20
rod pushes the piston forward. The brake fluid in the cylinder flows back to the reserve
tank through the return port until the primary cup blocks up the return port. After the
primary cup passes through the return port, the brake fluid in the cylinder is pressurized
and opens the check valve, flowing through the brake pipeline to the sub cylinder. Thus,
each sub cylinder piston is forced outwards. This brings the friction pieces on the brake
shoes into contact with the brake drum and slows or stops the truck. Meanwhile, the
cavity caused behind the piston is filled with brake fluid led through the return port and
inlet port. When the brake pedal is released, the piston is forced back by the return spring.
At the same time, the brake fluid in each sub cylinder is pressured by the return spring,
returning into the mast cylinder through the check valve. With the piston in its original
position, the fluid in the master cylinder flows into the reserve tank through the return
port. The brake fluid in the brake pipelines and sub cylinders has a residual pressure
proportioned to the set pressure of the check valve, which makes each sub cylinder piston
cup securely seated to prevent oil leakage and eliminates a possibility of air locking when
the truck is sharply braked.
Fig. 2-2 Master cylinder
(1) Connecting rod (2) Push rod (3) Dust cover (4) Snap ring (5) Secondary cup
(6) Piston (7) Primary cup (8) Spring (9) Check valve
2.1.3 Service brake
The service brake is of double brake shoe type which is fitted to the each end of the
To Next Page
Loading...
Need help?
General
