There are many kinds of forklifts that are operated by propane gas. Forklifts that use propane are very easy to refill. The gas is stored inside a pressurized tank on the back of the truck. The propane is pushed into the engine, where it is converted into vapor and the vapor combines with air. The throttle of the forklift is utilized to be able to control the vapor flow. A spark plug fires up the mixture of vapor and air creating pressure that makes the pistons move. The pistons run the hydraulic pump and turn the wheels.
Forklifts that utilize propane are suggested for use in warehouses and other buildings since they are clean burning with low emissions.
The hydraulic system of the forklift is what enables it to lift and transport really heavy stuff from place to place. Tubes, cylinders and a pump make up the hydraulic system. The pump forces dense fluid through the tubing and into the cylinders. The build up of pressure pushes a piston, which raises the forks. When the operator lowers the forks, the hydraulic fluid flows out of the cylinders and back into the pump.
Propane forklifts work well where maneuverability is needed. Not like a car, a forklift utilizes its back wheels to turn, that enables the forklift to turn fast on a tight radius.