Control Valve, Safety Valve, And Inching Valve - Yale A7S1 Service Manual

8000 YRM 2199
1. END PLATE
2. PISTON
3. O-RING
4. FORWARD GEAR
5. RETURNING SPRING
6. REVERSING GEAR
7. BEARING
8. SEAL RING (A)
CONTROL VALVE, SAFETY VALVE, AND
INCHING VALVE
The Control Valve is mounted on the inner side of the
transmission case cover (see Figure 10). The control
valve includes three components: controlling slide
valve, constant pressure valve, and adjusting valve.
Controlling Slide Valve: Used to control
•
forward and backward functions.
Constant Pressure Valve: Maintains the oil
•
pressure of the hydraulic clutch to be within the
range of 1.1-1.4 MPa (159.5-203.1 psi).
Adjusting Valve: It is located between inching
•
valve and controlling
controlling slide valve is fully open, this valve
will start adjusting to reduce the impact of clutch
during engagement.
9. INPUT SHAFT ASSEMBLY
10. THRUST COLLAR (A)
11. NEEDLE BEARING
12. THRUST SHAFT COLLAR (B)
13. AXIS SNAP RING
14. SPRING SEAT
15. STEEL BALL
16. PLUG
Figure 9. Forward/Reverse Clutch Pack
slide valve. When
Hydraulic Transmission Case and Torque Converter
17. SEAL RING (B)
18. SPACER
19. BRAKE SHOE
20. STOPPER
21. DISC PLATE
22. FORWARD OIL CIRCUIT
23. REVERSE OIL CIRCUIT
The Overflow Valve: The overflow valve is connected
to the transmission case and allows the oil pressure
from the torque converter to maintain within its
operating range 0.5-0.7 MPa (72.5-101.5 psi). See
Figure 16
The Inching Valve The inching valve is installed on
the left side of transmission case. The spool is
connected to the linking rod of the inching pedal. This
spool will move forward when inching pedal is
pressed. The oil pressure of the hydraulic clutch will be
reduced, causing the truck to move slowly. See
Figure 11.
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