Brake system - Bolero
Mahindra institute of learming excellence, Nasik
Brake equipment's specification Servo Boost ratio TMC Dia
: LSC 65 (9”) :5:1 : 15/16”
Front System Caliper Assembly : Collete II. Size : C 57 Pad grade
: Apache 522/12(Black) [ Asbestos free ]
Rear system
:
Size
: Dia 280 x 50
Lining grade
: Apc 108 crown contact asbestos free
Wheel cylinder
: Dia 25.40 mm
Typical braking system
Installation layout of bolero brake system
Working principle of brake booster
Brake released condition
N.R.V Vacuum Out put rod
Vaccum Diaphragm
Brake applied condition
N.R.V Air Out put rod
Vacuum Diaphragm
Tandem master cylinder Type Size Nominal Stroke Length Split Ratio Reservoir Circuit Pipe Tightening Torque
: : : : : : :
As/as Dia 15/16 Inch 30 mm 60 : 40 Close Coupled H Split primary to front 16.00/10.00nm
Exploded view of servo - Tandem master cylinder assembly
Function of main parts Master cylinder : Generates hydraulic pressure to apply on the disc and / or drum brakes. Disc [ Rotor ]: Transmit the stopping force from the disc brake caliper to the road wheel.
Disc brake caliper : Provides stopping force at the wheel by clamping the disc pads against the disc / rotor.
Booster: Provides power assistance to reduce the amount of 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 of the brake drum.
Function of a sealing ring A] Works as seal. B] It helps for piston return.
Working of Caliper
Brake Oil
Housing
Bleed Screw
Inlet Hole Ventilated Rotor
Friction Pad With Back Plate
Dust Cover
Seal
Caliper seal working principle ( Recuperation )
Piston on released condition
Piston Seal Relaxed Housing
Piston on brake applied condition
Piston Seal Distorted Housing
Piston movements during pad wear
Piston Seal Distorted Housing
Auto adjustment after pad wear
Piston Seal Relaxed Housing
Caliper Type Size Finish Pad grade
: : : :
Disc
:
Torque data :
Colette II. 57mm Zinc plating with yellow passivation. Apache 522/12 (black colour) [Asbestos free.] 281 mm diameter 21 mm thickness Limit 19 mm Bleed screw 7 to 10 NM Pin 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 are replaced • Apply grease ( red rubber) over sliding pin while replacing pad.
REAR DRUM BRAKE
Exploded view of rear brake assembly - Bolero
Rear brake Type
:
Size
:
HNSS ( hydraulic non servo sliding shoe ) 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
M&M Brake System Matrix Nashik Models
Veh
Front Brake WC Type Size Size
Servo Assy
Rear Brake WC Type Size Size Size
Model
Identification
CL 340
Classic
Kdv
Caliper C57
522/12 HNSS 11x2'' 1''
Commander 750
Hard top
Nsk
HLSS 11x2''
1''
Marshal DI
Royale
Nsk
HLSS 11x2''
1''
ARMY
Kdv
Caliper C57
522/12 HNSS 11x2'' 1''
Single Cab
Kdv
Caliper C57
522/12 HNSS 11x2'' 1''
Kdv
Caliper C57
522/12 HNSS 11x2'' 1''
Kdv
Caliper C57
Single Cab
Export
Double Cab
6''
TMC Assy Size 1''Alumnium
GP valve
HNSS 11x2'' 1''
1'' Flange Mtd
NA
HNSS 11x2'' 1''
1'' Flange Mtd
NA
6''
1''Alumnium
GP valve
6''
1''Alumnium
522/12 HNSS 11x2'' 1''
6''
7/8 Cast iron
Caliper C57
522/12 HNSS 11x2'' 1''
6''
1''Alumnium
HLSS 11x2''
1''
HNSS 11x2'' 1''
6''
1''Alumnium
Armada
Regular
Marshal
4W Drive
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
Nsk
Caliper C57
522/12 HNSS 11x2'' 1''
9''
15/16" Al
Bolero
Nsk
Valve
Bolero
ST
Nsk
Caliper C57
522/12 HNSS 11x2'' 1''
9"
Bolero
DI
Nsk
Caliper C57
522/12 HNSS 11x2'' 1''
7"
Clutch Clutch MC assy Sc Assy
GP valve
19.05
22.22
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''
Maxx
Fiestara
Nsk Caliper C57
522/12 HNSS 11x2'' 1'' 9"
Nsk KBX KBX
KBX
Scorpio
HNSS 11x2'' 1'' 7"
KBX KBX KBX KBX
KBX
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''A lumnium
550 DP
Kdv HLSS 11x2'' 1''
Tourister/Mouka
Zbd HAS 11x2'' 1.12" HAS 11x2" 1" 9"
Commander
Soft Top
HNSS 11x2'' 1''
GP valve
19.05
22.22
19.05
22.22
7/8'' Flange mtd 1''A lumnium
RV ratio 2.78:1
Spring rate 6.80Nm
BOOSTER DETAILS ON M& M SR.No.
