The high-pressure hose connecting the two hydraulic cylinders is bent forward and closely follows the crankshaft gear near the ninth main bearing. This setup poses safety risks, such as the potential for the joint to shift, causing the hose to bend backward and obstructing the operator's line of sight. As a result, the main bearing tensioner was ultimately scrapped. After a thorough review and considering feedback from on-site operators, the design was modified. The lower part of the cylinder was raised, while the height of the cap hole was reduced. The high-pressure hose was replaced with a rigid straight tube and equipped with a safety shield to improve both safety and visibility during operation.
In the initial design of the cylinder head Bolt tensioner prototype, the four hydraulic cylinders were connected in the hydraulic system. During testing, it was observed that the piston of the last cylinder moved downward more than the others after the system was unloaded, indicating poor return performance. To ensure synchronization among all four cylinders and reduce manual effort, the downward movement of the piston was increased. This improved work efficiency and made the process safer. Additionally, the appropriate diameter of the oil pipe and its fittings were carefully selected. High-pressure hoses were re-purchased under the same test conditions, and different diameters of rigid oil pipes were designed, manufactured, and tested in sequence. Comparative experiments were conducted to evaluate the results, and the best-performing rigid oil pipe was selected.
During field use, it was found that the lever provided for tightening the nuts had a short service life. This was due to oil residue and sand accumulating between the Nut and the bolt during disassembly, making the lever difficult to operate. The original material was too hard, leading to breakage, while a softer material caused deformation. Eventually, the lever failed and had to be discarded. Although the valve stem was later improved, the service life remained unsatisfactory. This issue still needs to be addressed to ensure long-term reliability and user satisfaction.
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