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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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§4928. Boom Hoist Mechanisms.

(a) When using recommended boom hoist reeving and with rated loads suspended, the boom hoist shall be capable of raising the boom, holding it stationary without attention from the operator, and lowering it only when coupled to its prime mover.

(b) The boom hoisting mechanism shall be provided with a clutching or power engaging device permitting immediate starting or stopping of the boom drum motion. The boom hoisting mechanism also shall be provided with a self-setting safety brake, capable of supporting all rated loads, with recommended reeving.

(c) Brakes and clutches shall be provided with adjustments where necessary to compensate for wear and to maintain adequate force in springs.

(d) The boom hoisting mechanism shall be provided with an auxiliary ratchet and pawl or other positive locking device as an added safety feature.

(e) The boom hoist drum shall have sufficient rope capacity to operate the boom at all positions from horizontal to the highest angle recommended when using the certified agent's recommended reeving and rope size.

(1) No less than 2 full wraps of rope shall remain on the drum with boom point lowered to the level of the crane supporting surface.

(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.

(f) The drum diameter shall be sufficient to provide a first layer rope pitch diameter of not less than 15 times the nominal diameter of the rope used.

(g) Automatic means shall be provided to stop drum motion when highest permissible boom angle is reached.

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


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

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