Hitch Control Valve - New Holland T8010 Manual

Section 35 - Hydraulic Systems, 3PT - Chapter 9

HITCH CONTROL VALVE

General
The hitch control valve is a closed center valve that receives oil from the PFC hydraulic system. To control the
pump during hitch operations, signal pressure is sent from the valve to the PFC pump. The raise and lower
functions of the valve are operated by regulated pressure received from the regulated hydraulic system. The valve
is mounted in the remote valve stack and consists of the following components:
Raise and Lower Solenoids
The raise and lower solenoids, (1) and (2), when energized by the Electronic Hitch Controller, will move the raise
and lower pilot spools (3) and (4) inward through contact with the control pins (14).
Raise and Lower Pilot Spools
The raise and lower pilot spools (3) and (4) control the amount of regulated oil pressure allowed to pass the spool
lands to operate the raise spool (5) and lower control piston (7).
Raise Spool
The raise spool (5) is held in position by a spring which blocks the flow of oil from the PFC pump. Regulated
pressure from the raise pilot spool (3) will move the spool against spring force, which will open the PFC pump port
and expose PFC pump pressure to the load check ball (10) and the signal port.
Lower Poppet
The lower poppet (9), lower pilot poppet (8) and spring (15) trap oil in the hitch cylinder circuit. The lower pilot
poppet (8) is held on its seat by a spring (15) and cylinder circuit pressure, which is allowed to get to the back side
of the spool through an orifice (16) in the poppet.
Load Check Ball
The load check ball (10) traps oil in the hitch cylinder circuit to hold the hitch in a raised position. The ball is
unseated when PFC pump pressure exposed to the ball by the raise spool over comes the pressure in the hitch
cylinder circuit.
Manual Raise or Lower Control Pins
The raise and lower solenoid each contain a pin (14) in the center of the outer end that can be used to manually
activate the raise spool and lower control piston.
Overload Relief Valve
The overload relief valve (6) will allow oil from the raise/lower port to flow into the pilot chamber of the lower control
piston (7). The piston moves to the right and pulls the lower pilot poppet (8) off its seat when the hitch sees an
overload.
35-9-14