Sauer Danfoss 45 Series - Service Manual

Questions and Answers

M
Maria DavisAug 5, 2025
Why is my Sauer Danfoss Water Pump system operating hot?
- C
  Courtney HernandezAug 5, 2025
  Your Sauer Danfoss Water Pump system may be running hot due to several reasons. It could be that there isn't enough hydraulic fluid to cool the system properly, so ensure the reservoir is filled to the correct level and is the right size. Another potential cause is insufficient airflow, high air temperature at the input, or undersized heat exchangers. Clean, repair, or replace the heat exchanger as needed, and verify it's the correct size. Also, fluid passing through the relief valve adds heat, so adjust the external system relief valve setting according to the manufacturer's recommendations, ensuring it's above the PC setting. Finally, high inlet vacuum can also contribute to overheating; correct the inlet pressure/vacuum conditions.
A
Anthony KingAug 17, 2025
How to fix pressure or flow instability in Sauer Danfoss 45 Series?
- L
  longbrentAug 17, 2025
  Pressure or flow instability in your Sauer Danfoss Water Pump can often be attributed to two primary issues. First, air in the system can cause erratic operation. To resolve this, activate the PC to allow the system to bleed air and check the inlet line for leaks, eliminating the source of air. Second, sticking control spools can also lead to instability. Inspect the spools to ensure they move freely in the bore; clean or replace them if necessary.
V
Vicki SmithOct 26, 2025
What to do if my Sauer Danfoss Water Pump has low output flow?
- T
  tfarmerOct 26, 2025
  If your Sauer Danfoss Water Pump has low output flow, there are several potential causes. Insufficient hydraulic fluid can limit output, so fill the reservoir to the proper level. High fluid viscosity or low fluid temperature can prevent proper pump operation; allow the system to warm up or use a fluid with the correct viscosity grade. An external relief valve set too low can also cause this, so adjust it following the manufacturer's recommendations, ensuring it is above the PC setting. A low PC setting can prevent the pump from achieving full stroke; in this case, adjust the PC and LS settings. High inlet vacuum or low input speeds can also decrease flow, so correct the inlet pressure conditions and adjust the input speed accordingly. Lastly, an incorrect rotational configuration can caus...

Summary

INTRODUCTION

Safety Precautions

General safety advice and specific warnings for hydraulic systems.

Symbols Used in Sauer-Danfoss Literature

Legend and explanation of symbols used in the manual for clarity.

General Description of Pump Operation

Explains the mechanical principles of Series 45 G Frame axial piston pumps.

System Circuit Diagram and Operation

Illustrates the hydraulic system circuit and the function of the PVG valve.

TECHNICAL SPECIFICATIONS

Mounting, Ports, and Rotation

Details on mounting flanges, auxiliary pads, port types, and shaft rotation.

Control Options and Types

Overview of available control options like Pressure Compensator (PC) and Load Sensing (LS).

Performance Ratings and Parameters

Key performance ratings, including speed limits, pressure, and torque.

Hydraulic Parameters and Fluid Properties

Hydraulic parameters, temperature ranges, viscosity, and filtration requirements.

FEATURES

Displacement Limiter and Input Shafts

Optional limiter to control displacement and details on available input shafts.

Auxiliary Mounting Pad Options

Information on auxiliary pads for mounting other hydraulic pumps.

CONTROL OPTIONS AND OPERATION

General Operation Principles

Explains how bias and servo pistons control swashplate angle and pump output flow.

Pressure Compensator (PC) Control Explained

Details how the PC control maintains constant hydraulic circuit pressure as flow varies.

Load Sensing (LS) Control Explained

Describes the LS control which matches pump flow with system demand via pressure drop.

PRESSURE MEASUREMENT

Tools and Gauge Installation Guide

Details on necessary tools and how to install pressure gauges at specific ports.

INITIAL START-UP PROCEDURES

Pump Start-Up Sequence

Step-by-step guide for starting up a new or reinstalled Series 45 pump.

FLUID AND FILTER MAINTENANCE

Fluid and Filter Maintenance Recommendations

Recommendations for maintaining fluid cleanliness and specified change intervals.

TROUBLESHOOTING

Noise, Vibration, and Response Issues

Diagnoses issues like excessive noise, vibration, and sluggish actuator response.

System Temperature and Flow Problems

Addresses overheating and low pump output flow conditions.

Pressure, Flow, and Inlet Issues

Resolves pressure instability, PC setting, and high inlet vacuum problems.

ADJUSTMENTS

PC Control Setting Adjustment

Step-by-step guide to adjust the Pressure Compensator (PC) control setting.

LS Control Setting Adjustment

Step-by-step guide to adjust the Load Sensing (LS) control setting.

MINOR REPAIR

Shaft Seal Replacement Procedure

Procedure for replacing the lip-type shaft seal without major disassembly.

Auxiliary Mounting Pad Service

Steps for removing, replacing, or exchanging auxiliary mounting pads.

Control Assembly Service

Detailed steps for disassembling and reassembling the control unit.

Plug and Fitting Torque Specifications

Specifications for installing and torquing various plugs and fittings.

Sauer Danfoss 45 Series Specifications

General

Mounting	SAE standard mounting
Fluid Type	Hydraulic Oil
Weight	Varies depending on model
Shaft Type	Standard splined shaft
Type	Axial Piston Variable Displacement Pump