If you read everything on this webpage you'll know what to do.
Here's what I got from there
2. Lawnmower Engines with Vertical Shafts.
This is where the fun begins!.
Now there are a few options you have. You can take the easy option, fast and fairly good, or you can go advanced. It depends on the time you want to put into the kart, Your engineering skills, Speed and acceleration. Don't worry about the mechanics yet.
The options are as follows:
1. Belt and Pulley.
2. Bevel Gears, from a shaft driven motorcycle.
3. Gearbox of a Tractor Lawnmower.
4. Differential of a car!.
Firstly Advantages and Disadvantages.
Advs: Simple to set-up. All you will need is two pulleys and a drive belt. Quick solution.
Disadvs: Loss of power through slippage. Heating up. Life of Belt very short.
Advs: Effective. No power loss. Last forever. Low maintenance.
Disadvs: Hard to set-up. Difficult to get right. Time consuming. Can be expensive if second hand parts are not available.
Advs: Very Effective. Simple. Complete with gears. Low maintenance. Easy to set-up.
Disadvs: Can be far too expensive if no scrap tractor lawnmower available.
Advs: Cheap. Effective. Little power loss. Low maintenance. Relatively available.
Disadvs: Difficult to set-up. Heavy. Awkward.
Again it depends on the materials you have or can get easily. If you can get a tractor lawnmower gearbox, then your sorted!.
The problem with lawnmower engines is that they have a vertical drive shaft, usually coming out from underneath the engine itself.
With the belt an pulley system, it's a case of mounting a small pulley wheel on the end of this vertically drive shaft, and another on the back axle (or any horizontal shaft). What happens the belt is that it actually is turned through 90 degrees, what you are hoping that the sides of the V pulley and the tension on the belt will keep the belt on!. As a result of the belt rubbing off the side of the pulley wheels, heat is produced, and as result slippage occurs. Another factor is that belt ware is a matter of hours of operation.
However specialised round pulley wheels are available that take a round belt and are used for such simpler application of changing the motion of drive by 90 degrees.
With Bevel Gears from a shaft driven motorcycle one can "Bodge" (make out of scrap) together a drive system. I made the whole thing myself. I wouldn't be too enthusiastic about the idea, but it works. I found it hard to connect up the engine shaft to the pinion shaft of the bevel gears. However if you can couple them up correctly, then your problem is solved. It's just a case of mounting a sprocket on the other bevel gear which is now horizontal with respect to the engine shaft. The only thing is, coming across this mechanism, of a friend or going out to a motorcycle scrap yard/ breaker to get it. Don't choose this method if you want a quick fix.
Gearbox of a Tractor Lawnmower. The marvellous thing about these, is that their driven shaft (input power shaft to the gearbox) is actually a vertical shaft. It's just a case of linking up a chain or a belt in a straight line linking the vertical shaft of the engine to the vertical shaft of the gearbox. And the great thing is that the drive shaft from the gearbox (output shaft) is horizontally driven. From this shaft, sprockets and a chain can be used to give power and torque.
A Differential of a Car can be easily adapted to turn the vertical rotation of the engine into horizontal rotation of the rear axle. If you are thinking of making a real off-road vehicle, then this could be the solution for you!. It is a case of implementing the differential/ entire back axle of a small car into the back axle of your kart. Turn up the differential so that the input shaft is pointing up in the air, and in line with the engine shaft.
Well these are all I have come across. If you have any more, please tell me, I'd love to experiment around with other ideas.
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