Control Options; Operation - Sauer Danfoss 45 Series Service Manual

ContRoL oPtions

Series 45 G Frame Open Circuit Axial Piston Pumps
Service Manual
Features
The Series 45 Frames G have two possible control options, a Load sensing (LS) control
with Pressure Compensator (PC) or a PC only control.

operation

General
The bias piston and spring (1) acts at
all times to push the swashplate (2) to
maximum angle causing the pump to
stroke. The servo piston (3) acts against
the bias piston and spring to reduce
the swashplate angle causing the
pump to destroke. Swashplate angle
determines pump outlet flow.The pump
control, depending on conditions in the
system circuit, sets swashplate angle
by metering system pressure to the
servo piston.
PC control
The PC control design maintains a
constant pressure in the hydraulic circuit
as flow varies.The PC control modulates
pump flow accordingly to maintain
system pressure at the PC setting as
the PC adjusting plug (4) and spring (5)
defines.
When system pressure, acting on the
non-spring end of the PC spool (6),
overcomes the force of the PC spring, the
spool shifts porting system pressure to the servo piston and the swashplate angle
decreases. When system pressure drops below the PC setting, the PC spring shifts the
spool in the opposite direction connecting the servo piston to pump case and the
swashplate angle increases.The swashplate is maintained at whatever angle is required
to keep system pressure at the PC setting.
520L0605 • Rev AB • December 2010
Cross-section pump
3
2
1
bias spring and servo piston set swashplate
Cross-section PC control
6 5
PC spool shifts to port system pressure to
P106 068E
position
4
P104 049
servo piston
13