Compressor project(s)

[Gareth J]

Well, well. Looks like we may have a new winner?

Spotted this matching fitting underneath the intake:

Soo, a soft start mechanism?

Havnt quite fathomed how a positive oil pressure closes the unloader valves yet though...

 

[Rig Pig]

Interesting! Pop some photos up when you delve inside.

 

[normspanners]

The bit with the diaphragm does that create a pressure on the none oil side, in some way also does the connector on the flange that unit bolts to (the one that is vert up) then complete the piping to the two tees ?
That gauge would then be the oil pressure gauge

 

[normspanners]

I am perplexed as to why it is all connected to a seperate casting that in particular is part of the inlet setup,
is there some kind of inlet valve/restrictor in that unit the air filter bolts to, it doesnt look big enough but it could stop air being drawn in to the head until oil is up,
on my picture it is plumbed on the opposite side, the stud and nut on yours seems to indicate that that is a straight through drilling.

 

[normspanners]

Sorry regards the motor I missed the bit about it stating 1ph and the start clutch as you call it, is it a switch maybe?
then that would make it 1ph

 

[Gareth J]

Sorry regards the motor I missed the bit about it stating 1ph and the start clutch as you call it, is it a switch maybe?
then that would make it 1ph

Yep, it's a centrifugal switch. It operates the start capacitor. It's a single phase motor, I've had it since new. The one that came with the compressor is 3 phase

Some more dismantling is required to get to the bottom of the oil system...

 

[Gareth J]

I think that diaphragm must be a bit of a red herring.

I was thinking about that mangled end on it that's pointing up connecting to the mystery "t", but nope

It's a pointed screw that seals off the oil flow. I can't be sure, but it looks like it was well and truely screwed "home" when I removed it.

There is nowhere in that diaphragm to take off an air connection. There is a hole to atmosphere in the cap (non oil side). As far as I can fathom, the purpose of that diaphragm can only be to even out the pressure pulses from the pump so the dial reads steadier. That or it's there just to confuse me.

Why it's all around the manifold is also a mystery, the inlet is clear through the head to the filter, no mechanisms.

The hole we assume is for the oil comes in the bottom and out the side with the gauge. I couldn't get the stud out of the other end of the manifold without damaging it.

So, what attaches to the mystery "t"??!

It must be for a signal from the pressurised tank, otherwise how would the pressure switch know what pressure to flip in/out at.

...implying the unloaders weren't being used?

Argh

 

[HughF]

Unloader compressor been converted to pressure switch operation, quite common...

 

[normspanners]

If the red tee in your hand was connected direct to the reservoir the unloaders would be unloading all the time they usual go to a valve like this

which sends a signal to the unloaders when required pressure is met, if the pressure switch is exactly a pressure switch , so that it was NC, then when it get the signal it goes NO and switches off the motor but when the pressure drops you lose the signal the motor starts but the unloaders are not energised so it is hard work on the motor, especially with star delta thrown into the equation.
The normal way to stop gauge fluctuations is to just limit the flow to the gauge with a small aperture. Why though have they plumbed it all the way up to the head?.
The normal is to have the gauge in the position as shown in the blue unit shown by rig pig.

 

[normspanners]

the diaphragm looks as if it is bolted on by a banjo bolt that is female threaded for the gauge to screw into so the gauge would be seeing the pulses in the main pipe anyway because it is straight through.
is that another hole in the side of the diaphragm bit?, it looks in line with one of the screw holes on the side wall

 

[eil]

There is an old thread where Archie put up a pic of his which I would say is the same as yours.
http://www.mig-welding.co.uk/forum/attachments/img_0103-jpg.8521/

 

[normspanners]

There is an old thread where Archie put up a pic of his which I would say is the same as yours.

eil That one has the oil gauge in the usual place on the crank case right by the oil pressure relief valve.

 

[graffian]

I should get a pump like that and attach it to my land rover.

 

[Gareth J]

That speck you can see that looks like another oil way in the diaphragm housing is just that- a speck of dirt. Only one way in or out.

The oil diaphragm could be an actuator? Diaphragm gets pushed out as oil pressure increases operating something else I don't have.

Let's forget what it was used for, its clearly incomplete anyway.

Is there an air valve I could use that diaphragm with that opened the unloaders when oil pressure drops off?

 

[normspanners]

I have tracked a guy down on another forum in new zealand who used to work on them and service them that was his job many years ago, I joined the forum and and messaged him but he doesnt know/remember re --that diaphragm unit either!!.
The problem with using a valve is the pressure made by the diaphragm would be short lived and the pressure would bleed away, before the next start.

 

[normspanners]

What I have done in the past is to have a solenoid valve, than is NC in air circuit with the unloaders --------- then when in 'star' it opens and unloads the compressor,--------- as it gets to speed and delta kicks in the solenoid valve shuts again allowing the unloader valves to close and that lets the compressor start to make air but only when the delta is in.
That stops the motor being overloaded in the star phase of starting.

 

[eil]

The oil pump on my old aerostyle is just a single plunger which works off a lobe on the crank, so you could well be right that it smooths out the pulses of the oil pump or when shut down keeps a supply of oil above the plunger ready for the next start up .

 

[Gareth J]

I have tracked a guy down on another forum in new zealand who used to work on them and service them that was his job many years ago, I joined the forum and and messaged him but he doesnt know/remember re --that diaphragm unit either!!.
The problem with using a valve is the pressure made by the diaphragm would be short lived and the pressure would bleed away, before the next start.

That's some committed research, thanks!

I understand the issue with needing a "supply" of air to maintain them in the open position. How about something along these lines;

What I have done in the past is to have a solenoid valve, than is NC in air circuit with the unloaders --------- then when in 'star' it opens and unloads the compressor,--------- as it gets to speed and delta kicks in the solenoid valve shuts again allowing the unloader valves to close and that lets the compressor start to make air but only when the delta is in.
That stops the motor being overloaded in the star phase of starting.

Yea, I could go with something like that, could wire one into a pressure switch too so it fires the unloader one side at an intermediate pressure. Trying to keep spending down though....

Pulley's arrived so I can rig it up to see if the motors up to the job first!

 

[normspanners]

I understand the issue with needing a "supply" of air to maintain them in the open position. How about something along these lines;

That might work but you would need a tee with a one way NRV valve-- open to air to 'regenerate' the air in in the control line to the solenoid, because after a time the air would bleed away leaving a vacuum, and would not work, why use it though? just use an 'oil over air' solenoid / pilot valve would work as I had suggested.

The oil pump on my old aerostyle is just a single plunger which works off a lobe on the crank, so you could well be right that it smooths out the pulses of the oil pump or when shut down keeps a supply of oil above the plunger ready for the next start up .

I totally agree eil but seems a massive 'work round' and why make a casting that goes on the inlet tract with all the drillings and THEN the diaphragm unit where a restricted coupling would work adequately and 98% have the gauge in normal place that works ok.
though IIRC they do have a little pulse to the gauge when running and hot.

 

[Gareth J]

I agree, there must be a reason for this to be mounted in the manifold. I'll take the bolt out if the end at some point as its the only thing I've not dismantled yet.

What does an air over oil solenoid look like?