New Holland T8010 Manual page 905

Raise Function and Troubleshooting
FUNCTION
Hitch Control Valve in Raise - To raise the hitch, the hitch raise solenoid (1) must be energized by the Electronic
Hitch Controller. When the solenoid is energized, the armature in the solenoid moves toward the valve contacting a
control pin (14) which moves the raise pilot spool (3) inward. The amount of movement of the spool depends on the
amount of current applied to the solenoid by the controller. The amount of current the controller applies to the
solenoid depends on the command information the operator has sent to the controller. As the raise pilot spool (3) is
shifted inward, it meters regulated pressure from the regulated circuit (12) to the left hand side of raise spool (5).
The metered regulated pressure shifts the raise spool against the spring, allowing oil from the PFC pump circuit
(11) to flow past the spool land to the hitch load check ball (10) which is seated by pressure from the hitch cylinders
created by the load on the cylinders. At the same time PFC standby pressure is sent through the signal port and
signal check valve to the PFC pump compensator, which will activate the pump to increase flow output. As
pressure increases, the load check ball is lifted off the seat, allowing flow to the hitch cylinders.
The hitch will stop raising when the controller shuts off current to the raise solenoid (1). Regulated pressure acting
on the right hand end of the raise pilot spool will shift the pilot spool outward shutting off regulated pressure supply
(12) and opening the return port (13) to release the pressure on the raise spool. The spring will shift the raise spool
(5) shutting off the PFC inlet port. The pressure in the hitch cylinders will seat the hitch load check ball (10) trapping
the oil. The signal pressure will bleed off through the orifice in the raise spool (5) and allow the pump to return to
low pressure standby.
TROUBLESHOOTING
Problem - Hitch will not raise
1. Check the function of other systems (Transmission, Remote Valves).
A. If other systems do not function properly, refer to the troubleshooting section on the non-functioning
system.
B. If other systems function properly, go to Step 2.
2. Check for HITCH fault codes
A. If fault codes are present, refer to fault code troubleshooting in this section.
B. If no fault codes are present, go to Step 3.
3. Check for manual operation of the control valve by pushing in on the manual control pin (14) in the center of the
outer end of the raise solenoid with a small punch or 1/8 inch rod.
A. If the hitch raises, test hitch raise solenoid for proper electrical function and recheck HITCH fault codes.
B. If the hitch does not raise, refer to the Hydraulic Troubleshooting the PFC System and the regulated
pressure system. If the hydraulic system functions properly, go to Step C.
C. Check for free movement of the raise pilot spool (3) and raise spool (5). Repair or replace as necessary.
Section 35 - Hydraulic Systems, 3PT - Chapter 9
HITCH CONTROL VALVE
35-9-18