JLG 400S - Service Manual

Other manuals for JLG 400S

Operation Manual140 pages

Operation And Safety Manual145 pages

Questions and Answers

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wlambertJul 28, 2025
Why is my JLG Lifting Systems operating hot?
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  hflowersJul 28, 2025
  If your JLG Lifting System is operating hot, it could be due to several reasons. First, check the hydraulic fluid level and fill the reservoir to the proper level, as an insufficient amount of fluid won't meet the system's cooling demands. Another cause might be a failing or obstructed heat exchanger; make sure it's receiving adequate airflow and is in good operating condition—repair or replace it if necessary. Lastly, a system relief valve that's unseated for too long or has failed can cause overheating. In this case, repair or replace any malfunctioning relief valves and verify the machine loads aren't excessive.
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Wendy WelchAug 6, 2025
What to do if JLG 400S won’t shift or is slow to start?
- C
  christopher86Aug 6, 2025
  If your JLG 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. Make sure these signal lines aren't obstructed or restricted and that the signal pressure is adequate to shift the motor. Also, check the control orifices installed in the motor, as they determine the motor shift rate. Ensure the proper orifices are installed and not obstructed; clean or replace them as needed.
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Amy BlackNov 15, 2025
How to fix excessive noise and vibration in JLG Lifting Systems?
- T
  Trevor AndersonNov 15, 2025
  Excessive noise and vibration in your JLG Lifting Systems can stem from several issues. Insufficient hydraulic fluid can lead to cavitation, causing system noise; ensure the reservoir is filled to the proper level and that the oil supply to the motor is adequate and lines are unobstructed. Air trapped in the system lines or motor can also cause cavitation; ensure these lines and components are purged of air. A loose or incorrect shaft coupling can produce vibrations; ensure the correct coupling is used and fits properly on the shaft. Misaligned shafts create excessive frictional vibration, so ensure the shafts are properly aligned. Finally, hydraulic oil with viscosity above acceptable limits can result in cavitation; replace the hydraulic oil with the appropriate fluid for operating condi...

JLG 400S Specifications

General

Power Source	Diesel
Platform Height	40 ft
Machine Width	2.44 m
Machine Length	6.4 m
Machine Height	2.59 m
Working Height	46 ft
Swing	360 Degrees Continuous
Drive Speed - 2WD	4.25 mph
Overall Width	2.44 m
Overall Length	6.4 m
Stowed Height	2.59 m
Ground Clearance	1 ft
Platform Capacity	227 kg
Platform Capacity - Unrestricted	227 kg
Machine Weight	5, 443 kg