JPH09220964A - Load receiving platform lifting device for motor truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the difference between the top surface of a load receiving platform and the ground and to improve work efficiency, by providing a balance cylinder between a lifting cylinder and a tilt cylinder and by automatically operating the lifting cylinder and the tilt cylinder to thereby lower the tip of the load receiving platform. SOLUTION: If a solenoid valve 52 is opened by an electric signal by the moving down operation of a load receiving platform 10, a lifting cylinder 24 is contracted by self weight of the load receiving platform 10 to return oil to an oil tank 30. If a signal continues to be sent in a state where the load receiving platform 10 is in contact with the ground, the pressure of a lifting circuit is decreased to imbalance the lowering side, thereby discharging oil of the balance cylinder 28, whereby a piston of the balance cylinder 28 is moved to a lowering side to lower a tilt cylinder 26 so as to fix the volume of a tilt side circuit and to turn the tip of the load receiving platform 10 to the ground, which eliminates the difference between the top surface of the load receiving platform and the ground and improves work efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on the rear part of a truck such as a truck or a trailer and moves the cargo up and down to raise and lower the cargo tray of the truck for facilitating cargo handling work. It relates to the device.

[0002]

2. Description of the Related Art The above-described lifting device for a receiving tray is commonly called a tailgate or a liftgate and has been widely used since it is convenient for cargo handling. An elevating cylinder for vertically moving the platform up and down substantially on the same plane as the floor surface of the freight vehicle using a link mechanism, a tilt cylinder for rotating the cargo receiving table to a position substantially vertical to the floor surface, and these cylinders. It is equipped with a hydraulic unit such as an oil tank to be operated, a hydraulic motor, a hydraulic pump, and the like.

[0003]

For example, in order to load a heavy truck on a freight vehicle equipped with the above-described load receiving platform lifting device,
When the wheels of the trolley are placed on the upper surface of the load receiving platform of the load receiving platform lifting device by rotating from the ground, it is desirable that the end of the load receiving platform is as close to the ground as possible, so as shown in FIG. Although the cross section of the edge of the loading tray has a sharp angle, to move this loading tray, a lifting cylinder that moves up and down,
It is composed of a tilt cylinder that is rotated to a vertical position, and the descending circuit and the tilt circuit are independent of each other, and the solenoid valves are electrically operated to discharge the oil from the cylinder. Therefore, (1) the lifting cylinder is lowered. To ground the load carrier to the ground, and (2) then actuate the tilt cylinder to drain the oil and lower the end of the load carrier, thus actuating the tilt cylinder again. Moreover, delicate adjustments were required and work efficiency was very poor.

An object of the present invention is to automatically raise or lower the electric signal transmitted to a solenoid valve of a hydraulic cylinder which is operated when a load such as a heavy truck is placed on a cargo carrier of a freight vehicle. The purpose of this is to improve the working efficiency significantly by operating the cylinder and the tilt cylinder to lower the end of the load receiving table to eliminate the step between the upper surface of the load receiving table and the ground.

[0005]

In order to achieve the above-mentioned object, an elevator cylinder for vertically moving a cargo receiving table to substantially the same plane as a floor surface of a freight car by using a link mechanism, and the cargo receiving table are provided on the floor. A tilt cylinder that rotates to a position substantially vertical to the plane and a hydraulic unit that operates these cylinders, such as an oil tank, a hydraulic motor, and a hydraulic motor, are provided, and between the lifting cylinder and the tilt cylinder. By using the pressure difference between the lifting circuit and the tilt circuit by piping the balance cylinder, when the lifting cylinder is actuated to vertically lower the cradle and ground it to the ground, the tilt cylinder is automatically tilted. There is provided an apparatus for raising and lowering a cargo tray of a freight vehicle, wherein the cylinder is tilted until the tip of the cargo tray is grounded.

[0006]

1 is a hydraulic circuit diagram for operating a cargo carrier of a freight vehicle according to the present invention, and FIG. 2 is a cargo carrier of a conventional freight vehicle. FIG. 3 shows an elevating device, and FIG. 3 shows a state in which the rear end edge of the load receiving base is grounded and the wheels of the dolly are rotated and placed.

As shown in FIG. 2, an ordinary cargo carrier lifting / lowering device is used for a cargo carrier 10, a rear part of the cargo carrier 10, two upper and lower pivot portions 12, 14 and a floor of the cargo car. Also, pivot parts 16, 18 are provided at two upper and lower positions of the lower part of the part, and a first arm member 20 for rotatably connecting the pivot parts 12, 16 and the pivot parts 14, 18 are rotatably provided. A parallelogram link mechanism is formed by the connecting second arm member 22, and the link cylinder is used to raise and lower the cylinder 24 for raising and lowering the same to the substantially same level as the floor surface of the truck. The tilt cylinder 26 is configured to rotate to a position substantially vertical to the floor surface.

