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.


April 11, 1997

Mr. Kenneth J. Yotz
Senior Vice President
Environmental, Management
     and Training Systems, Inc.
919 St Andrews Circle
Geneva, Illinois 60134-2995

Dear Mr.Yotz:

This is in further response to your letter of January 12, requesting clarification of the Occupational Safety and Health Administration (OSHA) Powered Industrial Truck standard, 29 CFR 1910.178(a)(4). I regret the delay in responding to your. Your questions have been included in this response for clarity.


  1. Clearly, OSHA (and ANSI) requires that modifications and additions which affect the capacity and safe operation require prior written manufacturers' approval [29 CFR 1910.178(a)(4)]. What measures are available to an employer if the manufacturer is no longer in business?

    Reply: 29 CFR 1910.178(a)(4) requires that "Modifications and additions which affect the capacity and safe operation shall not be performed by the customer or user without manufacturers prior written approval. Capacity, operation, and maintenance instruction plates, tags, or decals shall be changed accordingly." In the event that a powered industrial truck manufacturer has been sold to another company and is no longer in business, the user or customer must contact the purchasing company to request approval. In the event that the original powered industrial truck manufacturer is no longer in business and has not been purchased by another entity, the user or customer would be required to contact a Qualified Registered Professional Engineer for approval of such modifications and additions.
  2. Experience has demonstrated that manufacturers of forklifts and attachments are reluctant to provide written approval due to liability considerations. Are any other options available to employers who wish to use manufactured or fabricated attachments with a forklift? Are a safety analysis and marking of the forklift by the employer acceptable? If so, must the analysis be performed by a registered engineer.

    Reply: With regard to compliance with 1910.178(a)(4), employers must seek written approval from powered industrial truck manufacturers when modifications and additions affect the capacity and safe operation. However, if no response or a negative response is received from the manufacturer, OSHA will accept a written approval of the modification/addition from a Qualified Registered Professional Engineer. A Qualified Registered Professional Engineer must perform a safety analysis and address any safety and/or structural issues contained in the manufacturer&39;s negative response prior to granting approval. Machine data plates must be changed accordingly.
  3. Some companies purchase or fabricate booms and other lifting devices for use with forklifts. Essentially, they can be utilized to make the forklift a mobile crane. It seems that I can vaguely recall an old OSHA case decided by an ALJ which addressed this issue, but I do not recall the outcome. If these devices are used, does the OSHA crane standard apply or does any ANSI standard apply which could be referenced by OSHA to demonstrate knowledge under Section 5(a)(1) of the OSH Act?

    Reply: The use of such lifting devices usually affects the capacity and safe operation of a powered industrial truck, therefore the user would be required to request approval from the manufacturer for such modification and addition to the powered industrial truck. OSHA will evaluate what standard would be particularly applicable to forklifts modified with booms or other devices on a case-by-case basis. Also, a June 1996, OSHA Hazard Information Bulletin regarding this subject is enclosed for your information.

The OSHA, powered industrial truck standard was adopted from the B56 consensus standard. You may wish to contact the ASME B56 Committee for a further request of interpretation regarding requirements for modifications and additions to trucks, which affect capacity and safe operation, at the following address:

Secretary of the B56 Committee
345 East 47th Street
New York, New York 10017



We appreciate your interest in occupational safety and health. If we can be of further assistance, please [contact the office of General Industry Enforcement at (202) 693-1850].


John B. Miles, Jr., Director
Directorate of Compliance Programs

[Corrected 4/7/2009]