https://hvac-talk.com/vbb/attachment.php?attachmentid=817065&d=1593794019

Usually you leave a little slack, the belt should have a bit of movement up and down when you push it. But shouldn’t squeal or slip. Roughly speaking around 1” up and down.
Too tight and you’ll destroy the bearings from too much tension.

 

http://www.powerdrive.com/Downloads...com/Downloads/ECatalogs/VBeltDrive/Belt Tension Checker Instruction Sheet ..pdf

https://www.bestorq.com/library/techinfo/whytension.pdf

http://mpair.com/assets/pdf/general/belt.tensioner.pdf

 

Keep reading

 

One kinda interesting rule of thumb that I learned from a mechanic one time is that when you’ve got the belt about right you will be able to grab it and twist it 90 degrees but no further. Hopefully I explained that well enough. On a 5 ton unit it’s not something to fret yourself over too much. Also on really small stuff like that you can almost always roll the belt off and put the new one on without even touching the adjustment. If the new belt feels right and the old one got plenty of life out of it then I’d leave the adjustment alone. Last week I replaced a 1000 lb motor that used three belts and had no vfd and yes those belts were tight and yes we had to adjust the motor to get them off [emoji23]

 

First thing an apprentice should be trained to do when changing filters.... should always use a tension gauge until you are used to the feel.

Tension gauge, new & used settings.
Correct pulleys & belts match. Depth in groove correct, number belts typically fractional hp only.
Pulley less than 1/32" wear. Use a .032 wire and key stock as gauge.
Parallel and angular alignment using straight edge or string.
Amp and voltage check
TES check, fan rpm check

If not done correctly, belt failure, pulley wear, motor overheating, bearing failures, improper air flow...

Sometimes we still have to read.

file:///F:/Service%20info/browing%20belt%20size%20calculation.pdf
file:///F:/Service%20info/Optibelt-v-belt%20Installation-and-Maintenance-Instructions.pdf

 

If you're getting into commercial start using the correct terms. Pulleys are for rope and sheaves are for belts. That may not sound like a big deal but a lot of experienced HVAC guys take notice of such things to form a first opinion.

 

My fault if I gave the false impression that I knew what I was talking about. But I will keep that in mind Wayne. Maybe you could slide over some of the terminology over my way so I don't look like a fool when I ask questions. Thanks!

 

Purchase the Browning tension checker and follow the included instructions, pulley....oops, sheave alignment is the key to long belt life.

 

One rule of thumb is to tighten the belt just until it doesn't squeal on start up. Any more, as mentioned, you'll take out the bearings too soon.

The problem with that rule of thumb is more and more units are having VFD's for the blower. So with that 'slower' start up, you'll never get that squeal even on a system with the belt much too loose.

 

Wayne does make a good point. I've always used that as a gauge with techs also.

If you're getting into commercial, its even more important to raise your level of professionalism. When you start talking to manufacturers for tech support, its very easy to get confused, or for the guy on the other end of rhe line to get confused by incorrect terms.

Also, in the commercial world, you'll find yourself standing in front of owners, engineers, etc. "Sounding" like you know what you're doing can be more important than actually knowing what you're doing!

Used to work with a stationary guy at a hospital. He would call me up and say, "man, I cut this thing on and nothing happened!" I always had to take 5 minutes to slow him down to figure out what exactly he was trying to say. Funny thing is, he's now some sort "engineer"!! LOL!!

 

