Anti-two-blocking devices on construction cranes

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

April 11, 1989

Mr. Phillip M. Mapp
Safety Director
Kimmins Industrial Service Corporation
[Recipient address omitted]
Dear Mr. Mapp:

This is in response to your correspondence to Mr. Paul Hansen, Director of OSHA's Baton Rouge Area Office and a followup phone conversation with Mr. Anthony Brown of my office requesting an interpretation of 29 CFR 1926.550(g)(i)(3)(C), "Crane and Derrick Operational Criteria".

The requirement for a "positive acting device" and the term "anti-two-blocking device" are interchangeable. The appropriate terminology would be "positive acting anti-two-block device." The purpose and intent of this requirement is to assure that a remote signaling device (flashing lights, bells, buzzers or horns) is not used to warn the operator if he is approaching a two-block situation. A positive acting anti-two-block device provides for an automatic cessation of the lifting action when the headache ball or block approached the end of the boom or jib.

In responding to your second request, the standard does apply to all cranes, including friction rigs and hydraulic cranes.

If this office can be of any further assistance, please let use know.

Sincerely,
Gerald P. Reidy, Director
Office of Construction and
Maritime Compliance Assistance