1910.180(c) Load Ratings

Load ratings - where stability governs lifting performance.

The margin of stability for determination of load ratings, with booms of stipulated lengths at stipulated working radii for the various types of crane mountings, is established by taking a percentage of the loads which will produce a condition of tipping or balance with the boom in the least stable direction, relative to the mounting. The load ratings shall not exceed the following percentages for cranes, with the indicated types of mounting under conditions stipulated in paragraphs (c)(1)(ii) and (iii) of this section.

Type of crane mounting	Maximum load ratings (percent of tipping loads)
Locomotive, without outriggers:
Booms 60 feet or less	1 85
Booms over 60 feet	1 85
Locomotive, using outriggers fully extended	80
Crawler, without outriggers	75
Crawler, using outriggers fully extended	85
Truck and wheel mounted without outriggers orusing outriggers fully extended	85

     Footnote(1) Unless this results in less than 30,000 pound-feet net stabilizing moment about the rail, which shall be minimum with such booms.

Stipulations governing the application of the values in paragraph (c)(1)(i) of this section for crawler, truck, and wheel-mounted cranes shall be in accordance with Crane Load-Stability Test Code, Society of Automotive Engineers (SAE) J765, which is incorporated by reference as specified in Sec. 1910.6.

The effectiveness of these preceding stability factors will be influenced by such additional factors as freely suspended loads, track, wind, or ground conditions, condition and inflation of rubber tires, boom lengths, proper operating speeds for existing conditions, and, in general, careful and competent operation. All of these shall be taken into account by the user.

The following stipulations shall govern the application of the values in paragraph (c)(1)(i) of this section for locomotive cranes:

Tipping with or without the use of outriggers occurs when half of the wheels farthest from the load leave the rail.

The crane shall be standing on track which is level within 1 percent grade.

Radius of the load is the horizontal distance from a projection of the axis of rotation to the rail support surface, before loading, to the center of vertical hoist line or tackle with load applied.

Tipping loads from which ratings are determined shall be applied under static conditions only, i.e., without dynamic effect of hoisting, lowering, or swinging.

The weight of all auxiliary handling devices such as hoist blocks, hooks, and slings shall be considered a part of the load rating.

A substantial and durable rating chart with clearly legible letters and figures shall be provided with each crane and securely fixed to the crane cab in a location easily visible to the operator while seated at his control station.