TRANSMISSION HYDRAULIC CONTROLS
SYSTEMS OPERATION
TM 5-3805-263-14&P-2
TRANSMISSION VALVES
This chart gives a description of the function of the transmission control valves.
VALVE
DIFFERENTIAL LOCK
VALVE (9)
MANUAL MODULATION
VALVE (14)
DIFFERENTIAL, CHECK
AND SAFETY VALVE (15)
FUNCTION
Controls the engaging of the differential clutch (on machines with a
differential).
Lets the operator control P2 pressure to the directional clutches and
move the machine a little distance at a time.
Controls the pressure difference between the speed and the directional
clutches.
Opens a return passage to release the oil from behind the load piston
during a shift.
Keeps oil from going to the directional clutches if the machine is
started in any speed except NEUTRAL.
PILOT SELECTOR VALVE
(16)
Sends signal pressure to the two speed selector valves that are needed
for the selection of a specific speed.
SPEED SELECTOR VALVE
(17) (Two Position)
Sends pressure oil to No. 4 clutch or to drain.
SPEED SELECTOR VALVE
(18) (Two Position)
Sends pressure oil to No. 5 clutch or to the transmission reservoir.
RELIEF VALVE (20)
Keeps the system pressure at 340 psi (2335 kPa).
COOLER BYPASS VALVE
(24)
Keeps the pressure in the cooler at 150 psi (1030 kPa).
LUBRICATION RELIEF
VALVE (25)
Keeps the pressure of oil for lubrication at 75 psi (520 kPa).
PRIORITY REDUCING
VALVE (29)
Sends signal pressure to the pilot selector valve. After a signal pressure
of 83 to 96 psi (570 to 660 kPa) is reached, pressure oil is then sent to
the system.
MODULATING REDUCING
Controls the increase of pressure in the directional and speed clutches
VALVE AND LOAD PISTON
to gradually engage the clutches.
(31 and 32)
SPEED SELECTOR VALVE
(36) (Two Position)
Sends pressure oil to No. 3 clutch or to the transmission reservoir.
SPEED SELECTOR VALVE
(35) (Three Position)
Sends pressure oil to No. 6 clutch or No. 7 clutch or it keeps oil from
going to the No. 6 clutch and No. 7 clutch.
2-16
