Master Cylinder Assembly: Notes
The master cylinder assembly produces hydraulic pressure to operate the brakes when the brake pedal is pressed.
The assembly is attached to the front of the brake servo assembly, and comprises a cylinder containing two pistons in tandem. See Fig 1 . The rear piston produces pressure for the primary circuit and the front piston produces pressure for the secondary circuit. A brake fluid reservoir is installed on top of the cylinder. The reservoir is internally divided to provide an independent supply of fluid to each brake circuit, and so prevent a single fluid leak from disabling both primary and secondary brake circuits. Should a failure occur in one circuit, the remaining circuit will still operate effectively, although brake pedal travel and vehicle braking distances will increase. If the fluid level in the reservoir is too low, a float operated switch in the reservoir filler cap connects an earth to the instrument pack, which illuminates the brake warning lamp.