Setting sheave depth on motor shaft

[Bellaireroad]

I am setting up a new motor on my compressor with a sheave and bushing. The pump flywheel is pressed on, so depth on the shaft is not adjustable.... any tricks to setting the sheave depth on the motor shaft, so the belts line up? Other than trial and error and eyeballing it?

 

[nine4gmc]

The motor bracket on the tank should have slots to let you move the motor in/out to line up with the pump pulley.

 

[2oolhound]

I use a straight edge like a level or something solid along the big pulley. Then allow to the difference to the edge of the grooves if there is any.

 

[Bellaireroad]

The motor bracket on the tank should have slots to let you move the motor in/out to line up with the pump pulley.

The slots let you move it in and out to tighten the belt but not adjust the pulley depth

 

[Bellaireroad]

I use a straight edge like a level or something solid along the big pulley. Then allow to the difference to the edge of the grooves if there is any.

This is kind of what I was thinking.. I was going to clamp a straight edge to the pump fly wheel, and try to get the sheave tightened down to the appropriate depth off the straight edge. But it will be some trial and error, cause the bushing will move some on the shaft as the sheave is tighten down

 

[Marctrees]

The pulleys need to be totally inline using a straightedge.

Whether you slide the pulley of the motor on it's shaft, or drill adjustment holes, whatever makes more sense. Marc

 

[Bellaireroad]

The motor bracket on the tank should have slots to let you move the motor in/out to line up with the pump pulley.

The slots let you move it in and out to tighten the belt but not adjust the pulley depth

 

[Marctrees]

Don't sweat it if it's a mm or 2 off, just try to get it close as possible.

Really, on a typical compressor setup, even +- under 1/8" is good enough IMHO.

But try to get closer. Marc

 

[rlitman]

Don't sweat it if it's a mm or 2 off, just try to get it close as possible. Marc

2mm off is quite a bit. But you should be able to eyeball it to be good enough.

 

[2oolhound]

This is kind of what I was thinking.. I was going to clamp a straight edge to the pump fly wheel, and try to get the sheave tightened down to the appropriate depth off the straight edge. But it will be some trial and error, cause the bushing will move some on the shaft as the sheave is tighten down

Where is this bushing? Both pulleys need to be ridgid on their shafts with no bushings. It sounds like you have end float on the motor shaft. If you align the belt well it will keep the end float centred. Otherwise you need thrust washers inside the motor to control end float.

The straight edge touching each pulley at the front and back edges will ensure they are on the same plane and aligned. When you adjust belt tension you must make sure the alignment is held in place too.

If tightening the pulley or sheave down causes it to move in or out try putting a spacer like a wrench or nut between the pulley and the motor case to hold it where you want it.

 

[Bellaireroad]

where is this bushing? Both pulleys need to be ridgid on their shafts with no bushings. It sounds like you have end float on the motor shaft. If you align the belt well it will keep the end float centred. Otherwise you need thrust washers inside the motor to control end float.

This is a 7.5 HP motor, uses a sheave/bushing mount.

 

[rlitman]

This is a 7.5 HP motor, uses a sheave/bushing mount...

And the bushing has a taper fit, so it will slide a little bit as you tighten it, but not all that much. You've got the right idea. It can be a little trial and error. But the last few of these I've done, I've set it offset just about 1/16" and pulled it right into position while tightening.

 

[claymont]

I am setting up a new motor on my compressor with a sheave and bushing. The pump flywheel is pressed on, so depth on the shaft is not adjustable.... any tricks to setting the sheave depth on the motor shaft, so the belts line up? Other than trial and error and eyeballing it?

The Woods catalog has specs and setup information in it.
http://www.tbwoods.com/-/media/File...ogs/belted-drives-and-sheaves/p-1687-tbw.ashx

Here's some information on alignment:
http://www.lubsys.com/knowledge/knw_align04.htm

 

[rsanter]

I use a round rod set into the pulley groove, it helps eyeball when it is lined up

Bob

 

[racingtadpole]

Put a dust coat of aerosol paint on the pulleys, fit the belt, rotate by hand a few times, it will remove the paint right on the outer edge of the side its misaligned to. Rinse and repeat until alignment achieved noted by either even paint loss or no paint loss depending on pulley depth/belt section depth. Clean pulleys once square.

 

[Sask dude]

I'd use a string
String should touch 4 spots

 

[EOC_Jason]

When I did mine I just used a long straight edge against the flywheel and eyeballed the belt to make sure it was the same distance the whole way and likewise the sheave on the motor was parallel. I double-checked after tightening down everything.

My sheave is thinner than the flywheel so there is no way to run a straightedge directly across both, hence just having to make sure everything is parallel to the plane of the flywheel.

 

[crguy]

Put a dust coat of aerosol paint on the pulleys, fit the belt, rotate by hand a few times, it will remove the paint right on the outer edge of the side its misaligned to. Rinse and repeat until alignment achieved noted by either even paint loss or no paint loss depending on pulley depth/belt section depth. Clean pulleys once square.

Worst idea so far. Don't have a straight piece of wood or metal?

 

[larry_g]

I'd use a string
String should touch 4 spots

The problem with this string is that one could rotate the motor to get the string to touch at 4 points and still be out of line. You need a straight edge. You also need the faces of the sheaves to be on a parallel line to confirm that the motor and compressor shaft are parallel to each other.

If you clamp the straight edge to the compressor pulley and then measure that the BELT and motor pulley is parallel to the straight edge then your in. ( this is taking EOC Jason's method to the next level.) You may have to rotate the pump a bit to get this, don't assume the compressor crank is perpendicular to the mount.

lg
no neat sig line

 

[Bellaireroad]

And the bushing has a taper fit, so it will slide a little bit as you tighten it, but not all that much. You've got the right idea. It can be a little trial and error. But the last few of these I've done, I've set it offset just about 1/16" and pulled it right into position while tightening.

Thanks, got it mounted today. The bushing had a set screw on the keyway which kept it from sliding a lot, still took two tries to get it just right


Sent from my iPhone using Tapatalk Pro

 

[Dozerhand]

You did it the right way by tightening the set screw then sucking the pulley to it. It's probably not critical on an air compressor that is inside but when I would do one of those on a machine that sat outside after it was all pulled together I would loosen the key way set screw. if you leave the set screw tight after a few years outside in illinois it's froze solid and you have to torch it out.

 

[Marctrees]

rlitman - I'm sayin on a typical comp the shafts c to c is like 2 feet +.

So look at the minor angle if a little off.

In that distance, I figure +- up to 1/8" is acceptable.

2mm is like nothing at that distance.


That said, I would try to get on the nuts, but sometimes difficult.

I'm sayin WORST acceptable if needed case.

Just my experience. Marc

 

[Dingleburry]

Use a straight edge. Hold tight to compressor pulley, and above motor pulley. Rotate compressor pulley with straight edge over top of motor pulley. Get it as close as possible after tightening. Making sure no angular misalignment. Measure missalignment with calipers, between straight edge and face of pulley. loosen bushing and move the amount of missalignment you just measured. Retighten. Throw a dial indicator on motor pulley and tighten bolts so it runs true.
Can clamp straight edge ro compressor pulley.
This is assuming the grooves on pulley are same distance from the face...

 

[foghorn1966]

I use a string to line up the inside edges of the shieves. When you pull the string tight it will be easy to see if the shafts are parallel as well as the pulleys being in-line.