MODEL
1
Maxx
2
Maxx IFS
3
Bolero
4
Camper
5
Savari
6
Marshal
7
Single cab
6"Servo Type 28 booster B R 2.2
Double cab
6" Servo Type 28 booster B R 2.2 TMC Dia 22.2 cast iron
8
PREVIOUS 6" Servo Type 28 booster B R 2.2
9" Servo Type 65 booster B R 5 9" servo Type 38 booster B R 3.85 6" Servo Type 28 booster BR 2.2TMC Dia 22.2mm (cast iron)
EXISTING 7" Servo LSC booster B R 3.15 9" Servo Type 65 booster B R 5 9" Servo LSC 65 booster B R 5 9" servo LSC booster B R 3.85 9" servo LSC booster B R 3.85 TMC Dia 25.4 Aluminium 6" Servo Type 28 booster B R 2.2
FUTURE
9" Servo LSC 65 booster B R 5
7" Servo LSC booster B R 3.15 9" Servo LSCbooster B R 3.15 9" servo LSC booster BR 3.85 TMC Dia 25.4 Aluminium
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 left Front right Rear left Rear right.
Brake care • Always exercise cleanliness when handling any part of the 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 BRAKE CYLINDER BORES ! • DO NOT USE PETROL OR KEROSENE TO CLEAN THE PARTS • DO NOT UES EVEN THE OLD BRAKE FLUID FOR CLEANING . • WHICH MEANS YOU CAN USE ONLY ----NEW BRAKE FLUID.
• Don’t handle rubber seals or internal parts with greasy hand. • Don’t use cotton waste for cleaning, since the threads of cotton waste may likely to block the ports and holes of the component. • Don’t use drained brake fluid for topping up. Bleed brake fluid 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 patches with brake fluid and wipe out with clean cloth.
• Don’t use sharp tools for pushing the piston out of cylinder, use wooden stick or hylem rod for removing the piston out of the cylinder. Sharp tools like screw driver may likely to spoil the bore finish. • Don’t skim the brake drum beyond the recommended oversize.
Note Always use genuine spares.
Normal conditions Following conditions are considered normal and not indicate that 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 the wear of friction material in calipers as well as in rear brakes. reservoir need topping up with fresh brake fluid when the fluid level warning indicator glows continuously on the dash board. • If the fluid level fall off is very high with a change in the brake pedal feel, there could be a leak in the system which should be identified and rectified immediately.
Abnormal conditions Following conditions are considered abnormal and indicate that 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 be air in the system. • Slight brake binding If the reservoir cap vent hole is clogged the brake could start binding slightly apart from other general causes of brake binding.
• Brake pedal effort is excessive This could be due to insufficient vacuum coming to booster, obstruction in pedal cross shaft and linkages. If the 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 brake shoes, high piston knock in calipers on high speed turnings.
BRAKE PROBLEM DIAGNOSIS Sl.No
Problems 1 Pull, Vibration, Pulsation
Test Brief Description To determine if concern is First use foot brake and then parking in front or rear braking brake. If the condition (I.e. pull, system 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
Ref. Value
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
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.
4 1. Brake judder.
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.
2. Erratic brake pedal travel. 5 Hard brake
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.
Booster vacuum test
6 Brake judder
Disc run out check
Should read more than 40.5Xpa (12in-Hg) Maximum brake disc run out allowed is 0.1 mm
7 Brake judder
Hub face run out check
Install pressure gauge on the brake booster hose end. Check the reading. 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. Position the dial gauge so that it contacts the hub. Rotate the hub. 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
8 Poor hand brake Parking brake cable operation adjustment
1000 psi front 680 - 750 psi rear
Nut torque - 4Nm
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 brake failure. • Brake fluid being hydroscopic in nature, will absorb moisture from the atmosphere and lead to lowering of boiling point and corrode internal parts of hydraulic cylinders. • Brake fluid is subjected to repeated heating & cooling cycles which can lead to gradual deterioration of its properties hence it is absolutely essential that the brake fluid be drained and replaced once in a year. • Always exercise cleanliness when handling any part of the hydraulic system
• Never handle rubber seals or internal parts with greasy hands • 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 for cleaning or using spurious brake fluid for filling / topping up. • If old seal is swollen, contamination is established. Drain the brake fluid and refill it with fresh brake fluid and change all rubber parts in the system.
Maintenance Every week Brake fluid level should be checked every week and it should be between min. and max. markings in the reservoir. Clean the reservoir cap before topping up the brake fluid. Brake inspection Check the brake lining for wear at during every service. Every 6months or 30,000 kms Overhaul the tandem master cylinder and wheel cylinder. Replace shoe return springs whenever lined shoes are replaced. Every year Brake fluid should be replenished once in every 12 months
Service Limits Lining :- 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, the cylinder to be replaced. Master cylinder :- If the clearance between the plunger outer diameter and bore diameter exceeds 0.20mm, the cylinder to be replaced. Hoses :- To be replaced once in two years or if any damage is noticed.
