Danfoss Series 42

Introduction
Overview..............................................................................................................................................................................................5
Warranty.............................................................................................................................................................................................. 5
General instructions........................................................................................................................................................................ 5
Safety precautions............................................................................................................................................................................6
Symbols used in Danfoss literature............................................................................................................................................7
1998 Model Release
Overview..............................................................................................................................................................................................8
Description of change.....................................................................................................................................................................8
Functional Description
Overview..............................................................................................................................................................................................9
General description and cross-sectional view....................................................................................................................... 9
The system circuit.......................................................................................................................................................................... 10
Pump features.................................................................................................................................................................................10
Filtration options............................................................................................................................................................................12
Displacement limiters...................................................................................................................................................................14
Charge check / high pressure relief valves........................................................................................................................... 14
Bypass valves...................................................................................................................................................................................15
Auxiliary mounting pads.............................................................................................................................................................15
Control Options
Manual displacement control (MDC)......................................................................................................................................17
Electrical displacement control (EDC).................................................................................................................................... 17
High current electrical displacement control (HC-EDC).................................................................................................. 18
Non-feedback proportional hydraulic (NFPH) control.....................................................................................................18
Non-feedback proportional electric (NFPE) control..........................................................................................................19
Forward-Neutral-Reverse (FNR) three-position electric control................................................................................... 20
Technical Specifications
Specifications...................................................................................................................................................................................22
Pressure Measurement
Required tools.................................................................................................................................................................................23
Port locations and pressure gauge installation.................................................................................................................. 23
Ports and pressure gauges......................................................................................................................................................... 23
Initial Start-Up Procedure
General...............................................................................................................................................................................................25
Start-up procedure........................................................................................................................................................................25
Fluid and Filter Maintenance
Recommendations........................................................................................................................................................................ 26
Troubleshooting
Overview........................................................................................................................................................................................... 27
System operating hot...................................................................................................................................................................27
System response is sluggish...................................................................................................................................................... 27
System will not operate in either direction.......................................................................................................................... 28
System will not operate in one direction.............................................................................................................................. 29
Neutral difficult or impossible to find.....................................................................................................................................29
Adjustments
Overview........................................................................................................................................................................................... 30
Displacement limiter adjustment............................................................................................................................................ 30
Pump neutral adjustment...........................................................................................................................................................32
Control neutral adjustment for MDC and EDC/HC-EDC.................................................................................................. 33
Minor Repair
Standard procedures....................................................................................................................................................................35
Size and torque for plugs and fittings....................................................................................................................................35
Charge relief valve.........................................................................................................................................................................37
Optional speed sensor................................................................................................................................................................. 39
Service Manual
Series 42 Axial Piston Closed Circuit Pumps
Contents
520L0638 • Rev 0300 • July 2015 3