[Kartbuilding] Question : Wooden Kart - Belt Drive & Idler Clutch Pulley

Stephen Burke sburke at burkesys.com
Fri May 11 17:46:36 IST 2007

Hi Joe,

You seem to be familiar with the basic setup of the wooden kart, lawnmower 
engine and belt drive. The following pages are a recap of this:

Now - adding a 3rd pulley wheel to act as a clutch (allowing the kart to 
idle) can be done afterwards. So if you are not too sure, I would 
recommend you proceed as planned and connect up the engine and rear axle 

Onto the 3rd idler pulley wheel explaination. After the above drive setup 
has been completed, a Lever (simply a steel bar with a hinge at one end, 
and a handle at the other) is mounted, with a small freely spining pulley 
wheel in the middle of this lever. The lever should be able to move up or 
down (placed between the rear axle and the engine). The idea is that the 
lever with the free spinning pulley can be moved in against the drive belt 
and moved away from the drive belt. Once the lever is in place, a larger 
V-belt is purchased (or move the engine closer to the rear axle, so the 
drive belt is loose, and the kart will not move).
Start the lawnmower engine. The kart will not move, because the v-belt is 
loose. In order to get the kart moving, the Lever is moved in against the 
V-belt. This will cause the v-belt to tension/tighten, and as a result 
grip the pulley wheel on the engine and on the rear axle, and the kart 
will move forward.
Do you get the idea?

The freely spining pulley in the middle (or at one end of the lever (and 
pivot it in the middle) can be a simple bearing which runs freely and can 
be moved in against the V-belt. Some pictures of an idler pulley can be 
seen at:

So imagine, introducing the above into the following:
so that the lever controls the tension of the drive belt.

If you are still unsure as how it works, email me back, and I'll see if I 
can draw a diagram etc.

Best of Luck,

On Thu, 10 May 2007, Joe Alisasis wrote:
> Hello
> I am planning on building a recreational go cart out of wood.  I am using a
> lawnmower engine with a belt and pulley drive system.  My question is if the
> belt is connected to the pulleys directly with tension will I still be able
> to idle or stand still while the motor is running? Do I need some sort of
> centrifugal clutch or something.  I want to keep the design as basic as
> possible.  In your schematic of the belt and pulley system for a wooden cart
> I did not see any clutches.  You did mention a third tensioner pulley but
> that may be too complicated for me.  Thanks for any help you can provide
> Joe A

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