Oshkosh JLG 400S - User Manual

Questions and Answers

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Mark CookAug 7, 2025
Why is my Oshkosh JLG 400S operating hot?
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  jameslewisAug 7, 2025
  If your Oshkosh Lifting System is operating hotter than usual, it could be due to an insufficient amount of hydraulic fluid, which fails to meet the system's cooling demands. To resolve this, fill the reservoir to the proper level. Also, check the heat exchanger for adequate airflow and proper operation; repair or replace it if necessary. Finally, a system relief valve that's unseated or malfunctioning can cause overheating. Repair or replace any faulty relief valves and ensure the machine's loads aren't excessive.
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daniellewisAug 16, 2025
How to reduce excessive noise and vibration in Oshkosh Lifting Systems?
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  Debra MartinAug 16, 2025
  Excessive noise and vibration in your Oshkosh Lifting Systems can stem from several causes. Insufficient hydraulic fluid can lead to cavitation, causing system noise; fill the reservoir to the correct level and ensure adequate oil supply to the motor. Trapped air in the system lines or motor can also cause cavitation; ensure all system lines and components are purged of air. A loose or incorrect shaft coupling can produce vibrations; ensure the correct coupling is used and properly fitted onto the shaft. Misaligned shafts create frictional vibration; ensure the shafts are properly aligned. Finally, hydraulic oil with viscosity above acceptable limits will result in cavitation; replace the hydraulic oil with the appropriate fluid for the operating conditions.
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Maria LarsenAug 26, 2025
What to do if Oshkosh Lifting Systems won’t shift or slow to start?
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  Catherine MccarthyAug 26, 2025
  If your Oshkosh Lifting Systems won’t shift or is slow to start, it could be due to obstructed or restricted flow through the servo control signal lines, which can cause slow or no shift conditions within the motor. Ensure that the signal lines are not obstructed or restricted and that the signal pressure is adequate to shift the motor. Also, the size and condition of the supply and drain orifices affect the shift rate; ensure the proper control orifices are installed in the motor and that they are not obstructed. Clean or replace them as necessary.