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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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§4929. Load Hoist Drums.

(a) The load hoist drum assemblies shall have power and operational characteristics to perform all load hoisting and lowering functions required in crane service when operated under recommended conditions.

(b) Where brakes and clutches are used to control the motion of the load hoist drums, they shall be of such size and thermal capacity to control all rated crane loads with minimum recommended reeving.

NOTE: Where maximum rated loads are being lowered with near maximum boom length or operations involving long lowering distances, power controlled lowering usually is necessary to reduce demand on the load brake.

(c) Load hoist drums shall have rope capacity with recommended rope size and reeving to perform crane service within the range of boom lengths, operating radii and vertical lifts specified by the certified agent.

(1) No less than 2 full wraps of rope shall remain on the drum when the hook is in its extreme low position.

(2) The drum end of the rope shall be anchored by a clamp securely attached to the drum or a wedge socket arrangement approved by the crane or rope manufacturer.

(3) Drums shall be provided with a means to prevent rope from jumping off the drum.

(4) Fiber rope fastenings are prohibited.

(d) Diameter of the load hoist drums shall be sufficient to provide a first layer rope pitch diameter of not less than 18 times the nominal diameter of the rope used.

EXCEPTION: On small cranes of less than 10,000 pounds capacity a smaller drum may be used, provided that when lifting loads the actual pitch diameter is not less than 15 times the rope diameter and the rope safety factor is not less than 5.

(e) Means, controllable from the operator's station, shall be provided to hold the drum from rotating in the lowering direction and be capable of holding the rated load indefinitely without further attention from the operator.

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


1. New subsection (c)(4) filed 12-12-84; effective thirtieth day thereafter (Register 84, No. 50).

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

3. Repealer of subsection (f) filed 6-27-94; operative 7-27-94 (Register 94, No. 26).

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