Thread: Do conventional compressors have a direction?

I did a search for this and all the info about direction on the web was based on the pressure head cooling fan direction but my compressor has no fan. It's a three phase 2 cylinder two stage compressor that I replaced the motor on and it seems to work fine but I'm just wondering if direction matters on something like this.

Hi,
I would say if it dose it would have a big arrow cast on it.
Regards

I have dealt with single, twin and triple cylinder single stage compressors (all fan cooled) and the direction of the fan has mattered but the direction of the compressor head hasn't, beyond the fact that the two a mechanically locked together.

Haven't had anything to do with multi stage units, but suspect that for them it would depend on the relative timing between stages. If the first stage is at TDC when the second stage is at BDC (staggered 180 deg) it probably would not be an issue as stage 1 would be discharging into stage 2 at its lowest internal pressure regardless of direction. However if the stages were staggered by a different amount, say 120 deg, then direction of rotation would effect output and efficiency, as it would effect the interstage scavaging.

Another consideration is lubrication. Most compressors are splash fed lubricated, and if the big end incorporates an oil slinger, rotational direction could be significant. As A Duke has said though, a directional arrow is usually cast into the drive pulley or crank case end if it is considered important. Of course if the compressor had a gear type oil pump, and I've never heard of one that does, it would be absolutely vital to get it correct.

Thanks Guys.

I had a close look all over the compressor and could not find a rotational direction and its been running on and off all day and doesn't seem unusually hot.

They generally have an arrow which shows rotation direction (although I can't recall seeing it on Clisbys).

The oil slinger is pretty basic and is the usual conrod cap spur which works in either direction.

The main rotation issue seems to be cooling fan air direction.

When the comp is rotating in the correct direction, the cooling fan is blowing at the the comp head/barrel for optimum effect.

I've run them the wrong way and had no problem.

Originally Posted by BobL

I did a search for this and all the info about direction on the web was based on the pressure head cooling fan direction but my compressor has no fan. It's a three phase 2 cylinder two stage compressor that I replaced the motor on and it seems to work fine but I'm just wondering if direction matters on something like this.

Are you sure there's no fan? Not even the spokes on the pulley offset to move the air?

Originally Posted by Karl Robbers

Are you sure there's no fan? Not even the spokes on the pulley offset to move the air?

The spokes on the compressor pulley are 40 mm wide but have no pitch or offset on them. The cylinders/heads are surprisingly cool after a charge or recharge and can still easily touch them with my hand. The outlet to the tank is hot but not outrageous. Its a V4 Clisby. I timed both the fwd and reverse direction and the time to pump down or recharge is within 5 seconds of each other.

Now I need to change the oil on this sucker. Anyone know where to get the RCR 100 oil that it says to use on the side of the compressor?

I dont think it would apply to compressors but some engines deliberately have the gudgeon pins slightly offset from the centreline of the piston which apart from other factors definately makes them directional.

This discussion brings up an interesting point - I've never seen a Clisby compressor with a fan type compressor pulley. They are always solid.

So Clisbys don't have any forced air flow for cooling.

I have always used ATF in mine and never had a problem.

Rob.

Originally Posted by nearnexus

This discussion brings up an interesting point - I've never seen a Clisby compressor with a fan type compressor pulley. They are always solid.
So Clisbys don't have any forced air flow for cooling.

The new models all seem to have fans.

Originally Posted by BobL

The new models all seem to have fans.

I haven't looked at their latest stuff.

Do they still use the classic red Clisby designed compressors, or are they just re-badged imports ?

Rob

HI,
I have never had anything to do with twin stage Air Compressors, but I have always known Air Compressors to run Anti-Clockwise.

Originally Posted by BobL

The spokes on the compressor pulley are 40 mm wide but have no pitch or offset on them. The cylinders/heads are surprisingly cool after a charge or recharge and can still easily touch them with my hand. The outlet to the tank is hot but not outrageous. Its a V4 Clisby. I timed both the fwd and reverse direction and the time to pump down or recharge is within 5 seconds of each other.

Now I need to change the oil on this sucker. Anyone know where to get the RCR 100 oil that it says to use on the side of the compressor?

RCR100 is a BP product is Shell Corena P100 - BP RCR100 both are a special compressor oil

Originally Posted by rescuepanda

RCR100 is a BP product is Shell Corena P100 - BP RCR100 both are a special compressor oil

Sure - I worked that out fairly quickly. What I want to know is where to get it.