Finding the correct V-belt size?

[subarub4]

I have a question, I have a old V-belt that's really worn and has no markings, it went to a commercial room ventilation fan for the 4 bathrooms, I can't seem to find anyone local that has the belt and wondering if I should just wait until Monday and go to granger?

In the meantime I wonder if I can find at least some way to at least have an idea on the size?

 

[OxJaw]

Here's a video showing how to measure one that you have. If you don't have one to measure take a piece of string and wrap it around the pulleys then measure the string and width of the pulley.

 

[Flange]

There are plenty of online calculators for v belts.

 

[subarub4]

I wish I would of known before I removed the motor off the mount.. It's been sitting in a non-working sate for at least a min of 10 years.. i had to go to the auto store to get a puller to get the pulley off the motor.

 

[colin39]

Cut it in half and measure it?

 

[subarub4]

Are you just measuring the top part and length? I need to make sure it's the right thickness.

 

[Fixnair]

You can get close with the formula: [ (d+d)x1.57]+2CD. Where D= large pulley diameter,
d= small pulley diameter & CD is the distance between shaft centers.
Be sure to set your motor in the center of the adjusting slots.

 

[subarub4]

like I said I wish I knew before I took the motor off.. I'm just going to let Grainger size it up

 

[Jrican]

http://www.baldor.com/pdf/CA4000_Catalog/PT7_vdrives.pdf
happy reading!

(start at pg 60)

 

[subarub4]

http://www.baldor.com/pdf/CA4000_Catalog/PT7_vdrives.pdf
happy reading!

(start at pg 60)

Looking at that chart I would have need to know the shaft speed of what the motor was turning? I've never seen it work before.. it's most likely hasn't turned in over 10 years so it's a guess on my part I mean everything is pretty rusty right now.

 

[Jrican]

It's an AC electric motor. The shaft speed is predetermined.
http://www.engineeringtoolbox.com/synchronous-motor-frequency-speed-d_649.html
60 Hz., yours is 2, 4, or 6 pole (almost guaranted). check the name plate on the motor.

Unless you are using a VFD, which is probably not good idea for that motor.

 

[dogdog]

for those fans it looks similar to the attic fan ones, those are common size are either 3L 4L type A or B. the size just take a piece of rope and roll and measure the diameter between the two pulleys. (you have video on that one too) you have to find the right one that fits those pulleys. The pulley have to sit flush on the groove otherwise it will come off after it rotates....


Maybe this would help...
if you have a drill press, those belts are type B which is common for most drill press, if it don't fit those grooves on both pulley then you needed the 3L belts to start with..

http://www.vbelts4less.com/V-Belt-Specs_ep_45.html

 

[subarub4]

It's an AC electric motor. The shaft speed is predetermined.
http://www.engineeringtoolbox.com/synchronous-motor-frequency-speed-d_649.html
60 Hz., yours is 2, 4, or 6 pole (almost guaranted). check the name plate on the motor.

Unless you are using a VFD, which is probably not good idea for that motor.

This thing was installed back in '63 it's a open motor I'm replacing to a identical model but drip proof like I said I can't say for sure how long it has not been working because I took over the building maintenance and all I can tell is it looks like it's been over 10 years.

btw no load speed is 1725 RPM

for those fans it looks similar to the attic fan ones, those are common size are either 3L 4L type A or B. the size just take a piece of rope and roll and measure the diameter between the two pulleys. (you have video on that one too) you have to find the right one that fits those pulleys. The pulley have to sit flush on the groove otherwise it will come off after it rotates....


Maybe this would help...
if you have a drill press, those belts are type B which is common for most drill press, if it don't fit those grooves on both pulley then you needed the 3L belts to start with..

http://www.vbelts4less.com/V-Belt-Specs_ep_45.html

the belt that came off looks like it was slipping or whipping because of some deep wear marks in one spot

I will see what I can find

I think you might be right about it being 4L

Thinking about it since the pulleys are so rusted I might as well change them.. So since the pulley for the fan looks to be 10 In in diameter and the small one on the motor is 2"

 

[subarub4]

Ok back here today and the belt is 22" long with a width of 3/8"

 

[redwrench60]

Seems to me you should be able to match it up at any local auto parts store. Most parts stores keep V belts in two widths and length in 1/2" increments.
The numbers on the new belts tell you all you need to know. There will be a little variation but an example would be:
First one or two digits show the width: 5/16, 3/8 ect.
Next two are length.
Next one or two show if it's half size like 22 and a half inch.

Look at their numbers and you can figure it out.

 

[subarub4]

I went to 3 auto stores none had it.. Tried a local lawn mower place and nothing.. I know what I need now so it's less of a issue now.

 

[ADSR]

pantihose?

 

[dogdog]

Ok back here today and the belt is 22" long with a width of 3/8"

3/8 is 3L not 4L so you might needed to search for 3L220 that is 3L with 22" belt.

I had a hard time searching for one when I was trying to restore that attic fan, the pulley at the motor was 3l/4L compatible the pulley on the fan is only 3L which is 3/8. it will slip if I put in the 4L or type A belts from most HVAC places. The belt must sit flush into the grooves.


something like this
http://www.grainger.com/product/DAYTON-V-Belt-3L220?searchQuery=3L220

 

[subarub4]

Well I will be replacing both pulleys not at the pc right now but it gave specs for both 3L and 4L

 

[dogdog]

if you are absolute sure your pulleys are 4L compatible. HF sells one Type A belt for $22 the flexible link ones which is a type A belt should fit 4L same spec.

http://www.harborfreight.com/vibration-free-link-belt-43771.html

 

[subarub4]

Well since this thing would only stop in a power outage I don't think I need one of those fancy belts

 

[Jrican]

btw no load speed is 1725 RPM

Then you have a 4 pole motor.

 

[subarub4]

Then you have a 4 pole motor.

The motor never listed the poles.. I know it's 1 phase.. you can try and figure out on here.

 

[subarub4]

One question if the belt is 22 inches do I need to buy a 23 inch belt? The motor and fan are fixed I can see it being a issue trying to loop around the fan pulley and the extra inch would be enough but not enough for it to slip when the fan is mounted back level


*edit

Forget what I just said.

Missed my coffee