Motor rotation how do you look at it

So I have been needing to replace the motor on the big compressor I have. Northern has a good deal on a 5HP draws 15 amps at 220 volts. But it says it is clockwise rotation. So is that from you standing behind it and the pulley shaft pointing away from you or is that as your looking at the shaft and it pointing to you. The compressor I have rotates counter clockwise with the pulley end of it pointing towards me so is that really clockwise?? Compressor part is behind the pulley. Clockwise and counter clockwise has always got me

It is usually viewed from the motor or engine side,so yours would be clockwise.Someone else will chime in if I'm wrong.

Old,
Most motors can be reversed by changing 2 wires. Some motors it's easy to do, wires are outside the motor. If you can't do it a motor shop can.

One time I couldn't reverse wires on a capacitor run motor, so I took motor apart and reversed the rotor.

You can't do that on a capacitor start motor.

Answer, rotation is determine when you are looking at the shaft. What do you do if motor has double shaft??LOL

On a piston type compressor it may not matter,they do one thing on the up stroke and the other thing on the down stroke.

That was the first thing to be checked on the start up of newly installed equipment. Electricians would be standing by to check rotation. Would reverse wiring if rotating the wrong direction. The question brings to mind two other things that I cannot seem to get cemented in my mind, right and left side of the tractor and engine firing order, front to back, back to front. gobble

(quoted from post at 17:41:21 08/20/18) Old,
Most motors can be reversed by changing 2 wires. Some motors it's easy to do, wires are outside the motor. If you can't do it a motor shop can.

One time I couldn't reverse wires on a capacitor run motor, so I took motor apart and reversed the rotor.

You can't do that on a capacitor start motor.

Answer, rotation is determine when you are looking at the shaft. What do you do if motor has double shaft??LOL

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eorge, those are usually CWLE or CCWLE, meaning as viewed from lead end. Most single shaft motors are as viewed from shaft end, but some single shaft fan motors will also be marked CCWLE or CWLE.

Can't answer the rotation question, but that is not a real 5 HP motor. More like 2 1/2 HP.

Don't know what you need, but compare it to the FLA amps on your old motor.

(quoted from post at 17:48:32 08/20/18)

(quoted from post at 17:41:21 08/20/18) Old,
Most motors can be reversed by changing 2 wires. Some motors it's easy to do, wires are outside the motor. If you can't do it a motor shop can.

One time I couldn't reverse wires on a capacitor run motor, so I took motor apart and reversed the rotor.

You can't do that on a capacitor start motor.

Answer, rotation is determine when you are looking at the shaft. What do you do if motor has double shaft??LOL

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George, those are usually CWLE or CCWLE, meaning as viewed from lead end. Most single shaft motors are as viewed from shaft end, but some single shaft fan motors will also be marked CCWLE or CWLE.

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Sorry guys, what is a lead end???

Something like 746 watts per hp
15x220=3300
3300/746=4.4236 hp

With a single phase you loose quite a few watts to friction.

Old motor was rated at 6HP but it was a Harbor freight motor I got 25 or so years ago. It give up maybe 4 or 5 years ago and I have not gotten around to replacing it. I'd have to see if I could even find the old motor to see what it may or may not have been

This is an old big 2 stage compressor and it has rotation clearly marked on the flywheel/pulley and looking at it form the pulley end it is counter clockwise rotation. The motor I am looking at is clockwise rotation and non reversible for $244. Can get a reversible one for $289 so may have to go that way. I miss my big compressor and have been getting by with a junk oil less compressor that has a bad shut off pressure switch and the pop of goes when it has to high a pressure and is a real pain

Info from the web. Jim
One end or the other

Hello Dusty MI,

My old Craftsman air compressor, was 120V motor marked 1 H.P. Was label @ 21amp
draw. That is what it was regardless of pressure?

Guido.

If there is a model number on the compressor it may tell the HP and RPM requirements.

(quoted from post at 19:30:42 08/20/18)

(quoted from post at 17:48:32 08/20/18)

(quoted from post at 17:41:21 08/20/18) Old,
Most motors can be reversed by changing 2 wires. Some motors it's easy to do, wires are outside the motor. If you can't do it a motor shop can.

One time I couldn't reverse wires on a capacitor run motor, so I took motor apart and reversed the rotor.

