New Holland T8010 Manual page 133

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10
1
1. PORTING TO MASTER CLUTCH
2. INCHING VALVE BODY
3. MODULATOR SPOOL
4. REGULATED PRESSURE SUPPLY
5. PROPORTIONAL CURRENT CONTROL SOLENOID
As the inching pedal is let up, the transmission controller sends a current signal to the inching valve PCC solenoid.
The current value is based on the inching pedal position. The solenoid spool shifts, metering oil through the center
of the spool assembly down to the bottom of the modulator piston assembly.
As the pressure builds the modulator piston assembly begins to move up, against the force of both the inner
modulator and preload springs. As the modulator piston assembly moves up, the center pin of the modulator piston
assembly moves into the bore of the modulator spool. The modulator piston assembly does not directly shift the
modulator spool. The inner modulator spring force begins to shift the modulator spool.
As the modulator spool shifts upward it simultaneously blocks the master clutch return and opens the master clutch
supply to the inlet regulated supply. At the same time the inlet regulated supply is also ported through a cross
drilled and end drilled holes to the top of the modulator spool. The balance between the increasing inner modulator
spring force and pressure against the increasing clutch pressure at the top of the modulator spool causes the
master clutch pressure to gradually build.
Section 21 - Transmission, Drivelines - Chapter 1
4
REGULATED PRESSURE
INTERMEDIATE PRESSURE
TANK/SUMP PRESSURE
21-1-44
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3
RT98F015
6. PRELOAD SPRING
7. INNER MODULATOR SPRING
8. PISTON CENTER PIN
9. MODULATOR PISTON ASSEMBLY
10. CHECK VALVE
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RH02F072