Operation and maintenance manual

Section 250-0050
SM 2158 7-02
1
BRAKING SYSTEM - Brake Manifold Valve
SM - 2749
DESCRIPTION
The brake manifold valve can be identified as item 2 in
Section 250-0000, BRAKING SYSTEM SCHEMATIC.
Mounted off the cradle assembly at the rear of the cab,
the brake manifold valve distributes hydraulic oil flow
from the priority unloader valve to the treadle valve,
front and rear brake circuit accumulators, priority
unloader accumulator and parking brake at the rear
wheels. The valve also provides appropriate returns to
tank for the hydraulic oil.
OPERATION
Numbers in parentheses refer to Fig. 1. Refer to Figs. 2
and 3 for hydraulic schematics.
Hydraulic oil from the priority unloader valve enters the
brake manifold valve at port 'P'. Oil pressure moves
check balls (9) from their seats (10) and allows oil to
flow through ports 'ACC1' and 'ACC2' to the brake
accumulators.
Pressurised oil exits the brake manifold valve through
port 'PY' and flows to port 'P1' on the treadle valve,
and, through port 'P2' on the brake manifold valve to
port 'P2' on the treadle valve.
Solenoid Cartridge - De-energized
When the emergency brake switch is activated (pushed
in), the electrical signal between the switch and
solenoid coil (3) is opened, de-energizing solenoid
cartridge (2). Oil flows through solenoid cartridge (2)
and exits the brake manifold valve through port 'A' to
the directional control valve. The oil travels through the
directional control valve and into the 'Px' port in the
treadle valve for an emergency brake application.
Fig. 1 - Exploded View of Brake Manifold Valve
1 - Valve Body
2 - Solenoid Cartridge
3 - Solenoid Coil
4 - Locknut
5- Plug
6- Retainer
7 - 'O' Ring
8- Spring
9 - Check Ball
10 - Seat
11 - 'O' Ring
12 - 'O' Ring
13 - Backup Rings
14 - 'O' Ring
15 - Backup Rings
16 - 'O' Ring
17 - Backup Rings
18 - 'O' Ring
19 - Plug
20 - Park Brake Pressure Switch
7
6
8
9
10
1
4
3
2
5,18
19
20
16
14
12
17
15
13
11
PY
P
PS1
PS2
A
B
P2
PS3
P1
P
ACC1
ACC2
T