Small gas engines have many uses around the home, mostly in lawn care products. Lawn machines that use gas engines have many benefits, but also a few drawbacks, when compared to their electrically powered counterparts. Small gas engines have significantly improved in reliability. Because of improvements in gaskets and machining accuracy, small gas engines generally have few mechanical problems.
Small gas engines provide power to gears and blowers. They are used in garden tractors, lawn mowers, tillers and snow blowers to drive wheels, providing propulsion, as well as turning blades for grass or dirt or snow. String trimmers and edgers also use gas engines to turn a drive shaft that drives a wheel of string or a cutting implement. A leaf blower uses the engine to power a fan with a high volume of air.
There are basically two types of small gas engines: two-stroke and four-stroke engines. The four-stroke engine uses four strokes of the piston. There is one piston stroke for each of the following: intake, compression, combustion and exhaust. The intake brings gasoline into the piston chamber. Compression compresses the gasoline. Combustion ignites the gasoline and powers the piston down. Exhaust drives the burnt gases out of the piston chamber. The two-stroke engine combines the intake and exhaust strokes because both the top and the bottom of the piston are utilized by the engine. Also, the compression and combustion events are combined, making for only two strokes.
Small gas engines have fuel tanks, which hold gasoline for the four-stroke engine and a gas-oil mixture for the two-stroke engine. A spark plug ignites the fuel and a control allows the user to adjust the amount of fuel going into the engine to speed it up or slow it down. Small gas engines also have air filters. The four-stroke engines have oil reservoirs to keep the piston properly lubricated.
Small gas engines provide much more power than electric models and can keep going with the simple refilling of the fuel tank while electric models require hours of recharge time for their batteries. Lawn machines powered with electric motors require long extension cords or batteries that can need recharging before the job is complete, but they do not require a check of oil levels.
A proper maintenance routine will help prevent breakdown of gas engines and the machines that they power. At a minimum, the air filter should be changed once per year. For machines used daily, they should be checked frequently and changed or cleaned when they appear to be getting clogged. Oil levels should be checked after every few uses. All mechanical links should be cleaned annually and sprayed with a lubricant.