The bolt securing the crosshead pin of the reciprocating machine has broken!
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One of the two-stage, double-row, four-cylinder reciprocating compressors in our factory began to experience excessive vibration recently. Upon inspection, it was found that the bolt securing the crosshead pin in the second stage cylinder was broken, the stop block was severely worn, and the crosshead pin as well as the copper bushing were also somewhat worn. It can now be confirmed that the bolts were tightened during installation, and the locking plates are also properly secured. Please have the experienced colleagues analyze this. What else should be noted during the next installation?
I’ve encountered this situation elsewhere; the reason is likely that the crosshead pin moved axially by a significant amount, which caused the baffle bolts to break. It seems that your baffle bolts are no longer functional; it’s time to replace them. Another issue is that the clearance between the small-head copper sleeve and the crosshead pin is too large. An improvement here is to make a hole in the crosshead pin and insert a bolt through it, thereby tightening both ends and restricting its axial movement.
1. Excessive wear of the connecting rod bearings, along with vibrations, causes the bolts to loosen, leading to fracture； 2. Excessive tightening of the bolts during fastening has caused cracks ； 3. Excessive or insufficient wear of the connecting rod journal bearings leads to bolt fracture.
As an addition for the second floor, replace the connecting bolts with high-strength bolts, or modify the crosshead pin structure by lengthening the smaller end of the pin and then adding an external thread to it; a large nut can be used along with a split pin, and this approach yields good results.
4# zhangtian*: It will definitely work if tightened with nuts, but such large nuts are inconvenient to install. Additionally, there won’t be enough space to fit the weight blocks outside the crosshead pin – how can this issue be resolved?
The reasons for the looseness are likely threefold: damage to the pin, screw, or the threads at the bottom of the pin hole, as well as an overly loose fit between these components; please check carefully.
I’ve encountered this situation elsewhere; the reason is likely that the crosshead pin moved axially by a significant amount, which caused the baffle bolts to break. It seems that your baffle bolts are no longer functional; it’s time to replace them. Another issue is that the clearance between the small-head copper sleeve and the crosshead pin is too large. An improvement here is to make a hole in the crosshead pin and insert a bolt through it, thereby tightening both ends and restricting its axial movement.
The crosshead is a taper bushing; mainly, the clearance between the crosshead and the crosshead bushing is out of spec, and the clearance between the bolts and their holes is too large. It is recommended to replace the crosshead, which will solve the problem.