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Type "A" and "B" Gates are both recognized methods for power press safeguarding. The "A" gate is used in both full and part revolution clutch presses while the "B" gate is for part revolution presses only.


"A" Gates

Type "A" Gates protect the operator during the entire machine stroke. This means the gate will not open until after the crankshaft rotation is complete (360°) and the machine is stopped at top dead center. Although Type "A" Gates can be used on either part or full revolution clutch presses, best safety practice is the "A" gate should be used only on full revolution clutch presses. [29 CFR 1910.217(c)(3)(i)], [(c)(3)(i)(f)], [29 CFR 1910.217(c)(3)(ii)] and [(c)(3)(ii)(a)]

Type "A" Gate Operation
Type "A" gate operation
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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.




"B" Gates

Type "B" Gates protect the operator during the downstroke only. The gate starts to open before the crankshaft rotation is complete (generally after 180° crankshaft rotation). The gates must open on the upstroke of the machine cycle before the crankshaft rotation is complete. [29 CFR 1910.217(c)(3)(i) and (g)] [29 CFR 1910.217(c)(3)(ii) and (c)(3)(ii)(b)]


Type "B" Gate Operation
Type "B" gate operation
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The "B" gate only protects the operator on the down-stroke of the press slide. The following is a typical sequence of operation of a complete cycle on a press which uses a "B" gate.

1. Initiate the cycle. As long as there are no obstructions, the gate closes by gravity.

2. Once the machine reaches the portion of the stroke where the pinch point has been eliminated and before the stroke has stopped, the "B" gate and the slide go up at the same time.

For more details, please see "B" Gate Sequence of Operation.



"A" and "B" Gate Requirements
  • In both cases, operators must be prevented from placing their hands or any other body parts in the point of operation during the die-closing portion of the press stroke. [29 CFR 1910.217(c)(3)(i) and (c)(3)(i)(b)]

  • The guard itself must comply with applicable standards. [29 CFR 1910.212(a)(2)]

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