What Is a Four Stroke Engine in a Lawnmower?
Gasoline engines have been incorporated into many tools and implements over the years, including for power lawn mowers. The lawn mower is taken for granted today, but its design, conception and creation have revolutionized lawn care. Does this Spark an idea?
Other People Are Reading
-
History
-
Reel-type lawn mowers date to the 1800s. Steam engines were tried at first, but failed. Gas engine-powered lawn mowers were introduced in 1919, but did not gain popularity until after World War II.
Two-cycle Mowers
-
One of the earliest commercial gas-powered mowers was produced by Ole Evinrude, whose company made two-stroke marine outboard engines.
-
Four-stroke Mowers
-
Four-stroke engines produce one power stroke for each of the four cycles of the engine. They are more efficient and produce less smoke than two-cycle engines.
Cycles
-
The cycles of a four-stroke engine are intake, compression, power and exhaust. Air/fuel is drawn into the cylinder as the piston moves down the cylinder and compressed as the piston moves back up. The ensuing explosion forces the piston down and the burned air/fuel out of the cylinder as the piston returns to the top of the cylinder.
Differences
-
The two-cycle engine has no intake or exhaust valves and produces one power stroke for each crankshaft revolution. Intake, exhaust and compression occur at the same time as the piston is moving up. They require oil to be mixed with the fuel to lubricate internal parts, and their lighter weight lends them more useful for tools such as gas-powered weed trimmers and chainsaws.
Popularity
-
While some two-stroke engines are still used on lawnmowers, the four-stroke engine is most popular because of its reliability, convenience, abundance and lower emissions. They are used in applications from simple push-type mowers to riding lawnmowers.
-
