What are the causes of excessively high temperatures during operation of a geared motor?

Excessive temperatures during operation of a geared motor are often the result of a combination of factors, requiring a comprehensive investigation from various perspectives, including load, lubrication, heat dissipation, and mechanical coordination.

Abnormal load is a common contributing factor. When the actual load exceeds the rated load, the transmission components of the motor and gear reducer experience additional torque, increasing meshing friction. For example, when a conveyor belt jams, the resistance at the output end of the gear reducer suddenly increases, causing the temperature of the contact area between the worm and worm wheel to rise significantly in a short period of time. Furthermore, frequent starting and stopping or forward/reverse switching can cause transient shock loads, leading to periodic overheating of the motor windings and gear surfaces.

Lubrication failure directly impacts heat dissipation efficiency. Lubricant oil with an inappropriate viscosity grade (such as using high-viscosity oil in low-temperature environments) can reduce fluidity, prevent the formation of an effective oil film, and generate heat through direct friction between the metals on the meshing surfaces. Excessively high oil levels increase churning resistance, converting it into additional heat energy. Long-term oil changes can lead to oxidation and deterioration of the oil, significantly reducing its thermal conductivity and rendering it ineffective in cooling.

Failure in the cooling system can block heat transfer. Broken motor fan blades or clogged protective covers can significantly reduce forced cooling capacity. Thick dust buildup on the reducer housing can hinder natural convection cooling. In high-temperature environments (such as metallurgical workshops), high ambient temperatures can significantly reduce the cooling system's heat exchange efficiency, leading to heat accumulation.

Mechanical fit issues can cause abnormal friction. Excessive coaxiality between the input shaft and the motor shaft during installation can lead to unbalanced bearing loads and increased roller-raceway contact temperature. Inadequate bearing clearance can generate excessive frictional heat during operation. Improper worm gear meshing clearance can cause dry friction on the tooth surfaces, rapidly increasing local temperatures.

Also, aging motor winding insulation, poor contact between terminal blocks, resistive heat, or component seizure caused by ambient dust intrusion can cause abnormal temperature rise. A comprehensive assessment should be made based on operating sound and vibration.