Hitachi DH40FA Instruction Manual - Page 15

English MAINTENANCE AND INSPECTION WARNING: Be sure to switch power OFF and disconnect the plug from the receptacle during maintenance and inspection. 1. Inspecting the drill bits Since use of a dull tool will cause motor malfunctioning and degraded efficiency, replace the drill bit with a new one or resharpening without delay when abrasion is noted. 2. Inspecting the mounting screws Regularly inspect all mounting screws and ensure that they are properly tightened. Should any of the screws be loose, retighten them immediately. EL WARNING: Using this rotary hammer with loosen screws is extremely dangerous. 3. Maintenance of the motor The motor unit winding is the very "heart" of the power tool. Exercise due care to ensure the winding does not become damaged and/or wet with oil or water. 4. Inspecting the carbon brushes: (Fig. 17) The motor employs carbon brushes which are consumable parts. When they become worn to or near "wear limit", it could result in motor trouble. When an auto-stop carbon brush is equipped, the motor will stop automatically. At that time, replace both carbon brushes with new ones which have the same carbon brush Nos. shown in the figure. In addition, always keep carbon brushes clean and ensure that they slide freely within the brush holders. CAUTION: Using this rotary hammer with a carbon brush which is worn in excess of the wear limit will damage the motor. Wear limit No. of carbon brush 0.67" (17 mm) 0.28" (7 mm) Fig. 17 NOTE: Use HITACHI carbon brush No.73 indicated in Fig. 17 15