4.2.2 Brake valve (Fig. 4.3)
(1) Non-brake state
Since the brake valve A port is open, the nozzle of the pump and powered steering
is interlinked, the operation of steering is normal in the state of non-brake. When the
brake pedal isn’t been pressed, the oil pressure in the chamber D won’t go up in that the
port B is close.
(2) Brake state
A. When pressing the brake pedal, the piston 10 shifts to the left, valve sleeve 7 and
recoil piston 5 are pressed to the left by the spring group 8, in the meantime, the return
spring 6 is compressed to the left.
B. A port is closed owing to the shift of the part 7, and chamber D disconnects with
the port of the return oil tank, and the chamber D connects with the port of pump in that
the port B is closed.
C. Now the valve sleeve 7 shifts to the left, the oil pressure of the pump port and the
chamber D rises in that the C is compressed, in the meantime, the recoil piston 5 is
pushed by higher oil pressure in the chamber D .
D. When the max. pedal force acts on the right end of the piston, the bolt and the
pedal bracket can limit the position in order to make the oil pressure in the chamber D
lower the max. adjusting oil pressure.
E. When your foot releases the pedal, the valve sleeve 7 returning to the original
position relies on the opposite force, the process of the brake ends.
(3) Reservoir working performance
When the oil pump stops working (engine flameout) or damage, the reservoir is on
working performance.
A. Press the brake pedal, valve sleeve 7, backswing piston 5, check valve pin 3 will
be shifted left, the pin tips the ball over, at the same time, chamber D is connected with
reservoir connector, acts on the brake cylinder with reservoir pressure.
B. Leaves the pedal, valve sleeve, backswing piston and pin moves left, the ball of
check valve is connected with valve seat (check valve closed) acting by spring force,
the pin stops in the corresponding position.
C. Backswing moves right, chamber C opens, the oil of brake cylinder goes back to
the oil tank through chamber D.
4.2.3 Energy reservoir (Fig.4.4)
The energy reservoir can supply energy when the engine stops working or the oil
pump is in trouble. The type of the energy storage is spring type.
The buzzer of the warning switch sounds continuously when the reservoir doesn’t
storage energy.
When pressing the brake pedal, the oil pressure exceeds 3.9MPa, the check valve
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