OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

December 21, 1992

Mr. Bernard A. Stankevich, P.E., CSP
Engineering Department
W101 Aetna 151 Farmington Avenue
Hartford, Connecticut 06156

Dear Mr. Stankevich:

Thank you for your inquiry of June 24, requesting an interpretation of Occupational Safety and Health Administration (OSHA) standards concerning a two-hand control device, used to operate a mechanical power press in continuous mode. We apologize for the delay in responding.

The enclosed OSHA requirements for two-hand controls, 29 CFR 1910.217(c)(3)(i)(e), (c)(3)(vii) and STD 1-12.21, specify by design, construction and separation the concurrent use of both hands to trip the press. This means that the control circuitry must be such that the press cannot be tripped unless the initiating depression of the control buttons occurs at the same or nearly the same instant for each button. A discrepancy of only a small fraction of a second is allowed between the initiating depressions of the buttons. Since this is the case, it appears that the control circuitry of the press referenced in your letter does not conform to the requirements of 1910.217.

We are providing the following additional clarification of the issue with respect to all mechanical power presses. If the two- hand control is adjusted to the requirements of OSHA 29 CFR 1910.217(c)(3)(i)(e) and (c)(3)(vii) standards, and STD 1-12.21, and then, one of the buttons of the two-hand control device is tied down, the power press would be inoperable since the two hand controls could not be operated concurrently to initiate and maintain the continuous operation of the press. The initiation of the initial stroke requires the nearly simultaneous depression of both of the controls. Any adjustment of the two-hand control device that does not require concurrent use of both hands for operation of the press is in violation of the OSHA 29 CFR 1910.217(c)(3)(vii). If one of the buttons is released during the continuous run, the control circuitry must be such that the press will stop.

The clutch/brake control systems which contain both single and continuous functions must be designed so that completion of continuous circuits may be supervised by the employer. The initiation of continuous run must require a prior action or decision by the operator in addition to the selection of continuous on the stroking selector, before actuation of the operating means will result in continuous stroking.

We appreciate your interest in employee safety and health. If we can be of any further assistance, please do not hesitate to contact us.


Roger A. Clark,
Directorate of Compliance Programs