Terex TS14G, Maintenance Manual

Page: 285 / 376

Section 250-0190
SM 1795 4-99
1
BRAKING SYSTEM - Park/Emergency Control Valve
SM - 2240
DESCRIPTION
The park/emergency brake control valve can be
identified as item 8 in Section 250-0000, AIR
BRAKING SYSTEM SCHEMATIC.
The park/emergency brake control valve is mounted
on the right hand side dash panel in the operators
compartment.
The valve controls air pressure delivery to the relay
emergency valve for actuation of brake chambers to
apply the brakes. In the 'PARK' position it exhausts the
air from the spring applied brake chambers, to apply
the parking brake.
Fig. 1 - Sectional View of TypicalPark/Emergency Control Valve - Lever in Brake 'Release' Position
22 - Valve Cover
23 - Screw
24 - Torsion Spring
25 - Cam Pivot
26 - Pin
27 - Control Lever
15 - Valve Seat
16 - Valve Plunger
17 - Spring
18 - Chamber
19 - Cam Follower
20 - Bracket/Spacer
21 - Nylon Cam
8 - Exhaust Valve
9 - Exhaust Passage
10 - Valve Spring
11 - Lower Half Piston
12 - Annular Chamber
13 - Air Transfer Hole
14 - Chamber
1 - Valve Body
2 - Adjuster Screw Plate
3 - Adjuster Screw
4 - Spring Cup
5 - Graduating Spring
6 - Piston Assembly
7 - Lower Half Piston
OPERATION
Numbers in parentheses refer to Fig. 1.
When control lever (27) is in the 'Release' position, the
vehicle spring brakes are held off by the maintenance
of air pressure in the brake chambers.
Cam (21) has pushed down cam follower (19) and
plunger (16) against spring (17) to close exhaust
passage (9). The existing delivery pressure in
chamber (18) has pushed down piston assembly (6)
against graduating spring (5) to close inlet valve seat
(15) on inlet/exhaust valve (8). The valve is now
'lapped', ie. both the inlet and exhaust valves are
1
2 3 4
5
6
7
8
9
10
12
13
14
15
16
17
18
19
20
21
22
23
24 25
26
27
11
DELIVERY AIR PORT
SUPPLY AIR PORT
EXHAUST PORT
Courtesy of Machine.Market