Sakai TW352 - Description and Operation of Parking Brake (Negative Brake) Circuit

2-054
Brake System
3-2. Description and operation of parking brake (negative brake) circuit
TW5022048
9
3
1
f
e
c
a
b
4
5
2
6
5
2
6
3
1
4
10
8
7
5
3
4
2
11
1
6
From charge circuit
To tank
Parking brake applied
Fuse
Fuse
Indicator lamp
Parking brake released
★Pushing down on
the foot pedal switches
off the brake switch.
Description
・Consists of brake pedal (1), foot brake switch (2),
centering rods (3), (4), parking brake switch (5),
F-R lever (6), brake release solenoid valve (7),
parking brakes (negative brakes) (8), (9), (10)
and brake lamp relay (11).
Operation
Parking brake switch set to PARKING
position
・The contact points of parking brake switch (5)
open the circuit to the brake release solenoid
valve (7) and energizes the indicator lamp circuit.
・The indicator lamp comes on. The parking brakes
(8), (9) and (10) are applied.
★
The brake release solenoid valve
becomes deenergized.
Parking brake switch set to RELEASE
position.
・The contact points of parking brake switch (5)
close the circuit to the brake release solenoid
valve (7) and open the brake indicator lamp
circuit.
・The indicator lamp comes off. Parking brakes (8),
(9) and (10) are released.
★
The brake release solenoid valve is
energized.
Braking in an emergency
・Depressing brake pedal (1) as far as it will go
breaks the contact points of foot brake switch (2),
opening the circuit of brake release solenoid. At
the same time, the pedal movement moves either
centering rod (3) or (4) to bring the F-R lever to
the neutral position. This deenergizes the brake
release solenoid circuit to apply the parking brake
(negative brake) by means of the compression
spring load. Dynamic braking takes place.
★ The shematic drawing above is the circuit of TW352 and TW502.