I am assuming that are talking about a V-belt sheave and not a pulley and the P means that it is a variable pitch sheave.

I use the "rule of thumb" that the length of the bore NOT in contact with the shaft must be less than the diameter of the shaft. I would be more worried about the motor than the sheave.

You should confirm your dimensions and installation requirements with your motor manufacturer. He can tell you if your set-up will work - if he can't - it's time for a new supplier.

Also on a V-Belt drive the motor should have roller bearings and not ball bearings.

Coupled motor drive shaft = ball bearings

V-Belt motor drive shaft = Roller bearings

Not sure if that really applies to bearings on motors that small, I rarely use any motors under 100 HP. ■

Originally Posted by Gary Blenkhorn

Also on a V-Belt drive the motor should have roller bearings and not ball bearings.

Coupled motor drive shaft = ball bearings

V-Belt motor drive shaft = Roller bearings

Small motors are standard 'off-the-shelf' items. While you may be able to specify non-standard features i.e. special bearings, when the chips are down and you need a replacement in 2 days the non-standard will be 2 months.

Use off-the-shelf standard and save yourself grief

If the motor is from a reputable manufacturer he will tell you the max overhung load on the motor shaft and it's position on the shaft. If they can't go to a better motor supplier!

What is important is the position of the centreline of the belt load relative to position the manufacturer specifies his load on the shaft. You can calculate your effective bearing load based on the above data. ■

(1) Take moments about the rotor non-drive end bearing to establish the bearing load in the drive end bearing using the quoted maximum overhung load and it's position on the shaft extension.

(2) Then take moments about the rotor non-drive end bearing using the resultant load from your belt drive and its position (which will be different to manufacturers position) and establish the bearing load in the drive end bearing. Your bearing load needs to be smaller (or equal) to that calculated in (1). ■

(1) Take moments about the rotor non-drive end bearing to establish the bearing load in the drive end bearing using the quoted maximum overhung load and it's position on the shaft extension.

(2) Then take moments about the rotor non-drive end bearing using the resultant load from your belt drive and its position (which will be different to manufacturers position) and establish the bearing load in the drive end bearing. Your bearing load needs to be smaller (or equal) to that calculated in (1). ■

Important note: Just because you have a belt drive does NOT necessarily mean that every motor must have a roller bearings. Typically, up to and including 25Hp you will very rarely find cylinder roller bearings. For this application you could also completely avoid the issue of overhang if you increased the diameter of both sheaves and narrowed the drive to 1 belt. In case this is already a single belt application this issue could also be due to the type bushing used. If so, I am further speculating that the current bushing has a shoulder. You could switch to a so called Taper Lock design that does not built as wide as the conventional ones.

Attachments

conventional bushing with shoulder (DOC)

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I didn't read in the posts from aregdo that he was using bushes?

Also I haven't come across your "conventional bushing", only the Fenner taperlock illustrated in the photographs (which I first knew in the 1960's)

http://www.fptgroup.com/fenner.asp?t...es&pageid=2668 ■

Hello designer,

You are absolutely correct, the Taperloc ones have been around seemingly forever. In NorthAmerica neither this style nor Fenner are all that popular. TB Woods, Browning and Martin sell more the shoulder variety style bushings that are not interchangeable with Taperlock.

In the end it does not really matter. He needs to pick a method that solves the problem no matter what the style is anyway - where and what he buys or implements depends more on which continent he lives and works. Have a great rest of the week. ■