Manual disengage for a centrifugal clutch

[Cycle]

Hi, Jan!

I got the rear gears you cut for me micro-polished and coated with tungsten sulfide to reduce friction. I'm waiting on the delivery of one needle bearing, then I can put it all together with the hybrid ceramic bearings, lower-RPM clutch springs, and taller rear gears.

Shouldn't be long now, I hope.

I'll have to email you about the camshaft grind, as well.

Can you do rim fabrication? I'm going to order the sprag clutch soon, so I can mock up the rim offset... if I can't find a CNC machinist who can fabricate a new rim for me, I'll go with Christ's recommendation, buy a new rim, cut the center out of it, weld in a solid disc, and cut the holes for mounting the sprag. I'll have to hire it done, as I don't have aluminum welding abilities. The only thing I'm worried about in doing as Christ recommended is the durability of the welds. I'll also have to figure out some way of affixing the sprag center hole to the axle... the axle is a splined type, whereas the sprag has a keyway... so some sort of bushing and some means of locking it in so it can't move axially.

[janvos39]

Hi Darren.
We have capability on both welding aluminum and CNC machining. So if you have drawings of the wanted mod than I can review them. I hope you have a large sprag in mind that can hold the torque. For the attachement of the sprag center I think wire edm is the best option. If the center is thick enough the wire edm can be done in the center . If not than a bush with splines inside and a keyway outside can be made by edm.

[Cycle]

Hi, Jan.

Yeah, the sprag I've got in mind is plenty stout for the application:

Stieber ALF2D2 30-500
ALF2D2 & ALF4D2 Types | Self-Contained Freewheels | Stieber Clutch
http://www.altraliterature.com/pdfs/...A4_AL-F4D2.pdf

4100 RPM overrunning speed (which equates to ~240 MPH on this scooter)
500 Nm (369 lb ft) of torque (I think the scooter makes about 15 lb ft)
Supported by two 160 series roller bearings
About 560 Kg (1235 pounds) combined carrying capacity on the two roller bearings
Oil filled and lubricated

So it'll be pretty much bulletproof in this application. I'll be replacing the 160 series roller bearings in the sprag with hybric ceramic bearings, as well, to make it roll just that little bit easier.

[PeterS]

This may or not help, the centrifugal clutch problem is something I've been looking at lately too. There are photos on the link below.

De ligmotor
Automatic clutch has to go.
Front wheel fairing has to go.

There is no clutch lever on the handlebar, as soon as you touch the clutch pedal the clutch disengages and the next gear is selected. To prevent the engine from stalling there is a second, centrifugal, clutch that disengages if the rpm drops below 2000.
To slow the engine down and make it use less fuel I have changed the sprockets from a 14/35 to a 17/28 combination, the first gear is now almost as long as the second gear used to be. Therefore it takes a long time before the centrifugal clutch finally totally engages.
I would rather have a manual clutch and be in control myself.
I have welded the centrifugal clutch and taken out some small parts like a small brake shoe that is used to slow the crank shaft down. Then I have drilled a hole in the engine cover welded some home made parts on and connected a cable to the clutch.
It works surprisingly well, light and precise action as if it was oem. I can even hook a new clutch cable in while peeking trough the dipstick hole.

[rustygirl]

Hi Cycle,
Any updates? I have a Helix clone that could use something like this.
Thanks

[Cycle]

Hi, rustygirl.

No updates on the sprag clutch yet. I'm still looking for someone who can fabricate a custom rim with the offset necessary to hold the rim. I'm considering putting it off until I get the new trellis frame built, as it's likely that'll require a different offset anyway.

Another thing I'm considering is sort of like what the Insight does... the engine doesn't idle, it turns off. Crack the throttle a bit, and it starts up again. That'd let me do pulse-and-glide automatically. Get up to speed, shut the throttle, the sprag clutch freewheels and the engine shuts down. When I've reached the lower speed, crack the throttle, the engine starts up, rev it up until the sprag isn't freewheeling anymore, and pulse back up to the upper speed. With an IVT, it gets even better, because you can put it into a really tall gear ratio and work the engine hard (throttle nearly wide open) to get up to speed, rather than revving its lungs out.

I've got to figure out something better than the OEM starter, though.

[stiletto2]

A guy on another site is working on getting his rear wheel modified with a sprag clutch. Good for P&G but there would be no engine braking with a set up like that. Brakes on the bike would get a lot of use. OOPS! He's here too.. Sorry about that Cycle.

BTW. I've wondered about the drive pulley face (variator) of a CVT being moved in & out via a hydraulic armature that is controlled manually or optionally by electronic control.
And that makes me think why not do something similar for the clutch end of a CVT as well with electro-mechanical devices that could move the clutch shoes on or off?

[Cycle]

The problem I've got with the OEM clutch is that the clutch pads are too small, so they tend to get glazed. Then the clutch starts getting "grabby"... almost no slip, it's either on or off. That's why I've got an order in for a Dr. Pulley HiT clutch as an interim fix until I can find and fit an IVT to the bike.

[user removed]

The original Honda 50 Super Cob had both mechanical and centrifugal clutch, 55 years ago.

regards
mech

[rustygirl]

Originally Posted by stiletto2

A guy on another site is working on getting his rear wheel modified with a sprag clutch. Good for P&G but there would be no engine braking with a set up like that. Brakes on the bike would get a lot of use. OOPS! He's here too.. Sorry about that Cycle.

BTW. I've wondered about the drive pulley face (variator) of a CVT being moved in & out via a hydraulic armature that is controlled manually or optionally by electronic control.
And that makes me think why not do something similar for the clutch end of a CVT as well with electro-mechanical devices that could move the clutch shoes on or off?

Stiletto
Woods make variable speed pulleys that can be manually varied. They go from 3:1 to 1:3. Fun when you play with final drive calculations. I'm thinking about mating a set to a diesel generator engine. 1800 rpm. The sprag clutches were used in borg warner overdrive units behind 3 speed manual transmissions into the 60,s.