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Point and Squirt Toy.. Feasible?
scootz - 28/8/12 at 06:36 PM

My tiny brain was wandering today whilst thinking about simple drivetrains and I started to wonder what an engine connected straight to a diff via a centrifugal-clutch would be like to drive.

I was thinking of a 250kg vehicle and a 9500rpm engine peaking at 130bhp at 6500rpm.

I started fiddling about with a diff ratio calculator and came up with what I thought looked like a reasonable set of figures for a point-and-squirt sunday toy (the calculator only ran to 8000rpm)...






Any thoughts on how such a machine would drive, and how quickly it would accelerate?

Confused but excited. - 28/8/12 at 07:40 PM

130BHP in a 250Kg vehicle? Scootz, squirt is definately the correct verb!

scootz - 28/8/12 at 07:45 PM



No doubt it would be very 'on/off'.

Been having a look and there seems to be some centrifugal clutches out there that can handle 130-ish bhp and can be set-up to engage around 1000rpm (used in motorbike engined small planes).

clairetoo - 28/8/12 at 07:57 PM

Have a look at drag racing `slider' clutches - 1000 plus horsepower , and 0 - 330 in 4.6 seconds.........
Top fuel cars also use a single speed / slider clutch setup - and they run over 6000 HP..........

adithorp - 28/8/12 at 08:15 PM

I'd expect it'd be a bit over-geared off the line unless you had big torque.

scootz - 28/8/12 at 08:21 PM

Getting going might be where a 'normal' clutch would come in handy... high revs and dump it.

AdrianH - 28/8/12 at 09:29 PM

How about the old DAF variomatic drive?

Adrian

adithorp - 28/8/12 at 10:23 PM

quote:
Originally posted by AdrianH
How about the old DAF variomatic drive?

Adrian


Took some doing to drive hard. If you put your foot down hard it just changed down the ratio and went nowhere. The trick was wind it up slow and then NEVER lift off the throttle.

The Volvo 340 vario clutch and bell-housing might be worth a look though. The vario "box was at the back with just the bell-housing with an out-put shaft on the back of the engine and the prop (light weight ally job) running at engine revs. Was on a Renault engine and wouldn't surprise me if the bolt pattern is similar to their later engines.

alistairolsen - 27/9/12 at 09:23 PM

Look at some of the high capacity non geared karts for an idea! Generally slowish off the line trying to pull a long gear, good in the midrange and very buzzy up top