Pulley and Sheave: Difference
Ever Power
Ever Power
Dec 6, 2019·3 min read

Pulleys have been used by mankind from time immemorial. They are used to make lifting heavy objects easier. A pulley allows a person to lift a particular load with less effort than what would have been required without a pulley. They are typically made with ropes and wheels. The term pulley is interchangeably used with the word sheave. This is not correct as they are different things. Here are the differences between a sheave and a pulley:-
The basic difference — A pulley is one of the six types of simple machines that have been used for humans for a long time. It is a basic mechanism. The sheave that is pronounced as shiv is part of the pulley. It is the wheel with grooves where the rope fits in to.
Complimentary — Pulley without a sheave changes the direction of the pull to lift the load but it doesn’t change the force or energy required to lift the object. By adding multiple sheaves we get a mechanical benefit as it reduces the energy or force required to lift a particular object. The force required reduces in half with each sheave you add to the rope but this cannot be done indefinitely as the utility with each sheave decreases till its negative.
Problem — Though adding multiple sheaves reduces efforts, but it can also cause fiction. You cannot add an unlimited amount of sheaves as after a few the force required will start increasing with each added sheave, due to the friction caused by them. This increase in sheaves and ropes will make your work harder rather than easier. The solution to this is a compound pulley where the sheaves are added above and below each other and supported by an axle. This will increase the efficiency of your pulley by adding more sheaves.
Simplicity — Maximum work can be done by attaching a single sheave to a rope. There are certain things to keep in mind while doing this. Firstly, the surface area of the sheave should be at the possible minimum to the rope attached. Secondly, the sheave needs to be abrasion-free. Lastly, the sheave must not be prone to warping. If these three things are kept in mind while making a pulley, your device should do its job without glitches or additional problems related to the same.
Expert opinion — according to engineers who have worked with pulleys for a long time, the differences can lie in context. Pulleys and sheaves can mean different things depending on the industry you ply your trade-in. Another common answer that we got from experts is a sheave is mostly used as the name for a drive pulley. It can also depend on the area of the world you are staying like in Some parts of the united states where sheave is used as a substitute for a pulley. Another response that we got while asking for differences is that Sheave Pulley is a heavier duty pulley. Most experts though agree that there is no difference between a sheave and a pulley. The difference arises when you go into further details and they are also few and far in the middle.
Etymology — the word pulley has been in use in the English dictionary since the early 1000 A.D. Before that the word for pulley in greek was polos which were used as far back as 400A.D. Whereas, pulleys have been used from around 200 B.C. the history of the pulley is long and the story of its name is incomplete. Sheave is an even older name than a pulley and can be traced back to the proto-germanic language where a Scheibe means a disc or a bundle. The history of the sheave is unfortunately not clear except its maybe origins.
Dictionary — It’s always good to check the dictionary to check the meaning and difference between two things. According to the dictionary, a pulley means “a wheel on an axle or shaft” and a sheave means “ a pulley with a grooved wheel”. Therefore, it means that pulley with grooved wheels is sheave and all others are pulleys.
There is not much difference between a sheave and a pulley. You may say that a sheave is a particular type of heavy-duty pulley and it is a part of the pulley. The difference lie is details of use and location but for the amateur user, there is a negligible amount of difference. These sheave pulleys are available around the world and in different qualities and sizes for suiting your work. To know more about sheaves and pulleys, please visit https://www.ever-power.net/pulley.

 

I have read the articles about what the "experts" say however in the beginning there was a pulley and they were used for rope. When belt drives came along they were called sheaves because the grooves were different than a pulley. If you ordered a pulley you got the same basic thing as a sheave with the difference being the groove and years ago nobody at the supply house even thought about giving you a sheave when you ordered a pulley.
My comment wasn't meant to belittle anyone. Call it whatever you wish but another thing I have heard "experts" say is in the beginning pulleys were used to change direction. That is also false they were mostly used for mechanical advantage.
At any rate I wasn't trying to upset anyone. I'm sorry if that happened.

 

I’m used to terminology difference verbal and written. Reviewed and written mfg literature. Edited out trade names and tried to use industry standards and often found there is no standard so just looked for most common used. Bolts & screws were terms most often misused. Tried to keep Sales, Installation, operation & maintenance, and parts literature consistent .
Sometimes lots of opinions.
Southern boys may know what a “pecker head” is, while someone from another part of the country think something different.
Always recommended you have the vendor parts manual before ordering parts so you can confirm the correct component by name and pn.

 

I'm not here to impress, I'm here to learn. So I don't mean any disrespect to anyone that's trying to share their knowledge, but I'm not looking to be judged by my terminology either. I'm sure as time goes and I get more accustomed to commercial, I know the words will come. Being in the kitchen for 18yrs, it took me a few months just to get basic things down like terminals and spade connectors. But I really do appreciate all of you who share their knowledge and passion for the trade that I am looking to expand in.

 

A kid I grew up with came from down south and a bolt to him was a tap and a nut was a burr. After terms are used interchangeably for a while whether right or wrong they become acceptable.

 

I've known worthless techs that can BS anyone, while really good techs that can't express themselves professionally, are thought of as being idiots.

Regardless of your skill level, a high level of professionalism gives a service technician credibility.

Maintainance men know what a pulley is....a service technician knows what a sheave is, how to apply it, why you use the sheave you are using, and how to properly install, align, and tension it.

 

Not sure how or when I picked up the terminology I use, anyway, it goes like this:

Let's say I need to write up one of these, I call it a motor sheave or a blower pulley. It may have started if/when someone told me that is a sheave, pointing to the adjustable motor sheave. I may have thought that since it was adjustable, that made it a sheave.

No matter, it seems everyone always knows what I'm talking about. All that really matters is the guys behind the counter give me the correct part.

 

Exactly what I was taught many years ago and still use those terms still. Blower Pulley and motor sheave if its adjustable otherwise its a motor pulley, Ive never even heard any tech speak of them different than that. Defenatly never heard of a blower sheave though, thats a new one for me.

 

Totally agree with what EHSX said in post #6, and.........

Simply stated, a pulley is a machine. A sheave is a component in a pulley. Grammatically correct, or not, the words pulley and sheave continue to be used interchangeably.

