spiders
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- pembrokeshire
hi has anyone converted one to run off front pto, I have but when I close tap it shreds the belts, is there a relief valve that should go off to prevent this? And where would I look? Cheers.
Jcb 2cx compressor
- Thread starter spiders
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Stock
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- The Emerald Kingdom,
Are you running it in the right direction, there was one in wales for sale on here yesterday................
spiders
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- pembrokeshire
I assume it goes right way, makes air fine with taps open just when you close them there’s no relief.
spiders
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- pembrokeshire
Pheasant Surprise
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- Woodbridge, Suffolk
Here’s an old thread of yours @spiders
Is this the same 2CX compressor you were discussing near 6 years ago?
https://thefarmingforum.co.uk/index.php?threads/jcb-2cx-compressor.4828/
spiders
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- pembrokeshire
Yes it’s been cluttering the workshop for a while now, if I don’t sort it soon I’ll be selling it! I’ve geared it up 3-1 with pullies, so speed should be good, where is the unloaded valve? It has Plenty of oil in it.
Pheasant Surprise
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- Woodbridge, Suffolk
Are you mounting it on front PTO or rear PTO? Gearing is probably OK on 540 speed PTO, but check rotation direction is correct.
3:1 sounds a bit high on front PTO @ 1000 rpm...maybe OK on tickover.
Screw compressors have an unloader valve (big poppet basically) on the main air input right on top of the air-end (compressor screws).
Piston compressors run at full blast and either need to be idled down to slow up the air output when nothing’s using air and/or blow it off excess air via a relief valve on the output side.
Pheasant Surprise
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- Woodbridge, Suffolk
Sorry I just read this. You must have either a relief valve or don’t completely shut the taps on the output when she’s running, otherwise you will stall the compressor as the air has nowhere to go.
When you turn the taps off a standard, road tow screw compressor, the regulation system pulls the engine back to idle (or revs it right back at least). It also closes the unloader (input valve), so that there is a minimal amount of air that can get drawn into and then through the screws. The is also a blow-off (emergency really) relief valve on the output side usually on top of the oil separator / air receiver vessel.
Have you got a pic of the plumbing and unit on yours?
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spiders
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- pembrokeshire
Pheasant Surprise
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- Woodbridge, Suffolk
Just wondering if someone has modified yours - so any photos of piping following air input to compressor and air output plumbing - may show if something has changed or been taken out.
spiders
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- pembrokeshire
Pheasant Surprise
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- Woodbridge, Suffolk
If it’s making air turning in the direction it was supposed to turn that’s great. Don’t be tempted to try and run it the other (wrong) way. A screw compressor should only ever rotate in the correct direction when in work. You risk damaging it pretty quickly running it the wrong way. It won’t make any air and won't be circulating oil correctly.
I’m not familiar with the specifics of a 2CX compressor, but the bracket with the valve and pneumatic cylinder and linkage would have been the speed control assembly on the original Airmaster. This would have worked like on a road tow compressor with a direct engine - modulating the revs/speed of the engine depending on air demand....basically the more air needed, the higher revs on the engine, the less air needed, the lower the revs. The linkage and control pipes etc is obviously disconnected on yours now as it not needed / not able to change the driving engine revs.
As with most engine driven screw compressors, the original fitment in the Airmaster the speed control valve/cylinder would work together with the unloader valve on the inlet/suction side the compressor. You can see the unloader valve on your first photo, it’s the alloy bit on top of the air end with the control lines going to it. This is what the exploded view looks like on JCB Parts
So the way the air regulation system works on most screw compressors:
- when they’re running “unloaded” the inlet/unloader valve (the main poppet) is shut, blocking off most of the air getting drawn into the screw assembly. There’s usually a small pilot hole or similar to allow a small amount of air to be drawn in so the compressor makes just enough air to run the regulation system and push the lube oil around.
- when they’re running “loaded” the unloader valve main poppet will either be wide open, or some degree of partially open. Thus allowing for up to the full amount of air to be drawn in to the air end.
If the regulation system on yours has been altered, or isn’t working properly, the unloader valve poppet may not be closing when there’s little or no air demand (e.g the taps being shut).
I suspect your compressor is running “fully loaded” all the time and has no way of controlling the amount of air coming into it. Also there’s now no speed control feedback and depending on the input speed of your PTO, you may be over-gearing it. I reckon this is why the belts are shredding when the air taps are shut.
Pheasant Surprise
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- Woodbridge, Suffolk
@spiders - see attached JCB 2CX Service Manual extract for the Airmaster compressor.
Couple of things to note:
1. loaded speed of the compressor should be between 2120 - 2140 rpm
2. off-load speed of the compressor should be between 1550 - 1570 rpm (obviously you'll have to change the revs on the tractor PTO to suit)
3. check the pressure regulator (off-load air pressure regulation), and the safety valve (on side of receiver) is operating correctly. See page 31-1
4. check the unloader valve is not stuck open - see fault finding on page 20-1 - there may be a puncture in the diaphragm inside either the unloader/piston assembly or inside the pressure regulator.
Hope that may help!
Couple of things to note:
1. loaded speed of the compressor should be between 2120 - 2140 rpm
2. off-load speed of the compressor should be between 1550 - 1570 rpm (obviously you'll have to change the revs on the tractor PTO to suit)
3. check the pressure regulator (off-load air pressure regulation), and the safety valve (on side of receiver) is operating correctly. See page 31-1
4. check the unloader valve is not stuck open - see fault finding on page 20-1 - there may be a puncture in the diaphragm inside either the unloader/piston assembly or inside the pressure regulator.
Hope that may help!
spiders
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- Location
- pembrokeshire
Pheasant Surprise
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- Woodbridge, Suffolk
Apparently the compressor unit in these 2cx Airmasters is based on a CompAir Holman unit.
I've got a CompAir compressor here and got some workshop manuals / parts lists for them on my computer, so had a quick flick through and some of the parts diagrams are near identical!
So who knows, perhaps another potential parts supply source if Mr JCB isn't feeling too generous in spare parts prices.
I've got a CompAir compressor here and got some workshop manuals / parts lists for them on my computer, so had a quick flick through and some of the parts diagrams are near identical!
So who knows, perhaps another potential parts supply source if Mr JCB isn't feeling too generous in spare parts prices.