Haulotte Group HT21RT O, Maintenance Book

Page: 218 / 282

218 4000511390 E03.16 USA / GB
Upper boom
Procedure of dismantling / reassembling hydraulic rotary actuators
MS0028
9 - Troubleshooting Guide
Problem See
Shaft rotates slowly or not at all 1 - 6
Operation is erratic or not responsive 7
Shaft will not fully rotate 8 - 9
Selected position cannot be maintained 3 - 4 - 7
Causes Solutions
1. Insufficient torque output Verify correct operating pressure. Do not exceed OEM's pressure
specifications. Load may be above maximum capacity of the actuator.
2. Low rate of fluid flow Inspect ports for obstructions and hydraulic lines for restrictions and
leaks.
3. Control or Counterbalance valve has internal leak Disconnect hydraulic lines and bypass valve. Leave valve ports open
and operate the actuator through housing ports (do not exceed OEM's
operating pressure). The valve must be replaced if a steady flow of
fluid is seen coming from the valve ports.
4. Piston and/or shaft seal leak Remove the plug and the housing's valve ports. Operate the actuator
through the housing ports. Conduct the internal leakage test as
described in the Testing Section of this manual.
5. Corrosion build-up on the thrust surfaces Re-build the actuator. Remove all rust and then polish. Replacement
parts may be needed.
6. Swollen seals and composite bearings caused by
incompatible hydraulic fluid (Standard actuators
only)
Re-build the actuator. Use fluid that is compatible with seals and
bearings. Contact HAULOTTE Services® for more information.
7. Air in actuator Purge air from actuator. See bleeding procedure starting of this
manual.
8. Twisted or chipped gear teeth overload conditions Check for binding. Actuator may or may not be able to be rebuilt and
may need to be replaced.
9. Port fittings are obstructing the piston during stro-
ke Check thread length of port fittings. Fittings should not reach inside the
housing bore.