Abstract: Hydraulic tensioning system, as an important equipment for providing constant tension in passenger ropeways, is widely used in the equipment system of passenger ropeways. This article focuses on the process of the Duobeimaya hydraulic tensioning system changing with load, and analyzes the two different tensioning modes of the Appelmayr hydraulic tensioning system. It analyzes the high-frequency shaking fault of the hydraulic cylinder in this cableway tensioning system, as well as our troubleshooting process and precautions.
Keywords: Passenger Cableway Tensioning System Form Analysis, Fault Analysis, Car Locking, Inspection Points, Force Analysis
1 Analysis of the Tensioning System Form of Passenger Cableway
The tensioning system of the carrying cable of the circular passenger ropeway mainly includes three types: heavy hammer dynamic tensioning, hydraulic clearance tensioning, and hydraulic fixed tensioning. Adopting a gap moving tensioning system, the deflection and load variation of the steel wire rope are smaller than those of fixed tensioning, and the operating environment generally does not have a large span. The use of gap tensioning for cableways of the same length allows for the selection of thinner steel wire ropes and smaller design tension for the station foundation, ensuring that investment costs can be reduced while meeting the operational requirements of the equipment. The design of the fixed tensioning system is greatly optimized compared to the old version of the clearance system, but hydraulic fixed tensioning is suitable for large-span and high-capacity cable cars. With its perfect practicality, applicability, and simplified maintenance process, it has been widely used in circulating passenger cable cars in recent years. The Jinsha Cableway belongs to an intermittent mobile tensioning system. Below is an analysis of the troubleshooting of my hydraulic cylinder shaking last year.
2 Fault analysis
High frequency jumping phenomenon of cylinder block 2, no stop signal triggered by cableway. Fault phenomenon process: Turn on the main power supply, reset the main drive system, and the hydraulic tensioning system (the hydraulic tensioning system of Jinsha Cableway is a dual cylinder system) is operating normally. When the inspection and repair vehicle is about to reach the station, it is overloaded on one side. Due to the tension exceeding+5%, the hydraulic tensioning trolley experienced high-frequency jumping when the hydraulic cylinder was depressurized. When the pressure was relieved to the starting position, the jumping state slowed down and the frequency decreased about one meter later. After the pressure was released to about 1.5 meters, the shaking phenomenon immediately returned to normal. During this period, the hydraulic system operated without any obstacles and no stop signal was triggered. After normal operation, when the carriage carrying tourists arrived at the station (one-sided heavy load), the tensioning car cylinder 2 (downward side) bounced abnormally again, and the movement trajectory was consistent with the trajectory when the one-sided heavy load departed. But when both carriages are loaded (with uniform load tension), there is no abnormality in the action of the tensioning trolley.
Fault system analysis: 1. The high-frequency jumping phenomenon of the tensioning trolley piston rod (upward heavy load downward No.2 cylinder body) can cause damage to the piston rod sealing kit, resulting in hydraulic oil leakage. At the same time, high-frequency jumping can scratch the hydraulic rod, and uneven tension can also cause great damage to the roller bearings of the tensioning trolley, posing a great hidden danger to the safety of cableway operation. Based on our observation, it is unlikely that the trajectory phenomenon of the hydraulic cylinder shaking of the tensioning trolley is caused by a fault in the entire hydraulic station body. Therefore, the suspicious points that may cause high-frequency jumping are as follows:
1. Check and measure the limit block of the fixed point of cylinder 2 to see if there are any signs of displacement, observe that the original marking line has not changed, and compare the data of the two cylinders with a caliper without any abnormalities. This is one of the causes of hydraulic rod jumping.
2. Measure the inclination of the hydraulic cylinder and compare the parameters of whether two parallel cylinder bodies are in the same (5 degrees) horizontal position. If there is inconsistency in the inclination angle, it will cause cylinder body jumping due to uneven force.
3. Compare the data of the running position of the hydraulic tensioning trolley on the upper bridge, measure the distance between the four fixed points of the trolley and the bridge at fixed points, and check whether the deflection of the trolley before and after meets the requirements. Also, check whether the left, front, and right parameters of the trolley are consistent, as these four parameters directly affect the trajectory of the trolley.