You can't do that on a capacitor start motor.

Answer, rotation is determine when you are looking at the shaft. What do you do if motor has double shaft??LOL

Click to expand...

George, those are usually CWLE or CCWLE, meaning as viewed from lead end. Most single shaft motors are as viewed from shaft end, but some single shaft fan motors will also be marked CCWLE or CWLE.

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Sorry guys, what is a lead end???

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n most small air conditioning fan and blower motors, the motor has no terminals, but instead wires coming out of it and the "lead end" is where the wires exit the barrel (wires are sometimes shaft end, sometimes other end and of course with shaft on both ends on window units the CWLE type designation is needed)..

Old,
5 hp, 15 amps and 220v really doesn't mean anything when it comes to compressor motors.

You need starting torque. Usually compressor motors have a very large start capacitor. Some motors have 2 starting capacitors. A friend's 5 hp compressor motor needed a third capacitor to get the job done.

If your new motor can't get the job done. Try using a smaller pulley on motor. If that doesn't work, loosen the belt and let it slip a little on start.

I have a compressor sold by snap-on. I removed one belt so motor didn't have to struggle in winter. Cheaper to replace belts than motors.

One of my compressors is made out an automotive AC pump, and it has an oil pump that has to rotate the right direction for it to pump oil. I would think some other compressors would have oil pumps too.

(quoted from post at 16:41:21 08/20/18) Old,
Most motors can be reversed by changing 2 wires. Some motors it's easy to do, wires are outside the motor. If you can't do it a motor shop can.

One time I couldn't reverse wires on a capacitor run motor, so I took motor apart and reversed the rotor.

You can't do that on a capacitor start motor.

Answer, rotation is determine when you are looking at the shaft. What do you do if motor has double shaft??LOL

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George, "compressor duty" (read CHEAP) replacement motors for "consumer grade" air compressors are generally NOT made with provisions to allow reversing.

old, call northern and ASK if rotation is looking from "shaft end" or "opposite shaft end".

As I remember from some years age, General Electric tended to list the rotation of their motors as viewed "from opposite of shaft end", while a lot of other manufacturers listed rotation "viewed from shaft end.

You aren't gonna know for SURE unless you can find deatiled "specs" for the motor, or the seller can tell you. (HOPEFULLY, accurately!)

Also, before buying, check "Surplus Center", last I looked they had a wide variety of compressor motors.

(quoted from post at 22:28:44 08/20/18) One of my compressors is made out an automotive AC pump, and it has an oil pump that has to rotate the right direction for it to pump oil. I would think some other compressors would have oil pumps too.

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Russ, I agree with you, if anything but a "consumer grade" compressor, it will likely have a (directional) oilpump.

Also, even cheap pump "heads" generally have slanted webs in the belt pulley that act as a fan to blow air back over the compressor, and need to run the correct direction.

This compressor is not a cheap one by any means. It does in fact have a fan pulley so the fan cools the compressor. Best way I can explain this big thing is what you would see in a common gas station of the late 60s early 70s and probably dates back around that time. When I got it, it has a 12 HP gas engine on it but I did not want to deal with gas and exhaust in my shops so I installed a 6HP Harbor Freight motor on it but after 20 or so years it died on me

This is a big 2 stage compressor like what one would have seen In a gas station of the 60s and 70s. Belt drive unit 2 stage 2 piston compressor bit 18 inch or so double pulley. Was a mobile unit when I got it with a 12 or so HP gas engine but I did not need it mobile so I switched it to an electric motor some 25 plus years ago. Put on what was called a 6 HP from Harbor freight and it lasted 20 or so years. Pulley has a cooling fan on it and an arrow showing which way it need to spin and looking at it from the pulley side it has to go counter clock wise

This compressor is one that who know who set up. Tank is I do not know form where compressor is a 2 piston I think 2 stage. Has big pulley about 18 inch in diameter with a fan in the pulley. Think of what you would see In a gas station in the 60s or 70s. Tank is who know what or where from. I've had it since around 1992. It at one time had a 12 or so HP gas engine on it as a mobile rig. I put an electric 6HP motor on it when I put it in my shop.

