How Does a Lawn Mower Work?

how does a lawn mower work

There used to be a time when man depended on grazing animals and laborious simple machine to keep his pasture trimmed. It’s a different story today; science and technology have made such task less laborious with the advent of machines that are more effective.

The lawn mower is a tool most people are familiar with but how a lawn mower works is something not all can explain. It was invented by Edwin Bunning in 1830 and has since evolved into different types with almost the same function.

1. How the reel mower works

The reel mower is the most primitive mowers which consist of a cylindrical blade that spins when pushed. The spinning action of the sharpened blade trims the grass as the mower is pushed across the lawn. The driving force is the man power used in pushing which causes the cylindrical blade to move. The reel mower is still preferred by some over the newer generation mower as it makes little noise and it’s cheaper.

2. How the internal combustion engine lawn mower works

The first internal combustion engine mower became available 72 years after Bunning’s invention of the reel mower. The mower engine operates similarly as the automobile engine. The motor can be a two cycle burns the mixture of gasoline or four cycle which have a separate lubrication system. It requires air fuel and a spark to work and the imbalance of these components can make it malfunction. The principle of the engine operation is simple. The sharp blade is made to spin by the cyclical action of the piston which is connected to the crankshaft. The piston movement is caused by combustion of the fuel in the combustion chamber and is ignited by a spark plug which forces the piston down. The fuel and air pass through filter and are move to the combustion chamber through the carburetor. The fuel to air ratio can be adjusted by the choke which is common to most lawnmower engine and it help improve starting.

The lawnmower engine powers the rotatory movement of the blade; the spin is fast enough to cut grass. The blade are slightly curved, this and the enclosed space of the mower desk create a suction that lifts the grass to stand straight. The makes it easier for the blade to cut through the grass which ordinarily will bend when the blade passes through. The grass is prevented from flying in various directions by the desk. The desk is attached to four wheels and a bag is usually attached to it to collect the grass. The some mower does not collect the grass they instead return them to the ground through a particular direction.

3. How the electrical lawn mower works

The electric mower as the name implies means it is powered by electricity how this lawn mower works is what will be explained. The electrical mower was introduced in 1930 shortly after the internal combustion engine. An electrical mower can be corded which are mostly preferred by small yard owners and cordless. The electrical lawn mower is powered by an electrical motor which is able to convert electrical energy to mechanical energy to run the blade. Magnetism, electricity and motion are the driving principle in a motor engine. The motor can be powered by an alternating current (power grid or a generator) or a direct current (battery). The battery is charged electrically and the energy is stored in chemical form which is then released in form of electrical energy.

A. The corded electrical mower

The mower electrical motor uses magnetism to create motion, as a basic principle opposite side of a magnet attracts. The same side repels each other; example is the north pole of a magnet repelling the north pole on another magnet. The attracting and repelling force creates a rotational motion. The electrical engine is designed for continuous rotation and produces a torque (rotary force) that propels the external blade attached to it. The solenoid produces a controlled magnetic field when an electric current passes through it. The solenoid produces the mechanical force.

The motor maybe brushed (common to the cordless lawn mowers). The speed of the blade can be varies by adjusting the operating voltage or the strength of the magnet. Brushes have a disadvantage of wearing off and most DC powered lawn mower has been replaced by the brushless DC motors. The brushless motor is also known as the electrical commutated motor (ECM).  It can be power by a direct current or an alternating current which drive each phrase of the motor via a close loop controller. The close loop controller controls the speed and torque of the motor which invariable affects the speed of the blade.

B. the cordless electrical mower

The cordless electrical lawn mower is powered by batteries which are usually bout 1 to 4. The battery is usually rechargeable; they store energy in form of chemical energy and release it in form of electrical energy. Electrons flow from one electrode to another through the external circuit. Charged ions also flow through an electrolyte in which the two electrodes are connected which helps to balance the flow. The flow of electron produces electrical current that helps drive the motor to which the lawn mower blade is attached.

4. How the riding mower works

Still on how a lawn mower works, the next type is the riding mower. The riding mower looks like a small tractor and is preferred by large lawn owners. They come in different horse power and size. Driving a riding lawn mower is similar to driving a motor vehicle. It has it pedal which can be used to control the brake and acceleration. The steering helps the human controller to control the direction of the mowers movement. The mower blade and the wheel are powered by engine power. Most riding lawn mowers are powered by an internal combustion system which runs on fuel.

5. How the robotic mower works

The robotic mowers are another type of lawn mower recently developed. It requires little or no human input to operate. Earlier robotic lawn mower works by following Boundary wire set up by it human user. Robotic mowers are electrically powered and some are powered by solar panels which convert energy from sunlight into electrical energy. The newer generation contains a sensor such s the rain lift and touch sensor. The lift sensor stops the blade from rotating when the mower is lifted and touch sensor which helps detect obstacle.


The lawn mower has in no doubt evolved though with the same function (trim the lawn) but different mechanism. They differ in complexity, and the powering force from the archaic man power to the modern electrical and gas powered engine.

Related Resource

Self Propelled Lawn Mower Guide

Jack J. Goodwin

Hi! I am Jack J. Goodwin owner of I’m writing here lawn mower, snow blower with some different types of mower product. Keep stay with us.

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