The mechanism for lifting goods is also called the mast. It consists of inner mast, outer mast, fork frame, fork, sprocket, chain, lifting cylinder and tilting cylinder. The lower end of the outer mast is hinged on the frame, and the middle part is hinged with the inclined oil cylinder. Due to the expansion and contraction of the tilting oil cylinder, the mast can be tilted back and forth (the inclination is generally 6 ° ~ 12 °), so that the fork and fork are stable and the goods are being transported. The inner mast is provided with rollers and is embedded in the outer mast. When the inner mast rises, it can partially extend out of the outer mast. The fork rack has wheels and is embedded in the inner mast for up and down movement. The bottom of the lifting cylinder is fixed at the lower part of the outer mast, and the piston rod of the cylinder moves up and down along the lead rod on the inner mast.
The top of the piston rod is equipped with a sprocket. One end of the lifting chain is fixed on the outer mast, and the other end is connected to the fork rack by bypassing the sprocket. When the top of the piston rod is lifted with a sprocket, the chain lifts the fork and the fork rack together. At the beginning of lifting, only the fork is lifted, and the inner mast can be driven to rise after the piston rod reaches the inner mast. The inner mast's rising speed is 1/2 of the fork. The height that the fork can lift when the fork is lifted and the inner mast is not moving is called the free lift height. The general free lifting height is about 300 mm. After the fork frame is lifted to the top of the inner mast, the mast that the inner mast and the fork frame are raised at the same time is called a fully free-lift mast. Forklift sprocket wheels of more than 10 tons are mostly fixed directly on the top of the inner mast. The lifting cylinder lifts the mast from the beginning, so it cannot be lifted freely. A free-lift forklift can enter a slightly higher door opening. The fully free-lifting forklift is used in low places, and it does not cause the disadvantage that the fork cannot be raised to the prescribed height because the inner mast is roofed to the roof, so it is also suitable for operation in the cabin and container. In order to make the driver have a better field of vision, two lifting cylinders are used and arranged on both sides of the mast, which is called a wide-field mast. This type of mast gradually replaced the ordinary mast.
