New Holland CX720 Repair Manual page 2481

Relief valve - Static description (C.20.F.16 - C.30.A.20)
Shuttle Spool Valve (16a).
When the pressure in either of the drive lines increases (forward or reverse selected) pilot pressure will act on one side
of the shuttle spool valve, moving the spool valve to connect the return line to the flushing relief valve and pressure
release solenoid valve.
Flushing Relief Valve (16b).
With the motor running in forward or reverse the pressure in the return line will act on the flushing relief valve opening
the valve to case drain.
Pressure Release Valve Circuit (16c).
With the pump in neutral, pressure on each side of the motor may prevent gear changing (transmission lock up).
When a gear change control is moved the pressure release solenoid (16c), Fig.2 , will energized, moving the solenoid
valve, connecting the low pressure side of the circuit (through the shuttle spool valve) to the pressure release valve
pilot. The pressure release valve will move connecting the motor drive lines to equalize the pressure in both lines
allowing a smooth gear change to take place.
16.
16a.
16b.
16c.
16d.
POWER TRAIN - TRANSMISSION Hydrostatic
BSC1287A
Drive Motor Shuttle Spool and Flushing Valve
2 4/7/2006
C.20.F / 29
1
Drive Motor
Shuttle Spool Valve
Flushing Relief Valve
Pressure Release Solenoid Valve
Pressure Release Spool