# Thread: Using a belt tension checker

1. Regular Guest
Join Date
Apr 2018
Posts
8
Post Likes

## Using a belt tension checker

I have been using the Browning tension checker similar to this one

I was wondering the proper way to use it. The scale to set the shaft inches on it looks as if it in is in increments of 10. I have seen a couple manuals that ask you to measure the shaft between rotors and divide that by 64. For most sizes I see that would give you a number smaller than one, which would have you basically be setting the O-ring at the bottom of the checker. This doesn’t seem like it would be very accurate to me or if I am just misunderstanding things.

Anyways anyone who is more familiar with those things could hopefully clear this up for me. Or if there is another more accurate way to check belt tension I should look into would also be helpful.

2. Professional Member
Join Date
Apr 2007
Location
Posts
259
Post Likes
• Measure the center-to-center distances on the shafts. This is your span. Set the large O-ring to this measurement.
Yes, this is in 10 lb increments, so it can be hard to be dead accurate.

• Zero the small O-ring.

• Place the tension checker in the center of the belt and apply force. Stop when it reaches it's original position. Use the adjacent belt as a reference.
I utilize a ruler or thin angle as a straight edge if it's a single belt.

I use these all the time. The older guys think I'm crazy. You must have the tension chart for the brand and model of belt that you are using.

The "divide by 64" you referred to is the ratio of deflection. The belt will push down 1/64" for every inch of span.

For example: Belt Span = 32"

32 ÷ 64 = 1/2" of deflection

The longer the belt, the greater the deflection.

3. Download the instructions. I use it on every belt driven job.

4. Regular Guest
Join Date
Apr 2018
Posts
8
Post Likes
Thank you very much this was helpful.
Originally Posted by FrostGiant
• Measure the center-to-center distances on the shafts. This is your span. Set the large O-ring to this measurement.
Yes, this is in 10 lb increments, so it can be hard to be dead accurate.

• Zero the small O-ring.

• Place the tension checker in the center of the belt and apply force. Stop when it reaches it's original position. Use the adjacent belt as a reference.
I utilize a ruler or thin angle as a straight edge if it's a single belt.

I use these all the time. The older guys think I'm crazy. You must have the tension chart for the brand and model of belt that you are using.

The "divide by 64" you referred to is the ratio of deflection. The belt will push down 1/64" for every inch of span.

For example: Belt Span = 32"

32 ÷ 64 = 1/2" of deflection

The longer the belt, the greater the deflection.

5. I wouldnt use it on any smaller units, say 5-7.5 tons. Some systems even state right by the blower to only tighten untill blower doesnt squeel on start up. I believe others here could elaborate better on that.

Sent from my iPhone using Tapatalk

6. Professional Member*
Join Date
Dec 2004
Location
Chicago area
Posts
6,539
Post Likes
Originally Posted by Core_d
I wouldnt use it on any smaller units, say 5-7.5 tons. Some systems even state right by the blower to only tighten untill blower doesnt squeel on start up. I believe others here could elaborate better on that.

Sent from my iPhone using Tapatalk
I think that it depends on the mounting design of the motor or the plate the motor is on.

Resilient mount motors move quite a bit when under the same tension you would run standard foot mount.

And some motor brackets, such as are used by Carrier on smaller units are very flimsy and will bend.

Sent from my iPhone using Tapatalk

7. Great info, I didn't even know this tool existed. I'll be getting one for sure as I'm a bit of a perfectionist rather than a good-n-tight type of wrencher.

8. Professional Member
Join Date
Jan 2015
Location
Iowa
Posts
1,016
Post Likes
A discusion on belt tensioning (and alignment), the right or wrong ways of tightening the belt could go on for weeks and months. There is so much more than just getting the tension "right". Go on-line and download the instructions for your tool that will get you a long way toward the good, but not all the way. If you are into the vibration diagnostics you can dial in the best tension and performance.

But back to belt drives. What is the correct way, the one that provides the correct air flow and last a long time. As a tech/mechanic our job is to deliver an air flow that meets the design requirements for each system and provide the most cost effective and reliable system as we can. There are many factors you have to take into consideration.

A deflection/tension gauge does two things. 1. It gives you a value to write on the service ticket for the owner or next tech to work on it. 2. By using the tool to let's say make adjustements so you have: 1/2" deflection with 20 pounds of force, you teach yourself just what it takes to get those parameters (experience). There is an art as well as science in setting up belt drives.

We each have our own method of getting there. As long as you understand what you are trying to achieve and you deliver it, you don't need to follow the recommended values dictated by fan and belt manufactures. (with an explaination)

Heat is the #1 destroyer of belts, where does the heat come from (process air, bad alignment, too much tension, too little tension, bad design. Bad design meaning: wrong belt size, wrong number of belts, wrong belt type, wrong sheave, wrong bearing type, wrong motor size, wrong fan size, poor designed belt guard just to mention a few. All belt manufacturers agree if you increase the temperature at which the belt operates by 10F you will reduce the service life by 50%. Engineers have been known to get it wrong, the HVAC tech before you might have got it wrong, the homeowner who worked on it last screwed it up, are all possible

The variable are endless. What is correct is dependent on each drive combination. But the general guidelines for the tension gauges are an excellent place to start. For HVAC system I routinely work on drives from 1/4HP to 250 HP systems. The basics are the same, enough belt tension so there is no belt slip when running, minimal slip when starting, minimal heat generated, alignment good to excellent depending on drive speed. To make each one perform the best takes more than tension.

This post has gotten long, so Ill end
Good Luck

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

## Related Forums

The place where Electrical professionals meet.