33 BRAKES Fig. 34 CV / CV Tandom Master Cylinder for ABS PRIMARY GLAND SEAL incase of any failure / malfunction the entire Tandem Master cylinder assy. to be replaced. Working principle : In the normal “Brakes-off” position, the brake fluid can flow unrestricted between the dual line systems and separate chambers in the integral fluid reservoir. Fluid movement to the independent cylinders is controlled by Two valves - (center valves). Hence it is called CV/CV master cylinder Ref Fig. 34 When the brake is applied the push rod pushes master cylinder primary plunger of the bore. This master cylinder is divided into two chambers. The primary train is composite assembly and is resting on stop washer through a connecting pin. Connecting pin is rectangular in section and has a hole at center. One end of the valve stem passes through this hole. The connecting pin is assembled in to the circular hole on primary plunger as shown in Fig. 34 The poppet valve train consists of poppet valve assembled on the valve stem. This composite assembly is ahead upon by a valve spring. The end of the valve spring is resting on the distance sleeve. The distance sleeve is held rigidly with the plunger by 6 or 8 crimps on the plunger. A similar arrangement is provided for secondary train also. The secondary plunger has a center slot into which the stop pin reciprocates. A cover plate is assembled in-between the scondary grommet and connecting pin to prevent falling off of connecting pin from cylinder body. This plate also acts as a baffle and reduces the velocity of fluid jet that will emerge from secondary feed ports on return. Secondary and primary plunger train moves as a composite assembly. At this juncture the poppet valve (centre valves) of both primary and secondary closes the respective sealing faces of the plunger and pressure is developed. During further stroke of the primary plunger, the pr imary spr ings cmopressed and pressure is developed. The pressurized fluid is forced though pipelines to the calipers and wheel cylinders. When the brake is released, the master cylinder plungers move back creating partial vacuum in front of poppet valves (center valves) deseating by deflecting poppet spring and the port are opened and the brake fluid can again move unrestricted between separate systems and the fluid reservoir. Servicing : The master cylinder is not serviceable After every 40,000 kms/24000 miles or 2 years, whichever occurs first, the master cylinder should be replaced with genuine master cylinder assy. WASHER (RETAINING) RETAINER SPRING (POPPET) STOP PIN SLEEVE SECONDARY GLAND SEAL POPPET VALVE ASSY CONNECTING PIN SPRING RETAINER RECUPERATING SEAL (PRIMARY) STOP WASHER CIRCLIP PRIMARY PLUNGER
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