Type "A" and "B" Gates are both recognized methods for
power press safeguarding. The "A" gate is used in both
clutch presses while the "B" gate is for part revolution presses only.
The "A" gate is
designed to enclose the point of operation before the press
stroke can be started, and it must remain enclosed until all
slide motion has stopped. The following is a typical
sequence of operation of a complete cycle on a press which
uses an "A" gate.
1. Initiate the cycle. As long as there are no
obstructions, the gate closes by gravity.
2. The machine makes one complete cycle and returns to
"top of stroke" and stops.
3. The gate opens, after the cycle has stopped.
For more details, please see "A" Gate Sequence of Operation.