TM 5-3825-226-24
NEUTRAL WITH ENGINE RUNNING
When the engine is started with the console
selection lever in the NEUTRAL position, the oil pump
(15) pulls oil from the reservoir (18) through the
magnetic strainer (16) and sends the oil to the filter (13).
Oil from the filter is sent to the selector valve (19) and to
the pressure control valve (1).
With the spool (14) for direction selection in the
NEUTRAL position, the passage to the direction
clutches is not open to the flow of oil.
Some of the oil from the oil pump is sent to the
pressure control valve (1). The oil with pressure goes
into the inlet ratio valve (5) through an orifice and works
between the slug and the ratio valve to move the ratio
valve to the right and close the passage to the reservoir.
Pressure oil also goes through a passage and a
drilled hole in the modulation relief valve (2) and to the
left end of differential and safety valve (6). The
pressure oil in the drilled hole in the modulation relief
valve (2) also opens a poppet valve and works between
the slug and the modulation relief valve (2).
When
the
pressure
of
the
oil
gets
to
approximately 75 psi (5.3 kg/cm2) (517 kPa), the
pressure oil between the slug and the modulation relief
valve moves the valve to the right and connects
passages to send oil to the torque converter (4).
This pressure oil also moves differential and
safety valve (6) to the right just far enough to open the
oil chamber at the left end of the differential and safety
valve to the reservoir through the body of selector valve
(19). In this position, the oil chamber for load piston (3)
is connected to a passage to the reservoir.
Because no pressure oil is in the chamber for load
piston
(3),
the
oil
pressure
can
not
go
over
approximately 75 psi (5.3 kg/cm2) (517 kPa). This oil
pressure is primary pressure.
With the console selection lever in the NEUTRAL
position, all the clutches are open to the reservoir and
they can not engage. Because no speed or no direction
clutches are engaged, the machine will not move.
If the engine is started with the console selection
lever in any position except NEUTRAL, pressure oil is
sent from selector valve (19) through the orifices in
differential and safety valve (6) to the right side of the
valve. The force of the pressure oil plus the force of the
springs hold differential and safety valve (6) to the left.
In this position, the direction clutches (No. 1, No. 2 and
No. 3 clutch) can not get pressure oil and will not
engage. Because no direction clutch is engaged, the
machine will not move.
While the console selection lever is in the
NEUTRAL position, the pressure oil in the spring side of
differential and safety valve (6) is free to go to the
transmission reservoir through the body of selector
valve (19). The pressure oil on the left side of the
combination valve then works against the spring force,
and differential and safety valve moves to a neutral, or
balanced position. In this position, the direction clutches
have no pressure and will not engage.
2-91
