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jverhaag

Hydraulic pump

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jverhaag

Guys

I need your collective wisdom.

I have a power max 4041 with a ark loader. The hydraulic pump has been eating keys. I can get about an hour or two of work out of it before it shears the key and the sheave goes rolling across the field. After fighting this for several weeks I took the sheave into the machine shop and had a new center hub and key way machined/built for her ($135.00). This seemed to have fixed the problem, temporarily.

I then developed a leak in the pump. It started out small, leaking around the shaft and than she started to hemorrhage hydraulic fluid. Today she spit the sheave, and all of the fluid in the field. I got her back to the barn dragging the bucket and I pulled the pump.

I took the pump into the hydraulic shop to have it rebuilt. The guys at the shop told me that that the rebuild kit is no longer available and I would have to have a pump "built" to replace the little Cessna pump that is on the tractor.

A new pump is going to set me back $450. That's a lot of money for a pump and a 40 year old tractor. Given what you know about these tractors, pumps and your experience what options do I have? (besides shooting her through the hood and burying her in the field, which would be a helluva a job without a working tractor }:)).

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Marty-MN

I was able to use a generic pump from northern tool on my L-12 loader after the by-pass started sticking and the cessna pump started leaking. the shaft size was a problem but made a bushing to make it work.

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jverhaag

Thank you. Surplus does indeed have a lot of pumps. I'm not sure what I need though.

The manual I have is remarkable vague on gpm rates, cubic in rpm, rpm required, etc?

Anyone know the specifics of the Cessna pump used on the ark loaders?

Thanks

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HubbardRA

I would replace that pump with a power steering pump from a 60s or 70s Chevy or Ford. You can pull the reservoir off them and plumb the return line into the hole that is inside the existing reservoir. Either of those should be large enough and relatively easy to find. You don't want a pump that is too large for the engine to drive.

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midnightpumpkin

This is the pump that was recommended to me by Powermax Paul (who has recently rejoined this forum).

http://www.northerntool.com/shop/tools/product_200329708_200329708

The pump needs to match the Cessna in terms of volume. Too much and the loader will be to fast to control, to slow and the loader will be sluggish.

You could try the power steering pump, it would certainly be cheaper, pulley size could be adjusted to compensate for to much or to little volume.

John U

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jverhaag

Hubbardra: I like the idea and price but have no idea what make or model vehicle to look for. Could you make a suggestion.

John: I was hoping I would hear from you.:D I assume the original sheave will not work with the new pump. I also assume I would need to re-drill the mounting bracket to accommodate four bolts as opposed to two. What size pulley/sheave would you recommend for this pump. I don't know much about hydraulics so I am learning as I go.

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HubbardRA

I have a friend who has used the power steering pumps to build hydraulics on three different larger tractors. He has tilt bed trailers and a fork lift setup on one tractor. He shims the bypass on the pumps to increase the operating pressure. I think they usually bypass at about 1500 psi. Most of the pumps are around 2 gpm.

I have three power steering pumps in my garage right now. That is why I would use a power steering pump.

As John said, you can change the pulley ratios on the pumps to increase the flow and decrease the pressure, or increase the pressure and decrease the flow. This is controlled by pump size and engine power.

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acfarmer

Personally I'd call Surplus Center and match up the pump you have as they have Cessna pumps and cheaper clones.Also you need to check out the rest of the hydraulic system for problems like a stuck bypass valve which will cause the key shearing and the pump to split and check for any small pieces of metal in the system.

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midnightpumpkin
quote:Originally posted by acfarmer

Personally I'd call Surplus Center and match up the pump you have as they have Cessna pumps and cheaper clones.Also you need to check out the rest of the hydraulic system for problems like a stuck bypass valve which will cause the key shearing and the pump to split and check for any small pieces of metal in the system.


id="quote">
id="quote">John V,I would agree that there is something wrong in the system. To shear a key would take a lot of pressure in the system.If you go with the Northern Tool pump, I would use a pulley similar to what you have. Surplus center has pulleys with seperate sheaves so you can select the shaft size and select the pulley size.Good luck.John U

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HubbardRA

Shearing the key could mean that the bypass is stuck or has been messed with. If the bypass does not work and you deadhead a cylinder, it will kill your engine instantly. At full power that puts a lot of load on that key.

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jverhaag

Given the abuse/neglect the tractor received before I got it a stuck/out of adjustment bypass would not be surprising. How does one go about testing/adjusting a bypass?

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acfarmer

Put a gauge on the pressure line or take the relief valve apart and

see if everything is working and freed up.Very few people have a pressure gauge on L&G hydraulics but its always a good idea on any hydraulic system.Also large hydraulic systems have a gauge on the return line as a stopped up return line which is where the filter is will also cause major problems.

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