M936A2 crane rotation

[jamboly]

I can't get the crane to rotate on the M936A2. All other boom functions are working. It seems like there is some sort of brake function keeping it from turning. It tries to start turning, but has a hard stop. It does this in both directions. I checked to make sure there was nothing in the gear teeth where they mesh.
Any recommendations?

 

[73m819]

how far does it turn before the stop, is this a new to you 936 if so if it does not travel a all, look down at the turntable, right in front towards the rear winch where the rotation stop is, there is a place for a pin to lock the rotation during travel, most wreckers this pin is mia, see if that pin is there

 

[jamboly]

This is a new to me (from GL) wrecker. I checked to see if the pin was in, but it wasn't. However, it acts if if the pin was in there, with a little slop. There is very little movement, but some. Other than the bars that go from the boom to the truck bed (I believe they are called shipping bars), is there anything else that would keep me from trying to mlly (come along or something like it) turn the crane?

 

[73m819]

I would FIND OUT what is locking things up before I froced it, try taking the cover off the swing gear case, to see if there is a broken gear in there, the motor drives a worm gear, this in turn drives the swing drive gear. but before you do anything MAKE sure that that travel swing lock pin is out, make sure that the hole is OPEN, not a bolt or something esle down in the hole, LISTEN for a THUNK. also drop the boom supports as there is very little free rotation allowed with these rigged, I know you already did this but needed to say it anyway, one more thought, look at the swing pinion for a broken or bent tooth, if everything is good then it sounds like a gear box fault as NO rotation in eather direction,

clean around cover good, remove the 6 cover bolts, put 3 into the jack holes, tighten EVENLY to lift cover, as you lift, try to save the gasket, if not you will have to make a new one, once the cover is off this will allow you to look in the rotation drive case. if you have to to see in there, the LOwer plug on the case side is the drain, later before the cover goes back on fill the case to the upper plug. with the cover off,I would try to swing if you can not see anything wrong in the case, to see what happens and again listen

the 936 and the 816 share the same wrecker bed, let me look at the 816 rotation drive, tm 9-2320-260-34-2 in section 16-28 covers the rotation drive

 

[jamboly]

Thanks. This sounds like fun. I may hold off until Thanksgiving to tackle this one.