If you have used a gas engine-powered push lawn mower, you have already operated a vertical shaft engine. Due to the relative availability of old vertical shaft engines, they make an economical choice for the power source of a home made go kart. But, anyone who has built or tried to build a go kart from a lawnmower engine has faced a fundamental mechanical problem. The vertical rotation of the engine must be converted to horizontal rotation in order to turn the wheels of the go kart. This is not as simple as turning the engine on its side as carburetion techniques of almost all lawnmower engines do not allow operation in anything other than the upright position. This article will explain some ways how to use a vertical engine for go karts.
The pioneers of the outboard motor industry also had to address the problem of transferring vertical rotation to horizontal rotation. One solution to the problem of how to use a vertical engine for go karts takes a page out of outboard motor construction. In an outboard motor, the vertical engine turns a shaft that turns bevel gears attached to the shaft of the propeller. The key is use of the bevel gears – a set of gears designed to transfer rotational power to a defined angle and thus transferring vertical rotation to horizontal rotation. A go kart builder would be lucky to have at his/her disposal bevel gears salvaged from an old outboard motor to implement into the design of the go kart.
A simpler solution to the problem involves the use of a simple belt and pulley system. The go kart builder would attach pulleys to the vertical engines drive shaft and to the axle of the go kart. Then, a belt would be attached to both pulleys. Vertical rotation is transferred to horizontal rotation through a twist in the belt. Unfortunately, this method of how to use a vertical engine for go karts is not as dependable. The belt would be subject to slippage and breakage, as most belts are not intended to be twisted while in motion.
This article explained two methods of using a lawnmower engine in the construction of a go kart. There are surely several other methods of solving the vertical rotation to horizontal rotation engineering problem, but these two methods would be the most economical and practical for a home hobbyist. The use of bevel gears in go kart construction is more reliable as long as construction is precise, but construction is more complicated and expensive. The twisted belt and pulley method is easy and cheap, but not really reliable. It is up to the builder of the go kart to determine which method they would prefer to use.