New Holland T8010 Manual page 903

Neutral Function and Troubleshooting
FUNCTION
Hitch Control Valve in Neutral - The hitch control valve is a closed-center valve. In neutral there will be no electric
current supplied to the raise or lower solenoids (1) and (2) and no oil flow through the valve. The pilot spools (3)
and (4) are blocking the supply of oil from the regulated circuit. The raise spool (5) is blocking the supply of oil from
the PFC system and is held in place by a spring. The lower poppet (9), lower pilot poppet (8) and the load check
ball (10) are blocking the return of oil from the hitch cylinder circuit. The overload relief (6) also blocks the return of
oil from the hitch cylinder circuit. The lower poppet (9) is held on the seat by a spring (15) and the oil trapped
behind the poppet by the lower pilot poppet (8). Pressure from the hitch cylinder circuit gets behind the lower
poppet through an orifice (16) in the side of the poppet.
TROUBLESHOOTING
Problem - Hitch will not hold position or leaks down.
1. Check the function of other systems (Transmission, Remote Valves, etc.).
A. If the other systems do not function properly, refer to troubleshooting of 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 found, follow procedures outlined in HITCH fault code troubleshooting in this section.
B. If no fault codes are found, go to Step 3.
3. With a load on the hitch, raise the hitch to maximum height and disconnect the hitch cylinder drain line from the
rear frame housing.
A. If oil flows from the drain line as the hitch settles the cylinder(s) is/are leaking internally. Repair cylinders
as needed.
B. If no oil flows from the drain line go to Step 4.
4. Check and repair the hitch valve as needed.
A. Check load check ball (10) and seat if seat is damaged replace the hitch valve.
B. Check the lower poppet (9) and seat, lower pilot poppet (8) and seat. If any components are damaged
repair or replace as necessary.
C. Check overload relief assembly (6) and seat. If any components are damaged repair or replace as
necessary.
Section 35 - Hydraulic Systems, 3PT - Chapter 9
HITCH CONTROL VALVE
35-9-16