The real difference here is that a professional calls it a sheave, and the others think it's a pulley. Professionals, as they mature in our trade, learn a new language. Learning, and properly using that new language is extremely important when you need to accurately convey information.

It's telling when someone calls it a pulley. It's also telling if someone is not familiar with the industry standard for tensioning a drive belt. That is a piece of knowledge that newbies are taught very early on in their career.

 

I personally could care less. I prefer the use of the word pulley.

Sheave always makes me think of a makeshift instrument for stabbing used in prison.

Also I was always taught like Beerme. Sheave was always an adjustable motor pulley. Everything fixed was just a pulley.

Nobody worth a damn is gonna be thrown for a loop if someone calls it a sheave or a pulley.


Sent from my iPhone using Tapatalk

 

I thought this place was supposed to be a place to share knowledge?

If you were to browse the Browing catalog you will find those variable pitch sheaves that you're referring to, listed as VP, or MVP.

For example, if I wanted to order a 3.5 inch variable pitch sheave for my small exhaust fan, I might ask for a 1VP35. If it was a two grove sheave, I might ask for a 2VP35.

It would also be important to know the number, and type of belts that I might need. Having the ability to calculate the belt length for my new sheave combination is also important.
Oh, and we don't willy nilly change sheaves.

We need the ability to calculate the rpms of our sheave combinations, the ability to calculate the new anticipated amp draw, and, if this is a fan, or water pump, you should have the ability to understand the fan curves, or pump curves associated with the equipment

 

Rule of thumb... The least amount of tension without slipping is the best for most small systems. You get a quiet and long life that way.

I’m sure someone has already posted how to measure it properly already but many units it doesn’t really apply because that would cause noise and added friction (only noticed on some small fractional motors)

There is a bit of a real world art to it a lot of the time.

What size motors are you servicing?

 

It's surprising my comments caused so much controversy. It reminds me of when I corrected a guy that pronounced potable water as pot able water. When I told him it was pote able he refused to believe it until Webster told him so. The reason I corrected him was that he was about to call a client.

The dictionary is part of the reason sheave and pulley are commonly thought of as the same. One description that I know of is "a sheave is a pulley with grooves". That describes the difference but in terms that insinuate they are the same.

 

I appreciate the comment and I’m glad I got to look into something new...also I’m guilty of using “potable” wrong since I looked into that as well. So I appreciate that as well.

I think the poor guy just wanted to know about belt tension. Even though a pulley can be called a sheave and vice versa it’s not that important. What was important was belt tension. Calling something a sheave just wasn’t something he needed to be corrected on especially since he’s new to the trade. Your original comment (whether it was intended this way or not) kinda made it sound like he was a fool for using the word “pulley”. Myself and a few others are just making the point that he doesn’t need to feel that way or worry about it. The truth is that it isn’t a big deal for any professional to use the word “pulley” so he doesn’t need to feel unprofessional for doing so.

https://phoenix-mfg.com/Pulley-Versus-Sheave_b_21.html

 

A few months ago a guy lost his marbles and went off on a bunch of us for using the word "Freon". I think he might have gotten banned over it. In my opinion, using the correct term is important, but it's not worth getting your panties all wadded up if someone else doesn't.

Just please don't use the word "hot" before the word "water heater". That one always gets to me for some reason, and I have to fight the urge to blurt out "It's a COLD water heater, dummy!".

:cheers:

 

But isn’t a boiler radiator a hot water heater hahaha [emoji851]

 

I had to think about this one, but I'm pretty sure a radiator is technically a water cooler. Maybe you could call it a "heater water cooler". Oh hell, I give up. Call it whatever the eff you want.

 

I'm not going to go off on any of you. Please understand I wrote specifications for 25 years and terminology is crucial when writing them. The old adage that interpretation of the specs is per the engineer only goes so far. If a spec stands on it's own the engineers interpretation doesn't mean anything because there is no interpretation. For example if you say the shaft shall be made of 304 stainless steel.

This isn't not a big deal to me at this point at all.

 

Regarding the term 'hot' water heater, depends on when you consider the water hot versus cold. For example, if I want my hot water at 150*F, and the 'hot' water heater is cycling within a 20*F range, and I consider cold water to be 60*F or less, then I have a hot water heater.

 

Holy shit you just blew my mind [emoji23]

 

Here's another one I had a 'discussion' with an engineer about. And for what it is worth, he was the single best engineer I have ever worked with.

We were to install two small boilers. Design water temp maybe 185*F max. I asked him why he called them boilers. He answered, because they are over 150*F. I said at normal pressures, water does not boil at 150*F. He replied in a weird way, something like, since the water is hotter than what is considered safe, they are boilers.

We kinda just looked at each other, neither of us accepting the others reasoning.