TRANSMISSION HYDRAULIC CONTROLS
SYSTEMS OPERATION
TM 5-3805-263-14&P-2
FIFTH SPEED REVERSE
When the selector lever is moved from FOURTH
REVERSE to FIFTH REVERSE, the pilot selector
valve (16) lets the signal pressure in passage (G) go
to the reservoir and sends signal pressure to passage
(E).
When the signal pressure in passage (G) goes to
the reservoir, the spring force on the speed selector
spool (18) moves the spool to the left and lets the
pressure oil in the passage for the No. 5 clutch (23)
go to the reservoir. The signal pressure in passage
(E) moves the speed selector spool (17) to the left
and opens the passage to the No. 4 clutch (22) to
system pressure.
When the passage to the No. 4 clutch (22) is
opened,
system pressure has a decrease as the
pressure oils fills the passage for the No. 4 clutch
(22). As the No. 4 clutch fills, a decrease in
pressure in passage (21) causes a decrease in
pressure on the left end of the differential, check,
and safety valve (15) and lets the valve move to the
left.
When the differential, check, and safety valve
(15) moves to the left, pressure oil in the No. 2
direction clutch goes to the reservoir. The pressure
oil in passage (19) also goes to the reservoir
through the differential, check, and safety valve
(15). A decrease in pressure in line (19) causes the
load piston (32) to move to the left and the
modulating reducing valve (31) to move to the
right. Also, a decrease in pressure in passage (19)
causes a decrease in pressure in the passage for the
No. 7 clutch (37) and the clutch is now not
engaged.
As the passage to the No. 4 clutch (22) is filled,
an increase in pressure to passage (21) moves the
differential, check, and safety valve (15) to the
right and closes the passage from passage (19) to
the reservoir. Now the system pressure has an
increase.
The modulating reducing valve (31) gives the
modulation to the pressure oil until the P1 pressure
in the No. 4 and No. 7 clutches is at approximately
340 psi (2350 kPa) and the P2 pressure in the No. 2
clutch is at approximately 280 psi (1950 kPa) with
the engine at HIGH IDLE. When the engine is at
LOW IDLE, P1 pressure is approximately 310 psi
(2120 kPa) and P2 pressure is approximately 250
psi (1720 kPa). The shift is now complete.
