Anthony Liftgates don't break often, but even the most rugged parts don't last forever. Damage or normal wear and tear can interfere with normal liftgate operation. We've prepared this section to help guide you step-by-step through the most common troubleshooting procedures for liftgate repair. Simply locate and click the description that most closely matches your issue, then follow the troubleshooting steps outlined on that page.

<< Return to Troubleshooting Guide

Platform will lift rated loads, but drifts down.  

Possible Cause #1 Air in hydraulic lines.
Action -            

Fill reservoir to within 1/2'             of full with platform on ground with factory recommended Pennzoil             Arctic hydraulic fluid, Dextron II if not available. (Power             down models fill to 1/2' of full with platform raised).


(Diagnosis time -10 minutes / Repair time - 10 minutes).

Part Numbers - N/A
Possible Cause #2 Lowering valve stuck partially or fully open.
Action -            

With platform on ground, remove lowering valve and inspect. Clean if dirty. Replace if plunger not freely moveable.




(Diagnosis time - 1/2 hr. / Repair time - 15 minutes).

Part Numbers -            

ATU-121 (Monarch Lowering Valve)


ATU-479 (Fenner Lowering Valve)

Possible Cause #3 Cylinder piston seal blown allowing fluid to leak past piston when trying to raise platform.
Action -            

Remove breather hose from end of cylinder. Activate power unit to raise position, if hydraulic fluid pumps out o f breather port, repack or replace cylinder. (If under warranty, replace cylinder - DO NOT repack or dismantle.




(Diagnosis             time - 10 minutes / Repair time - 1/2 hr.).

Part Numbers -            

ATU-25100 (AST-1500, AST-2000, ASTL-1800, ATU-1800)


ATU-50100 (ASTL-2500, AST-2500, ATU-2500 Cylinder)


ATU-75100 (AST-3000, ATU-300, ATU-3500 Cylinder)


ATU-25113-WR (ATU-25100 Seal kit)


ATU-50123-WR (ATU-50100 Seal kit)


ATU-75112 (ATU-75100 Seal kit)

Warranty Information:
Base Warranty:            

3 Years on mechanical structure.


2 Years on hydraulic & electrical components.


Warranties are void if genuine Anthony parts are not used.