M936A2 Cannot engage crane PTO

[peter34668]

Hello everyone,
My latest project is a 1991 M936A2 and I'm having some trouble. All the issues so far I have been able to fix and have been very straight forward. The truck last served in the reserves and unlike the rest of the trucks I purchased it was poorly maintained. Every other grease fitting is frozen and it doesn't look like it's been used much in quite some time. I would even bet it once served in a salty environment.

I have only had it for a week and I have worked through every problem I have encountered with the exception of one big one. I cannot get the crane/rear winch PTO to engage. Before I start pulling things apart I thought it would be a good idea to run it by all of you. I have all the manuals on the truck and I think I'm doing it right but I still cannot get that rear PTO driveshaft spinning. (I can get the front PTO to work for the front winch)

What I have been doing is to start the truck, set the parking brake, keep the truck's transmission in neutral, put the transfer case in neutral, push the main PTO control lever to the left of the driver's seat toward the rear of the truck, put the truck's transmission in 1-5 and set the throttle to high (1300 or above). I think at some point I can hear the PTO engage meaning I hear something but when I look under the truck that PTO isn't turning.

I should add that when the PTO lever is pulled back I hear air escaping. I assume that is to set the spring brakes like it says in the manual.

Any help would be appreciated, I would hate to start pulling things apart only to find out it was something simple. I did call the previous owner who is a small used car dealer and he assures me he had the crane operating at one time. I asked him what he did but he said it was over a year ago and he doesn't remember.

Thanks in advance

 

[M35A2-AZ]

Make sure the transfer case is in Neutral and as you are trying to move the PTO into gear you may have to move the transfer case lever up and down a little.
The M936 Transfer cases were used a lot and are not as tight as on other trucks.

 

[fasttruck]

Read the applicable TM yet ? I do not have one for the M936 but the M 816 (which I have) has another control under the boom in front of the winch, a power divider to select wheither crane or winch operates. On a M816 all the levers in the cab are set first and the shaft from the t case to the power divider is turning. You have to disengage the clutch with an air control at the rear to engage the power divider. The only air control associated with the crane on a M 816 is the clutch control. But then I believe on a 936 the pump is on the t case and not under the crane so maybe there is no shaft to turn ?

 

[M35A2-AZ]

The m936 has a drive shaft and pump and no controls back by the rear winch like the M816.

 

[peter34668]

The lever attached to the transfer case that engages the pto is bent. I will take it off and straighten it tomorrow.

 

[BKubu]

Try to figure out why it is bent. Someone may have tried to force it. It could mean that something else is binding up or out of adjustment.

 

[peter34668]

Try to figure out why it is bent. Someone may have tried to force it. It could mean that something else is binding up or out of adjustment.

Its working 100% now. The lever was bent because a brute used his force rather than his brain. Anyway, it's all working and I have been playing with it all morning. I have all the issues fixed, it's completely lubed and once the filters arrive I will have it as close to 100% it will get under my administration. I just need to go find someone to rescue

Now I just need to find a M929 and a M931 with a low boy trailer to finish my collection. Wait maybe I need a bigger barn first!

 

[Pipeliner]

What Infound on mine was the lever beside the seat was not engaging the PTO shaft off of the Transfer case. Someone had bent the arm on the fork on the transfer case for the hydraulic pump Mine came out of an overhaul and the front PTO was not adjusted right and the rear one was not engaging off the Transfer case. Go through the procedure and make sure that shaft is actually rotating. Many of the wreckers have the same problem. They were not greased, and they tried to force the Lever in. In doing so they bent the arm on that fork.