Lesson 1/Learning Event 2
In a hydraulic brake system, the force is applied to a piston in a
master cylinder. The brake pedal operates the piston by linkage.
Each wheel brake is provided with a cylinder. Inside the cylinder
are opposed pistons which are connected to the brake shoes. When the
brake pedal is pushed down, linkage moves the piston within the
master cylinder, forcing the brake liquid or fluid from the cylinder.
From the master cylinder, the fluid travels through tubing and
flexible hose into the four wheel cylinders.
The brake fluid enters the wheel cylinders between the opposed
pistons. The pressure of the brake fluid on the pistons causes them
to move out. This forces the brake shoes outward against the brake
drum. As pressure on the pedal is increased, more hydraulic pressure
is built up in the wheel cylinders and more force is exerted against
the ends of the brake shoes.
When the pressure on the pedal is released, retracting (return)
springs on the brake shoes pull the shoes away from the drum. This
forces the wheel cylinder pistons to their release positions and also
forces the brake fluid back through the flexible hose and tubing to
the master cylinder.
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