Mitsubishi Electric UM 10t, Instruction Manual

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23
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Maintenance and Inspection of Brake
Electromagnetic Hoisting Brake
The hoisting brake is located on the end face of the hoisting motor. The brake stops and holds a
load.
For the 5t
､
10t types, the brake gear is engaged to the motor shaft.
The 5t
､
10t types are provided with an automatic adjusting device that keeps the gap constant
between the iron cores even if the brake disk is worn out. The gap therefore does not need to be
adjusted. If the brake does not work effectively and the load travels a considerably long distance
after applying the brake, judge that the brake disk is worn out to the limit. In this case, replace
the brake disk with a new one.
[Procedure for disassembling and re-assembling the brake and replacing the brake disks for
the 5t ,10t types]
(1) Remove the lid screwed on the end face of the stationary core, and remove the helical
compression spring. Evenly loosen the bolts. Remove the spring, taking care not to
damage the packing.
CAUTION! : When loosening the bolts of the lid, you may notice that the lid is sticking to
the casing due to the sticky packing. In this case, apply a shock to the lid
before completely removing the bolts. In this way, you can prevent the lid
from springing out.
(2) Using the bolts removed from the lid, temporarily tighten the movable iron core and the
pressure plate.
CAUTION! : If the movable iron core and the pressure plate are not temporarily tightened,
the adjusting ring may fall off, or two retaining springs (small springs that
ensure easy falling down of the adjusting ring) may be missing.
(3) Remove the stationary core, taking care not to damage the packing. The brake coil is in the
stationary core.
CAUTION! : This packing prevents “entering of water into the brake casing”, and also
prevents “electromagnetic leakage from the electromagnet”. If the packing is
broken, replace the packing with a new one. If the brake is reassembled
without a packing, the suction gap will be narrowed by 0.8 mm (= packing
thickness “t”). In this case, the brake may be locked up, and the motor may be
seized. If the electromagnetic leakage occurs, the responsibility of the brake
may be deteriorated.
(4) Remove the temporarily tightened movable iron core, adjusting ring, and pressure plate to
remove the brake disk and the braking plate.
CAUTION! : When replacing the brake disk, clean the inside of the break box. Be sure to
remove abrasion particles from the back of the braking plate, contact face of the
brake box, and the guides (lugs) of the brake disk and braking plate.