Complete 936 newbie

[The FLU farm]

Alright, so I recently bought an M936A1 and have been trying to read up on what makes those things tick. It'll primarily be used to move a few things around, such as containers, and also to get my FLU 419s unstuck as needed.

It wouldn't surprise me if I get volunteered to get other people's stuff unstuck at some point in the future. Things that are too large and heavy for a regular vehicle or even a winch equipped FLU419 to handle. I doubt I'll ever drive it more than 10 miles (one way) on the road.

Anyway, what I could really use some guidance about is what I absolutely shouldn't do when it first gets here. It'll most likely be me driving it off the trailer, and then down the driveway. And there's no way I won't be trying to operate the crane since now the fluids will be somewhat warm by the time it gets to the garage.

I'm fully aware that none of these machines are idiot proof, and I'm a pretty good idiot, so that's why I ask for advice. Thanks in advance.

 

[98G]

Alright, so I recently bought an M936A1 and have been trying to read up on what makes those things tick. It'll primarily be used to move a few things around, such as containers, and also to get my FLU 419s unstuck as needed.

It wouldn't surprise me if I get volunteered to get other people's stuff unstuck at some point in the future. Things that are too large and heavy for a regular vehicle or even a winch equipped FLU419 to handle. I doubt I'll ever drive it more than 10 miles (one way) on the road.

Anyway, what I could really use some guidance about is what I absolutely shouldn't do when it first gets here. It'll most likely be me driving it off the trailer, and then down the driveway. And there's no way I won't be trying to operate the crane since now the fluids will be somewhat warm by the time it gets to the garage.

I'm fully aware that none of these machines are idiot proof, and I'm a pretty good idiot, so that's why I ask for advice. Thanks in advance.

Do not back up in low range.

Do not operate the rear PTO at low RPM.

 

[The FLU farm]

Thanks!

It would've never occurred to me not to back up in Low. Most of my stay-at-home vehicles are always in Low. Ideally 2WD Low.

By rear PTO I guess you mean the winch, and that the reasoning is to avoid creating heat. I'm a low rpm person, so I'll have to keep that in mind.

 

[Mullaney]

Thanks!

It would've never occurred to me not to back up in Low. Most of my stay-at-home vehicles are always in Low. Ideally 2WD Low.

By rear PTO I guess you mean the winch, and that the reasoning is to avoid creating heat. I'm a low rpm person, so I'll have to keep that in mind.

.
The crane PTO needs to be operated at either 1500 or 1800 rpm's. Not sure which, but I am almost certain the higher speed. The real reason is to keep you from burning up your Allison Automatic.

You already know about hydraulics, but obviously weight on the end of a wire will turn you over if it gets beyond your reaching point. Don't try to "side load" the crane boom. Pick up whatever it is that you want to lift straight up and straight under the boom. Gently swing with the weight as close to the ground as possible. Know your weight. Don't try to overload the crane and use the load chart.

Carefully inspect the hoses. If the hoses look cracked or if the outer covering is "skinned off" replace them. There is one large check valve under the truck near the pump. That is about all there is to protect you, your crane, whatever you were lifting, and anybody standing near you. I had a hose (that I knew I should have replaced) that busted. That tiny little hole in the hose shot hydraulic oil maybe 75 feet in the air. Hydraulic oil under high pressuer WILL CUT you like a sharp knife.

Other than that, One last thing: I suggest that even though they are manual - and a pain in the butt - Use Your outriggers!

 

[KN6KXR]

Thanks!

It would've never occurred to me not to back up in Low. Most of my stay-at-home vehicles are always in Low. Ideally 2WD Low.

By rear PTO I guess you mean the winch, and that the reasoning is to avoid creating heat. I'm a low rpm person, so I'll have to keep that in mind.

The issue is that in low range it automatically engages the front axle. The t-case is a weak spot and in reverse the output gears can separate and crack the case (under heavy loads). Attached memo on the issue. Instead of installing the interlock kit as the memo indicates most folks disconnect the actuating mechanism. There are a few ways of doing this. I have yet to do this on my M936A2. I just don't back up in low. At the end of the day I'll likely disconnect the auto engage for the front axle and just use the switch in the cab. I like having the control.

As for RPM when the power is fed to the rear deck try and you will see. With t-case and tranny in neutral engage power divider. You may have to bump tranny to drive then back to neutral to engage divider. Then put in drive high 1-5. As you use manual throttle to raise RPM you'll hear it shift to high gear around 1600rpm. That's where you want to be I run mine about 1700rpm. You have to keep the shaft speed to the rear deck hydraulic up and since it's a slushbox tranny that means staying above the kick down rpm make sure you are in top gear. Older wreckers could run lower they had manuals you could just stick it in 5th. Just play around you'll hear it...... Your shift points might be a bit different than mine just listen for it.

My swing gearcase imploded not too long ago. Total PITA to repair and cost me about $2k in parts (some of which I got a super deal on). The truck was pretty new to me hadn't really gotten to working it and checking everything. After the rebuild I went through it all and lo and behold got a bunch of water out of the hoist case. Axles were 1 gallon shy each, front winch oil was milky..... Go through it all. I also fixed my CTIS but had to renew all three right side seals. Found the bearings a bit shy on lube put that on your list as well.

I'm kinda in the deep end on mine. RSMS did a shit job. Got questions fire away if I can answer them I will.

 

[KN6KXR]

Also you may have different crane motors. Either the Hydreco or Intertech/Parker. The Hydreco was an older motor and has no case drain. The Parker came later and replaced it. Some TM's have the older one, some the newer, some one of each (like my wrecker). They are functionally the same BUT some notes:
-The Hydreco is good for about 800-1000 psi supply according to my hydraulic guy.
-The Parker is good for closer to 1400psi.
-The Parker has a case drain and on mine they missed it. So it pissed out under hoisting. I ran a drain with copper tube to a grease gun hose at the pivot and then installed a valve at the tank bung when I had it drained out for other work. Problem solved.
-When I had the system down I installed a gauge with a quick connect port off the valve block. An elbow, some fittings... presto I can see the pressure as I work the crane. I suggest doing this. I tune my tractor hydraulics this way why not my wrecker?

 

[The FLU farm]

Thanks, guys, this is great info. I really appreciate it.

Ironically, I had already thought about making the front axle not automatically lock in, since I prefer 2Low on most things. Would've never guessed it'd help things.

Maybe the hardest thing for me to learn will be running the engine at a high rpm. With the Unimogs I tend to use the lowest rpm possible, largely because I find it easier to keep up when the levers act more in unison with my limited skills.

Obviously I have a lot to learn, which is okay since I love learning. Again, thanks for the lessons.

 

[Mullaney]

Thanks, guys, this is great info. I really appreciate it.

Ironically, I had already thought about making the front axle not automatically lock in, since I prefer 2Low on most things. Would've never guessed it'd help things.

Maybe the hardest thing for me to learn will be running the engine at a high rpm. With the Unimogs I tend to use the lowest rpm possible, largely because I find it easier to keep up when the levers act more in unison with my limited skills.

Obviously I have a lot to learn, which is okay since I love learning. Again, thanks for the lessons.

.
Don't worry over the speed. Those big long knobs will let you ease the lever forward or back to gently move the boom or raise the winch. I call it "sneaking up on the action". Valve doesn't have to be pushed all the way forward for sure. Having FLU's hydraulic experience, this truck's operation will come to you easily...