Hitachi EX75UR Centre Joint Seal and Lock Questions.

[Binty]

Hi all. 1st time post. I’m in Trouble…. My Centre Joint Lock/Stop broke and I twisted up/broke a HYD fitting. Access is a nightmare…. However I have managed to drop the joint unit from its mounts which enabled me to recover and repair the lock/stop WITHOUT REMOVING THE SLEW MOTOR. I am now re-installing the centre joint By jacking it back from underneath. 2 big problems I’m facing are: 1. the rubber seal hasn’t pushed back up through the ‘floor’ despite jacking the unit fully up. HOW DO I RETRIEVE IT to its correct position?? 2. The top part of the centre joint swivel is not correctly aligned with the lock attachment bolts. It’s out by about 20 degrees. How can I turn the top of the joint To align the lock device?
I made a tool which fits down between the 4 HYD lines on the top of the Centre Joint upon which I welded a socket. Using extensions and a power bar, I have tried to wrestle the unit around but it will not budge! Please help. I have spent THREE DAYS upside down in that damned hole!

 

[Kobe Steel]

Sounds like the CJ maybe too tight to turn so you may want to remove the CJ completely and check it out on the bench. If you have not replaced the seals in the CJ then it shouldn't be very difficult to rotate. Not sure what is happening with the rubber seal over top. Try taking some pic and posting so we can get a better understanding of the problem.

Best regards

 

[Binty]

Thanks for the tips. Iv heard the CJ may be hydraucally locked since I still have all the hoses connected…? I’ll try undoing the hoses and seeing if I can turn it.

as for the seal/ boot, I have since learned it must be slid DOWN over the joint from above, and pushed into the seat with a screwdriver. From underneath is impossible

 

[Binty]

Update for any poor soul trying to fix a similar broken CJ lock..

There is no way to turn the CJ by hand due to the friction of all the Teflon seals inside. Local Excavator service said they have a special tool they bolt on to the CJ then use a large hammer to smash it around to the correct position And even then they are a battle. I tried making a tool, but it broke. I was faced with reassembling everything and slewing the digger to align the CJ with the Lock.


after 4 days, I’m now all but assembled… except for attaching the repaired Lock, which can not be installed with hyd lines connected.

history... Lock was found to be broken after a HYD line was twisted up and broke due the CJ spinning with slew ( due to broken Lock). The Lock had been modified by a previous owner and had been effectively welded in. To remove the lock, hyd fittings were removed from above, CJ lowered Leaving the underneath Hyd fittings attached (didn’t want to drop 35kg unit completely as I’m working alone with limited space and equipment) This gained access to the broken lock ( tabs had sheared off where it bolts to CJ). However the Cj seal was still attached to the CJ down below. After much struggling, the boot was hooked and pulled up through the floor.

New lock fabricated using broken pieces for template and placed in previous owners capturing bracket. ( v difficult task given no way to measure the hole spacing accurately given CJ position) then boot seal and Hyds refitted to enable digger to function So as to slew digger to correct position to attach lock.

so now it’s all in position but of course, I can’t access the lock attachment holes due to all the hyd lines in place.. so thus begins DAY 5 upsidedown in the hole.

 

[Binty]

Update. new lock holes didn’t align with CJ Holes. Had to tear all lines and fittings off again, drop CJ, recover Lock, slot holes, reassemble. A lot faster 2nd time around.