3M 3M-Matic S-857, Instructions And Parts List

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13
Theory of Operation
(Continued)
APPLICATION CYCLE, FEED SEQUENCE
Valve V-4 directs air to the PA port of the pilot valve P-
2 causing it to shift and direct air to the rod end of the
jaw and feed cylinders. Air travels from the pilot valve
P-2 through line 17, the feed cylinder retract flow
valve, and line 23 to the rod end of the feed cylinder
and through line 16 to the rod end of the jaw cylinder.
As the cylinders retract, the jaws on the jaw assem-
bly open to receive the tape that the feed assembly is
advancing. As the feed assembly advances, the tape
pick up roller pivots upward out of the path of the feed
assembly. At the end of its stroke, the feed assem-
bly actuates valve V-6 which directs a pulse of air to
the PB port of the pilot valve P-2. This causes valve
P-2 to shift and direct air through line 14, valve V-5,
and line 26 to the head end of the jaw cylinder. The
jaw cylinder extends and the tape holding haws close
to retain the free end of the tape advanced by the feed
assembly.
When the jaw cylinder is completely extended, the
jaws close and retain the free end of the tape and
valve V-7 is actuated. Valve V-7 directs air to the
head end of the free cylinder. This causes the feed
mechanism to move back to the machine rest
position. The machine is now ready for the next
cycle.
Figure 3-4 – Feed Sequence