Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Contents
Introduction
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Danfoss | September 2020
Hydrostatics Servicing Overview................................................................................................................................................ 5
General Servicing Instructions.....................................................................................................................................................5
Safety Precautions............................................................................................................................................................................6
Independent Braking System................................................................................................................................................. 6
High Inlet Vacuum...................................................................................................................................................................... 6
Manufacturer's Warranty..........................................................................................................................................................6
Symbols used in Danfoss literature............................................................................................................................................6
The Basic Closed Circuit................................................................................................................................................................. 8
Case Drain and Heat Exchanger..................................................................................................................................................8
Tandem Pumps Design.................................................................................................................................................................. 9
H1T pumps pictorial diagram....................................................................................................................................................10
H1T Tandem Pumps Schematics..............................................................................................................................................11
System Schematic for Tandem Pumps...................................................................................................................................12
Pressure Limiter Valves................................................................................................................................................................ 13
Pressure Limiter Sectional View.......................................................................................................................................... 13
EDC Operation........................................................................................................................................................................... 17
Manual Override (MOR)............................................................................................................................................................... 18
Manual Displacement Control (MDC) ....................................................................................................................................18
MDC Operation..........................................................................................................................................................................19
MDC Torque................................................................................................................................................................................20
Neutral Start Switch (NSS)..................................................................................................................................................... 20
Case Gauge Port M14.............................................................................................................................................................. 20
Input Speed......................................................................................................................................................................................23
Independent Braking System...............................................................................................................................................23
System Pressure..............................................................................................................................................................................23
Servo Pressure.................................................................................................................................................................................25
Charge Pressure..............................................................................................................................................................................25
Charge Pump Inlet Pressure.......................................................................................................................................................25
Case Pressure...................................................................................................................................................................................25
External Shaft Seal Pressure....................................................................................................................................................... 26
Temperature.................................................................................................................................................................................... 26
Viscosity.............................................................................................................................................................................................26
H1 Pumps General Specification.............................................................................................................................................. 27
Fluid Specification......................................................................................................................................................................... 29
Start-Up Procedure........................................................................................................................................................................33
Safety Precautions......................................................................................................................................................................... 35
High Inlet Vacuum....................................................................................................................................................................35
Unintended Machine Movement....................................................................................................................................... 35
AX152886481761en-000405 | 3
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