Views: 0 Author: Wondee Autoparts Publish Time: 2021-10-18 Origin: Wondee Autoparts
A landing gear is an indispensable part of the semi-trailer. It is usually installed in the front of the semi-trailer, which consists of the left and right leg. Its function is to support the front end of the semi-trailer after the semi-trailer is separated from the tractor. As shown in Figure 1 below.
Common semi-trailer landing gears have two speed gears: the high and low gears. Both the high gear and low gear can be used at no load, and only the low gear can be used when under load. The lifting stroke of a semi-trailer landing gear is usually 17 inches (430mm) and 19 inches (480mm), and the mounting height is between 870mm-1000mm. The rated load is usually 24 tons, 28 tons and 32 tons, and the static load is usually 50 tons, 60 tons and 80 tons.
The following types of semi-trailer landing gears are commonly used:
1. Hand-driven landing gears
(1) It can be divided into the following two categories according to different transmission modes:
1) Single-acting landing gear(Two-side operation landing gear)
As shown in Figure 2 below. This landing gear is divided into internal gearbox legs and external gearbox legs. Both legs of this landing gear are equipped with 2 crank handles and 2 gearboxes, The left and right legs can be raised and lowered independently by the crank. This landing gear is highly adaptable and can be used on both flat and uneven roads.
(Figure 2. Single-acting landing gear / Two-side operation landing gear)
2) Linkage landing gear(One-side operation)
As shown in Figure 3 below. This landing gear has a gearbox and a crank on only one of the two legs. The leg with the gearbox and the crank is called the driving leg, the other is called the driven leg. The two legs are connected by a middle transmission rod. Rotating the crank clockwise or counterclockwise will raise or lower the 2 legs at the same speed. Compared with the single-acting landing gear, the lifting efficiency of this landing gear is doubled. This landing gear is only suitable for flat roads, otherwise it must be reliably leveled with pads before it can be used normally.
(Figure 3. Linkage landing gear / One-side operation landing gear)
It can be divided into the following two categories according to the position of the gearbox:
1) Outside-gearbox landing gear (Landing Gear with outside-gearbox)
As shown in Figure 4 below. The gearbox of a landing gear is outside of the leg, which is convenient for disassembly, repair and maintenance. There are mainly FUWA styles, JOST styles, HOLLDAND styles and other styles.
(Figure 4. Outside-gearbox landing gear / Landing Gear with outside-gearbox)
2) Inside-gearbox landing gear (Landing gear with inside-gearbox)
As shown in Figure 5 below. The gear set is installed in the square tube of a leg. It was invented by JOST.
(Figure 5. Inside-gearbox landing gear/Landing gear with inside-gearbox)
2) Short-mounting-plate landing gear, as shown in Figure 7 below.
The main components of a semi-trailer landing gear are the driving leg or the gear-side leg, the driven leg or non-gear side leg, the landing feet, the transmission rod and the crank.
The main maintenance parts are as follows:
1) Landing gear foot
There are 4 common landing gear feet, as shown in Figure 8 below.
This foot is the standard configuration of the landing gear and is the most widely used.
A-foot landing gears are usually installed on the air suspension semi-trailer to avoid bending of the legs because of abnormal working of the air suspension and height change difference in the front and the rear of the trailer while loading and unloading. As shown in Figure 9-1 and Figure 9-2 below.
(Figure 9-1. Semi trailer body displacement, and T-foot legs bending)
(Figure 9-2. A-foot landing gear for Semi trailers with no bending)
As shown in Figure 10 below. In addition to the same advantage as the A-foot landing gear, the S-foot landing gear can also work normally on a softer road, because the S-foot has a square bottom plate with a larger support area.
(Figure 10. S-foot of landing gear for Semi trailer)
R-foot landing gears are generally installed on semi-trailers that often need to be transported by ship and dropped on the deck to effectively avoid the bending and breakage of the landing gear caused by the displacement of the semi-trailer due to the shaking of the ship.
As shown in Figure 11 below. As a wearing part the crank on the landing gear is easy to lose. It is frequently purchased by customers.
According to the structure of different models in different regions, the common sizes of cranks are as follows, as shown in the table below.
As shown in Figure 12 below. The transmission rod has two types: the square tube section and the round tube section. Its length can be customized according to customer’s requirements.
(Figure 12. Landing gear transmission rod)
As shown in Figure 13 below. This mounting plate is used to install connecting rods to ensure the verticality and the overall rigidity of the landing gear in the horizontal and vertical directions.
As shown in Figure 14 and Figure 15 below. There are two main styles of mounting plates:
"L" type mounting plate for long back plate landing gears.
"W" type mounting plate for short back plate landing gears.
This type of landing gear is an innovative application of electromechanical hydraulic integration in the trailer industry, which is an upgraded product of the traditional landing gear.
This landing gear has an integrated micro hydraulic system, which drives the oil pump by a drive motor. When the oil pressure reaches the rated, the solenoid valve is turned on or off to control the flow directions of the oil, so that the two oil cylinders can be expanded or contracted individually or at the same time, that is, the legs are raised and lowered.
The landing gear has a high degree of automation. Within the effective strokes of the two cylinders, it can automatically compensate and balance the height, which is suitable for various common road conditions.
The lifting or dropping is controlled by a on/off button without manual turning the crank. The crank, the transmission rod and the transmission gearbox are omitted at the same time. The lifting efficiency is high, and the larger lifting capacity can be realized.
It is specially suitable for drop-and-pull transportation, such as in a large port, in pursuit of high efficiency, high frequency, and no manual turning cranks. The disadvantage is that the weight is heavier, the cost is very high, and the maintenance cost is higher. The current market share is low. As shown in Figure 16 below.
(Figure 16. Hydraulic landing gear )
This type of landing gear uses the compressed air from the trailer tanks as the power supply, the pressure relief valve to adjust the air pressure to the rated pressure, the solenoid valve to controls the flow direction of the air, and two internal cylinders to expand and contract individually or at the same time to lift and drop the landing gear.
Similar to hydraulic a landing gear, it omits the crank, the transmission rod and the gearbox. It has a high degree of automation. Within the effective strokes of the two cylinders, it can also realize automatic height compensation and balance, which is suitable for various common road conditions.
The lifting or dropping is controlled by a on/off button without manual turning the crank. The lifting efficiency is high, and the larger lifting capacity can be realized.
It is specially suitable for drop-and-pull transportation, such as in a large port, in pursuit of high efficiency, high frequency, and no manual turning cranks. Compared with a hydraulic landing gear, the weight is lighter, the cost is not so high, and there is no environmental pollution from oil.
(Figure 17. Pneumatic landing gear )
From: WONDEE Autoparts