As shown in FIG. 3, in order to load a heavy trolley on a freight vehicle equipped with the above-mentioned cargo cradle lifting device, the wheels of the trolley 48 are mounted on the upper surface of the cargo cradle 10 by rotating from the ground. At this time, since it is desirable that the end portion of the load receiving tray 10 has as little step as possible from the ground, the cross section of the edge has a sharp angle. However, in order to move the load receiving tray, the lifting cylinder 24 that moves up and down and the vertical position. The tilt cylinder 26 that is rotated to the right and the parallelogram link mechanism are only included. The lifting circuit and the tilt circuit of the cargo receiving stand 10 described above are independently operated and the solenoid valves are electrically operated to operate the oil from the cylinder. However, the above problem occurred.

The present invention aims to solve the above problems by disposing a balance cylinder 28 between the elevating cylinder 24 and the tilt cylinder 26 as shown in FIG. 1, but the details will be described. Then, the oil tank 30, the hydraulic motor 32, and the hydraulic pump 3 which are normal hydraulic units.
4, a pressure adjusting valve 36 is provided, a suction filter 38 is installed in the pump 34, and a check valve 4 is installed in the piping between the pump 34 and the three-way solenoid valve 40.
2 is provided, and a descending solenoid valve 44 and a flow control valve 46 are provided in a pipe branched from the pipe between the three-way solenoid valve 40 and the check valve 42 to communicate with the oil tank 30. A flow control valve 50 is provided in the pipe between the 40 and the two lifting cylinders 24, 24.
A drop-prevention solenoid valve 52 is provided in the pipe between 0 and one of the lifting cylinders 24, and a sudden drop prevention solenoid valve 5 is provided in the pipe between the other lifting cylinder 24.
4 is provided to communicate between the pipe between the three-way solenoid valve 40 and the two tilt cylinders 26, 26 and the pipe between the three-way solenoid valve 40 and the two lifting cylinders 24, 24. The balance cylinder 28 according to the present invention is provided in the pipe to be connected, the fall prevention solenoid valve 52 is provided in the pipe between the balance cylinder 28 and one tilt cylinder 26, and the pipe between the balance cylinder 28 and the tilt cylinder 26 is provided. A sudden drop prevention solenoid valve 54 is provided in the pipe.

With the above-described structure, (1) When the solenoid valve 52 is opened by an electric signal from the position of the cargo receiving table 10 in FIG. 2 by the descending operation, the lifting cylinders 24, 24 are compressed by the weight of the cargo receiving table 10 to compress the oil. Return to the oil tank 30,
(2) If a signal is continuously sent from the state where the load receiving base 10 is grounded to the position shown by the chain double-dashed line in FIG. 3, the pressure in the lifting circuit decreases and the balance on the lifting side is lost, and the balance cylinder 2
The oil of No. 8 is discharged, and the piston of the balance cylinder 28 moves up and down to keep the volume of the tilt side circuit constant, and the tilt cylinder 26 descends and rotates until the tip of the load receiving base 10 lands.

[0011]

As described above, according to the present invention, by arranging the balance cylinder between the elevating cylinder and the tilt cylinder, a solenoid of a hydraulic cylinder that operates when a load such as a heavy truck is placed on a cargo carrier of a truck. The electric signal sent to the valve is made into one, and the lifting cylinder and the tilt cylinder are automatically operated to lower the end of the load carrier to eliminate the step between the upper surface of the load carrier and the ground, thus improving work efficiency. Can be greatly improved.

[Brief description of drawings]

FIG. 1 shows a hydraulic circuit diagram for operating a cargo carrier of a lorry according to the present invention.

FIG. 2 shows a loading platform lifting device for a conventional truck.

FIG. 3 shows a state in which the rear end edge of the load receiving platform is grounded and the wheels of the truck are rotated and placed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Load receiving table 12 Axis part 14 Axis part 16 Axis part 18 Axis part 20 First arm member 22 Second arm member 24 Lifting cylinder 26 Tilt cylinder 28 Balance cylinder 30 Oil tank 32 Hydraulic motor 34 Hydraulic pump 36 Pressure adjustment Valve 38 Suction filter 40 Three-way solenoid valve 42 Check valve 44 Solenoid valve for lowering 46 Flow control valve 48 Bogie 50 Flow control valve 52 Fall prevention solenoid valve 54 Rapid fall prevention solenoid valve

Claims (1)

[Claims] 1. A loading tray, a lifting cylinder for vertically moving the loading tray up and down on a plane substantially flush with a floor surface of a freight vehicle using a link mechanism, and the loading platform at a position substantially vertical to the floor surface. A tilt cylinder for rotating, an oil tank for operating these cylinders, a hydraulic unit such as a hydraulic motor, a hydraulic pump, and the like are provided, and a balance cylinder is piped between the lifting cylinder and the tilt cylinder.
By utilizing the pressure difference between the lifting circuit and the tilt circuit, when the lifting cylinder is actuated to vertically lower the landing table and ground it to the ground, the tilt cylinder automatically operates and the loading platform is operated. The cradle lifting device for a freight vehicle, which is tilted until the tip of the ground touches the ground.