Danfoss 51 Series - Service Manual

Other manuals for Danfoss 51 Series

Service Kit Instructions2 pages

Repair Instructions36 pages

Questions and Answers

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Michael HallAug 16, 2025
Why is there excessive noise or vibration in my Danfoss 51 Series Engine?
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  Deborah SellersAug 16, 2025
  Excessive noise or vibration in your Danfoss Engine can stem from several causes. Insufficient hydraulic fluid can lead to cavitation, so ensure the reservoir is filled to the proper level. Air bubbles can also cause cavitation; look for foam or bubbles in the reservoir and check for leaks on the inlet side of the charge pump. Loose shaft couplings or misaligned shafts can also create noise and damage; replace loose couplings and correct any shaft misalignment. If shaft splines are worn excessively, replace or repair the motor.
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Roger JohnsonAug 21, 2025
What to do if Danfoss 51 Series motor operates normally in one direction only?
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  Emma SmithAug 22, 2025
  If your Danfoss Engine motor operates normally in only one direction, it could be due to a few reasons. If charge pressure is low in one direction, the loop flushing shuttle spool may be sticking; measure charge pressure in both directions and inspect/repair the spool if needed. If the control shifts the motor to minimum displacement in one direction, it may lack sufficient torque; measure servo pressures to check control operation and repair the control or correct the input signal. If the pressure compensator operates in one direction only, the motor will stay at minimum displacement in the other direction; check the brake pressure defeat spool for sticking or improper signals and repair the spool or correct the input signal.
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Jennifer JacksonOct 26, 2025
What to do if my Danfoss 51 Series Engine has improper output speed?
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  Jessica MullinsOct 26, 2025
  If your Danfoss Engine has an improper output speed, it could be due to several reasons. Insufficient hydraulic fluid reduces system efficiency, so fill the reservoir to the proper level. An improper threshold or pressure compensator setting can also cause this issue; check and adjust these settings as needed. A sticking pressure compensator piston or spool, a blocked or restricted orifice, or a sticky control piston can also lead to improper shifting. Check and repair or replace these components as necessary. Ensure the control input signal is correct. Finally, excessive internal leakage can lower charge pressure, affecting system performance. Install a loop flushing defeat option and monitor case flow. If case flow is excessive, the motor may require major repair, and you should contact ...
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Jennifer MatthewsOct 31, 2025
Why is my Danfoss Engine system operating hot?
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  Daniel SmithOct 31, 2025
  Several factors can cause a Danfoss Engine system to overheat. Insufficient hydraulic fluid, a blocked heat exchanger, or low airflow can prevent sufficient cooling. High loop flushing relief valve settings, too-low system relief valve settings, entrained air, or excessive internal leakage can also contribute to overheating. Ensure the reservoir is filled to the proper level. Check the temperature upstream and downstream of the heat exchanger, and clean, repair, or replace it if necessary. Monitor case drain flow and adjust the loop flushing relief valve setting or replace it with an orificed type relief if low. Adjust system relief valve settings. Look for foam or bubbles in the reservoir and check for leaks on the inlet side of the charge pump. To check for excessive internal leakage, in...
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istricklandNov 5, 2025
What to do if my Danfoss 51 Series Engine has low output torque?
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  Michelle SmithNov 5, 2025
  If your Danfoss Engine has low output torque, it could be due to low system pressure at the motor. Measure the system pressure and increase the pressure limiter or relief valve setting if it's too low. A low loop flushing relief valve setting can also cause improper supply pressure; measure charge pressure and adjust the valve setting if needed. High pressure compensator or improper threshold settings can cause improper motor displacement; check and adjust these settings. Blocked orifices, sticking pressure compensator pistons, or a sticking 4-way spool can also cause issues; inspect and repair or replace these components. If using a two-position control, inspect the solenoid valve. Ensure the control input signal is correct. Finally, excessive internal leakage can cause charge pressure to...
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lcolemanNov 10, 2025
How to fix a sluggish Danfoss 51 Series Engine system?
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  Joshua BrightNov 10, 2025
  A sluggish Danfoss Engine system can result from several issues. A blocked or restricted orifice will cause sluggish response, so remove, inspect, and clean all orifices, ensuring the appropriate ones are installed. Inappropriately high threshold or low pressure compensating settings can also cause this; check and adjust if necessary. A sticky 4-way spool or control piston will cause sluggish response; clean and inspect these, replacing if necessary. An improper or erratic input signal to the control may cause sluggish response; check and correct if necessary. Inappropriately low pressure settings at the loop flushing relief valve or system pressure can also be culprits; measure and adjust as needed. Excessive leakage will cause lower charge pressure and affect performance. Install loop fl...