Vickers vane pump question

bhawk · Nov 23, 2015

The attached pic is from the power steering pump on my Cockshutt 540. It is Vickers. I took the pic as I dis-assembled the pump to replace the seal on the front shaft. That has been done.
However, the way the vanes sit in the rotor does not look right to me. The rotor has rounded edges on the inside, whereas the vanes have the rounded edges to the outside against the ring. I am thinking someone before me put this together wrong.
Your opinions?
I am restoring this tractor. I bought it not running. This summer I got it running and drove it up and down my driveway a few times. The power steering seemed to work okay, except for the leak.

Mike(NEOhio) · Nov 23, 2015

Those slots are distorted, especially on the right side. My guess is some debris got sucked in. Or someone took a hammer to it. The vanes would be extended on the suction side so the inner end would be at the middle of the slot. The dimples on the rotor are no help. Is there damage on the cover? As long as the vanes can move it will push some oil but not develop full pressure.

bhawk · Nov 23, 2015

The slots are not distorted in real life, I guess my camera or the angle gives a false depiction of the slots. Everything seems to be in pretty decent shape. I was just curious about the position of the vanes.

P Heisey Harleysville, PA · Nov 23, 2015

Hi bhawk,

The vanes are inserted into the rotor correctly.......rounded edge goes on the outside as shown.

I agree with Mike. The wear on the rotor slots is significant. We have the rebuild kits on stock here.

Phil Heisey

215-256-8651

Gambles · Nov 23, 2015

In a former lifetime, I turned wrenches being a forklift mechanic. My previous employer had several Cat forklifts that used this setup.
When rebuilding this pump, I found that they best way to keep those little vanes in place during assembly was white lithium grease that came in an aerosol can. It had just enough "stick" to keep the vanes in place, but allowed them to slide out and make contact with the housing once the engine was revved up. And yes, the rounded edges face outward.
Your mileage may vary....

oliver90owner · Nov 24, 2015

The reasons for the rounds on the rounded edges on the rotor are in production and for design. Slots were cut radially from outside edge with a milling cutter mounted axially. The rounded inner edges give stress relief to the rotor - to avoid crack propagation (more likey if there were sharp corners).

The reasons for the rounded leading edges on the vanes is simple, too. Less contact area (therefore greater closing pressure) and no need to cut the vanes to accurately align with the outer casing (flat ended vanes would touch on the leading and/or trailing edge - a design disaster, either way (non-radial forces on the vanes and either wear on leading edge or loss of seal if only rubbing on trailing adge - hydraulic pressure on the vane would try to lift it off the casing).

All simple design parameters, really. Hope that helps.

RAB

bhawk · Nov 24, 2015

Many thanks to all for the explanations. Now it all makes sense.

Vickers vane pump question

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Mike(NEOhio)

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P Heisey Harleysville, PA

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Gambles

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oliver90owner

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