4. Check if the metal support track fixed wheel and walking wheel are on the centerline or if there are signs of bearing jamming, causing uneven force distribution and resulting in cylinder jumping when the car is dragged and walking.
If the above inspection results are all normal, it may be due to the blockage of the load protection valve, uneven oil intake on both sides, causing asynchronous oil intake and causing cylinder block jumping. When we connect the 0-600har pressure gauge to the M connection of the two hydraulic cylinder block load holding valves and run the system, if there is no change in pressure, it indicates that the hydraulic cylinder block load holding valves are functioning properly.
3 Actual troubleshooting and locking of tensioning trolley
After the above fault analysis and reasoning, we carried out troubleshooting according to the established plan the next night. When the above steps gradually checked the inclination of the car cylinder, the inspectors found that the entire tensioning car was offset towards cylinder 1, and the piston rod was tightly attached to the fixed hole of the bridge, and two scratches were scraped off the bridge. The reason is that the gap between the horizontal balance walking wheel and the guide rail of the fixed trolley under the trolley is unreasonable, resulting in a large difference in the walking resistance of the trolley. When overloaded on one side, it causes the tensioned trolley to tilt, and under load? Due to uneven force distribution between the two cylinders, the second cylinder body experiences greater force than the first cylinder, causing high-frequency jumping of the second rod. When the extension length reaches a certain value, the forces on both sides are balanced, and the car automatically adjusts under tension, and the vibration disappears.
Troubleshooting:
Remove the fixed U-shaped ring of the tensioning trolley and measure the cylinder angle (five degrees). Use two hydraulic jacks to move the hydraulic tensioning trolley to the center position and lock it. After comparing the quantified data of the four corners to normal. Use a jack to press down on the small car.
Figure 1
Figure 2
(Use tools to support all four points to prevent the tensioning trolley from suddenly moving and leaving operational hazards when dismantling the fixed wheels.) Remove the supporting fixed wheels under the trolley one by one, and lock the wheel body after contacting the walking track of the beam trolley. Before locking the fixed module, use a U-shaped fixing plate to lock the fixing screw (as shown in Figure 2) to prevent the car from shifting. Adjust and lock them one by one. After the adjustment is completed, is the jack ready? Relieve pressure, rotate the cableway forward and backward for a few minutes, repeat the forward and backward movement of the car, retest the position of the car again, and after it is normal, fix the cylinder body with a U-shaped ring and install it. Use a level to measure the angle, and the inclination angle of the two cylinder bodies at the same parallel measurement point must be consistent. To avoid uneven force caused by inconsistent angles. Causing unnecessary malfunctions. Mark each point properly and strengthen visual management in the later stage.
4 Key inspection points and suggestions for later maintenance
The phenomenon caused by the hydraulic tensioning system this time, although did not cause a hydraulic failure shutdown, is a hydraulic system hazard that needs to be highly valued. Although it cannot highlight the essence of the fault in the short term, it will cause a major safety accident at a special time point. Therefore, the maintenance of passenger ropeways not only needs to be carried out in real-time according to the requirements of technical specifications and operation manuals, but also based on the abnormal phenomena in various parts of the equipment under different working conditions, static, dynamic, and different loads. Promptly eliminate safety hazards and close the big picture. For the equipment hazards we have eliminated this time, I personally think there are several points that need to be noted. Firstly, we need to incorporate the measurement of the position of the hydraulic tensioning system's small car into our regular quantitative data detection system, and include it in our semi annual inspection project to timely review the parameters of the small car; Secondly, when we carry out hydraulic cylinder displacement, after completing the displacement process, we need to add the important content of measuring the position of the trolley to avoid safety hazards from happening again. Finally, for me, as a special equipment among the eight major categories of special equipment in our country, passenger ropeways still need to improve our concept of safe operation. We need to constantly strengthen our professional ethics learning. For the safety operation of passenger ropeways, I have always believed that "responsibility is greater than ability". Only with a high sense of corporate responsibility, a high degree of ownership spirit, and a high degree of professional ethics can we deeply instill safety in people's hearts and protect the enterprise.
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2024-11-12