Danfoss H1 User Manual

Item Description Action
Charge pressure with pump
in neutral
Low charge pressure insufficient to recharge system loop. Measure charge pressure with the pump in neutral. If
pressure is low, go to next step.
Pump charge relief valve A pump charge relief valve that is leaky, contaminated, or
set too low will depressurize the system.
Adjust or replace pump charge relief valve as necessary.
Charge pump inlet filter A clogged filter will under supply system loop. Inspect filter and replace if necessary.
Charge pump A malfunctioning charge pump will provide insufficient
charge flow.
Repair or replace the charge pump.
System pressure Low system pressure does not provide enough power to
move load.
Measure system pressure. Continue to next step.
Charge check / HPRVs Defective charge check / HPRVs cause system pressure to
be low.
Repair or replace charge check / HPRVs.
Input to control Input to control module is operating improperly. Repair or replace control.
Optional control cutoff valve Control cutoff valve coil not engergized. Ensure charge pressure to control via port X7. If none,
confirm control cutoff valve coil is energized. If still no
pressure, repair or replace control cutoff valve.
System noise or vibration
Item Description Action
Reservoir oil level Low oil level leads to cavitation. Fill reservoir.
Aeration of the oil/pump
inlet vacuum
Air in system decreases efficiency of units and controls. Air
in system is indicated by excessive noise in pump, foaming
in oil, and hot oil.
Find location where air is entering into the system and
repair. Check that inlet line is not restricted and is proper
size.
Cold oil If oil is cold, it may be too viscous for proper function and
pump cavitates.
Allow the oil to warm up to its normal operating
temperature with engine at idle speed.
Pump inlet vacuum High inlet vacuum causes noise/cavitation. Check that inlet line is not restricted and is proper size.
Check filter and bypass switch.
Shaft couplings A loose input shaft to prime mover coupling will cause
excessive noise.
Replace loose shaft coupling.
Shaft alignment Misaligned input and prime mover shafts create noise. Correct misalignment.
Charge/system relief valves Unusual noise may indicate sticking valves. Possible
contamination.
Clean/replace valves and test pump.
May be a normal condition.
Sluggish system response
Item Description Action
Oil level in reservoir Low oil level will cause sluggish response. Fill reservoir.
Charge check / HPRVs Incorrect pressure settings will affect system reaction time. Replace charge check / HPRVs.
Low prime mover speed Low engine speed will reduce system performance. Adjust engine speed.
Charge and control
pressures
Incorrect pressures will affect system performance. Measure and adjust charge and control pressures.
Air in system Air in system will produce sluggish system response. Fill tank to proper level. Cycle system slowly for several
minutes to remove air from system.
Contaminated control
orifices
Control orifices are plugged. Clean control orifices.
Contaminated control
screens
Control screens are plugged. Clean or replace control screens.
Pump inlet vacuum Inlet vacuum is too high resulting in reduced system
pressure.
Measure charge inlet vacuum. Inspect line for proper sizing.
Replace filter. Confirm proper bypass operation.
Service Manual
H1 45/53/60/68 Tandem Closed Circuit Axial Piston Pumps
Troubleshooting
©
Danfoss | June 2018 520L0928 | AX00000103en-US0303 | 31

Danfoss H1 Specifications

General

Brand	Danfoss
Model	H1
Category	Water Pump
Language	English