Terex TS14G, Руководство по обслуживанию

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Braking System - Park/Emergency Control Valve
Section 250-0190
SM 1795 4-99
2
closed. A constant pressure is being maintained in
chamber (18) and in the spring brake chambers.
When the control lever (27) is moved against torsion
spring (24) towards the vehicle 'Park' position, the
diminishing profile of nylon cam (21) allows spring (17)
to lift valve plunger (16), thus uncovering exhaust
passage (9). Since exhaust valve (8) remains seated
on valve seat (15), the air pressure in the spring brake
chambers and in chamber (18) commences to exhaust
to atmosphere through exhaust passage (9).
If the control lever (27) movement is halted between
brakes 'Release' and vehicle 'Park', the falling
pressure in chamber (18) allows graduating spring (5)
to lift piston assembly (6) until valve plunger (16)
closes exhaust passage (9). Since exhaust valve (8)
remains seated on valve seat (15), the valve is again
lapped, although with a lower air pressure in chamber
(18) and in the spring brake chambers.
In the vehicle 'Park' position, valve plunger (16) has
made a full upstroke so that air pressure in the spring
brake chambers and chamber (18) is completely
exhausted through exhaust passage (9). This allows
graduating spring (5) to lift piston assembly (6) to the
top of it's stroke. However, exhaust passage (9)
remains open and as inlet/exhaust valve (8) is still
seated on valve seat (15), no supply air can enter
chamber (18) and the vehicle brakes are now held on
by the springs in the brake chambers.
When the control lever (27) is moved from vehicle
'Park' towards brakes 'Release', the increasing profile
of nylon cam (21) depresses cam follower (19) and
valve plunger (16) until exhaust passage (9) is closed
and inlet/exhaust valve (8) is unseated from valve
seat (15). An increasing air pressure is then admitted
to chamber(18) and the spring brake chambers to
release the vehicle brakes. The maximum delivered
pressure is limited by the setting of graduating spring
(5).
REMOVAL
Numbers in parentheses refer to Fig. 1.
WARNING
To prevent personal injury and property
damage, be sure wheel blocks are properly
secured and of adequate capacity to do the job
safely.
1. Position the vehicle in a level work area, move
control lever (1) to the 'Park' position and switch off the
engine.
2. Block all road wheels and place the battery master
switch in the 'Off' position. Open drain cocks on air
tanks and drain air from all four air tanks. Close drain
cocks on air tanks when air is exhausted.
3. Clean valve (1) and surrounding area with a suitable
solvent. Support valve body and remove mounting
hardware securing valve body to dash panel.
4. Ease valve body up from the dash panel. Tag and
disconnect air lines and electrical connection from
valve body, to aid in installation. Fit blanking caps to all
open lines and ports.
5. Remove valve body from the dash panel.
INSTALLATION
Numbers in parentheses refer to Fig. 1.
Note: Tighten all fasteners to standard torques listed
in Section 300-0080, STANDARD BOLT AND NUT
TORQUE SPECIFICATION.
1. Position valve on dash panel and install air lines and
electrical connection to valve body, as tagged at
'Removal'.
2. Secure valve body to dash panel using mounting
hardware as removed at 'Removal'.
3. Start engine and allow air pressure in the tanks to
build up to correct operating pressure. Check for leaks
at air lines and tighten as required.
4. Check operation of park/emergency control valve
for correct operation in both positions.
Courtesy of Machine.Market