Danfoss 45 Frame K2 Series Service Manual page 14

Service Manual
Series 45 Frame K2 Open Circuit Axial Piston Pumps
Features
14 | © Danfoss | April 2017
Fan Drive Control (FDC)
Fan Drive Control Principle
The Fan Drive Control is a unique electrically actuated pressure control solution that consists of a
normally closed proportional solenoid and one dual diameter spool sliding in the control housing.
System pressure acts on an area between the two spool diameters of the spool lands. This hydraulic force
is balanced with forces of springs and the solenoid when the spool is in the metering position. When no
current is sent to the solenoid it operates the pump at or below the PC setting which is adjusted
mechanically with the adjustor screw and lock nut. Increasing the control current proportionally reduces
the pump's outlet pressure until a minimum standby pressure is reached.
Control Block 12V and 24V
The minimum system pressure is given by swashplate moments of the pump and by servo system
leakages which produce a pressure drop across the control. In addition, fan motor type and fan inertia
impact minimum system pressure.
The Normally Closed Fan Drive Control coupled with a microprocessor allows the pump to operate at an
infinite range of operating pressures between a minimum system pressure and PC setting.
We recommend that a relief valve be installed in the pump outlet for additional system protection.
W
Warning
The Fan Drive Control is intended for fan drive systems only! Use in other systems could result in system
component damage or unintended machine movement. The Fan Drive Control is not intended to serve
at the primary system pressure relief. Loss of the input signal to this control will cause the pump to
produce maximum flow.
S45 pump with integrated FDC control schematic
B
M1*
L2
S
Legend
B
= Outlet
Gain
S
= Inlet
Orifice
L1, L2 = Case drain
M1* = Gauge Port is available
as an option. Standard
Choke
products provided
Orifice
without a gauge port.
L1
P109019
AX00000301en-US0101