Differential Lock - New Holland T8010 Manual

Section 25 - Four-Wheel Drive Front Axle - Chapter 2

DIFFERENTIAL LOCK

General Description – The Differential Lock consists of the differential lock piston, differential lock control valve,
differential lock control switch, brake pedal switches, true ground speed circuit, hitch position circuit, transmission
speed circuit, and electronic control modules (through the Data Bus). Because the differential lock is electronically
controlled, automatic operation is possible.
The PTO/Differential Lock valve is mounted externally on top of the rear frame transmission housing. The control
valve is supplied with regulated circuit pressure from the priority/regulator valve. This pressurized supply is directed
to the differential lock piston for engagement. If the differential lock is activated, pressurized oil from the regulated
supply circuit is ported to the differential lock piston in the differential carrier housing. As the piston extends friction
discs and separator plates are locked together. The separator plates are pinned to the differential carrier, while the
friction plates are splined to the left differential side gear. When the differential lock is applied, the clutch pack locks
causing the left side gear to rotate with the differential carrier. This eliminates all differential action, causing power
to be transmitted equally through both rear axles.
The PTO controller supplies current to the differential lock valve to activate the clutch based on commands from the
operator (Differential Lock switch) and signals supplied to it from the brake pedal switches, true ground speed
circuit, hitch position control system, and transmission speed signal circuit.
Diagnosing control system faults is accomplished by reading appropriate fault codes through the instrument cluster
display or the service tool. Refer to PTO system fault code section of this manual for a complete list of fault codes
related to the PTO, FWD, and Differential Lock system.
25-2-3