.

7 Brake judder Hub face run out check Position the dial gauge so that it contacts the hub. Rotate the hub.

8 Poor hand brake operation

Parking brake cable adjustment

Lower the parking brake control lever. Loosen the adjusting nut. Depress the foot brake six times. Raise the parking brake control lever by six clicks of the retchet. Tighten the adjusting nut

Nut torque - 4Nm

BRAKE PROBLEM DIAGNOSIS

Brake judder Maximum brake disc run out allowed is 0.1 mm

6

4 Check the front disc thickness variaces. Using a micrometer measure at eight positions 45 degree aprt and 15 mm away from the outer edge of the disc. Check mounting bolts of rotor for proper torque.

Disc thickness check If any of the reading vary by 0.015 mm or more or if thickness is less than 18 mm change the disc.

Disc run out check

Precautions• Brake fluid should be not be exposed to the atmosphere.• Lowering of boiling point could lead to vaporization of

the fluid under heavy braking which result in brakefailure.

• Brake fluid being hydroscopic in nature, will absorbmoisture from the atmosphere and lead to lowering ofboiling point and corrode internal parts of hydrauliccylinders.

• Brake fluid is subjected to repeated heating & coolingcycles which can lead to gradual deterioration of itsproperties hence it is absolutely essential that the brakefluid be drained and replaced once in a year.

• Always exercise cleanliness when handling any part ofthe hydraulic system

• Never handle rubber seals or internal parts with greasyhands

• Always buy brake fluid in sealed tins.• For cleaning master cylinder and wheel cylinder, use only

brake fluid. Never use mineral oils like petrol, kerosene,diesel, etc.,

• Seal swelling is due to the usage of mineral oils forcleaning or using spurious brake fluid for filling / toppingup.

• If old seal is swollen, contamination is established. Drainthe brake fluid and refill it with fresh brake fluid andchange all rubber parts in the system.

MaintenanceEvery weekBrake fluid level should be checked every week and itshould be between min. and max. markings in the reservoir.Clean the reservoir cap before topping up the brake fluid.Brake inspectionCheck the brake lining for wear at during every service.Every 6months or 30,000 kmsOverhaul the tandem master cylinder and wheel cylinder.Replace shoe return springs whenever lined shoes arereplaced.Every yearBrake fluid should be replenished once in every 12 months

Service LimitsLining :- Do not allow the lining to wear upto the shoe rim

or pad back plate.Wheel cylinder :- If the clearance between the plunger outer

diameter and bore diameter exceeds 0.25mm, thecylinder to be replaced.

Master cylinder :- If the clearance between the plungerouter diameter and bore diameter exceeds 0.20mm, thecylinder to be replaced.

Hoses :- To be replaced once in two years or if any damageis noticed.