Yes I know places sell motors etc. rated at this and that but in fact they are selling number that mean little or nothing. With the old motor I only used one belt because I could not find a 2 belt pulley that would work on the motor. This is a big compressor with 2 pistons and I think 2 stage like what you would see in an gas station or tire shop or the 60s or 70s

If it had a gas engine on it and you did not change anything but engine it probably is clockwise. That would only be true if the engine was on the same side as the compressor.

Engine was a common horizontal shaft engine powered by way if the drive shaft end of it. Been to many year ago that I switch it out. I do know looking at the Compressor pulley end of the compressor the arrow points to it working counter clockwise

Info about SPL electric motors..

That air compressor says it's 5 or 6 horsepower.
Well, not quite!

Sure, there's a big sticker on the tank, with a big "6 HP" on it. But if you look at the nameplate on the motor itself, the place where the horsepower is supposed to be listed, it is either blank, or says "SPL". (Someone's Probably Lying?) A closer look at the big sticker on the tank may even reveal some fine print saying "peak" horsepower.

We're talking about portable electric compressors here, that run off of an ordinary household outlet, 120 volts.

This is one case that I've reported to several "consumer protection" type agencies over the past years. Knowing what I do about electrical and mechanical things, I immediately had to take a second look when I saw these compressors on the floor at a local home center. The motor on it was physically way to small to be anywhere near 5 real horsepower, but the store's poster advertised it as "5 hp".

I made note of the electrical ratings on the motor, When I got home I ran the numbers, and taking into acount the efficiency and power factor of the motor, I concluded it was actually a 1-3/4 hp. unit, 2 hp. max.

So what's happening here is an outright lie. And it's several different manufacturers doing it. The air compressor manufacturer does not make the electric motor, but buys it from a motor manufacturer. The motor manufacturer knows it could get in trouble by putting a false horsepower rating on the motor, because there are standards for determining horsepower. If someone were to take that motor off of the compressor and use it in another application, the truth would come out. So to stay out of trouble, they don't mark the hp. rating on the motor. And they also call it a special "air-compressor duty" motor, and say 'do not use in any other application', or something to that effect. Gee, I wonder why?

So it's the air compressor manufacturers that are twisting the truth. Obviously the motor manufacturers are aware of it, but have their butts covered.

My complaints about this fell on deaf ears, for the most part. One manufacturer sent some papers to the consumer protection agency, with charts and graphs, explaining basically that if you can make a motor put out 5 hp. long enough to get a reading, then it's a 5 hp. motor. Uh Huh. But the agency accepted that answer. I don't imagine that anyone at such an agency would know a horsepower from a watt.

The truth is, 1 horsepower is the amount of power needed to lift a weight of 33,000 pounds a distance of 1 foot in one minute, or 550 foot-pounds per second. And a motor rated at 1 (real) horsepower could do just that. Also, most electric motors are capable of producing two or three times their rated power during start-up, just for a second or two, to get up to speed. This is probably where the "peak horsepower" rating comes from, but really has no useful purpose for the consumer.

Additionally, a standard wall outlet (120 volt) can produce only 1800 to 2400 watts of electricity. (Volts X Amps = Watts.) A commonly used formula for converting watts into horsepower is 1000 watts equals 1 horsepower. This accounts for losses in the motor. So a 15 amp wall outlet can run 1800 watts or only 1.8 hp., and a heavier duty 20 amp outlet, as you might find in your kitchen, could run 2400 watts, or 2.4 hp. So any appliance that runs on regular power, and claims to be more than a couple of horsepower, is BS!

Early in the 2000's, I read that there was a class-action lawsuit about the air compressors, and the manufacturers agreed to cut the BS, but I still see them for sale every day, all the way up to 6.5 hp. now. I recently found an imported unit that is brave enough to actually list "5hp" on the motor itself, but acording to the electrical info on the motor, same crap, it's 2 hp. max. I did file another complaint about this matter.

Update 5/17/07: My complaint did help somewhat, at least on the local level. Now all of the units that have "peak hp." ratings on them now also have a notice put on by the store (Mills Fleet Farm) explaining that the peak rating is a fake, and listing the real horsepower. The exception is the imported unit that outright claims to be "5hp." as stated on the motor label itself. No notice on this one!

