Figure 107. Synchronous motor KBA-2, showing use of spanner wrench.
to a position halfway betweem the two points.
the action of the armature and brushes for free-
The head of the screw is hexagonal so that fractions
dom from finds. A lug which straddles the
of turns can be counted. The armature should
armature spring serves as a backstop to limit the
operate satisfactorily over a range of approxi-
upward movement of the armature. Adjust this
mately 1 turn. If the range is less than 1 turn,
backstop by bending the lug so that brushes lift
the armature return spring may be too tight or
approximately one-sixteenth of an inch off the
the armature may be binding at the pivots. If
armature. Test by pushing the armature down-
the range is greater than 1 turn, the spring may be
ward with a pencil and noting the free armature
travel before the brush springs begin to compress.
k. Start Magnet (fig. 109). Poor operation
Motors with serial numbers above 1193 are
the start magnet in motors with serial numbers
provided with a different type backstop which
below 1193 may be caused by the magnet arma-
ture rubbing against the motor casting. This
Transceivers TT-1B/TXC-1 through TT-1F/
can be cleared by loosening the magnet mounting
screws and shifting the frame slightly. Check
TXC-1 have no start magnet.