Electric drive motor – 1760 Service/Repairs T-code 677, 678, 679
Valid from serial number 723984-
Date 2005-10-28
Order number 222995-040
• Dismantle the commutator end’s bearing shield (2) together with the carbon brush bridge (5) and carbon brushes (8) by unscrewing the eight screws (1). Now put down the motor with a firm resting point against the edge of the bearing shield, and carefully tap on the rotor shaft’s end with a rubber mallet. • Dismantle the drive end’s bearing shield (15) together with the rotor (9). Make sure not to damage the motor windings when the rotor is removed from the motor housing. • After dismantling the motor’s bearing shields and removing the rotor from the motor housing, the gear wheel in the rotor’s drive end is removed. This is done by unscrewing the nuts on the gear wheel and then pulling the gear wheel off with a puller. Note that the gear wheel is locked with Loctite to the rotor shaft. • Now release the inner locking ring together with the underlying washer. Pull out the rotor shaft from the bearing (18). • Release the outer locking ring together with its washer, and remove the bearing from the bearing shield. • Remove the bearing shield’s seal (17) and carefully clean the bearing shield. • Fit a new seal in the bearing shield.
9.2.2 Assembling of motor Assemble the motor in the reverse order. • Carefully check that the rotor can move freely in the direction of rotation and that the carbon brushes are flush with the commutator. • Check the motor’s insulation resistance (between respective winding and the motor housing). For a new motor this should lie between 2 - 3 Mohm. When a used motor has been exposed to impurities an insulation resistance down to approx. 1 Mohm is acceptable. • Fit a new O-ring in the drive shaft end’s bearing shield and a new seal on the collar of the bearing shield.
9.2.3 Cleaning An extremely critical factor to ensure correct functioning of the motor is that it is kept as clean as possible. The motor and the motor compartment must be regularly checked for dust, oil, and other impurities. A vacuum cleaner with an appropriate nozzle can be used to clean the motor if the motor windings and inner compartment are dry Compressed air can be used in combination with a vacuum cleaner. In which case the compressed air must be clean and dry. A cloth of non-fluffing material should be used if the windings have a coating. The cloth can also be moistened with a grease-dissolving, organic and volatile detergent that does not damage the windings. Use detergent sparingly to avoid it penetrating into the parts of the motor. 9- 4
Service Manual
7PM18, 7PM20, 7PML20
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