On your compressor driven pulley the "spokes" should be on an angle, rotation of the compressor should be that the air is pushed against the compressor head/body for cooling as the pulley turns, like a common household fan.
this is your "drive end" rotation, and you need a "drive end " rotation motor,in the same direction when looking at its shaft, drive end being the shaft end where the pulleys mount.
hope it helps, but i bet the problem is solved by now

How many CFM’s is the compressor rated for? My ‘big’ shop compressor, if I want to call it that, is 18 CFM’s with a 27 amp true 5 HP motor that is fed with 10 gauge wire.

old I looked up that motor, if you have a older model air compressor that motor won't work for you.
It runs at 3450 rpm, most older 2 stage compressors use a motor that runs 1800 rpm, dig old the old motor and check the tag or look up the compressors model number
Also that 15 amp motor is supposed to have 5 starting hp but only has 3 running hp.
A true 5 hp motor will take 20-21 amps at 220 volts.
My old Baldor 5 hp 1800 rpm compressor motor is rated at 21 amps.

Something I was told at a motor shop years ago has always stuck with me.He said,if a motor does not require a magnetic starter,you don't want it on your compressor.In other words,if it doesn't draw enough to hurt a pressure switch if wired direct,it doesn't draw enough to do a good job for you.Of course,he was referring to commercial shop compressors,not the handy little Sears ones we all plug in and use.He also showed me something interesting on my Kellog compressor.He hung an amp meter on the supply wire and started it up.It drew what the tag said it should on startup,and then when it got up to near shutoff pressure the amp draw started to climb.It spiked at shutoff pressure,high enough so I wondered why the breaker hadn't tripped.My compressor shuts off at 150 so that motor is up against quite a bit of resistance at cutoff time.I don't see how anybody could think they could match the 5 HP Baldor performance with a motor that weighs 1/3 of the Baldor.

Well this is not a factory built compressor set up it is one where some one got a compressor some place then mounted it on a tank and then set an engine on a mount on the tank. The motor I have been looking at is not an SPL motor or it is not listed as one. The higher priced motor is an SPL. Guess I need to go out and dig into the compressor area and see if the compressor has any info on it as to what it is and then post hat and see what you guy maybe able to tell me and help me with it. The old 6 HP as Harbor F called but many companies over rate things

Motor rotation is looking at the drive end -- the end with the shaft sticking out.
rotation

(quoted from post at 13:31:21 08/21/18) Motor rotation is looking at the drive end -- the end with the shaft sticking out.
rotation

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s long as that is not taken as an all encompassing universal truth.

A lot of motors can be reversed. Directions on plate covering terminal board on motor.

Most capacitor start motors cannot be reversed and that is what is needed on a compressor

(quoted from post at 21:32:38 08/20/18) Old,
5 hp, 15 amps and 220v really doesn't mean anything when it comes to compressor motors.

You need starting torque. Usually compressor motors have a very large start capacitor. Some motors have 2 starting capacitors. A friend's 5 hp compressor motor needed a third capacitor to get the job done.

If your new motor can't get the job done. Try using a smaller pulley on motor. If that doesn't work, loosen the belt and let it slip a little on start.

I have a compressor sold by snap-on. I removed one belt so motor didn't have to struggle in winter. Cheaper to replace belts than motors.

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Three capacitors means two start capacitors and a run capacitor .

Well I never tired to reverse a C start/C run. Just low torque split phase.

(quoted from post at 20:25:38 08/22/18) Most capacitor start motors cannot be reversed and that is what is needed on a compressor

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Oh yes they can be reversed . Just have to pull the end bell off the motor to access both leads on the start windings .

But not such an easy thing as on most motors and most common men would not have a clue how to do it and to take it some place would cost $30 plus

(quoted from post at 00:36:05 08/26/18) But not such an easy thing as on most motors and most common men would not have a clue how to do it and to take it some place would cost $30 plus

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Just reverse the polarity of the start windings .

If it is really that easy why do the companies who sell them say they are not reversible then???????????????????

Some are and some are not.
We have capacitor start feed line motors in our poultry building, there two wires inside the enclosure that you swap to reverse the motor.
If the motor is reversible it'll have the instructions on the wiring label.

Also in some instances the meaning of non reversible means you can't flip a switch to reverse the motor, but it can be wired to run in the opposite direction.

(quoted from post at 00:57:40 08/26/18) If it is really that easy why do the companies who sell them say they are not reversible then???????????????????

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For the same reason the manufacture label equipment with “no user serviceable parts inside “.