Bushed Pulleys

What you need to know before you install one.

Why do I use bushed pulleys, isn't it just another expense?

Bushes pulleys; as far as I'm concerned, they are an important part of 'KISS' engineering. a bushed pulley is something that can be used on a range of shaft sizes. I use the 'SK' sized bushing because it covers the range of sizes we DIYers normally find ourselves involved with. There are a few using the 48mm shafts, and the SK bushing covers this rather large size as well. If we step up one size to the SF bushing, we can even cover a 2 inch bore, this is the size of the Lister 6/1 crankshaft!

Bushed pulleys allow us to attach a pulley to a shaft with a VERY positive fit, if you do it near right, it'll never slip, it'll never come loose, you won't mangle a key way, and you can remove the pulley in sub zero weather with gloves on! Standard Bushings have two sets of hole in them, one can be used as 'pass throughs' the others are threaded. What you need to know BEFORE you install a bushed pulley is that one set of these holes are used as >JACKS< to 'JACK' the bushing back out of the pulley. This is typically done when the pulley is put on the shaft first, widest part of the hole facing the end of the shaft. Then you fit the 'SPLIT' tapered bushing on to the shaft small end first.

Some folks new to tapered bushing can't get the new bushing on, always check the shaft and the bushing and make sure they are the same size. Once you are sure of this, you will note that the bushing often needs to be opened up a little. Simply slip a screw drive in the slot, and gently tap on the butt of the screw drive until the bushing spreads enough to get it on the shaft.

Above: Here's a Metric 'SK' sized bushing, if you look close you might see the SK followed by the size. You'll also note six holes, three are larger and un threaded, three are threaded

Above: Note the split, this is a 'SPLIT' Tapered bushing, we can drive a screw driver into the slot to help spread the bushing a little to get it started over our shaft.

Above: Here we see the bolts in the threaded holes, note the end of the bolts are pushing on the face of the pulley, and this will 'jack' or help remove the bushing from the pulley. Since the bushing and the center hole of the pulley are tapered, they are always easy to pull, even with gloves on!

Above: Here's the most common method of mounting a bushed pulley, the FACE of the bushing (top most in this picture) is installed nearest the end of the shaft where it is easy to use the jacking bolts and easily remove the pulley, simply remove these bolts, AND install the jacking bolts.

In the above Photo, you can see that the bushing is NOT brought in tight against the pulley.

This is normal, and there is no reason to tighten the bolts past snug. There have been several people new to tapered bushings that have broken off the bolts trying to pull the bushing flush to the pulley! The two tapers work to secure the pulley onto the shaft as it it were welded on! Don't get carried away, and do go around in a circle and tighten the bolts a little as you go round and round to allow the pulley an bush to seat evenly, which will allow the pulley to fully align on the shaft.

Above: here's an optional (seldom used) method to mount the newer utterpower Pulleys. The bolts are passed thru the unthreaded holes in the pulley and into the threaded holes in the Bushing. In this case, the bolt heads would be outward, and the threaded holes in the pulley would be used as the jacking holes. This option is not possible with many pulleys, and one must inspect the threaded hole and be sure they are threaded all the way thru before mounting.

One other item worth mentioning. Do not assume that the bolts and threaded holes are the same! In this case, and other cases, the holes in the the pulley are 8.8 M8 Metric, and the bolts in the bushing are typically 5/16 18 thread for the SK bushing. Make sure you check these things out, and have the proper bolts BEFORE you attempt to install the pulley.

This page is to give you most basic advice, there are excellent pages to give you far more information, here's on example, using a google search using QD bushings will provide a lot of readings.

All the best,

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