Dangle_kt
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| posted on 13/2/11 at 09:38 PM |
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coupler...how to?
Hi Guys,
Planning a project that requires me to couple an output shaft of one motor to the crack of the bottom end of another.
I have seen people use couplers, which seem to be a cylinder of hardened steel, milled out on both ends to the relevant diameter and then pinned with
2 or 4 grub screws.
Have I understood this correctly? Because surly all the force is being taken by the 4 grub screws...
Just wondering if anyone on here had any experience with that sort of thing 
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daviep
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| posted on 13/2/11 at 09:54 PM |
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You need to be a bit more specific with regards to shaft sizes, speeds, max torque and power to get a useful answer.
If you plan to "close couple" two crank shafts together you are going to have to be very fussy about alignment of the two shafts.
Have a look at FENER COUPLINGS for a bit of guidance, mounting of the coupling is
usually by "taper lock" if fitting to a shaft.
Davie
“A truly great library contains something in it to offend everyone.”
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hillbillyracer
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| posted on 13/2/11 at 09:57 PM |
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I'm not sure about the couplers which you talk of but sprockets, pullies etc are often held onto motor shafts or the shafts on a machine by one
or two grub screws, but the drive is taken by a key on the shaft, with one of the grub screws tightened onto the actual key.
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NS Dev
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| posted on 13/2/11 at 10:18 PM |
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if you mean coupling two engines together then you'll need something altogether stronger than this type of thing!
The torsional vibration is intense and just smashes most couplers up.
You really need a splined coupling and possibly pair of very strong uj's
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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owelly
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| posted on 13/2/11 at 10:33 PM |
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...or two sprockets with a duplex chain joining the two?
http://www.ppcmag.co.uk
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Dangle_kt
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| posted on 13/2/11 at 11:17 PM |
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Sorry - should have shed more light.
Its an electric motor to a scooter output shaft (read crank)
Electric motor will be kicking out 5bhp MAX, not sure on torque...but not much.
I imagine a coupler is lathed up, but the key?
Sounds like a workshop rather than a hobbist job  and that tends not to be locost.
Thanks for the info so far guys - helpful as always.
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owelly
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| posted on 13/2/11 at 11:22 PM |
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The leccy motor should have a keyway machined into it. What is on the end of the scooter shaft. BTW, The leccy motor will have lots of torques.
http://www.ppcmag.co.uk
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Dangle_kt
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| posted on 13/2/11 at 11:27 PM |
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its an RC motor, so the torque isn't as big as I'd like...but so what - its cheap!
The scooter/motor is still in the planning stages, so I have no specifics. I'm thinking it all through and this was a gap in my knowledge.
As usual LCB comes to the rescue!
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hillbillyracer
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| posted on 13/2/11 at 11:36 PM |
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So is the electric motor to replace or assist the scooter engine?
Just thinking incase the two are to work together without a controller the electric motor will want to run at fixed speed where the engine will be
variable, & the motor will have a smooth steady RPM while the engine has peaks & troughs as the piston comes to compression & then under
the power stroke.
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Dangle_kt
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| posted on 13/2/11 at 11:48 PM |
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Sorry, more detail - its a dead scooter engine, essentially using the bottom end to provide a reliable transmission.
Other option is to get a sprocket on the crank, and run the motor where the top end used to be and join the two by chain.
Like I said, I'm weighing up the options.
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hillbillyracer
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| posted on 13/2/11 at 11:54 PM |
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I was thinking the original engine was'nt going to be part of it but thought I'd ask!
It does sound a decent idea to mount the motor where the barrel was & use a chain, much less alignment problems, barrel bolt holes would give
something to mount the motor to & there'd be scope with sprocket sizes to tweek the gearing if you needed to.
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Dangle_kt
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| posted on 14/2/11 at 12:00 AM |
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Thanks hillbillyracer.
I'd not really heard of couplings, and couldn't see how they could work - but now I do, and for the effort I think I think I'll go
with the other option!
Cheers everyone.
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