New Holland CX720 Repair Manual page 2775

1 Check Valve Seat (2 per valve)
3 Spring (1 per valve)
E-T II Valve Operation — Off Position
(Reference Figures 8 and 9)
NOTE: References to directions are as if viewing the valve from the rear, facing the front of the combine.
When the RWD switch in the combine cab is in the "OFF" position, current is no longer supplied to the solenoid valve
(1) Fig. 8. This causes the spring loaded spool in the solenoid to move away from the solenoid coil. When this
happens, hydraulic fluid flow from the low pressure spool will be closed off from port (A) to port (B) (which flows to
the pressure to engage side of the selector spool (2) Fig. 9, in the ON position) and allow fluid to flow from port (A) to
port (C), Fig. 8 (pressure to disengage side of the selector spool).
The return spring (3) Fig. 9, and charge pressure directed from the low pressure spool, through port (C) of the solenoid
valve, and through the drilled passage (14), Fig. 9, will move and keep the spool (2) Fig. 9, to the left side of the spool
bore. This is the disengaged position for the spool and the forward and reverse high pressure ports are closed off.
The rear wheels of the combine will now "free wheel". As the wheels rotate, the wheel motor pistons are pushed back
into their bores. The hydraulic fluid behind the pistons is directed back to the wheel motor supply/return ports (12),
(13), Fig. 9, of the E-T II valve. From there, the fluid from the right wheel motor flows through the flow dividers (7)
and the right check valve (8) and center passage (9). Hydraulic fluid then flows to the left side wheel motor reverse
supply/return port (12), and to the selector spool (2) Hydraulic fluid that exits the valve at the reverse supply/return
port (12), and from the left wheel motor is directed to the drain valve by a "tee" connection at the reverse supply/return
port (12), Hydraulic fluid flows from the "tee" to the drain valve through an external tube. A drilled passage (15), in
the selector spool allows hydraulic fluid that does not flow out of the valve through the reverse supply/return port (12),
to flow through the spool (2) through the case drain orifice (4) and out of the valve at the pressure to engage port (5).
From there, fluid is directed back to the solenoid valve via external tube where the fluid drains back to tank.
When the RWD is off, charge pressure that is directed from the solenoid valve to the selector spool is also directed
to the drain valve out of the pressure to disengage port (11), through an external tube. This pressure shifts the spool
in the drain valve that allows hydraulic fluid from the wheel motors (from the "tee" at the reverse supply/return port
(12)) to flow through the drain valve and out. From the drain valve, hydraulic fluid is directed back to tank through an
external tube that connects to the valve drain.
TRAVELLING - 2WD-4WD SYSTEM Hydrostatic
DS00M070
2 4/7/2006
D.14.E / 21
7
2 Check Valve Ball (2 per valve)