5 ton wrecker bed

[red]

Yes the wrecker bed hydraulic pump is powered off the transfercase PTO (1:1 gearing).

That's alot of valve banks to add haha. Individual component movements for each valve?

 

[tobyS]

On the military M939 series PTO, the pump turns faster than the engine (1.5x). I think the 925's use a pump rated about 27-30 GPM. A 20 GPM may seem a bit slow, but pressure is right. MY pump shown is rated at 17 GPM at 1000 rpm (pump speed), so it's about 30 gpm at engine 1200. (personally I like having an engine throttle control at the operator station, not fixed speed).

That is a lot of valve. But the line sizes appear small.

 

[Heavywrecker]

That's normal sized for the real world not over sized like the military **** lol


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[Heavywrecker]

That truck had a side pulled with 28k winches, and had 2 4x24 cylinders attached to stiff legs in the side puller, a boom with 2 8 k winches boom updown in out and wheel lift up down tiltup down and in out


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[Heavywrecker]

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[tobyS]

If you have 1/3 the flow, the military machinery that can seem excruciatingly slow (or fast and uncontrollable) happens 3 times slower. We undoubtedly have much nicer control available today.

The problem I'm running into is proportional control and that power beyond means every valve in series must have the full flow and then the spools are over-sized for smaller functions, grapples and such or fine positioning under load. Custom spools can solve the problem, but I haven't seen them yet. Are your spools custom fit to the flow requirements of each function?

I notice a heat maker in your setup, I think. It's where the inlet hose seems sized to the pump flow but the line that connects valve 2 and 3 are smaller than the full flow of the larger size hose. It acts as a heat generating orifice and restriction for speed over the first (and all) valves in the series.

Can you please make a list of each function? What will be done with that many sections? Are you making the control station from a different location or wireless remote?

 

[red]

The military wrecker beds were designed back in the 40's, hydraulics early days where they couldn't get the high pressures so they used high volume to do the job.


Some plumbing work to setup but should be ok. Higher flow rate from the pump would be better but worst case scenario the crane moves slower.

Oh saw your post on FB. According to someone on here who lifted the bed it's about 17k pounds. 5 ton wreckers are about 38k, 5 ton tractors are around 21k, his weight makes sense.

 

[Heavywrecker]

The bed empty weight is 17k?


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[Heavywrecker]

I'll get better pics of it all tomorrow, I'm 95% sure the one hose is for something additional it's almost like it's plumbed in after everything it was too **** windy and cold today to study it outside


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[doghead]

Please attach pictures, not use links to them, as our rules request.

use the paperclip button on your phone

 

[Heavywrecker]

Sorry I'm new


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[red]

The bed empty weight is 17k?


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Yep. Bed, crane, rear winch, manual outriggers, comes out to 17k

 

[Heavywrecker]

I don't think she's that heavy I'm thinking more along the lines of 12k tops


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[tobyS]

How many functions are you controlling from the operator station on the crane and how many at the machine side? Are you replacing the valves at the crane operator control station, where the operator is riding with the boom?

 

[Heavywrecker]

Want to ideally control it from elsewhere but there's no way to do that and keep it 360 swing, these 360 constant turn? Or do you have to go back when you hit the 360 matk


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[tobyS]

I can't answer that. I have a crane on an F600 that has 50' of stick that rotates completely. The multi section swivel is a pain in the but, but I'm glad to have 360* rotation.

I don't see why it wouldn't.

 

[Heavywrecker]

Sounds cool post a pic


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[red]

I don't think she's that heavy I'm thinking more along the lines of 12k tops
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His scale weighed it at 17k and the numbers add up in the TM. 5 ton wreckers weigh 38k, 5 ton tractors weigh 21k. Lose the 5th wheel and other tractor components, add in the frame reinforcements and the 18" of extra frame length, the power divider, then the bed and get 38k for the wrecker. Remember it's an old design and overbuilt.


Recently discussed the way to relocate the crane operators hydraulics down to the chassis in the thread 'rescued m816'. To do it correctly and maintain the full 360 continuous rotation would require a 10 passage hydraulic swivel. Price tag of 10-12k for it with 1" inside diameter passages. Possible to do just not economical. Or setup a wireless remote but it's pretty close to the price.

 

[Heavywrecker]

I have a wireless setup with air actuators and solenoids just have to figure out how to make the air threw the swivel and the power situation


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[red]

Need 1 more passage going through the swivel for the airlines to do it properly. Pricetag on the swivels (that I've found) is about 1k per passage.

That being said, could simplify the current hydraulic lines running to the swivel. It should only need 2 hydraulic lines running through it (1 low pressure from the tank, 1 high pressure from the pump).