Master Cylinder - BENDIX/DELCO-Moraine

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 move secondary piston forward at same time.

When pistons have moved forward, primary cups cover by-pass holes, hydraulic pressure is built up and transmitted to front and rear brake assemblies.

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. The proportioning valves are designed to provide better front-to-rear braking balance. Many master cylinders also have a built-in quick take-up feature which allows a large quantity of brake fluid to remain in wheel cylinders for quicker braking action.