Transmission Case; Transmission Pump; Transmission Hydraulic Schematic - Yale A7S1 Service Manual

8000 YRM 2199
1. SCREW PLUG
2. SCREW PLUG
3. SNAP RING
4. SPRING
5. SCREW PLUG
6. O-RING
7. INCHING VALVE
SHAFT
Figure 11. Inching Valve

TRANSMISSION CASE

The transmission case houses the input shaft, output
shaft, other internal components, and also functions as
an oil tank. An oil filter is available on the side of the
case to filter the oil that is drawn into the oil pump.
While the pipeline filter/oil filler cap are mounted in the
upper part of the case cover.

TRANSMISSION PUMP

The transmission Pump is installed between the torque
converter and the input shaft. It feeds oil to torque
converter and hydraulic transmission case by
actuating a pair of gears through pump impeller. See
Figure 12.
8. SPRING
9. SNAP RING
10. OIL SEAL
11. PAD
12. INCHING VALVE
BODY
13. INCHING SLIDE
VALVE
Hydraulic Transmission Case and Torque Converter
1. DRIVING GEAR
2. GUIDING GEAR SEAT
3. DRIVEN GEAR
4. PUMP SHELL
Figure 12. Oil Feed Pump

TRANSMISSION HYDRAULIC SCHEMATIC

After the engine is started, the oil feed pump draws out
oil from the oil tank (the bottom of transmission case)
through the oil filler. The oil then flows through the
control valve in which the pressurized oil is divided into
two parts. One part is fed to the hydraulic clutch, and
the other part is fed to the torque converter.
The oil necessary for operation of hydraulic clutch
flows into the constant pressure valve (the pressure of
this valve should be adjusted to
1.1-1.4 MPa (159.5-203.1 psi)). The oil from the
constant pressure valve then flows to inching valve, to
the controlling slide valve. It is also directed from the
inching valve into the impeller of torque converter
through overflow valve (the pressure should be
adjusted to 0.5-0.7 MPa (72.5-101.5 psi)). The oil
coming out of the torque converter is cooled down
through transmission cooler. It then lubricates the
hydraulic clutch and returns to oil tank. See Oil Inlet/
Outlet Connection Location
When in neutral, the oil circuit from controlling slide
valve to clutch is turned off. The constant pressure
valve is turned on to make sure all the oil is
transmitted to torque converter through the overflow
valve. When controlling slide valve is in the forward or
reverse position, the oil circuit from slide valve to the
forward clutch or to reverse clutch is connected to
make each clutch engage. When one clutch is
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