Operation; Loop Flushing - Danfoss 51 Series Service Manual

Service Manual
Series 51 and 51-1 Motors

Operation

Loop flushing

12 | © Danfoss | March 2016
Series 51 and 51-1 motors are designed to accommodate a loop flushing function. Installations that
require additional fluid removal from the main hydraulic circuit because of transmission cooling
requirements use a loop flushing function. The loop flushing function consists of a shuttle valve and a
poppet style relief valve or an orificed relief valve cartridge.
The shuttle valve acts as a resolver, directing fluid only from the low pressure side of the loop to the
motor relief valve. The shuttle valve is spring centered to the closed position to prevent high pressure
fluid loss from the circuit when reversing directions.
Loop flushing cross-section showing orificed relief valve
Orificed
relief valve
The poppet style relief valve regulates the charge pressure level in the system circuit when there is a
pressure differential in the main loop. When you use this valve, the pressure setting of the motor must be
less than the pump's charge pressure setting. The pressure setting of this valve is critical to achieving the
proper loop flushing flow rate.
Loop flushing cross-section showing poppet style relief valve
Shuttle valve
The orificed relief cartridge controls flushing flow under most conditions. A combination of orifice size
and charge pressure will produce a specific flushing flow. You may exchange the orificed relief cartridge
for one with a different flow rating.
Shuttle valve
P101 266E
Poppet style
relief valve
P101 267E
11008567 | AX00000013en-US0202