CPRV (Charge Pressure Relief Valve)
The charge pressure relief valve maintains charge pressure at a designated level above case pressure. The
charge pressure relief valve is a direct acting poppet valve which opens and discharges fluid to the HST
case when pressure exceeds a designated level. For external charge flow the CPRV is set according to
below table. The charge pressure relief valve setting is specified on the model code of the transmission.
Charge Pressure Relief Valve settings
Flow l/min [US gal/min]
LDU20/24
10.8 l/min [2 US gal/min]
Charge Pressure Relief Valve Function
Charge Flow
P400007
Control
Direct Displacement Control
The LDU20/24 features Direct Displacement Control (DDC) .The swashplate angle is set directly by a
control lever or linkage attached directly to the swashplate trunnion. Control lever movement changes
the speed and rotating direction of the motor by increasing or decreasing the swashplate angle.
The control input shaft is configurable on both of left and right hand side of the LDU20/24.
Control Handle Requirements
Maximum allowable trunnion torque is 79.1 N•m [700 lbf•in]. The approximate torque necessary to rotate
the control per 300 bar and 3000 rpm of system operating pressure is 25 N•m with standard valveplate.
The actual value will vary due to the influence of pump operating conditions. For mating dimensions, see
Installation drawings in LDU20/24 Technical Information Manual BC152886483777.
W
Warning
With no external forces applied to the swashplate trunnion, internal hydraulic forces may not return the
swashplate to the neutral position under all conditions of operation.
Service Manual
LDU20/24 Closed Circuit Axial Piston Transmission
Operation
©
Danfoss | June 2021
AX152886481311en-000304 | 11
