How to determine the fault of NMRV75-15-1.5KW worm gear reducer

NMRV75-15-1.5KW is an aluminum alloy shell worm gear reducer with a transmission ratio of 15, suitable for 1.5kW motors. The faults are mainly concentrated in four categories: worm gear wear, lubrication failure, bearing damage, and seal oil leakage. It can be gradually investigated through sensory judgment, operating parameter monitoring, and disassembly inspection. The specific operation is as follows:

1. Sensory judgment: Quickly identify explicit faults

(1) Abnormal noise judgment

Sharp whistling sounds occur during operation: often due to insufficient clearance between worm gears, uneven wear on tooth surfaces, or insufficient viscosity of lubricating oil, accompanied by slight vibration of the housing.

Periodic "clanging" impact sound appears: most likely due to gear tooth breakage, worm thread damage, bearing ball peeling, or cage fracture.

The noise intensifies significantly with increasing load, indicating poor contact between the worm gear and worm gear, or excessive coaxiality deviation of the input/output shaft.

(2) Abnormal temperature rise judgment

After 10 minutes of no-load operation, if the shell temperature exceeds 60 ℃ (based on an ambient temperature of 25 ℃), it may be due to excessive/insufficient lubricating oil, incorrect oil grade, or tight engagement of the worm gear.

Local (such as at the bearing end cap) high temperature (exceeding 70 ℃): mostly due to bearing damage, excessive interference during assembly, or dry lubricating grease.

(3) Oil leakage fault diagnosis

Oil leakage at the input/output oil seal: oil seal aging, shaft end wear and groove formation, or loose end cap bolts.

Oil leakage on the joint surface of the box: aging of the sealing gasket, uneven tightening torque of the box bolts, or deformation of the box.

Oil leakage at the oil level gauge: The sealing gasket of the oil level gauge is damaged or the thread is not tightened properly.

(4) Operation status judgment

Manual turning has high resistance and jamming: the worm gear and worm gear mesh is too tight, the bearing is stuck, or foreign objects enter the meshing pair.

The output shaft speed is significantly lower than the rated value: severe wear of the worm gear causes a decrease in transmission efficiency, or the motor load is insufficient.

2. Monitoring of operating parameters: quantitative analysis of hidden faults

Current monitoring: Connect an ammeter at the motor inlet end, and the normal operating current should be stable at 3-3.5A (the rated current of a 1.5kW motor is about 3A). If the current fluctuates frequently and exceeds 4A, it indicates that the gearbox is overloaded, the worm gear is stuck, or the bearings are damaged.

Vibration monitoring: Use a vibration meter to detect the vibration velocity of the shell, which should be ≤ 2.8mm/s under normal conditions. If the vibration value exceeds 4.5mm/s and is accompanied by a vibration peak that is synchronized with the frequency and speed, it is judged as shaft imbalance or bearing failure.