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.


July 25, 1991

Mr. William A. Guyer
Marketing Manager
Kelly Company, Inc.
P.O. Box 09993
Milwaukee, Wisconsin 53209-0993

Dear Mr. Guyer:

This is in further response to your letter of April 25, to Assistant Secretary Gerard F. Scannell, concerning clarification of the term "wheel chocks" and whether the employment of one chock would satisfy the requirements of the Occupational Safety and Health Administration.

You were correct in your assumption that the word, "chocks," as it appears in the OSHA standard 29 CFR 1910.178(k)(l), is a grammatical construction only and does not mean that OSHA would require the placing of multiple chocks under the conditions you have previously described, should fully satisfy the intent of the safety regulation if it effectively prevents movement of the truck during loading operations involving powered industrial trucks. Because of the above interpretation, your customer's application for a variance would not be necessary.

The Occupational Safety and Health Administration (OSHA) has a longstanding policy against approval of any product, and this letter may not be used as evidence of direct or indirect endorsement of your product by OSHA.

In addition to the above, we are concerned about apparent hazards in the Kelley System which appear to us to be evident from an examination of the pamphlet describing details of your system. The apparent hazards are listed, as follows:


  1. The system is hydraulic in nature. Any leak or rupture in the piping which carries the liquid could result in a truck not actually being chocked against movement. Potential users should be cautioned to inspect for these hazards before each use.
  2. The design of the chock and the track in which it sets, calls for accurate "spotting" of the trailer wheels along the track line. This would also be a responsibility of the eventual user of the product.
  3. The push button control panel relies, in part, on red and green lights. Thus, there is a remote possibility that the activation of the chocks could be misread by a truck driver or his helper if one happened to be color blind.



Please do not hesitate to contact this office if we can be of additional assistance.


Patricia K. Clark, Director
Directorate of Compliance Programs

[Corrected April 1, 2009]