4.
To inspect and replace motor Brushes Ref.104,
with the brush block assembly removed.
i.
Remove the three Screws Ref.82 and
remove the Wall End Guard Ref.84 to
expose the motor brush assembly.
ii.
Remove the four retaining Screws Ref.31
from the Shield Wall End Ref.30, insert two
of the screws into the ‘jacking holes’
situated adjacent to the countersunk
retaining holes.
iii.
Carefully tighten these screws until the
shield wall end is jacked clear of the outer
casting. Withdraw the shield-wall end.
iv.
With the brush block assembly complete
and the connecting leads still attached.
You will note that as the brush block
assembly is withdrawn the brushes spring
towards the center and often the brush
springs fall clear as the brushes are no
longer at the height to retain them. Take
care not to lose any springs.
v.
To remove a brush spring with a brush in
the operating position push the brush
spring down and towards the brush and lift
out.
vi.
Using a cross recess screwdriver remove
the four brush shunt (pigtail) retaining
Screws Ref.105 and lock Washers Ref.100.
vii.
Remove the four brushes. Remove the two
‘jacking’ screws.
viii. Thoroughly clean the brush assembly and
housing using a soft brush and a suitable
vacuum cleaner.
ix.
Inspect the four brushes for damage or
wear and if any one brush is found to be
damaged or worn to a length of 5/8“
(16mm) or less in length then replace all
four brushes.
x.
When replacing brushes ensure free
movement in each brush holder and fit the
brush with the shunt (pigtail) towards the
field coil. Ensure that each brush shunt is
connected securely with the screw, and
lock washer, two spare screws and lock
washers are provided with each pack of
brushes. Do not fit the brush springs at this
stage.
xi.
Pull each brush up to the top of the holder
using the shunt wire to retain it in this
position for the next stage.
xii.
Enter the assembly into the main frame
taking care to avoid contact between the
brushes and the commutator of the
armature, that the shield wall end is
correctly aligned with the main frame and
that no leads are trapped. There is a
depressed pattern on the shield wall end
and on the main frame to assist alignment.
Both the bearing fit and the main frame fit
are ‘light contact’ and may require lightly
tapping into position using a soft mallet.
DO NOT FORCE.
xiii. Replace and tighten the four countersunk
Screws Ref.31.
xiv.
Remove the four brush block retaining
Screws Ref.31 and the single timing Screw
Ref.34 from the Shield-Wall End Ref.30.
The brush block assembly is now free to
rotate. To fit the brush springs rotate the
brush block assembly counter clockwise
(over towards the rear of the machine) until
the lower brush holder is accessible, fit the
brush spring by inserting into the holder
with the coil spring over the brush then
push down until the tag comes into contact
with the holder, slide the tag away from the
brush and release. The brush spring will
clip into position. Check the spring and
brush for correct alignment and
free
movement.
xv.
Rotate the brush block assembly clockwise
and repeat to fit the remaining three
springs.
The switch and field cables
restrict the movement of the brush block
assembly, take care not to loosen or
damage these cables.
xvi. Return the brush block assembly to its
original position and align the timing
notch in the block with the timing hole,
screw the timing Screw Ref.34 into
position.
xvii. Secure the brush block assembly using the
remaining four screws Ref.34. DO NOT
OVER TIGHTEN.
xviii. Finally check that all cables are well clear
of moving parts before refitting the guard
wall and securing with the 3 Screws
Ref.82..
Note: To inspect and replace the motor brushes while
retaining the brush block assembly in place repeat
the procedure xiv. to xviii. above.
8
