The structural parameters and performance characteristics of the imported universal UN seals are well-suited to meet the design requirements. The UN-type seal features a Y-shaped cross-section, making it a type of lip seal. One of its key advantages is low frictional resistance—only 40% of that of a traditional “O†ring. Additionally, the initial friction during startup is independent of the parking duration or internal pressure, ensuring smooth and stable operation. These seals offer excellent stability, reliable sealing performance, and strong pressure resistance with a long service life and a wide operating pressure range. Their simple structure allows for single-turn sealing, reducing manufacturing costs, and they are easy to install without requiring special tools.
Safety precautions must be strictly followed when using these seals. They are equipped with an internal “O†ring for sealing, and the piston travel is limited. Due to the small bolt stretch compared to the designed piston stroke and structural constraints, installing a limit device is not advisable. Although such devices serve as safety protection, misoperations can lead to more severe damage. For example, at the Urumqi Locomotive Depot, a fixed tensioner was damaged and launched into the air due to a misoperation. During each stretching process, the pull body, cylinder head, and main bearing bolts are tightened until the piston reaches the bottom dead center before stretching begins.
To address these issues, several measures were taken. In October 2001, the first prototype was tested at the Hami Railway Locomotive Depot. The high-pressure hose connecting the two hydraulic cylinders was bent forward and in close contact with the crankshaft gear near the ninth main bearing, creating potential safety hazards. To resolve this, the joint position was adjusted to bend the hose backward, improving visibility but also leading to the scrapping of the main bearing tensioner. After careful analysis and incorporating feedback from on-site operators, the design was modified: the lower part of the cylinder was raised while the slot height was reduced, and the high-pressure hoses were replaced with rigid straight tubes, along with the installation of safety shields.
During testing, the four hydraulic cylinders used in the cylinder head bolt tensioner were connected in the hydraulic system. However, it was observed that the last cylinder’s piston moved downward slightly less than the other three after system unloading. Further investigation revealed that the cylinder did not return properly. To ensure synchronization among all four cylinders, reduce manual compression workload, improve efficiency, and enhance safety, the appropriate diameter for oil pipes and joints was determined through research. Measures included re-purchasing high-pressure hoses with a 6mm diameter, designing and manufacturing different-sized oil pipes under the same test conditions, conducting comparative experiments, and ultimately selecting the best-performing rigid oil pipe with a 5mm diameter.
In practical use, it was found that the lever provided for tightening nuts in the accessory set had a short service life. This was due to oil residue and sand between the nut and screw during disassembly, making the lever difficult to operate. The original material was too hard and prone to breaking, while softer materials tended to deform easily, eventually leading to the lever being scrapped on the Diesel Engine. Although the valve stem was improved, its service life remained unsatisfactory. This issue requires further attention and resolution.
Diesel generation welding machine, also known as engine welding machine, is a machine integrating the engine and the welding machine, the generator directly drives the welding machine to work by rotating the current, generally there are gasoline power, diesel and diesel power, the most commonly used, with a small power auxiliary power supply, can drive lighting and other low-power equipment. Working principle: firstly, the diesel engine drives the generator, and the electricity generated is used to provide AC power for the welding machine, and then the internal rectifier bridge is rectified into direct current, and finally the output is used as the welding power supply.
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