TM 5-3805-262-20
7. AIR HORN.
Located in hydraulic reservoir area. Controlled by horn valve located
on cab deck. Part of pneumatic system. Refer to page 1-26 for description.
8. CAB HEATER SYSTEM.
Located in cab console. Consists of heater valve, heater fan
switch, and resetable 3 ampere circuit breaker mounted on cab console panel and
heater core and heater fan motor mounted within console, Hot coolant from engine
cylinder block flows through heater core and returns to engine. Heater fan motor
blows air over heater core where it is warmed and exhausted over cab deck. Coolant
flow to heater core controlled by heater valve. Heater fan motor controlled by
push-pull heater switch .
1-31. HYDRAULIC SYSTEM See figure FO-11
HYDRAULIC PUMP.
Two section pump. One section provides hydraulic power for steering
s y s t e m ; o t h e r s e c t i o n p r o v i d e s p o w e r f o r l o a d e r s y s t e m . M o u n t e d o n r e a r o f , a nd
driven by, transmission. Steering section provides 23 gallons per minute flow at
2200 rpm at 2000 psi; loader section provides 52 gallon per minute flow at 2200 rpm
at 2500 psi.
CONTROL VALVE.
Three spool valve with open center passage. Open center passage
starts at inlet port of control valve and stops at outlet port. Return oil from cyl-
inders flows to output port through return passages in top and bottom. Supply pas-
sage starts at inlet port and stops at bucket spool. This supply passage permits
operation of bucket and clam cylinders at same time. Cylinders with least amount of
resistance will move first. When clam or bucket spool actuated, oil flow to lift
spool stopped. Lift cylinders will not move until both clam and bucket spools are
returned to neutral position. Load check valves connected between open center pas-
sage and A and B ports for each spool, Load check valves prevent reverse flow of oil
between cylinders and control valve as a spool is moved into a power position. Two
circuit relief valves used: one each connected between A and B ports and return
passage for bucket and clam spools. Circuit relief valves protect circuits when a
cylinder is made to move with spools in neutral. Adjustable main relief valve loca-
t e d a t i n l e t o f c o n t r o l v a l v e . I f p r e s s u r e a t i n l e t r e a c h e s s e t t i n g o f m a i n r e l i ef
valve while a spool is activated, main relief valve opens to protect hydraulic
system.
CONTROL LEVERS AND LINKAGES.
Position control valve spools allowing high pressure
h y d r a u l i c o i l t o a c t i v a t e c y l i n d e r s . C o n n e c t e d b y r i g i d r o d s t o c o n t r o l v a l ve
s p o o l s.
TILT CYLINDER ASSEMBLY.
Two used. Activated by control valve. Tilt bucket assembly
forward or rearward.
LIFT CYLINDER ASSEMBLY.
Two used. Activated by control valve. Raise or lower bucket
assembly.
BUCKET CLAMSHELL CYLINDER. Two used. Activated by control valve. Open or close buck-
et clam.
HYDRAULIC RESERVOIR.
P a r t o f f r o n t c h a s s i s a s s e m b l y . L o c a t e d b e h i n d f r o n t a c c e s s
door. Capacity is 17 gallons. Return oil filtered by 10 micron filter. Oil filler
cap located at top of reservoir; sight gage located at bottom front. Filter screen
located at bottom of reservoir in suction line .
1-29
