Section 250-0151
SM 1651 1-99
1
BRAKING SYSTEM - Parking Brake Valve
Fig 1. - Parking Brake Valve Installation
1 - Parking Brake Valve
2 - Bracket
3 - Bolt
4 - Lockwasher
5 - Washer
6 - Bolt
7 - Washer
8 - Lockwasher
9 - Nut
10 - Elbow - 45°
11 - Elbow - 90°
SM - 1653DESCRIPTION
The parking brake valve can be identified as item 13 in
Section 250-0000, BRAKING SYSTEM SCHEMATIC.
Mounted off the cab rear crossmember, the parking
brake valve is located in the hydraulic brake circuit
between the treadle valve and the front brake
pressure reducing valve.
The parking brake valve, on application of the parking
brake switch, mounted in the centre console to the
right hand side of the operator, allows the operator to
activate the parking brakes and the rear service
brakes without applying the front service brakes.
OPERATION
Numbers in parenthesis refer to Fig. 1.
Refer to Fig. 2. Pressing the parking brake switch to
the 'On' position sends a signal to energize the solenoid
in parking brake valve (1), opening the front brake lines
to tank. At the same time the solenoid in the brake
manifold valve is de-energized which allows full pressure
to enter the 'PX' port in the treadle valve to apply the
parking brakes and the rear service brakes. Refer to
Section 250-0050, BRAKE MANIFOLD VALVE.
Note: On emergency brake application, or engine
shutdown, an electrical signal to the emergency brake
switch will take priority over the parking brake switch
to provide a full brake application.
Refer to Fig. 3. Pressing the parking brake switch to the
'Off' position sends a signal to de-energize the solenoid
in parking brake valve (1) and energize the solenoid in the
brake manifold valve. In this condition all brakes are
released until a further brake application is required.
Refer to Section 250-0050, BRAKE MANIFOLD VALVE.
Application of the treadle valve, with the parking brake
switch in the 'Off' position, will allow oil to flow through
port 'C' in parking brake valve (1) and exit at port 'B' to
the front brake pressure reducing valve.
MAINTENANCE
Numbers in parentheses refer to Fig. 1.
The parking brake valve is a non-serviceable item and
should be replaced completely, if damaged, as follows:
Note: Tighten all fasteners to standard torques listed
in Section 300-0080, STANDARD BOLT AND NUT
TORQUE SPECIFICATIONS.
Fig. 2 - Parking Brake Valve - Solenoid Energized
Fig. 3 - Parking Brake Valve - Solenoid Energized
FROM FRONT
BRAKE LINES
FROM BRAKE
TREADLE VALVE
SM - 1666
SM - 1667
2
5
4
3
10
1
11
10
9
7
6,8
13
B
CA
13
B
CA
TO FRONT
BRAKE LINES
FROM BRAKE
TREADLE VALVE
To Next Page
Loading...
Need help?
General
