During the installation process of LF cooling tower fan reducer, what are the common mistakes in coupling assembly?

1. Rough installation techniques and illegal hammering

Wrong operation: When installing the coupling, directly use a hammer to hit the coupling or motor shaft.

Undesirable consequences: This violent operation will seriously damage the keyway, and even cause damage to the internal gear structure of the reducer and break the output shaft.

Correct approach: It is strictly prohibited to directly hammer the motor shaft end. The shaft end screw hole press-in method should be used (use bolts to press the transmission parts in), or the hot-fitting method should be used (the heating temperature is controlled at ≤135°C).

2. The centering and alignment accuracy is not up to standard or the method is improper.

Wrong operation: Installation based only on visual judgment or simple measurement with a ruler, without accurate alignment; or only performing cold calibration, ignoring the impact of thermal expansion after the equipment is in operation.

Adverse consequences: Misalignment is the "culprit" that causes equipment vibration and wear, abnormal noise in couplings, bearing heating and seal leakage.

Correct approach: You must use a dial indicator (double-meter method) or a laser alignment instrument for precise alignment, and avoid "visual alignment". It is recommended to perform "cold + hot double verification", that is, after the temperature of the equipment has stabilized after running for 2 hours, recheck the alignment accuracy and make fine adjustments to compensate for the deviation caused by thermal expansion and contraction.

3. Uneven force or improper torque on the fastening bolts

Wrong operation: When installing the flange bolts, tighten them casually, failing to tighten them diagonally in sequence, or failing to use a torque wrench to reach the specified pre-tightening torque.

Undesirable consequences: Uneven stress can easily lead to bolt breakage and coupling end faces being non-parallel, which can lead to residual prestress and accelerate the aging and loss of elastic components.

Correct approach: Tighten the anchor bolts in diagonal order and use a torque wrench to ensure that the pretightening torque meets the manufacturer"s requirements (such as 200~350N·m). At the same time, install spring washers and locking nuts to prevent loosening.

4. Improper control of fit clearance and shaft insertion amount

Wrong operation: The shaft hole and the shaft fit too tightly or too loosely; the shaft insertion amount is too short or too long.

Undesirable consequences: Too tight a fit will cause the bearing clearance to decrease and cause temperature rise, while too loose a fit will cause vibration and keyway wear; too short a shaft insertion will easily lead to damage to the sliding and clamping parts, and too long a fit will cause internal interference.

Correct approach: It is recommended that the coupling inner hole and the motor shaft adopt H7/g6 or H7/h6 tolerance; the shaft insertion amount must be equal to the length of the main body (hub). If the fit clearance of the shaft hole is ≥0.1mm, the coupling needs to be replaced or the shaft head needs to be repaired.

5. Ignoring the inspection of elastic components and connecting parts

Wrong operation: not cleaning the oil stains and burrs on the end face before installation; not checking whether the elastomer is aging and cracking; mixing old and new bolts.

Undesirable consequences: Impurities will cause installation eccentricity or stress concentration; aging elastic components cannot effectively buffer and absorb shock; inconsistent hardness of old and new bolts will cause uneven stress.

Correct approach: Thoroughly clean the end face and shaft hole before assembly; confirm the status of the elastomer and replace it with the same model of high-temperature-resistant elastomer if necessary; when replacing bolts, it is recommended to replace them in sets simultaneously.