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June 15, 2021
The main beam of the removable gooseneck semi trailer carrying cargo is lower than the rear wheel, and the cargo carried has a low center of gravity, good stability and passageability, and is suitable for transporting super-high and overweight large construction machinery and mining machinery
The gooseneck semi trailer can use the lifting cylinder installed on the vehicle to support the front part of the semi trailer body on the ground. After the tractor is separated from the saddle of the semi trailer, the tractor is driven away from the semi trailer. When the tractor leaves, the front part of the semi trailer can be placed on the ground through the lifting cylinder, and the lifting cylinder can be continuously manipulated to convert the gooseneck platform into a semi trailer ladder, thereby solving the problem of the large rear part of the gooseneck lowbed trailer. Difficult loading and unloading of mechanical engineering machinery and mining machinery.
Some models of gooseneck lowbed semi trailer frame are equipped with a hydraulic motor to drive the coiling machine, which is full of chains and live wire ropes. When the construction machinery and mining machinery that it transports have a small climbing ability, the winding yard machine can be used for auxiliary traction to increase the loading speed.
After the mechanical loading and unloading is completed, manipulate the lifting cylinder to restore the gooseneck platform to a semi-trailer driving state.
(1) Principle of hydraulic system
The power source of the gooseneck hydraulic system of the removable gooseneck semi trailer is the hydraulic pump station carried by the vehicle itself. The hydraulic pump station is driven by a small gasoline engine or a diesel engine to drive a gear pump. The pressure oil output by the gear pump drives 4 lifting cylinders to control the lifting of the gooseneck platform through the lifting reversing valve, and the other is driving the hoisting motor through the winding reversing valve.
Drive the hoist to operate. The lifting reversing valve and the hoisting reversing valve are connected in parallel. In order to prevent these two valves from affecting, the neutral function of these two valves is O type. In order to ensure the simultaneous expansion and contraction of the 4 lifting cylinders, a 2-stage shunting and collecting valve is adopted. A throttle valve is installed on the oil return circuit of the elevator and the hoist motor to control the movement speed of the elevator cylinder and the speed of the hoist motor.
(2) There is a problem
After testing, we found that the hydraulic system has two defects:
One is that the neutral function of the two reversing valves is O-type, that is, when the spool is in the neutral position, the P, T, A, and B oil circuits are all cut off. When the engine is running, the gear pump is always in a high-pressure state and consumes a lot of power. It will also shorten the service life of the engine and gear pump. The second is to control the synchronous expansion and contraction of the lifting cylinder with a two-stage shunt collecting valve, which requires a high precision of the shunt collecting valve, otherwise the simultaneous expansion and contraction of the 4 lifting cylinders cannot be realized. In addition, if the semi-trailer is parked on uneven ground, and the four lifting cylinders are synchronously expanded and contracted with a two-stage diverter and collecting valve, it will not be possible to manually adjust one of the lifting cylinders, resulting in unbalanced forces on the four lifting cylinders. .
In view of the above deficiencies, we have improved the hydraulic system of the gooseneck platform, that is, the parallel oil circuit is changed to the switching oil circuit, and the 2-stage shunt is changed to the first-stage shunt. The improved hydraulic system of the gooseneck platform is shown in Figure 3.
Drawing of the hydraulic system
(1) Switch oil circuit
Through the analysis of the loading system of the semi trailer, we found that the lifting cylinder controls the lifting of the gooseneck platform before or after the loading and unloading of the machinery, and the hoist hauls the machinery during the loading and unloading of the machinery. In actual use, the elevator and hoist will not be used at the same time. For this reason, the original parallel control oil circuit of the lifting reversing valve and the hoisting reversing valve is changed to the switching control oil circuit. oil. In this way, the original two reversing valves can be changed to one reversing valve, and the neutral function will be disconnected from the original P, T, A, and B oil circuits and changed to P and T conduction. When the action control valve is in the neutral position, all the oil output from the gear pump returns to the mailbox, and the gear pump runs at no load when the engine is running.
(2) Primary shunt
Through the analysis of the lifting process of the gooseneck platform, we found that the synchronization requirements of the four lifting cylinders when the gooseneck platform is raised and lowered are not high. For this reason, the lifting cylinder switching valve is used to replace the first-stage shunt collecting valve of the original hydraulic system lifting cylinder. The neutral function of the lifting cylinder switching valve is that the P, A, B oil circuits are connected, and the T oil circuit is closed. The second-stage shunt collecting valve of the lifting cylinder of the original hydraulic system is retained, and its collecting ports are respectively connected to the A and B oil circuits of the lifting cylinder switching valve.
The lifting cylinder switching valve can switch the oil supply of the lifting cylinders on both sides, so as to realize the oil supply of the lifting cylinders in three different ways: one is to supply oil to the 4 lifting cylinders at the same time when the switching valve of the lifting cylinder is in the neutral position; the other is lifting When the spool of the cylinder switching valve is in the left position, oil is supplied to the 2 lifting cylinders on the right and the oil inlets of the 2 lifting cylinders on the left are closed; third, when the switching valve of the lifting cylinder is in the right position, oil is supplied to the 2 lifting cylinders on the left. , The oil inlets of the 2 lifting cylinders on the right side are closed.
When loading and unloading machinery and the ground is uneven, the actions of the lifting cylinders on both sides can be separately controlled to make the ladders on both sides completely contact the ground, thereby solving the problem of the four lifting cylinders being out of sync after the first-stage splitter and collecting valve is cancelled.
After the hydraulic system of the lowbed trailer gooseneck platform is improved, the service life of the engine and gear pump of the hydraulic pump station is extended, the power waste is reduced, and the working temperature of the hydraulic system is significantly reduced. The diverting accuracy of the diverting and collecting valve has been reduced. When the ground is not level, it can be adjusted manually so that the lifting cylinder of the low-level semi-trailer of the springboard completely touches the ground.
Feedback of the removable gooseneck semi trailer from customer
Heavy equipment hauling can be cumbersome and difficult. For those of you who have shipped large equipment in the past, you know how technical the process can be. That is why the removable gooseneck semi trailer was created. With an removable gooseneck semi trailer you can hold heavy equipment lower to the ground and avoid issues with height permits and constraints.
Heavy Equipment Hauling
A removable gooseneck semi trailer, also known as a double drop or lowboy, is ideal for hauling large equipment. Each country, province, and state has restrictions for height when transporting equipment. With an removable gooseneck semi trailer, because it drops in the middle, you have more height to work with and can fit larger pieces of equipment on the trailer. The drop in the middle is known as the “well”. The well usually spans about 29 feet across. When you place a piece of equipment in the well you can legally take loads up to 12 feet tall making it ideal for large equipment and oversized loads.
Ease of Use
Another benefit of the removable gooseneck semi trailer is the "removable" gooseneck. This allows the front of the trailer to detach. After the front of the gooseneck has been detached, a large piece of equipment like a tractor or excavator can be driven directly onto the trailer. After the equipment is loaded, the gooseneck is reattached and the equipment can be secured in place. This simplifies the process of loading and unloading.