Because electric drill needs ventilation and heat dissipation, there is a lot of internal dust in long-term use. Dust can make lubricant on gear and bearing (sliding sleeve) deteriorate and absorb dry, aggravating wear, especially in alternative use. In order to ensure the rotary accuracy of electric drill and reduce the excessive clearance caused by bearing (sliding sleeve) wear, it is necessary to maintain clean interior and grease lubrication.
Loosen several self-tapping screw or screw outside the electric drill; lift half of the casing by placing it flat; the general structure of the new electric drill is semi-embedded, that is, all the mechanical and electrical components are installed in the other half of the casing.
Carefully remove the carbon brush first, then remove the end of the drill chuck, gently lift the motor to remove the rotor (don't touch the enameled wire), clean the rectifier on the rotor (the one that contacts the carbon brush), if it is too dirty or worn badly, use abrasive cloth to polish first, then use abrasive paper or metallographic abrasive paper to Polish to bright.
If the front and rear bearings of the rotor are sealed, the outside can be wiped clean. If the seal is broken, it should be replaced in time. Clean the helical gear shafts in front of the rotor
Clean the oil stain inside the shell. Clean the helical gears and bearing (or sleeve) at both ends of the drill chuck rod.
Loading the unloaded parts back, first loading the rotor; then loading the helical gear of the drill chuck rod; loading the carbon brush, if less than 7-8 mm, the carbon brush should be replaced in time. Carbon brushes should be installed and flattened. Final, find a little "Mobil" or "Shell" grease to add all parts between gear pair and bearing (or sleeve) to cover the other half after flattening check is correct, tighten the screw, and rotate by hand without feeling stuck before turning on electricity.
Disassembly of electric drill under live condition is strictly prohibited! Do not start without basic knowledge of electrical appliances!