Function Of Hydraulic Lifting Device

(1) Function

The main use environment of the lifting device is coal dust and flammable and explosive gas in the coal mine underground or wellhead, which is its basic function. The electronic control system of the hydraulic lifting device is simple compared with the electronic control system of the electronic lifting device. The problem is easy to solve. Because the hydraulic lifting device uses the hydraulic system to achieve the lifting and lowering of the mine load and its speed control and adjustment, the motors driving the main and auxiliary oil pumps only need to rotate in one direction, unlike the electronically controlled lifting device, which has a positive motor. , Reversal requirements; the main and auxiliary oil pumps of the hydraulic lifting device are started without load, and the starting equipment can be simple; the starting sequence of the two hydraulic pumps is to start the auxiliary oil pump first, and then the main hydraulic pump, and the magnetic start of the corresponding motor can be used The auxiliary contact of the relay in the control circuit is interlocked.

The electrical control system of the hydraulic jacking device mainly uses explosion-proof or spark-type electrical equipment. Commonly used components include automatic feeder switches, squirrel cage motors, magnetic starters, solenoid valves, dry-type transformers, leak detectors, and travel switches. And electric bells, etc.

(2) Overspeed and over-rolling protection function

The hydraulic lifting device is prone to speeding of the sports car during the working process, especially in the process of lowering the load. When the speed exceeds the rated higher speed, not only the mechanical or hydraulic components such as hydraulic motors are easily damaged, but also the hidden danger of causing major accidents. Therefore, the hydraulic lifting device design stipulates that when the speed of the sports car exceeds 15% of the rated speed, the system can automatically cut off the power.

The hydraulic jacking device has two types of overspeed protection devices, mechanical and electrical. The electrical overspeed protection device consists of a tachogenerator and an overspeed breaker. The mechanical overspeed protection device generally adopts a centrifugal type.

The common mechanical centrifugal overspeed protection device is installed on the main shaft of the hydraulic lifting device. The inner gear ring 6 is connected to the main shaft, and the spindle speed is input to the overspeed protection device. The inner gear ring and the shaft gear constitute the overspeed protection device speed increasing device. After the speed is increased, the shaft gear drives the rotating body to rotate at a high speed. Under the action of centrifugal force, the centrifugal block is thrown out and pushes the ejector rod through the lever; the higher the spindle speed, the greater the distance the ejector rod is pushed. When it exceeds 15% of the rated speed, the ejector pin touches the overspeed protection travel switch, which disconnects its contact, so that the main oil pump motor is de-energized, the hydraulic brake is used for emergency braking, and the hydraulic lifting device is stopped.

The electrical overspeed protection device is composed of a tachogenerator, a speed indicator and a speed switch to realize overspeed protection. When the lifting height of the lifting container exceeds the limit position (that is, over-winding), the lifting container and indicator will open the over-winding travel switch installed on the top of the indicator, and the power-off of the travel switch will cause the hydraulic lifting device to power off and hold the brake. When starting, flip the speed switch in the reverse direction to control the reversal of the liquid flow to lower the lifting container.

(3) Low voltage protection

A low-pressure protection circuit is installed. When the pressure of the hydraulic system rises more than the normal workbench pressure (1.2-1.25) times, the high-pressure relief valve opens, and the hydraulic oil flows into the low-pressure side pipeline of the main circuit through the high-pressure valve and the one-way valve. The system pressure will not continue to rise, and the hydraulic motor will not carry heavy loads, and the lifting device will automatically stop; if the supplementary pressure of the auxiliary fuel supplement system is too low, the low-pressure protection pressure relay will act and the power supply will be cut off, and the lifting device will also automatically stop , And the signal light is on, the alarm bell sounds.

In addition, the hydraulic jacking equipment has other protection functions, such as: when the hydraulic lifting equipment fails, it cannot be started; in the event of a failure during operation, the lifting device will automatically stop halfway; during emergency braking, the signal warning light will be on to warn that the fault has occurred .

Excessive wear of the brake shoe; the load system of the reel does not decelerate at the deceleration point; the oil temperature of the hydraulic system oil tank is too high, and the oil level is too low, which will cause the main oil pump of the hydraulic lifting device to stop, the brake brake to brake emergency, and the accident signal light On, the alarm bell alarms;

In the case of emergency braking, the driver can operate the foot brake switch (ES) to make the hydraulic lifting device stop in an emergency and disconnect the control power supply. Once the rope is broken when lifting or lowering the load, the fall arresters installed on both sides of the lifting container will urgently hold the tank road to achieve a forced stop.