IBM 727 Manual Of Instruction Download

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5. Remove these colla rs.
6. Remove the screws entering the rear of the shafts.

70 Remove the rear plate, which is held by six screws and four dowels.

8. The clutch and shaft assem blies may now be removed from the fram e. Note

carefully the position of any shims; do not interchange the two assem blies.

Assem ble in reverse order. After assembly, check the brushes for good tension

and square contact.

15. 5.3 Adjustments on Drive Clutch Unit

The commutator brushes are positioned to make contact squarely and in the cen

ter of the commutator rings. Loosen brush mounting screws to do this. Form ten

sion strap for a strong wipe to insure no arcing at the brushes. Excessive carbon

deposits have been found on the commutator rings. They produce contact resistance
affecting the operation appreciably and, therefore, should be removed.

The take-up spindle block is positioned vertically with the mounting screw s in

elongated  holes  to  bring the  chain  gear  level  with  the  chain  gear  on  the  left  stop-
clutch  drive-shaft.  Position  the  stop-clutch  drive-shaft  bearing blocks  so  that  the
worm  teeth  are  fully  meshed  with  the  teeth  on  the  stop-clutch  gears  and  the  shafts
are  free  from   binds.  The  forward  and  reverse  m otors  are  positioned  vertically  to

provide normal V belt tension— about one inch free play at the center of the longest
belt span.

15.6

VACUUM UNIT

1 5.6 .1 Removal and Adjustment of the Vacuum Columns (Figure 22)

Two methods are used to fasten the vacuum columns to the lower main plate.

On earlier machines, two mounting screws are used per column; on current machines,

four mounting screws are used. The removal and adjustment of both types is ex
plained.

The right column can be removed in the following manner. Remove the lower

clean-out cover, the lucite cover angle clamps and the lucite cover. Remove the

four screws (from rear) holding the lower end of the column to the manifold. Remove

the  screws  securing the  column  to  the  lower  main plate.  Remove  the  column,  being
careful  not  to  damage  the  flutter  valve  operating  arm.  Reassem ble  in reverse  order,
making  sure  the  neoprene  tubes  to  the  vacuum  column  switches  are  in place.

When necessary to rem ove the left vacuum column, it is quicker to rem ove both

columns and the manifold as an assembly, and then rem ove the left column. To do
this, disconnect the vacuum hose from the manifold and the leads from the flapper

valve microswitcheso Loosen the two screws holding the manifold to the machine
base. Remove the lower clean-out covers, the lucite cover angle clamps, the lucite

covers, and the screws securing both columns to the lower main plate.

When reassem bling the lucite covers, make sure they are tight against the vacuum

chamber  covers  (C)  and  the  lower  clean-out  covers  to  prevent  air  leakage.  Be  very
careful  when handling  the  angle  clamps  and  the  vacuum  columns  because  they  are
manufactured  with  a  very  close  tolerance  on  straightness.

Do not tighten the holding