how do lawn mowers work?

For the typical mower (which you push yourself) there is a small combustion engine, sort of similar to a car engine (you put fuel in, the fuel goes into the cylinders, the fuel ignites, and it pushes a piston which makes a shaft turn). Underneath the mower there is a rotating blade (imagine a typical ceiling fan. It looks like that, but it's stronger). The spinning shaft from the engine spins the fan blade, and the sharp blades cut the lawn. There's usually a knob on the side which adjusts the height of the mower, and the height of the mower determines how short the grass is cut.

To start the mower, you pull the cord, and then you adjust the throttle (the throttle allows air and fuel into the cylinder, so when you open the throttle, a small valve lets in more air and fuel so the combustion is harder, so the piston is pushed faster). In case you didn't know, combustion is basically a small controlled explosion inside the piston, and the gases which are released when the fuel ignites is what pushes the piston.

Some mowers are self accelerating, and have an accelerator you push which drives them along which you hold on and steer. Then, there's the ride on mowers, which is basically a very small car with a blade underneath. And finally, electric mowers, which are the same, but instead of running on fuel and using a combustion engine, they use an electric motor.

Hopefully that's enough information!

There are two types, rotary and reel. Rotary have the blade attached directly to the engine crank shaft which is mounted with the axis of rotation vertical. Reel type have a set of blades mounted on an open drum and the axis of rotation is horizontal. Either can be driven by electric of gas engines. Reel type are normally used for very fine cutting close to the ground as they give a cleaner cut.

go to gumtree , Bayswater Lawn Mowing Service could help.

They work quite well. You may wish to visit http://www.howstuffworks.com/ and enter your question there.