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impact wrench

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drmike:
Anyone know how air impact wrenches work inside?

I have one that seems to let all the air out through the exhaust. This is the second time this has hapopened and the first time Machine Mart refused a replacement and repaired it. Well that didn't last too well, exactly 12 months later it does the same again. I've had it apart but can't work out how the exhaust works.

Can anyone help?

Mike

hobbit:
Dont know about the workings, but I oil my air tools evertime i use them, but what I found with the air gun is to oil throughly, occasionally it sticks all I have to do is flick in into reverse and hit the trigger, then forwards, this normally stops it sticking

Range Rover Blues:
Almost all air tools use a sliding vane 'motor' that spins at very high speed.  The impact can be made in a variety of ways, depending on the use and cost etc. but typically they are some sort of torque lock with a hammer action on reset, which is determined by angle.  Put sumply it's a bit like how a torque wrench works except it happens twice every revolution. I also have one that spins up to speed and throws in then, so it's uselss for spinning nuts on and off but a demon at things that are stuck.

Anyway, sorry to hear your's is goosed.

drmike:
Looking at the innards there was a cylinder that obviously did the spinning with about 8 stiff 'fibre' rectangular inserts that could slide in and out of the slots they were located in. So, if the shaft/cylinder was spinning then centrifugal force would throw the rectangles out to form a 'seal' with the chamber the spinning stuff was located in.

My suspicion is that the rectangular things can't slide easily enough and therefore either don't allow the initial seal to start or don't alow them to fly out far enough to provide enough oomph to let the wrench work.

This is all worked out in my little head after I put it all back together. I think I will strip it down again and try easing all moving parts and have a good clean up.

I think I may be the culprit as there's lots of oil in there and it's a bit heavy being 3 in 1 not what I expect is far light air oil.

A good clean might do the trick!

Mike

Range Rover Blues:
Thes plasticky things are the vanes.  They spin inside a drum which is not cricular, so they slip in and out.  As they slip out the volume they surround expands, if this volume is full of compressed air, the air drives the drum.

Your PAS pump works exactly the same way, but in reverse (it's driven).  The air pressure may also be used to keep the vanes in contact with the outside wall of the cylinder.

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