Required Tools
The service procedures described in this manual can be performed using common mechanic's hand
tools. Special tools, if required, are shown. When testing system pressure, calibrate pressure gauges
frequently to ensure accuracy. Use snubbers to protect gauges.
Standard Procedures
C
Caution
Contamination can damage internal components and void the warranty. Take precautions to ensure
system cleanliness when removing and reinstalling system lines.
1. With the prime mover off, thoroughly clean all dirt and grime from the outside of the transmission.
Ensure the surrounding areas are clean and free of contaminants such as dirt and grime.
2. If removing the transmission, tag each hydraulic line connected to the transmission. If you disconnect
hydraulic lines, plug each open port to keep dirt and contamination out of the transmission.
3. Inspect the system for contamination. Look at the hydraulic fluid for signs of system contamination,
such as oil discoloration, foam in the oil, sludge, or small metal particles.
4. Remove the transmission.
C
Caution
Be careful not to damage solenoids and electrical connections when using straps or chains to remove
transmission from machine.
5. Perform transmission function test.
6. Before re-installing the transmission on the machine, test for leaks , drain the system, flush all lines,
replace all filters, and fill with new hydraulic fluid.
Charge Check/HPRV Adjustments
The Charge Check/HPRV combines the charge check and high pressure relief functions. Whenever you
replace a Charge Check/HPRV, operate the vehicle/machine through its full range of functions to ensure
proper HST operation. The Charge Check/HPRVs are preset at the factory. No adjustment is possible.
Checking for proper charge check/HPRV operation
If you suspect Charge Check/HPRV malfunction, swap valves and test operation. If the symptoms switch
direction, replace the faulty valve.
Service Manual
LDU20/24 Closed Circuit Axial Piston Transmission
Required Tools and Standard Procedures
©
Danfoss | June 2021
AX152886481311en-000304 | 21
