Forklifts are classified as small-engine vehicles, the same class in which lawnmowers are classed. Forklift engines all follow the principles of internal combustion. Various forklift brand names and models would have varying engine design and layout. Forklifts are made more toward generating high torque rather than for speed. They usually are geared to low speeds. The engine runs the forklift's drive wheels. The engine is also needed to lift and lower the forks through a series of chain pulleys. The majority of modern forklift engines are fueled by propane as they would be used indoors, where gasoline and diesel engines will be unsuitable due to the exhaust they generate.
A four-cylinder engine-block is typically found in a forklift. Much like the engine in small automobiles, the engines of the forklift have cylinders which contain pistons connecting to a camshaft. The head of each and every cylinder consists of an intake hatch, an exhaust hatch and a spark plug, each of them spring-loaded and one-way.
Propane passes through the opened throttle-plate in a fine spray, once the operator starts up the forklift engine. This fine spray mixes together with air that comes from the mass air intake before moving into the cylinder's head intake hatches. Each one of the four pistons is staggered to rise in a precise sequence, that compresses the propane and air mixture as each piston rises to the top of the head. With timing that is really precise, the engine's alternator and battery produce an electrical current that passes through the spark plug. The fuel ignites leading to an explosion that drives the piston back down to the bottom of the cylinder, leading to a continuous turning of the camshaft. In the cylinder, an air pressure imbalance causes the exhaust to be drawn out through the exhaust hatch as more fuel passes into the cylinder. Propane burns much cleaner compared to diesel and gasoline and the exhaust is not as harmful.