centrifugal or electric clutch

[Tiverion]

Hi folks,

Has anyone done any experiments with electric or centrifugal clutches on non-hub drives? I haven't found any electric clutches small enough but a clutch off a small brush cutter might be interesting if the engagement speed is not too high.

I'd be interested in what the forum thinks.

--
Bill

 

[Bluefang]

http://endless-sphere.com/forums/viewtopic.php?f=12&t=21388 Olaf-lampe is using a clutch with his motor, would be well suited to smaller motors if running sensor less controllers specially if you buy a clutch with a gear down as well like 5-1 ratio from a pocket bike.

 

[Tiverion]

Bluefang, that is an amazing bit of kit.

--
Bill

 

[spinningmagnets]

Centrifugal clutches used for Karting may be useful. There are two types. One with arms that swing out radially to grab the inside of a cup, and and a style where the swinging weights are levered to actuate axial plates. The bigger units may be strong enough for an E-motorcyle of modest size, and the smallest ones may be useful for a powerful E-bike.

My interest was in a simple and robust two-speed transmission for the electric motor. The plate-style clutch could be modified to be over-ridden by a lever, or locked out, as in a situation where you wanted to take a long hill (or off-road) while keeping the motor in low-gear. Some Karts have a simple automatic two-speed transmission based on two over-running freewheels and a centrifugal clutch.

I still haven't gotten around to adapting a Sturmey-Archer 3-speed hub (IGH) as a 3-sp transmission for a mid-power E-bike system, But a simple 2-speed using off the shelf industrial components could scalable, to become as light or as strong as needed. A third gear can have a measurable improvement in heat and efficiency, but a second gear would be a huge improvement.

Here's an expensive unit, but the pic shows the style I'm talking about:
http://www.cometkartsales.com/store/clutches/bully.htm

 

[amberwolf]

The Dogati Superleggera by J3tch1u uses a clutch, at least in the original design:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=15233&start=0

I planned on an electromagnetic clutch for my powerchair chaindrive setup on CrazyBike2, but never found one I could recycle/repurpose that would be small/light enough, and didn't take too much power to engage. Eventually I realized I could do the same thing using a dog-clutch instead, based on Thud's 2-speed dog-clutch setup, if I made it so that in between the two speeds was a "neutral". That way I could use either gear for acceleration or braking, but could coast with the neutral, since there would be no freewheel to the motor so that I could use it for regenerative braking. Never have been able to test the theory yet.

 

[Tiverion]

It certainly looks like the technology is not available yet, but you'll never know if you don't ask. The hive mind is a phenomenal resource and this forum is the best.

I just thought there might be a neat and tidy way of disconnecting a motor completely from the rest of the drive train. Maybe next week, month, year, ....

--
Bill

 

[amberwolf]

I think the dog-clutch is your best bet. Can be very small and compact; just make sure you engage it fast and hard, so you don't wear it or break it.

 

[Hillhater]

It certainly looks like the technology is not available yet,

Why do you say that ?
The clutch technology is certainly available,.
Small centrifugal clutches are used on many power tools and mini bikes etc
The problem is finding one of suitable specification, rpm range, cost , etc.

Has anyone looked at an 12 v electric clutch from a car Air con pump ?

 

[Tiverion]

It certainly looks like the technology is not available yet,

Why do you say that ?
The clutch technology is certainly available,.
Small centrifugal clutches are used on many power tools and mini bikes etc
The problem is finding one of suitable specification, rpm range, cost , etc.

Has anyone looked at an 12 v electric clutch from a car Air con pump ?

OK. Here's the spec.
Centrifugal or electric operation
handle 1kW continuous power
diameter of 65mm and thickness of 15mm
engagement at 1500 rpm and can handle 12000 rpm
unit cost $15 max
if electric can use 2A pull in for 100ms
max hold in current of 250mA

The last time I looked at an A/C clutch it was over 6" in dia and 1.5" thick and didn't incorporate current limiting. If you know of something that meets those specs and is adaptable to what we are doing with bikes, I'm sure I won't be the only one most pleased.

That's what I mean when I say the technology isn't available yet. When some large industry like auto needs something along those lines, then it will happen. Until then we can wait or move on to find a new solution to the problem. I like the latter idea.
--
Bill

 

[vanilla ice]

Like you say they are not optimized for weight or size.. but nice thing about kart ones is you can buy a new clutch with a built in sprocket for like $40! Wear it out, no big deal go get another one. Nice thing about the car a/c setup you are getting price advantage of the auto industry's mass production, plus you can always go to the salvage yard rather than buy new. I'd love to see somebody get a car a/c clutch into a bike!

http://www.mfgsupply.com/m/c/209768A.html The cheaper end of the kart stuff is crude but inexpen$ive.

 

[Hillhater]

OK. Here's the spec.
Centrifugal or electric operation
handle 1kW continuous power
diameter of 65mm and thickness of 15mm
engagement at 1500 rpm and can handle 12000 rpm
unit cost $15 max
if electric can use 2A pull in for 100ms
max hold in current of 250mA...

If you expect to find something that exactly meets your requirements ..and price .. you are dreaming ! :lol: