New Holland T8010 Manual page 664

PTO Clutch Engaged
When the PTO switch is actuated, the PTO controller sends a fixed current signal to the PTO solenoid. The
solenoid spool shifts, metering oil to the top of the modulator piston (2). As pressure builds the piston moves down
against the force of both the inner and outer modulator springs (3 and 4). As the piston moves down the center
stem of the piston moves into the bore of the modulator spool (5). The piston assembly does not directly shift the
modulator spool. The inner modulator spring force begins to shift the modulator spool. As the modulator spool first
begins to move, the metered lubrication oil supply to the PTO clutch is increased to prevent clutch wear as the
clutch is gradually engaged.
As the modulator spool shifts down it simultaneously blocks the PTO clutch return and begins increasing the clutch
supply pressure. The pressure available to the PTO clutch is also ported through a cross drilled and end drilled
holes to the bottom of the modulator spool. The balance between the increasing inner modulator spring force
against the increasing clutch pressure causes the pressure to gradually increase.
The engagement time for the PTO can range from approximately 2-6 seconds and is completely controlled by the
PTO controller based on monitored conditions (load, engine RPM, PTO shaft RPM).
1
MODULATION MODE
Section 31 - PTO - Chapter 1
2
3
4
RT98H067
1. PTO SOLENOID
2. MODULATOR PISTON
3. PRELOAD SPRING (OUTER)
4. MODULATION SPRING
5. MODULATOR SPOOL
5
6
PTO CLUTCH LOCK UP
6. VALVE INLET/SUPPLY PASSAGE
7. PTO CLUTCH OUTLET PORT
8. LUBE SUPPLY
9. LUBE OUTLET
31-1-13
7
8
9
RT98A024