One of our crane repair technicians successfully completed a job on a Liebherr LTM1160 for one of our customers in Texas.
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The customer reported issues with the crane’s main hoist speed, cane boom locking and unlocking, crane telescope percentage indications intermittent LMI (Load Moment Indicator) power loss and asked for a general tune up of the Liebherr Digi-Pal crane control system and the PAT DS350 LMI system. When we arrived the customer had the boom locking motors for telescope section 1 cached to keep the boom locking pins in unlocked position. This was needed to retract manually the telescope section in order to move the crane from a job site.
Liebherr Crane Repair and Troubleshooting items:
- The crane hoist speed was checked and found erratic and too fast for hoist down. We adjusted the Digi-Pal electronic cards to achieve the correct proportional output signals to the valves and also provided a general fine tune of all other hoist related cards.
- The crane boom hoist function (boom up and boom down) was tested and the adjustment of the related Digi-Pal cards was checked. We adjusted the Digi-Pal card for the lowering brake proportional output signal to obtain a smooth boom down operation.
- Due to high load indication, we tested the pressure transducer signals and found the zero value out of allowable tolerance and not adjustable anymore. The pressure transducer was changed and the crane was tested with a test load.
- The boom unlock and lock lights for telescope section T1 failed to operate correctly. We found both locking pins not moving freely and enough to unlock. Both pinning devices (air-motors) were removed in order to remove pins for rework. The pins were cleaned, reworked, greased and were moveable by hand as specified.
- During installation of the old pinning devices (air-motors), we noticed that those devices became weak over time and did not have enough stroke to fully unlock the boom pins. New pinning devices were ordered and installed
- We found one boom lock limit switch defective at one pinning device. The switch was replaced and the boom lock and unlock system tested.
- Boom length indication and boom percentage indication was tested and found only offset for telescope T2. Digi-Pal card was adjusted to fine tune the indication and output signal to the LMI.
- Due to poor connection at the percentage meter in the dash board we re-wired the percentage meter to avoid future shortages.
- Load Moment Indicator functions and indications were tested in all possible boom length % combinations.
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