Forklift Engines
Forklifts are classed as small-engine vehicles. The engines of the forklift all follow the principles of internal combustion, though the many makes and models of lift truck would have a different layout and design. Forklifts are made more toward generating high torque rather than for speed. They normally are geared to low speeds. The engine powers the drive wheels of the forklift. The engine is also needed to lift and lower the forks via a series of chain pulleys. The majority of modern forklift engines are powered by propane since they would be used indoors, where gasoline and diesel engines will be inappropriate due to the exhaust they create.

A four-cylinder engine-block is typically found in a lift truck. Much like the engine in small cars, the engines of the forklift have cylinders which contain pistons connecting to a camshaft. The head of each cylinder has an intake hatch, an exhaust hatch and a spark plug, each of them one-way and spring-loaded.

Engine Function
When the driver starts up the engine of the forklift, propane passes through the opened throttle-plate in a fine spray and mixes with air that comes from the mass air intake prior to moving into the head intake hatches of the cylinder. Each one of the four pistons is staggered to rise in an exact sequence, compressing the propane and air mixture as every piston rises to the top of the head. With very exact timing, the battery and alternator of the engine produce an electrical current that passes through the spark plug. The fuel ignites causing an explosion that drives the piston back down to the bottom of the cylinder, causing a continuous turning of the camshaft. An air pressure imbalance in the cylinder causes the exhaust to be drawn out through the exhaust hatch when more fuel passes into the cylinder. Propane burns cleaner than diesel and gasoline and the exhaust is not as harmful.