Master Cylinder - BENDIX: Notes

All master cylinders are dual-piston, single-bore assemblies. When brake pedal is depressed, master cylinder primary piston moves forward. Under normal conditions, combination of hydraulic pressure and force of primary piston spring moves secondary piston forward at same time. Some master cylinders have a residual pressure valve installed under tube seat insert in drum brake outlet. This valve keeps a small amount of pressure in drum brake systems and prevents air from entering system. Many master cylinders are equipped with fluid level sensor switches and integral proportioning valves. Proportioning valves are designed to provide better front-to-rear braking balance.