Case 580SR Service Manual page 188

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122
SERVO CONTROL FORWARD SECOND GEAR 4WD ENGAGED
System pressure is reduced to 5.5 bar by the pressure reducer this oil then supplies the 6 solenoids and elec-
tronic modulation valve.
When the powershift lever is moved forward and twisted anti clockwise an electrical signal is sent to:
Z The high low solenoid which energizes allowing pilot oil to flow to the shift spool.
Z The neutral forward solenoid which energizes allowing pilot oil to flow to the shift spool.
Z The powershift lever will then reduce the current to the modulation valve which gives an output pressure curve
from 0 to 5.5 bar to the pressure booster valve.
Z The modulation pressure curve is multiplied by 4 in the pressure booster so that a curve of 0-20 bar is avail-
able for the directional clutches.
Between the modulation valve and the booster is accumulator to dampen any hydraulic vibration.
Suction oil
High pressure oil
Torque Converter and Lubrication Oil
1. Transmission sump
2. Transmission breather
3. Suction strainer
4. Gerotor oil pump
5. Pressure oil filter 20 bar
6. Filter by-pass valve 4.3 bar
7. System pressure test port 20 bar
8. System pressure regulating valve 20 bar
9. Oil flow to converter
10. Oil flow to shift spools 0-20 bar
11. Pressure reducing valve 5.5 bar
SECTION 21 - TRANSMISSION
12. 2nd/1st Solenoid
13. Range modulation solenoid
14. 4WD solenoid
15. High/low solenoid
16. Neutral reverse solenoid
17. Neutral forward solenoid
18. Electronic modulation valve 0-5.5 bar
19. Accumulator
20. Pressure booster 0-20 bar
21. Modulated pressure to shift spools
Return to oil tank
Pilot pressure
Modulated pilot oil
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