Importance of maintenance, wear and service life of equipment are discussed. Defects and repair methods of different machine parts, guide surfaces, gears and keys, shafts and bearings, spline shafts, couplings and clutches, leadscrew and nuts, threaded joints, vee belt drive, machine hydraulics, and seals and packing are also studied together with the restoration of worn parts to be welded, metallization and plating, and lubrication.