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
75psi (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.
2-93
