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Subchapter 7. General Industry Safety Orders
Group 13. Cranes and Other Hoisting Equipment
Article 93. Boom--Type Mobile Cranes

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§4923. Load Rating Chart.

(a) A durable load chart with clearly legible letters and figures provided by the certified agent shall be securely fixed to the crane in a location clearly visible to the operator or within reach of the operator while at the control station. The chart shall contain a full and complete range of crane load ratings, consistent with the manufacturers' recommendations, at all stated operating radii or boom angles and for all permissible boom lengths, jib lengths and angles, also alternate ratings for use and non-use of optional equipment on the mobile crane, such as outriggers and counterweights which affect ratings. The chart shall also contain essential precautionary or warning notes relative to limitations on equipment and operating procedures, including indication of the least stable position. In addition, no crane shall be rerated unless such rating changes are approved by the certified agent. Load ratings shall be expressed in terms related to method of measuring boom angle and length or lifting radius.

(b) Where boom or jib ratings are limited by structural competence, such ratings shall be clearly shown and emphasized on the rating charts.

(c) Load ratings where stability governs lifting performance.

(1) 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 (2) and (3).

                                                 Type of Crane Mounting
 Maximum Load Ratings                             (% of Tipping Loads)                                                                
Locomotive, without outrigger (stabilizer) support1  
                Booms 60 feet or less............................... 85 
                Booms over 60 feet.................................. 852
Locomotive, using outriggers (stabilizers) fully extended and set... 80 
Crawler, without outrigger support.................................. 75 
Crawler, using outrigger fully extended and set..................... 85 
Wheel mounted using outriggers fully extended and set, with wheels  
                off supporting surface.............................. 85 
Commercial truck vehicle mounted crane with stabilizer
extended and set.................................................... 85 
Wheel mounted without outrigger support............................. 75 

NOTE: 1. As a precaution while testing for free ratings, outriggers should be loosely applied; rail clamps should not be used.

NOTE: 2. The difference between the backward stability moment and the forward moment resulting from the load should not be less than 30,000 lb-ft with the backward stability moment being the greater.

(2) The following stipulations shall govern the application of the values in (1) for locomotive cranes:

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

(B) The crane shall be standing on track which is level within one-percent grade.

(C) 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.

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

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

(3) Stipulations governing the application of the values in (1) for crawler, truck and wheel-mounted cranes shall be in accordance with the Crane Load-Stability Test Code, SAEJ765, 1969 or 1980 as applicable.

NOTE: 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.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: 142.3, Labor Code.


1. Amendment of subsection (a) filed 2-13-75; effective thirtieth day thereafter (Register 75, No. 7).

2. Amendment of subsection (a) filed 5-1-81; effective thirtieth day thereafter (Register 81, No. 18).

3. Amendment filed 8-29-86; effective thirtieth day thereafter (Register 86, No. 39).

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