Manual Clutch for Horizontal Shaft Motor

[John Matthews]

Your most likely market for this would be minibike drag racers, Shane at AGK can point you in the right direction.

I'd be interested in testing one on my dyno though. Do you know how much power it'll take? Also how much would it cost the racer and does it take the standard Bully type drivers?

As for Kers for karts if anyone can design and build it for $400 they'll win the lifetime achievement award in my book, almost like me racing with extra weight

Cheers,
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John Matthews
Heartbeat Power, LLC.

[Nathan Adair]

[Danny Downs]

[Brian Degulis]

My thoughts You don't run at 4500 RPM but when you take your foot off the gas entering a turn your TAG clutch dis engages. When you accelerate out of the turn the cluctch engages slowly. If it really locked up at 4500 then you would have very slow acceleration like you would in a shifter if you didn't drop gears. I think it would be very difficult to control the rate of engagement with a manual clutch. I'm no expert just my thoughts.


Brian

[Danny Downs]

[Jeff DeMello]

They race sprint tracks
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Jeff DeMello
Emmick F125 Pavesi

[Russell Stevens]

If you take your foot off of the gas, and the clutch isn't locked up... your engine would quickly drop to idle. The lock or partial lock of the clutch causes the engine to be driven by the wheels and maintain it's RPM relative to your ground speed. Exiting a turn at 4500RPM on my rotax is a slow climb till I hit about 6000RPM. This is a regular occurance when you take the 180 hairpin at our track slightly wrong. If you are getting a ton of drive at 4500RPM in a tag you either have a clutch that is slipping a lot at that RPM, or some crazy gearing. A centrifical clutch engages based on RPM, once engaged it doesn't care which side the rotational power is coming from. It will stay engaged until the rotational speed drops below it's lock threshhold. Model helicopters use the same type of clutch that the TAGS use (smaller scale) and have a one way bearing in the clutch. This is required to let the rotor "freewheel" for autorotation landings. If you don't have a one way bearing in the clutch the rotor blades slow down extremely rapidly when the motor flames out. This is because the clutch is locked till the RPM drops. I don't see a one way bearing listed for the Leopard or the Rotax. Try this experiment - Head down a long straight at about 10kRPM. Kill the ignition. Does the engine go silent or does it pop and try to turn over till your ground speed is slow enough to let the clutch dissengage?
Rusty

[Nathan Adair]

[Danny Downs]

[Paul Makarucha]

[Nathan Adair]

I've only had the engine completely die under serious panic-braking-style spin-inducing lockup. Otherwise it's never been more than a quick cut out under normal hard braking, and I usually try to keep the rears right on the edge of being talkative.

[Jim McMahon]

[Russell Stevens]

Danny,
I don't know your experience level with mechanics or karting. Please don't assume to educate me on mechanics 101. Try to follow along. Or read the "Cliff Notes" version that is posted just above this wall of text

1) When the RPM has reached the lock threshold for the clutch the axle and engine are locked together and will turn together at the ratio that is set by the gearing.
2) The only way to unlock the clutch is by dropping the speed of the engine below the lock threshold. Now unless the engine is seized, has a high enough compression ratio to cause slippage somewhere else in the system, the tires lock and slide, or the clutch slips and isn't really locked up this will only happen once the axle and engine have slowed enough to equate to an engine speed lower then the cluch lockup speed. Please refer to point one if this is confusing you. (hint: they are locked togetther by the clutch because the system is spinning above the lockup RPM)
3) Anyone who has driven a kart and locked up the brakes by accident and killed the engine will tell you that it either re-fires, or skids the tires and the clutch unlocks because the engine RPM fell below the threshold. At 10000 RPM if you shut the ignition off and turn it back on it will either re-fire or skid the tires. Either way the point that simply letting off of the throttle DOES NOT unlock the clutch is proven correct.

To your last point. you are correct. If the engine speed is not high enough to initially lock the clutch, the axle and engine are not coupled, and will turn (relatively) independent of each-other. However, this conversation is about what happend once the clutch drive section has been spun fast enough to force the friction surfaces to swing out and interface with the driven surface. Again once this happens it does not matter if the power is coming from the drive surface or the driven surface, and untill the RPM is low enough to allow the drive fingers to retract the two will remain coupled.

If you wish to go into this on a 201 or 301 level I'd be glad to explain the physics behind it for you.

Thanks
Rusty

[/quote]

It's impossible. With a centrifugal it will not start the motor. This is simple Mechanics 101. As soon as you let off the gas, the engine wants to return to idle and it will not couple to the motor. Same reason you can't start a kart by rolling down a hill. Even if you were already started then killed the motor it wont bump start the kart.[/quote]

[Danny Downs]

We are arguing the same point. I hold a degree in engineering so I am definitely well versed on the topic.

It's all about engine RPM and stall speed of the clutch. Once the engine RPM falls below stall speed, that's it you're decoupled. There may be a little slippage in the system but in a perfect world once you let off the gas it doesn't matter how fast you're going, the crank will decouple from the rear drive. Obviously if you skid and allow the motor to temporarily die, it's momentum will allow it to fire back up if the engine RPM was high enough.

We are arguing the exact same point! I like this kind of stuff, since when did internet forums get so technical!

[Russell Stevens]

My appologies sir. I took when you said the kart would not refire and that the clutch would decouple the instant the engine stopped running to indicate a disbelief in the principals of centripetal force. I can see from your most rescent post that this is only a partially correct understanding on my part.
Let me ask you something, one egg head to another. If you cut the ignition on the engine with the clutch in a coupled state, and you have an appropriate amount of inertia built up (in the form of the kart moving down the track), how is it that the driving portion of the clutch (the part with the fingers that is hooked to the output shaft of the engine) slows instantly past it's stall speed when it is being driven by the clutch bell that it is coupled to? If the clutch assembly is coupled and turning above stall speed what causes the centripetal forces that are keeping the fingers pushed against the clutch bell to simply vanish? My understanding was that the engine does not directly force these out into the bell, and that it was simply the rotational forces keeping them engaged. If this is the case, and again slippage in the system is not causing the driving portion of the clutch to loose RPM past the stall point, what forces are pulling the fingers away from the bell and causing the clutch to instantly disengage when the throttle is cut, or the ignition shut off at speed?

I understand what you are saying about RPM and stall speed, and think that you may be assuming that zero throttle <=> zero crank speed. This would be the only case where what you are saying makes sense. Throttle position has little to do with the actual crank speed when the crank is driven though an outside force (like an axle and a locked clutch).
Rusty