5 ton wrecker bed

[Heavywrecker]

Hello from Wisconsin!

I need some information from the military surplus genius' on this page!

I recently bought a 5 ton wrecker bed and need to know a few things about it. I would like to know the model and year range, also if anyone knows anything about how the hydraulic system is set up on this unit that would be great. I will be heavily modifying it to be used as a civilian wrecker/ towing unit. I will be mounting it on an 03 international 8100 and need to know what the specs are for the pump mounted on the wrecker bed. I would like to plumb it up to the pto pump on the truck for simplicity reasons, anyone know what the pump output and max psi are? Also am wondering what the size of the drag winch are, was told it was a 60,000lb unit but have seen most on the net are 45,000lb units. One last question, I will be needing to add a few winches and a hydraulic underlift to the system, this bed has an extra hose and port on the return manifold under the rotating piece, assuming this would normally go to the self recovery front mounted winch. Thinking this would be the spot to add my hydraulic spools for the underlift stiff legs and winches! I will attach pictures Thanks in advance, if any additional pictures are needed to identify things let me know!

 

[Heavywrecker]

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[Scar59]

Looks to be off a M936 (A1 maybe A2). I have an '84 M936. Hyd pump is PTO driven of the transmission.
Do a search on M936 Wrecker. the Tech Manuals are all available.

 

[Heavywrecker]

I've read the manuals, not word by word but have looked many times and have not seen anything about pump output and psi rating to run these units, and is the drag winch 60 or 45,000? 2 guys have said 60 I find it's a 45 lol


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[red]

Chances are the pump you currently have on the international won't be compatible with this beds' hydraulics. It's a old design, low pressure (max 2500 psi) high volume system.

The rear winch is rated for 45k however with the hydraulic drive system on it it's only rated for 30k. The bed was used on trucks from 1950's and up, originally had the winch PTO powered (check out the m543 and m816 for more details if interested). When they modified these beds to be used on the m936 wrecker they relocated the hydraulic pump to the chassis and decided to power both the winch and crane with hydraulics.

Rear winch is also not capable of free spool, it's power in/out only.

Don't know what that one extra port went to. The m936 (what that bed came off of) used a separate hydraulic pump for the front winch. I have the older model m816 wrecker.

 

[Heavywrecker]

Cool exactly what I was hoping for someone that owned one lol can you crawl under it and take a pic of the hydraulic lines going to the center piece or is yours not like that? Also the pump on the binder is 2500 psi and 20 gpm so hopefully that works!just need to figure out how to add another hydraulic spool valve to the setup


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[NDT]

Heavywrecker, don't mean to rain on your parade but I'm hoping you looked at the load charts carefully on the boom. That wrecker may look like a "rotator" on a big HD wrecker but it's not. There is about maybe 20% wiggle room on the weight capacity of the boom and then it folds up like a paper doll.

 

[red]

Mines different underneath. The m936 (yours) has the hydraulic pump located on the truck chassis, then pumps the fluid up through the hydraulic swivel to the crane/rear winch.

The m816 (mine) uses 2 separate PTO shafts under the bed. One shaft goes to the rear winch. The other shaft goes to a mechanical 90 degree box that is bolted to the base of the crane and the hydraulic pump sits on top of that (where your hydraulic swivel is). Picture of mine for reference


How the rear winch is powered on mine (m816, PTO shaft)



All the other main stuff is the same (the actual winch, the crane, controls, etc) just the location of the hydraulic pump is different and how the rear winch is powered is different.

Will have to research on the flow rate but pretty sure 20 gpm is lower than the normal hydraulic pump for these trucks.

Guessing you want the other valve bank mounted on the chassis for the wheel lift/other items? Easiest way to plumb that is to route the pumps high pressure line to that new valve bank first, then from the valve bank to the hydraulic swivel.

 

[Heavywrecker]

Yea we looked at them, this is going on our medium duty truck, we have a semi wrecker for the big **** this is mainly for car and trucks, the drag winch will be to assist the big one when winching something of size


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[Heavywrecker]

I suppose I could do that with a power beyond valve, like to have the drag winch to be full size plumbing so she barks


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[red]

For that use the bed should be fine then. The crane can lift:
10k no support legs, boom retracted, outriggers down
20k with support legs, boom retracted (to the rear of the truck)
4k no support legs, full 18ft extension, outriggers down
3k no support legs, full extension, no outriggers

Looking at your pic better of the hydraulic swivel, there are 4 hoses on the underside correct? The 2 similar sized hoses are for the rear winch supply/return. The largest hose headed towards the front is the low pressure from the tank to the pump. Other hose headed towards the front is the high pressure coming from the pump (what you would plumb into the other valve bank).

 

[Heavywrecker]

I'll crawl under it and get a better pic tomorrow, it looks like the thing was set up for another hydraulic something forward, there's also a return port facing forward that's open, that's why I was asking about the front winch looks almost like that's where that would go to


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[Heavywrecker]

That little hose hanging off the bottom goes to nothing it's just hanging out on the other end, the first thing in line from the pump pressure port is the drag winch then it comes woreatd and goes up the swivel to the boom


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[Heavywrecker]

I'm going to add the underlift, 2 8 k recovery winches with air free spool and 4 stiff legs/ stabilizers


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[Heavywrecker]

Robbing parts from this other bed I built


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[tobyS]

I may be able to help on the hydraulics sizing... but don't have one.

I thought the wrecker hydraulics came off of a transfer case PTO and not the transmission PTO. Need to verify that and get a pump size idea, even if by only the line size. Line size on valve would help too These are open center, so any valve in front of it needs to be a "power beyond".

Do you already have a tranny PTO or pump on the truck? Here is one I've put together for a deuce that uses the same PTO as most 939 series with Allison. It's about as large a displacement as a PTO should have (just under 4.0 cuin/r) and stay under the max hp...which is 45.

Some reinforcement of the boom would seem in order too.

 

[Heavywrecker]

Very similar pump, we have a pump mounted on an air pto off the eaton trans, she's a 2500 psi and 20gpm pump which is big most wreckers run an 8-10 gpm pump


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[Heavywrecker]

I will be adding 3 sets of spool valves, 2 4 bankers and a 3 bank using power beyond valves


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[Heavywrecker]

These are the valves I'll be adding


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[Heavywrecker]

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