Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

December 21, 1998

Mr. David L. Thorpe
Manufacturing Engineer
General Motors
Metal Fabricating Division Headquarters
5607 New King Street
Troy, Michigan 48098

Dear Mr. Thorpe:

This is in response to your letter of September 8, addressed to Mr. John B. Miles, Jr., Former Director of Compliance Programs. Your letter was to confirm your representative's conversation with Ms. Alcmene Haloftis of my staff concerning the use of slide locks (mechanical safety devices) in lieu of die blocks on mechanical power presses, as required by the Occupational Safety and Health Administration's (OSHA's) standard, 29 CFR 1910.217(d)(9)(iv). We apologize for the delay in responding to your letter.

First, this response is to correct the apparent misunderstanding of the communication between your representative and my staff member, Ms. Haloftis. It is apparent that you are under the perception that slide locks meet the intent of the referenced standard. The slide locks, however, are clearly susceptible to failure caused by the misalignment of the gear or the supporting pin; unlike the die block which has no mechanical components subject to failure.

Further, it should be noted, that the American National Safety Institute (ANSI) standard, ANSI B11.1-1998, does not recommend slide locks or devices which have components susceptible to failure.

Therefore, as Mrs. Haloftis recommended in the original telephone communication, this situation would be properly assessed through a variance application. The variance application would be addressing a specific use for a specific piece of equipment, under specific conditions. That is, a variance application would assess and determine the potential hazards of this type of safeguard specific to a particular power press, and would not determine blanket exception of all slide locks on all power presses which it seems that you intend to secure from OSHA. You may request to apply for a variance application from the Office of Technical Support by contacting Mr. Steve Witt, Director, at 202-693-2300.

Thank you for your inquiry. If you have questions regarding the preceding, please contact Ms. Alcmene Haloftis of my staff at 202-693-1850.


Richard E. Fairfax, Director
Directorate of Compliance Programs