Round Key Ways

What is the shaft diameter and speed? At 100HP I'd want to do some careful calculations.
 
If you are worried about keys tearing up a shaft, which they can in certain applications, heat shrink the sheaves or couplings to the shaft. I've seen this done on compressors direct coupled to engines and motors. 100 HP being one of the smaller compressors and up to 1200 HP on much larger compressors.

I've used round keys in highly stressed applications with excellent results. Much preferred over square keys in certain applications.
 
Thank you for the replies. The shaft is 40mm en24 . I will use the shrink method as well as using a locking element. Hopefully that should suffice . The engineers say it should.
thanks again
 
A 40mm shaft seems rather minuscule for 100 hp. Perhaps I misunderstood the post. Square keys have been doing a great job for multiple centuries. I agree with the post that suggested a taper lock bushing. That or a QD style tapered bushing provides the equivalent of a shrink fit, the ability to easily change shaft sizes on a sheave/pulley/sprocket, etc. The combination of a timing pulley with a taper lock bore and bushing should only cost a small percentage more than a bored to size of minimum bore sprocket. Much cheaper than buying a broach and a pulley. My 2¢.
 
Yes,a round key would indeed push upwards on the gear or pulley and tend to split it open,sometimes with success.
 
At what RPM is this shaft going to be running when under load? 100 HP through a 40 mm (1.575") shaft at 1000 RPM or higher would be no problem. It would probably be okay as low as about 500 RPM, but any lower than that could get a little dicey. Based on my experience, I would also go with a taper lock or QD style bushing to mount the pulley. Easy assembly and disassembly (usually) plus the ease with which pulley sizes could be changed. Additionally, a pulley mounted on a taper style bushing will usually run dead true. As already mentioned, the tapered bushing locks on to the shaft by squeezing down on it, with the key providing a solid lock. Despite the key being there, most of the energy is transmitted by the compressive force and friction of the bushing on the shaft.
 
george wilson said:
Yes,a round key would indeed push upwards on the gear or pulley and tend to split it open,sometimes with success.
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Not really. The round pin will shear off at the OD of the shaft. The hoop stress involved with the sheave or hub with a round key is much less than you think it would be. Of course, it's all based off of material strength of the components involved.

A shaft at 1.57" [40mm] diameter, as Terry said will handle 100 HP at 1000 RPM and and maybe less. Calculations plus service factors will determine that.

Taper lock bushings are a great way to secure a sheave or coupling to a shaft. Using a key or no key being used. The best method I've seen used is a shrink fit hub or sheave to a shaft, used on high HP motors, with no keys to mess with! This is generally used where there is high service factors involved, 2.0 or higher.
 
The reason I said a 45mm shaft seemed light to me is 100 HP 1750 RPM electric motors run 2-1/8" shafts and 1200 RPM run 2-3/8" shafts. Not knowing the entire set-up, including overhung load and ratio with a belt drive is why I thought it to be small. Just using rules of thumb and lack of detailed information always make me think of the old bromide "When in doubt, make it stout".
 
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