Forensic Engineers and Consultants

Archive: Cranes, Hoists, Lifting and Rigging

Load Holding Valves in Hydraulic Cranes

Hydraulic cranes absolutely rely on the integrity of their high-pressure fluid systems for safe operation.  A crane can become out of level when an outrigger cylinder leaks over time, possibly leading to a tip over.  A boom can collapse if a hydraulic hose ruptures.  It is not possible to absolutely prevent hydraulic cylinders from developing leaks or prevent hoses from rupturing during the life of a typical crane, therefore crane manufacturers provide load holding valves at key components to prevent these dangerous incidents.  In fact, ASME B30.5, Mobile and Locomotive Cranes, requires load holding valves or equivalent devices at outrigger cylinders, boom support cylinders, and boom telescoping cylinders. Read More

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Crane Incident Handbook

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Cranes are powerful lifting devices that we see everyday in construction areas, shipping terminals, and industrial sites. They are so common that we often pass by them with little thought. Cranes, however, can sometimes become involved in incidents that injure people or damage equipment. Read More

Not Falling for Your Job?

Periodically, Warren Engineers and Consultants are asked to perform inspections that require work at raised elevations. Typical jobs and tasks include climbing on commercial and residential roofs with steep pitches, working on scaffolding, climbing from one level to the next at a fire or industrial loss scene, riding in the buckets of lift equipment, and inspecting exterior structural elements such as windows and masonry.  Read More

Crane Incident Handbook

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Cranes are powerful lifting devices that we see everyday in construction areas, shipping terminals, and industrial sites. They are so common that we often pass by them with little thought. Cranes, however, can easily become involved in incidents that injure people or damage equipment. Read More

Wind Turbine Rotor Overspeed at Wind Energy Park

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A wind turbine was being erected as part of a small wind energy park.  The wind turbine tower and the nacelle housing the generator were successfully installed.  The three-bladed rotor assembly was installed and connected to the nacelle as the last major component of the wind turbine. Read More

Crawler Crane Calamity at Cement Plant

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A production building was being constructed at a cement plant.  A large crawler crane was being used to install the pre-assembled metal wall framing of the building.  The weights and lift radii of the four wall framing sections, along with the rigging spreader and other lift equipment, were within the rated capacity of the crane. Read More

Forklift Falls off Loading Dock

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A forklift fell off the loading dock of a warehouse as it was in the process of entering a semi-trailer that was being loaded.  The forklift fell because the semi-trailer and the connected truck rolled away from the edge of the loading dock as the forklift passed over the dock leveler into the trailer.  The repeated braking forces of the forklift as it carried loads onto the trailer caused the trailer to move away from the loading dock. The semi-trailer wheels were not chocked to prevent movement away from the loading dock. Read More

Crane Pile Driving: Who Owns This Loss?

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The boom of a hydraulic crane was bent while removing temporary sheet piles at a construction site.  A vibratory hammer had been placed at the top of the sheet piles to both drive and remove the piles. The vibratory pile driving placed no significant loads on the crane boom, as that operation relied on the weight of the sheet piles and the vibration of the hammer to sink the piles into the soil.  The vibration of the hammer and the lifting force of the crane boom were needed to remove the sheet piles from the soil. Read More

Mobile Crane Ground Support

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Mobile cranes depend on stability through their outriggers. These are the four “legs” that are deployed onto soil or other working surfaces adjacent to the crane.  When a mobile crane is set up at a site, the outriggers are deployed by a hydraulic mechanism that extends the four outriggers beyond the crane body and then jack the crane free of its wheels so that it is supported by the outriggers only. Read More

Crane Balancing Act

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The operation of many cranes is a balancing act — one very similar to the childhood experience of using a playground seesaw. When the equipment isn’t properly balanced, the crane may succumb to the tipping force and fall to one side. Such a tipover is more common in mobile cranes rather than fixed-tower cranes.
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