I. Immediate Inspection After Installation (Key Steps)
1. Visual Inspection:
Anti-loosening Marks: Check if the marks on the nut and bolt are aligned. Misalignment indicates looseness.
Cotter Pin/Locking Washer: Confirm the cotter pin is intact, the tail is pried open, and the inner wing of the locking washer is embedded in the bolt groove, with the outer wing tightly against the side of the nut.
Nut Condition: Check for cracks, deformation, or thread damage.
2. Functional Testing:
Torque Verification: Use a torque wrench to check if the tightening torque meets the initial requirements (below the initial value indicates failure).
Manual Inspection: Try to slightly tighten the nut with a wrench. If there is significant rotation (more than 5-10 degrees), the anti-loosening mechanism has failed.
II. Regular Maintenance Inspection (Long-Term Reliability)
1. Inspection Cycle: Important connections (such as engines and bridges) should be inspected monthly or quarterly; in vibrating environments, the frequency should be increased.
2. Inspection Method: Repeat visual and functional tests after installation, focusing on the anti-loosening marks, cotter pins, washer condition, and torque values.
3. Records and Maintenance: Record each inspection and address any issues promptly (e.g., replace cotter pins, retighten).
III. Inspection Points for Different Anti-Loosening Methods
1. Spring Washer: Check for complete flattening or breakage.
2. Double Nut: Check for tightness and absence of gaps between the upper and lower nuts.
3. Self-Locking Nut: Check for wear or detachment of the nylon ring.
4. Cotter Pin + Slotted Nut: Check for integrity of the cotter pin and whether the tail is pried open.
5. Locking Washer: Check if the inner wing is embedded in the screw groove and if the outer wing is tightly against the nut.
6. Connecting Steel Wire: Check for integrity of the steel wire and correct winding direction.
IV. Precautions
1. Environmental Factors: High temperatures and corrosive environments accelerate failure; increase inspection frequency.
2. Tool Selection: Use an appropriately sized torque wrench to avoid slipping or damaging the nut.
3. Safety First: For critical connections, perform load tests or vibration tests after inspection to ensure safety and reliability.
