Hitachi ZW180 Technical Manual page 366

When Brake is Released
1. When the operating force of the brake pedal is
released, spool input (3) is pushed back by spring
(4).
2. Compression of spring (5) is released, and spools
(7, 8) are returned to the non-operation position by
summation of the hydraulic reaction force acting
on the plunger and the load of spring (9).
COMPONENT OPERATION / Brake Valve
3
4
5
M2
7
M1
8
3. At this time, ports (BR1, BR2) and ports (M1, M2)
are blocked by spools (7, 8), and ports (BR1,
BR2) are connected to the port (T).
Pressure oil at the ports (BR1, BR2) side is
supplied to port (T), and the brake is released.
T
BR1
BR2
T3-11-6
9
T4GB-03-11-006