Semi-trailer landing gears are commonly known as landing gear. They are divided into left and right. As an indispensable part of semi-trailers, the commonly used landing gear generally have a travel route of about 45 cm, a closing height of about 90 cm, a rated load of 28 tons, and a static load of 40 tons. They all support the semi-trailer after the semi-trailer is separated from the tractor head, but the styles are different.
Single-acting landing gear
There is a gear box on each side of this type of landing gear, which is divided into internal and external. Through two cranks, it can be lifted and lowered independently. There are two gears, high and low speed. Generally, both high and low speed gears can be used without load. Low-speed gear must be used for loading. This type is the most basic traditional landing gear, which is highly adaptable and can be used on flat and uneven ground.
Linkage type landing gear
This type of landing gear has only one gear box. Through a crank, the left and right landing gears can be raised and lowered at the same time. It is also divided into two gears, high and low speed. It is an upgraded version of the most basic traditional landing gear, which is relatively single-acting landing gear. , The lifting efficiency has been doubled, but this kind of landing gear is only suitable for flat roads. On uneven roads, the support surface must be kept basically level by the cushion block before it can be used.
Aluminum alloy landing gears
This type of landing gear is a product that should be lightweight, with a dead weight of about 30-40KG, and most of it is single-acting. Its function is basically the same as that of single-acting landing gears, but many old drivers report that its use effect is not very ideal. It supports when fully loaded. Insufficient force, easy to damage, suitable for models that do not often take off the hook, the main highlight is only nearly half the weight of the traditional landing gears.
Hydraulic landing gear
This type of landing gear is an upgraded replacement product of the traditional landing gear, and it is also an innovative application of mechatronics in the trailer industry. This landing gear as a whole can be said to be an integrated micro hydraulic system. The oil pump is driven by the on-board power supply to drive the motor. After the rated pressure, the solenoid valve is turned on and off to control the direction of the oil circuit, so that the oil cylinder can expand and contract individually or at the same time, that is, the lifting of the landing gear.
This landing gear has a high degree of automation. Within the effective stroke of the oil cylinder, the landing gear can be automatically balanced, which is suitable for various road conditions. Tonnage supporting force, suitable for high-efficiency drop-and-pull transportation, but the weight is heavier, and the cost is about 5 times that of ordinary landing gears. In addition, there are currently fewer maintenance points and higher maintenance costs in the later period, resulting in fewer applications in the current market.
Pneumatic landing gear
This type of landing gear is adjusted to the rated air pressure by the automatic pressure relief valve through the pressure generated in the on-board gas cylinder. The pneumatic solenoid valve is turned on and off to control the direction of the gas path, and the cylinder hidden in the landing gear is controlled to expand and contract individually or at the same time, Which realizes the lifting of the landing gears.
This landing gear is similar to the hydraulic landing gear, without the crank handle and gear transmission mechanism, and has a high degree of automation. Within the effective stroke of the cylinder, the landing gear can also achieve automatic balance. It is suitable for various road conditions and only needs to be lifted by an electric switch. Operation, no traditional crank, high lifting efficiency, and also suitable for efficient drop-and-hook transportation. Compared with hydraulic landing gears, the dead weight is lighter, and there is no need to worry about oil leakage. At present, there are still fewer maintenance points, which are the same as hydraulic landing gears. same question.
Pneumatic hydraulic combined landing gear
This kind of landing gear is based on the principle of the above hydraulic and pneumatic landing gears. By using the high speed of the pneumatic landing gear when no-load and the stability of the hydraulic landing gear when lifting weights, the two are perfectly combined, and the lifting efficiency is improved during operation. Will be higher. However, before mass production is popularized, if the technology is not mature and the structure is more complex, the probability of failure will increase.