Difference of Horse Power & Torque in Lawn Mowers

Horsepower

• The horsepower rating of mechanical engines originally compared the abilities of steam engines to horses in pulling coal up a mineshaft. James Watt, who invented the steam engine, formulated the original standard in the 19th century. Over time, the standard definition of 1 horsepower was the power needed to lift 33,000 pounds 1 foot high in 1 minute. One mechanical horsepower came to equal 747.699 watts of electrical power. However, automobile makers and the manufacturers of lawn mowers came up with creative ways of defining horsepower make their products appear more powerful so the term had no dependable meaning. In January 2010, the EU restricted the use of the term only to supplement other ratings of engine power.

Torque

• Torque, the "rotational" or "angular" force is the amount of force is needed to make something rotate. In the United States torque is measured by foot pounds. Applied to lawn mowers, torque measures the force necessary to make a cutting blade rotate around its pivot point. The power of a lawn mower engine is its torque times the speed of its cutting blades. The listing of lawn mower torque will not give you a consistent way of comparing the power of lawn mowers because, like horsepower, the measurement is loosely understood by consumers and inconsistently applied by manufacturers.

Cubic Centimeters Displacement

• Because of the lack of standard meaning of horsepower and torque, many lawn mower manufacturers now include horsepower, torque, and the cubic centimeter (CC) displacement of the pistons in the specifications of their engines. Theoretically the higher the displacement in CCs, the more power the engine should deliver, but that does not necessarily follow. Some engines are more efficiently designed than others, so a lower number of CCs will produce the same power as a larger engine.

Type of Engine

• Lawn mowers either have 2-stroke or 4-stroke engines. In a 2-stroke engine compressed fuel explodes and fuel is inserted into the cylinder as the piston returns. A 4-stroke engine has a compression stroke and an exhaust stroke, each followed by a return stroke. You have to mix oil with gasoline with the more powerful 2-stroke engines that make more noise, and sometimes have problems meeting pollution standards. Four-stroke engines are usually less powerful, less noisy, pollute less and you do not have to mix gas with oil.