If you have done a careful job of breaking down a
machine into its components, the process of reassembly
should be the reverse order of disassembly.
A few simple steps are to be taken when
1. Make sure you mark the frame and mating end
bells (fig. 7-23), using a different mark for each
2. When separating the end bells from the frame,
use a mallet or block of wood with a hammer
(fig. 7-24). Never pry mating surfaces apart with
a metal object such as a screwdriver.
3. To prevent damaging the brushes, lift them from
the commutator and/or slip rings before
removing the rotor.
4. Protect the windings by inserting thin strips of
waxed paper between the rotor and stator.
Figure 7-24.--Parting end bells with a hammer and a wood
5. When using an arbor press to remove bearings,
take the proper precautions. (Place a pair of flat,
steel blocks under the inner ring or both rings of
the bearing. Never place blocks under the outer
into the bearing until the bearing is flush against
ring only. Line up the shaft vertically above the
the shoulder of the shaft). You may use a gear
baring, and place a soft pad between the shaft
puller to remove a rotor bearing, but take
and the press ram. After making sure the shaft
is started straight in the bearing, press the shaft
6. Never remove the bearings unless they are to be
replaced, or unless they must be removed to
allow the removal of the end bells.
7. If you are taking off a ball bearing and plan to
use it again, be careful to apply pressure to the
inner race only. If pressure has been applied to
the outer race, you will have to discard the
8. Never use a cleaning solvent on a sealed or a
semi-sealed ball bearing. Store these bearings in
a clean piece of waxed paper until you are ready
to use them.
9. Clean the end bells with a brush and an approved
solvent. Check them for crocks, burrs, nicks,
excessive paint, and dirt.
OF ROTATING ELECTRICAL
Preventive maintenance of armatures, rotors, or
windings consists mainly of periodic visual inspections
Figure 7-23.--Marking a motor frame and end bell.
and electrical testing to determine the condition of the