NANO

498

BRAKE SYSTEM

TANDEM MASTER CYLINDER (TMC)

General:

This is a light weight master cylinder with heat treated

Aluminum/Cast iron body and with bore anodized. It

has rigid steel pistons.

This Tandem Master Cylinder, is attached to the

transparent plastic brake fluid reservoir which is

inserted in to its inlet port, which has baffles to house

float of level indicator switch which shows the low

fluid level of reservoir and vertical baffles are

provided in order to divide the brake fluid of the

reservoir in two portions, one is for primary circuit,

the other one for secondary circuit. These baffles keep

bare minimum fluid on one circuit even if other circuit

is drained out. Fluid is circulated separately to

primary port and secondary port of TMC due to this

division.

TandemMaster Cylinder consists of two pistons, four

seals, two springs and spring seats. Out of which two

seals are fitted on secondary piston and two seals

are fitted on primary piston inside TMC bore.

Normal Operation:

Depression of the brake pedal forces primary piston

inside the bore, which in turn pressurizes the brake

fluid next to it and actuates brakes connected to

primary circuit. Simultaneously secondary circuit gets

operated and actuates another set of brakes.

One Circuit Operation Primary Failure:

Depression of the brake pedal makes primary piston

to move inside the bore, but due to failure of primary

circuit system can not hold the pressure, also brake

fluid next to it will not get pressurized. Still primary

piston keeps on moving finally compressing primary

piston return spring. When the primary piston return

is fully compressed the secondary piston moves and

pressurizes brakes connected to secondary circuit.

One Circuit Operation Secondary Failure:

In this case, the inward movement of the primary

piston has little effect in pressurizing the brake fluid

in the primary circuit initially, because the initial built

up of pressure in the primary circuit causes the

secondary piston to promptly yield and move inward

without much resistance as the secondary has a leak.

Very soon the secondary piston touches the cylinder

wall and hence stops moving forward. From this point

onwards, the pressure starts building up in the

primary circuit which actuates one set of brakes.

1 TMC casting

2 Primary piston assembly

3 Secondary piston assembly

4 Secondary piston stopper

5 Push rod assembly

6 Piston stopper complete

7 Brake oil reservoir

8 Closure plug

9 Spring pin