impact wrench

[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.

[chris.hunt22]

ALDI are doing Power craft ones, £15.99 with sockets and a 3 year warranty!!  I wouldn't buy one myself (stick to my £200 Ingersol Rand, gets anything off, even Landy bolts!!) but if its for a bit of garage DIY and general tinkering you can't go wrong

[drmike]

You think the Aldi one is OK? I can get a Sealey one for the same money - which would be the better bet?

It is indeed for the odd bit of garage work and spinning wheel nuts on and off.

Mike

[Hangover]

You think the Aldi one is OK? I can get a Sealey one for the same money - which would be the better bet?

It is indeed for the odd bit of garage work and spinning wheel nuts on and off.

Mike

Don't buy either mate,even if your not a regular user the difference between the better quality guns and the aldi specials is vast,the cheap ones have [throw it] poor power and they are cheap and nasty.

[drmike]

But cheap, they are at least cheap. If I could get a decent used one at cheap then I would.

Mike

[chris.hunt22]

They are probably both the same gun with different stickers on, if it doesn't undo the nut then just use a breaker bar, for £15.99 you can't go wrong!!

[drmike]

Roughly what I was thinking. I'm happy to use the torque wrench for final tightening and have teh air gun to spin the nuts off.

Just stripped my current gun down again and it's a bit better after cleaning the vanes but I had to whack it to get it to spin up. I think something mysterious is sticking but there's so little in there it's hard to see what it can be.

Mike

[tomarse]

I bought an aldi one. Comes with some sockets and in a case too, so it aint bad for the money.

I've tried it and it works! I managed to successfully round a bolt off and bend a halfords socket with it!  :lol:

Aldi have an air chisel too which is £8 and pretty good! (bin removing some concrete with mine today!)

[Tailendcharley]

:D  :D Screwfix do an in line oiler for these things...just keep the reservoir full of a light oil and it keeps whatever tool you're using oiled up...

 :D  :D Terry Smith  

[drmike]

I got the Aldi one yesterday.

On a very quick test it seems far better than the Machine Mart one which cost a good deal more.

I'm sure it's not industrial strength but it got a wheel nut off and put it back on again and the torque wrench said it didn't need further tightening so it may even have done it up too tight. The MM one never managed that.

So not bad (I hope) oh and a three year warranty not a 12 month one as per MM.

Mike