Belt Selection

Well, put the other belts back on, then.

check its design data and compatibility with each other

or either it may be over tighten

These two Gates belts are different sizes.

SPC 4000 is a metric belt 22/18 mm.

C-156 is non-metric 7/8 by 17/32 or to put it into metric 22.25/13.5.

The C 156 is nearly half the price - is this why it was changed?

All other things being equal you have substantially less surface area on the SC-156 and the belts will slip and wear.

My guess is that you also do not use proper belt tensioning or alignment tools and that you do not stop and re-tension after a few hours running.

Further to the suggestions by Kaisen, check alignment or wobbling of pulleys. This is main of cause of wearing in couple of hours. Slight smaller cross-section will not wear it so fast. But, due to difference in depth of the belt, it will not take seat at p.c.d. of the pulley. Though the belt length is same, taking seat at higher p.c.d. will tend to unduly elongate the belt. Have you checked belt load carrying capacity in the catalogue of its manufacturer? Have you changed all the belts or only the worn out belt? Normally, changing all the belts is suggested.

Before installing the RIGHT belts, check the sheaves for wear.

Is the inside of the sheave cupped? Does the top of the belt ride a little above the top of the sheave?

Dear Guest,

I will assume you are working on a drive consisting of at least 2 belts.

I will also assume this is some type of electric motor driven air compressor.

I will also assume that this drive may start and stop during its operation.

I will also assume that this is a new, or newer installation of the equipment.

I will finally assume that the equipment is within 10 years of age.

The above being said,

a. Air compressors are designed for maximum efficiency, and place the electric motor at or very near their full load horsepower rating. My experience is that most of the time the motors are well into the SF (service factor) rating of the motor.

b. Air compressor belt drives are calculated to provide the power transfer from the motor to the compressor with very little safety margin. In other words, the pulleys and belts chosen will 'get the job done' and that is about it.

The best maintenance that you can do for the equipment is put the best possible products in operation for the longest possible life expectancy.

I did not go through the charts to see horsepower ratings (metric belts SPC4000 verses the C Section) of your drive to see if a change would help. If there is an advantage to a change here, then get your money out and make the changes, including all the proper guarding that for sure may not fit after the pulleys are swapped out.

A more cost effective solution would be to closely evaluate the installation for airborne contaminants, such as oils/caustics/acids/humidity/temperature extremes etc., to first rule out environmental contamination of the drive.

Then, determine if you realistically have the capability to align and tension the drive belts/sheaves, and if this is a question, pay and have a pro for the install.

Finally, make absolutely certain you are getting a belt that has not been on a shelf for two or six years, waiting to be sold. Multiple belt matching is an art that is slipping away these days.... If you can find fresh belts, and a shop that will match them perfectly for you, all the better.

Be sure to keep us informed of your progress. I hope this helps.

Bravo Paul GA You certainly covered all the bases. the right thing to do is get the belts from the OEM who will ensure the belts match (one another). the speeds and conditions dictate yearly changes ....and still they will be noisy. cheap belts (mismatched) will not work at high speeds no matter how well you align the sheaves.

At the belt supplier, request 'matched' belts. They are made together, and are exact twins. Matched belts will stretch equally and share the load. If your supplier doesn't know what matched belts are, move on.

These days, if your belt manufacturer's quality control is so poor that you still have to match belts - then move on.

If you are tired of the belts being a source of worry then replace them with a service factor of 3 and use banded grip notch belts with new sheaves. Preferably Gates belts. Check the tension at

1 Hour

10 Hours

100 Hours

and every 1000 hiurs from then on

I did this with an air powered fueling station a few year ago and the same belt drive is still there. The previous comment about most manufacturers leaving no room for service factors is correct. Ugrade the drives on any air compressor.

dear sir,

SPC 4000 is a wedge type belt and carries more load than V belt of same crosssecton,that is reason for failure C 156 belts.Contact belt mfrs for more details.

ELLURU RAMAIAH

hi ,these two kinds of belt is different in terms of their dimensions i.e. their pulley also have different measurements, so you cannot use "c" belts on "spc" pulleys plus the fact that you are running your compressor at high speed,it will break your belts in no time.