5 ton wrecker bed

[Heavywrecker]

You can get a general idea from measuring the components which I did this morning


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[tobyS]

You can get a general idea from measuring the components which I did this morning


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Caution if you changed directions. Some pumps have the shaft seal open to the return and changing the in and out does not change that...it will blow out the seal. I'll assume you are right about the displacement but a part # and make would confirm that.

edit...not return port...intake.

 

[Heavywrecker]

No return port is still return port, swapped the gears in the housing and reversed the cover drilled both ways


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[red]

On a m936 the Tcase PTO, which powers that pump, spins at 1:1.


Why not just install the transmission PTO and run a shaft from it to that pump? With the transmission PTO turning at 1.5:1 then the truck doesn't need to run at anymore than 800rpm for absolute max.

On my m816 I run the crane hydraulics at idle and 4th gear (1:1), 5th gear (.78:1) if I want the crane moving faster but always at idle.

 

[Heavywrecker]

I have to find out exactly how fast that pump turned in operation, I know it's said to be 1-1 but is that confirmed or suspicion?


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[Heavywrecker]

Wish I could but apparently it's over the tq limit


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[Heavywrecker]

Because the pump is so huge


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[Heavywrecker]

How about psi? Any clue on that one


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[red]

Confirmed 1:1 on the tcase PTO speed. Pressure is 2500psi

 

[tobyS]

Confirmed 1:1 on the tcase PTO speed. Pressure is 2500psi

There is the reason this is not done with a transmission PTO. With pressure 2500 at 100 gpm, that's 146 hp. Granted you may never reach that amount of force and speed at the same time, but I don't have one of the wreckers to have operational experience on it to know how often the machine is taken to it's limits. HD does not necessarily mean fast. Slow can be handled... wimpy pressure ???...nah!

Myself, I'd go a smaller pump. What the heck needs that much speed (flow)?

 

[red]

There is the reason this is not done with a transmission PTO. With pressure 2500 at 100 gpm, that's 146 hp. Granted you may never reach that amount of force and speed at the same time, but I don't have one of the wreckers to have operational experience on it to know how often the machine is taken to it's limits. HD does not necessarily mean fast. Slow can be handled... wimpy pressure ???...nah!

Myself, I'd go a smaller pump. What the heck needs that much speed (flow)?

Remember these are from the early days of hydraulics. They couldn't get the high pressure so they went with high volume to compensate.

Haven't measured it but pretty sure it's less than 100gpm. When engaged my engine doesn't even notice the load.

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[tobyS]

Yea, farm style hydraulics. There is a big miss-match if he would try to run this pump off of a tranny PTO. If he's limited to a tranny PTO, he needs to work from that. I'm not sure about the pressure myself on this but I take your word that RV would be at about 2500. That means he has to have that much pressure or the machine will wimp out. On my crane, (not a wrecker) I spend about 95% of the time at very low speed of any function...except maybe the winch (I'm power in and out).

 

[Heavywrecker]

Buying a new trans that can handle more torque thru the pto, we will see what happens, gotta start slmewhere


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[Heavywrecker]

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[Heavywrecker]

Got it set onto the chassis today, need to modify a few things add a wheel lift and side puller and probably rear stiff legs, anyone have any pictures showing how these were originally mounted to the frame?


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[red]

Very large U bolts. Can see one on each side of this picture




And if you zoom in you can see them in this picture along the frame rail

 

[Heavywrecker]

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[Heavywrecker]

Coming along nicely have to get the pusher mounted tomorrow and change out the transmission! Had custom 1" hardened u bolts made for the body to mount it. Going to add a few heavy angle supports and a mount for the rear end and drag winch motor! Thing should be fun when it's done!


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[Heavywrecker]

Thanks for all of the information Red!


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[red]

No problem. Oh forgot to mention that the rear of the bed is also bolted to the chassis