Pulleys and Sheaves

I didn't know what a 'bushed' pulley was till I started having trouble with my DIY projects.

This is a living document and will grow as we learn more about the pros and cons of pulley types.

They come in all sizes and grades, we've covered the pros and cons of pulleys versus direct Drive elsewhere, so this will be about pulleys only.

Vee belts have been around for a long time, because they are typical, many DIYers are comfortable using them. Following are common mistakes DIYers make, sometimes they have to scrap the first set of pulleys and belts and start over. This can generate a considerable expense for your DIY project.

If you are going to build a generator using VEE pulleys, invest in larger diameter pulleys, a 3" set of pulleys offers the same ratio as a set of 6" pulleys, but the larger set will transfer far more torque, and usually last longer under load. Use the larger pulleys or live with the results of your decision to save a few dollars, it'll often cost you more in the long run, the smell of smoke under heavy load, black deposits in and around your gen set will be signs you under engineered your drive, the cooler your pulleys and belts feel right after pulling a big load, the better.  

I once destroyed a 220 volt AC deep well submersible pump when a belt slipped during the attempt to start it. It took me a while to figure out what had happened, but there in the manufacturer's notes was a warning that erratic power could destroy the coupling between the electric motor and pump! This was an expensive lesson, and I had plenty of time to burn it into my memory as I was pulling the pump; and coming to grips with the replacement costs. This experience is shared on the utterpower CD, and it is a constant reminder that I have learned too many things the hard way :-)     

Above: Here's an example of a 'real' pulley, the center accepts a bushing; the bushing is an off the shelf piece that is purchased to match the shaft of the equipment you will install the pulley on. This example is 20 inches wide and was designed to take a double Vee common back belt.

Above is a typical split tapered bushing. This 'bushing' is bolted to the pulley, once the pulley and bushing is positioned, the bolts are turned in and the bushing follows the taper into the pulley to 'lock' it on the shaft. In my opinion, this is a proper pulley for a generator you wish to rely on, if it's not a bushed pulley, you won't find it on the stuff I build, I've had my share of  loose pulleys, lost Allen screws, smoking belts, shaking and rattling noises in the middle of the night followed by darkness. The drive system is NOT a place to take short cuts, and the majority of the problems I've had with home built pulley driven gen sets are found in the drive system. 

Note the threaded holes, these are jacking holes, when you wish to remove the pulley, simply move the bolts out of the fastening holes into the jacking  holes to extract the pulley. Your Grandmother can remove a bushed pulley in 60 below weather, and you will appreciate this feature when it's time for maintenance, or when you wish to move the pulley to another shaft, you keep the pulley, and buy the proper sized bushing. These are commercial grade, and they can be purchased from any good supplier. If it's not a bushed pulley, it's likely to cause you trouble, I've seen a number of gen shafts tore up when one of those cheap hardware store sheaves came loose, if this happens to you, it will be at the worst possible time, and if you are married; your wife is likely to make a comment about how much money you spent, and for what? Then she'll light a candle, and go off to read the brochure on the new kitchen appliances she could have bought with the money...  

9/19/05

I was reading an article written by Richard Perez (Build your own 12 VDC engine Generator, Home Power #42 Aug/Sept 1994). You can find these articles on line at home power, and I encourage you to read this one! There is personal experience shared in this article that validates my findings, and it provides sage advice as to how you can build something that won't rattle apart. There's a few notes about gas engine experience, and this alone is valuable; this is the kind of information I crave; for it comes first hand from an experienced DIYer, not from some Joker Salesmen trying to convince you his stuff is best. One of the mentions is his experience with aluminum pulleys, and finding them totally unsuitable for even small home built  battery charging units. If you attempt to build with cheap pulleys, you will be buying pulleys twice.

Richard, thank you; this article is loaded with valuable information!

All the best,

George B.

Want something  far superior to VEE belts? see the Utterpower Drive for the Big Flywheel engines.