How do rotary lawn-mowers work?

By: Contributors

Rotary mowers are based on the use of a small but powerful engine that provides enough energy to spin a very sharp horizontal blade, which is what cuts the grass upon contact. The blade is located in a deck that prevents grass from flying all over the place when struck. In most cases, the motor is situated on top of the deck, which is usually mounted on four wheels. There's also a bag connected to the deck that is used to collect cut grass.

As far as power goes, the majority of rotary lawn mowers use an internal combustion engine. These rotary lawn mowers either use two-cycle or four-cycle motors. Rotary lawn mowers that are powered electrically, however, are run by solar power, a rechargeable battery or electricity (connected through a long cord). The motor is connected to a throttle, which tends to be located on the handlebar.


The large blade that does the cutting will usually spin at a speed of 3,000 rpms. While all rotary lawn mower blades are made of steel, some are straight while others are curved. Some blades are designed to slice up the grass into small pieces that can then be used as mulch. There are 2-in-1 lawn mowers that give you the option of either bagging or mulching. The 3-in-1 lawn mower allows you to bag the grass, mulch it or discharge the clippings. Mowers that are self-propelled have motors that move a drive shaft, which is either connected to a chain or a belt. The mower's wheels begin spinning once a gearbox -- connected to an axle - begins to rotate.