Replacement V-belt type / sizing question.

[julianf]

I have a small, belt driven, compressor here that needs a new belt.

The original belt had had all sorts spilt on it, was partially delaminated, and would spin off after 15 seconds or so. I cut and measured the remains to be aprox 43.5".

Here's a list of other points -

• Unit has no adjustment - motor and pump are a fixed distance from each other.
• Unit is about 2hp
• I measured the untensiond OD with a bit of 10amp 3core, and that was pretty much spot on 43"

My question is -

A section or B?
Length? (again, the unit has no scope for tensioning once fitted)


These are the items ive been looking at -

A section sizes -
http://www.ebay.co.uk/itm/A-SECTION...t=LH_DefaultDomain_3&var=&hash=item2c63ffa264

ie A40 or A41?

B section sizes -
http://www.ebay.co.uk/itm/V-BELT-B2...t=LH_DefaultDomain_3&var=&hash=item2c60220fc7

ie B39 or B40?


Could anyone advise? I have no experience in this area at all, and dont know how the sizing relates to the tension. Ie if i order a 42" belt, given my 43" measurement, am i ever going to be able to get it on, and will the tension be far too great if i do?

Thank you.

 

[rtbcomp]

You might find something useful here

http://selectors.fptgroup.com/

http://www.gizmology.net/pulleysbelts.htm

Whilst you've got in bits I'd look at providing some means of adjustment, such as elongating the motor mounting holes.

 

[gordon stephenson]

A section belts are 13mm wide, and B section belts are 17mm wide. Take your belt along to a bearing and power transmission supplier, they should have a jig to measure your existing belt,

 

[wristpin]

Strange that there appears to be is no adjustment ; are you sure that neither the motor or compressor can be moved?
Anyway regardless of that do you have the original manual that came with the unit , there may be a part number or size for the belt therein.
Next is the unit identifiable - manufacturers name and model? If so a bit of time with Google may come up with a number.
Finally if all that fails, take your old belt and your measurements to your local bearing and belt supplier and get them to use their expertise to match it- better than mail ordering the wrong size and all the hassle of returning it.

 

[julianf]

The motor was retrofitted to the compressor. It was originally (im told) on an engine, and the motor added at a later date (not by me, or by the previous owner, but before that...)

Certainly the motor should be adjustable, but it seems that it was a quick retrofit. Its not ideal, but, right at the moment, i just want to grab a belt and run the unit. It would certainly be better to make a sliding frame, but, at present, i have more pressing things to be spending time on : (

So, it was more a question about belt tensions than anything else. Its not worth trying to match the old belt, as there is not a great deal of it left. The unit was used in an environment that is hostile to rubber.

 

[daleyd]

Measuring the width of the pulleys should give you some idea of the section.

 

[normspanners]

If you have no adjustment you might be better going for a stretch belt there are two ways to do this there are two types of segmented belt; http://www.ebay.co.uk/itm/Fenner-Dr...pt=AU_HeavyMachineryParts&hash=item3a9f52cca0
or
http://www.ebay.co.uk/itm/Nut-Link-...K_BOI_FarmingEquipment_RL&hash=item3a94161130

or try to get a stretch automotive belt to suit
by using a non stretch belt that is too small you WILL damage the bearings on motor or comp-------- or have belt slip if it is too slack . it is virtually impossible to get a belt the right size and if you do, when it wears it will become slack and slip.

 

[RonA]

I have a small, belt driven, compressor here that needs a new belt.

The original belt had had all sorts spilt on it, was partially delaminated, and would spin off after 15 seconds or so. I cut and measured the remains to be aprox 43.5".

Here's a list of other points -

• Unit has no adjustment - motor and pump are a fixed distance from each other.
• Unit is about 2hp
• I measured the untensiond OD with a bit of 10amp 3core, and that was pretty much spot on 43"

My question is -

A section or B?
Length? (again, the unit has no scope for tensioning once fitted)


These are the items ive been looking at -

A section sizes -
http://www.ebay.co.uk/itm/A-SECTION...t=LH_DefaultDomain_3&var=&hash=item2c63ffa264

ie A40 or A41?

B section sizes -
http://www.ebay.co.uk/itm/V-BELT-B2...t=LH_DefaultDomain_3&var=&hash=item2c60220fc7

ie B39 or B40?


Could anyone advise? I have no experience in this area at all, and dont know how the sizing relates to the tension. Ie if i order a 42" belt, given my 43" measurement, am i ever going to be able to get it on, and will the tension be far too great if i do?

Thank you.

Just been through the same scenario fixing up an old power hacksaw with a Replacement belt but without the benefit of the old belt being available to compare with. Plenty of belt length calculators on v belt suppliers websites e.g. try bearingboys website. The only thing to remember is that B section belts sit high in some pulleys & the effective dia is to the top of the belt & not the pulley in that arrangement.
RonA

 

[Turbo]

A handy way of getting a belt size is to use a piece of light nylon rope. Wrap it around the pulleys, pull it tight, overlap the ends and cut to length (an extra pair of hands is useful). Then you heat the 2 ends of the rope until melted and hold them together until cold. Then you try your 'rope belt' for size. It will even drive a light load - it was fit to drive my pillar drill spindle! Then you can take your rope along to a supplier and get the exact size. Simples!

 

[brightspark]

there must be some adjustment on the motor or pump even if a small amount no belts are identical unless u are using a multi belt pulley and u can buy them in matched sets

 

[ford34/2]

there must be some adjustment on the motor or pump even if a small amount no belts are identical unless u are using a multi belt pulley and u can buy them in matched sets

Yup, specify matching pairs when more than one belt connects Motor to Machine. There every possibility one slips and the other knacks the bearings `cause its too tight., Amazing just how different the same size belt can be if you check two together.
So do you have to take off a pulley to get the belt back on?

Stan