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CON 243 Heavy Construction Equipment, Methods, and Materials Lecture 25 (Chap. 17) — Cranes The crane is the primary machine used for the vertical movement of construction materials.

Types of Cranes MOBIL CRANES (CRAWLER or WHEEL MOUNT) TOWER CRANES

Mobil Crane Nomenclature Mast Boom Rig Counter weight Outriggers

Counterweight jib Cab Counterweight Tower (mast) Trolley Tower Crane Nomenclature Load jib

Luffing jib Tower Crane configurations Saddle jib / hammerhead boom

Details of Tower Cranes

HOOK BLOCK HEIGHT

SAFETY OSHA Crane fatality data: Energized power lines50% Overturning19% Load dropped14% Boom collapsed12% Two-block 5%

Crane Accidents : 61.0% Overturning

Crane Geometry

Counterweight C Payload P ba Tipping Moment TM= P x a Stabilizing Moment SM = C x b For stability: TM << SM SM is constant for a given position of the platform

Over the front (front lifting) C L

Over the rear (Rear lifting) C L

C L Over the side

Crane Geometry Counterweight C Payload P ba Tipping Moment TM= P x a Stabilizing Moment SM = C x b TM = SM / safety_factor