JCB 3cx no full slewing range

[jeroenj]

Hi all!
My first post here, already learned a lot from this forum and the wonderful download section.
My friend/neighbor/co-worker recently bought a 1987 3cx black cab (serial number 320995)

We gave the machine little love, new filters and oil, grease points) and it is generally working good and at the moment ripping out big olive tree roots.
It got some issues however, one of them is that the back actor won't slew all the way to the left, it slews all the way to the right, but left only 1/3 of the way. We will change the slew gearbox oil again (will do soon as there was just grime inside the box when we filled it) so then there is a possibility to do something about it.
Anyone has any pointers as to what the reason might be? The boom is not physically blocked from the outside. I reckon it would be the rack&pinion not properly centered by someone in the past, or something inside blocking either the rack gears or one of the pistons.

Any help appreciated!

Jeroen

[Jeremy Rowland]

Hi Jeroen welcome to the site sure that somebody here can point you in the right direction, or trawl through some of the many JCB posts on here.

Jeremy

[Billy26F5]

Sounds a bit like it's not centred, not too familiar with the 3CX. If similar to previous JCB's it's quite a heavy job.
Sandy

[jeroenj]

So last week we had a big leak on the back actor boom ram, so we were forced to have some downtime. We decided to fix the slewing and replace the oil seals on the slewing pistons, as they were leaking as well.
Unfortunately I always forget to take pictures when doing these jobs, as I'm so absorbed in the work For reference here's how we did it:
Rotate the back actor to dead center.
Fully extend boom and dipper, bucket fully curled and on the ground.
Tied the boom/dipper on 2 sides to trees.
Lift the back of the machine a bit with the legs and placed a big wood block under the lower end of the boom
Removed the boom ram (to replace the seals)
Removed the pin holding the boom to the kingpost
Lowered the machine on the weels and drive forward a bit (so we could turn the kingpost, but not as far that we needed to undo all the hydraulic hoses)
Drained the slew gearbox oil.
Popped off the 2 slew cilinders.
Tied the kingpost to the carriage.
Supported with a jack, undo the bolts holding the bottom plate, then lowering the jack so the bottom plate together with the pinion support(?), pinion and kingpost shaft drop just enough to be able to turn the kingpost shaft.
Then came a very difficult part in finding out which part was not properly centered. first I tried to center the pinion and rack with the shaft up in place but I couldn't get it to center, so i lowered the shaft again so I could turn it and reinsert it at a different degree, to get the pinion and rack to center. After a lot of fiddling with two people, a jack and a lot of swearing, we got it back together centered properly. Closed the bottom plate with liquid gasket. Replaced the seals on the slew pistons, put the cilinders back on with a piece of wood and a sledgehammer, and again liquid gasket. (unfortunately we will have to replace one of the cilinders because it is badly pitted, we couldn't afford more downtime so we decided to put the old one back for now as a new will take a week to get here)
filled up the slew gearbox with new oil.
Repositioned the machine to the boom and replaced the pins and the boom ram.

Now we have the full 180 degrees slewing range! Very helpful uprooting and transplanting trees in a uneven sloped orchard.
Also took the chance to fix the fuel leak from the injection pump(throttle lever shaft o-rings were gone), that was a big pain to do, without the proper gasket for this pump. As well as fixing numerous hydraulic oil leaks(loose hydraulic line nuts, worn spool o-rings and retainers, burst hydraulic lines)
Now we can work without irrigating the orchard with 5 liters of diesel and 5 liters of hydraulic oil a day

After we finish the planting we'll have time to overhaul the transmission (suction strainer blocked multiple times with flakes wich look like the clutch disks are falling apart) and looking into the excessive black/grey smoke from the exhaust. For those I will make a new topic me thinks...

[Billy26F5]

Glad that's fixed, also glad you fixed all the other stuff too. I assume you have a CAV DPA, there are seal and gasket kits around if you need them, but do make sure no dirt gets in when fixing injection stuff.
Sandy