Terex TR60 Maintenance Manual page 436

Braking System - Treadle Valve
Section 250-0070
REMOVAL
Numbers in parentheses refer to Fig. 1.
WARNINGS
To prevent personal injury and property
damage, be sure wheel blocks are properly
secured and of adequate capacity to do the job
safely.
Hydraulic oil pressure will remain
within the system after engine shut down.
Operate the treadle pedal continuously until
the pressure has dissipated before carrying
out any work on the braking system or serious
injury could result.
1. Position the vehicle in a level work area, apply the
parking brake and switch off the engine.
2. Operate the treadle valve continuously to discharge
the braking accumulators. Block all road wheels.
3. Clean treadle valve assembly and surrounding area
with a suitable solvent. Ensure all hydraulic lines
connected to the treadle valve are identified for ease
of installation and, with suitable containers available to
catch leakage, disconnect hydraulic lines. Fit blanking
caps to all open lines and treadle valve ports.
4. Remove and tag electrical connections to stop light
pressure switch (55) and lockup drop out pressure
switch (54).
5. Release and remove mounting hardware securing
the treadle valve to the cab floor. Remove treadle
valve assembly to a clean area for 'Disassembly'.
DISASSEMBLY
Numbers in parentheses refer to Fig. 1.
1. Remove blanking caps from treadle valve ports and
drain oil from valve body (20) ports by rotating the
valve over a suitable container.
2. Secure the controller upright in a table vice.
3. Remove pedal (50) from actuator cam (36) by
loosening two capscrews (51) at the pedal heel. Note
that capscrews (51) need not be removed.
4. Loosen but do not remove nuts (30) from 'U' bolts
4
(32) securing actuator pivot pin (38).
5. Remove pivot pin (38) from actuator base (46) with
a punch and hammer. Remove actuator cam (36)
assembly and inspect for any abnormal wear or
cracks. Set aside for assembly.
6. Remove screws (43) securing retainer plate (44) to
actuator base (46).
7. Remove retainer plate (44), boot (42) and cap (41)
as an assembly by grasping boot (42) and gently lifting
from actuator base (46).
8. Loosen the socket head capscrews from adjustment
collars (1) and unscrew adjustment collars (1).
9. Remove capscrews (45) securing actuator base
(46) to valve body (20). Remove actuator base (46)
from valve body (20).
10. Remove stop light pressure switch (55) and lockup
drop out pressure switch (54) from plate (21).
11. Remove capscrews (53) securing plate (21) on
valve body (20). Remove plate (21) and discard
'O' ring (22) and face seals (23).
12. Remove controller from the vice.
13. Remove capscrews (29) and washers (28) from
the base of valve body (20). Remove base plate (27).
14. With valve body (20) upright, retaining plug (26)
should fall out. If retaining plug (26) does not fall out,
lightly tap the plug to dislodge.
15. Remove and discard 'O' ring (25) from counterbore
in the base of valve body (20).
Note: Throughout the following steps it is important to
keep the circuits and circuit components identified as
to which side of the unit they came from. For a given
circuit, all the components have a tolerance stack
which could vary. Keep the 'B1' and 'B2' components
separate.
16. With the controller upright on the work bench, hold
valve body (20) with one hand and push the 'B1'
actuator plunger (2) down with the other hand until
regulator sleeve (14) pops loose.
17. Repeat the above procedure to loosen the 'B2'
regulator sleeve (14).
SM 1225 Rev 1 9-99