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Axial piston air motor

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AStroud06/07/2022 13:42:46
36 forum posts
11 photos


Here's a picture of my own design axial piston air motor. There are 6 12mm dia pistons in the barrell which will rotate around the angled swash plate which will be on an axle to allow the angle to be varied. The aluminum valve plate is stationary, held against the barrell with a spring and will have radial adjustment to allow valve timing variation.

work in progress.jpg

To finish I need to shorten the shaft, mount the swash plate on an axle with gear and worm for adjustment and machine the ports in the valve plate. I also need to figure out the radial adjustment of the plate whilst allowing it to self align to the barrell.

I am slightly concerned there will be too much friction to allow it to run and possibly too much leakage at the valve plate/ barrell seal, we shall see.


noel shelley06/07/2022 14:30:28
1435 forum posts
23 photos

Hi Andrew, try to get an exploded diagram of a vickers PVB 20, variable demand hydraulic pump, it may answer some of your questions. One point since this is air will be lubricating the moving parts. I would have no rears about it ronning if the pistons are 12mm. Good Luck. Noel

PS I will look through some of my files I may have a diagram.

AStroud06/07/2022 16:17:40
36 forum posts
11 photos

Thanks Noel

Whilst there are many diagrams of hydraulic pumps and motors available I could not find much for air motors though I suppose there many similarities

I did consider air passages down the pistons to the swivel joints and possibly through the slipper pads for lubrication and pressure compensation but decided it was a step too far for the moment.


Bill Mull06/07/2022 23:31:30
32 forum posts

It looks pretty neat, let us know how it works, maybe try using lubricated air ? The mist of oil in the air might help it to run smoothly.

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