Why does YE3 motor have high efficiency but low temperature rise?

Starter bearings (commonly known as copper sleeves) often experience loose shaft necks and copper sleeves due to excessive wear during normal use, ultimately affecting the performance of the starter. There are two main reasons for the easy wear of starter copper sleeves:

One is that it bears a large load, which is an unchangeable reality;

The second issue is poor lubrication, which can be improved. The lubrication of the starter copper sleeve and armature shaft neck is mostly done by applying some lubricating grease during disassembly and maintenance. The starter cannot be lubricated without disassembly during normal use. When the starter is working, the outer circular surface of the shaft neck is in contact with the inner four sides of the copper sleeve, which squeezes out some of the lubricating grease from the friction surface, accelerating the consumption of lubricating grease and causing dry friction between the shaft neck and the copper sleeve during starter operation, exacerbating their wear. For this purpose, two oil grooves with a depth of about 0.8mm and a width of about 1.5mm were machined on the inner circular surface of the copper sleeve. During the maintenance of the starter motor, the grooves were coated with lubricating grease and reinstalled. After operation inspection, it has achieved the purpose of long-term lubrication and reduced the wear of the shaft neck and copper sleeve.