In addition to the manufacturer's designation, the bolt head also has a strength index designation, for example: 8.8; 10.9; 12.9; 14.9. Some bolts have the designation M and strength index stamped on the hexagon faces.
Bolts and screws protected with anaerobic sealant
An anaerobic sealant is applied to the thread of a bolt or screw in a special way before the assembly of the unit. These bolts can be identified by a colored strip that continues all 360° around the circumference of the bolt shaft. The anaerobic sealant is activated during the assembly of the unit, then hardens as a result of chemical transformations. This ensures reliable fixation of the bolt from unscrewing.
Unless otherwise stated, undamaged bolts with anaerobic sealant may be reused. To do this, follow these steps:
- Clean the bolt body and threaded hole from any remaining anaerobic sealant.
- Clean the threads from oil.
- Apply recommended thread sealant to threads.
A bolt with anaerobic sealant can be replaced with a similar bolt, provided that a special anaerobic sealant is used during installation.
Self-locking bolts and screws
Self-locking screws and bolts (meaning bolts with nylon insert or with thread distortion) can be reused provided that an increase in tightening resistance is felt when the locking part of the bolt begins to tighten.
The article was copied from this resource (www.LRman.ru)
Self-locking bolts or screws have a nylon insert that is installed during the manufacturing process of the bolt. These bolts can be identified by a colored insert that continues more than 180° around the circumference of the bolt shank.
Another type of self-locking bolt is a bolt with a thread that is slightly out of alignment with the thread of the counter hole or nut into which the bolt is screwed.
НЕ reuse self-locking bolts for critical connections (engine bearings, flywheel mounting bolts). Always replace a self-locking bolt, screw or nut with similar parts.
НЕ install conventional fasteners in place of the self-locking nuts, bolts or screws provided by the design.
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