m936 boom won't rotate more than 10 degrees, are there limiting pins

[Jeep Nasty]

I'm helping a friend with their newly acquired m936. We've read the TM's I got the rear pto working adjusted and engaged. all the controls work on the boom. The problem is when using left or right rotate it will only go about 10 degrees from center. I don't dee any limiting pins in the TM's so I'm not sure what I'm missing.

 

[M35A2-AZ]

I friend had a problem like that and it turn out to be that we were not lifting the boom up high enough, then it turn ok.
I had not seen a limiter like that before, his was a M936A2.
Try lifting the boom most of the way up then try turning it.

 

[BnaditCorps]

I friend had a problem like that and it turn out to be that we were not lifting the boom up high enough, then it turn ok.
I had not seen a limiter like that before, his was a M936A2.
Try lifting the boom most of the way up then try turning it.

To not wipe out stuff on the truck i presume is why it would be there, but that is still a bad thing, especially if you have to work in a hurry.

 

[Jeep Nasty]

That was one of my initial thoughts we have tried turning it with the boom in the highest position as well. Either way it goes about 10° to the left and suddenly stops want to go is about 10° to the right and suddenly stops. I'm not very educated on hydraulic stuff so I don't know if somethings wrong with the tearing of the motor once it hits A particular distance

 

[BnaditCorps]

That was one of my initial thoughts we have tried turning it with the boom in the highest position as well. Either way it goes about 10° to the left and suddenly stops want to go is about 10° to the right and suddenly stops. I'm not very educated on hydraulic stuff so I don't know if somethings wrong with the tearing of the motor once it hits A particular distance

Check to make sure that there is nothing blocking it (cables, boxes, chains, etc.) Then look for pins that may be holding it in a travel lock (that is my best guess on why it isn't moving). Also make sure it is in the right gear that could be one reason.

 

[grendel]

What holds it in a travel lock?

We took the boom isolation rods down.

 

[Suprman]

The boom support rods are the travel lock. I don't know of anything that should prevent rotation. Did you look all around and under the boom mechanism for foreign objects? Does it sound like its binding anywhere? If there were locking pins in place I don't see how it would be able to move 10 degrees. Do not try to turn the rotator unless you are seated in the doghouse with no one else on the deck.

 

[MtnSnow]

I would check to see if anything is caught in the cogs (teeth of the gears) of the rotater

 

[grendel]

I would check to see if anything is caught in the cogs (teeth of the gears) of the rotater

Could be something, as we get an equal amount of rotation each way. Is there an easy way to see those cogs?

 

[MtnSnow]

Honestly I have no clue as I don't have a 936....but with the equal rotation that's is all I could come up with...

 

[Augdog1964]

We use our 936 regularly for tank maintenance... we have never seen any limiting pins or anything that would limit rotation of the boom, on our wrecker.
You do need to make sure the boom struts are disconnected from the back of the bed of course, and stored up on the boom itself.
If equal rotation hard to imagine a blockage. Could be a field expedient change to the unit for a specific purpose however, it happens.

 

[grendel]

The rotation pinion motor is shot. It's leaking fluid through the pinion head itself. Made a new friend in an National Guard's SPC and 1SGT to work on it. They're out there now, dinking around with it.

Looks like I need to find a pinion motor rebuild kit.

 

[JohnnyBM931A2]

The rotation pinion motor is shot. It's leaking fluid through the pinion head itself. Made a new friend in an National Guard's SPC and 1SGT to work on it. They're out there now, dinking around with it.

Looks like I need to find a pinion motor rebuild kit.

Well.. At least you know what the problem is now.