Lawn Mowers

Lawn Mowers

Lawn Mowers can have a different appearance from model to model, but they all operate in similar principles. Lawnmower makers for many years offered a choice between two-stroke and four-stroke engine types. But in recent years, the four-stroke engine has come to dominate mower sales. Apart from the engines, two-stroke and four-stroke lawnmowers work the same way, cutting grass with a blade spun at high speed by the engine. In this paper, I would like to explain how the basic 4 cycle engine lawn mower works and what kind of issues a person might face it.

Most of them have a 4 cycle engine. Similar to automobile engine, four-cycle engine run on gasoline and have a separate hole for oil. To start the engine, the handlebar must be held down while the starter robe is pulled. On most models, when the handlebar is released, a grounded circle is closed and a break pad is applied to the side wheel to start the engine. As the robe is pulled, the started engages the drive cup on the fly wheel, rotates the crankshaft (see picture #1; a mechanical part able to perform a conversion between reciprocating motion and rotational motion). The rotating crankshaft connects to the piston (pic #2; a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms; it is the moving component that is contained by a cylinder and is made gas-tight by piston rings), which moves up and down within a cylinder, then the ignition process begins.

There are some elements that allow internal combustion engines to run. They are: air, fuel, compression and spark. Air and fuel enter the small engine through the carburetor. It’s the job of the carburetor to supply a mixture of air and fuel that will allow for proper combustion. During the intake stroke, the intake valve between the carburetor and combustion chamber opens. This allows atmospheric pressure to force the air-fuel mixture into the cylinder bore as the piston moves downward. But let me explain it more specific.

The fly wheel has a permanent magnets built into it and as it rotates pass the ignition coil, then the magnetic field is created. The magnetic field induces electricity, allowing the ignition coil to send voltage to the spark plug. Meanwhile, the intake valve opens, creating a vacuum that drives fuel and air through the carburetor, where it mixes before entering the cylinder. This is a first step that is called intake stroke of the engine.

Then the compression stroke takes the action. As the piston travels back up to the top of the cylinder, the intake valve closes. Spark plug now fires and ignites compressed fuel and air mixture, which forces piston to go down creating a power stroke. The momentum of the spinning fly wheel, provides enough force to push the piston back up. The exhaust valve (pic #3; internal combustion engine) opens and the combustion gases exit through the muffler. This is called the exhaust stroke. The engine will run and continue those four cycles until it is shot off.

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