Forensic Engineers and Consultants

Archive: Machinery and Equipment

Failure to Maintain Tow Hook Latch Results in Bystander Death

An unfortunate and tragic case that we investigated involved a commercial “rollback” recovery truck that was being used to transport a four-wheel drive diesel pickup.  The diesel pickup was not in running order with its’ engine in the bed of the truck.  Consequently, a commercial towing company was hired by the truck owner to transport the truck.  In the process of loading the truck onto the rollback, the truck came uncoupled from the winch and cable system.  The truck then rolled down the inclined bed of the rollback, running over and killing a bystander. Read More

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Water in the Light Fixtures??? How HVAC Defects Appear in Strange Places

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One of my more interesting calls and subsequent forensic investigations was regarding water accumulating inside of 2X4 fluorescent light fixtures in a suspended ceiling of a secondary school in South Carolina.

The client called and indicated that the metal chassis of the lights were sweating and generating enough water to accumulate on the diffuser lens of the lights.  Obviously, an on-site investigation was in order! Read More

Machine Guarding and Risk Assessment

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The Occupational Health and Safety Administration (OSHA) “Top 10 for 2018” violations once again have Machine Safeguarding earning a position on the list. Machine safeguarding was the 9th most cited standard as noted in the list below:

  1. Fall protection, construction (29 CFR 1926.501)
  2. Hazard communication standard, general industry (29 CFR 1910.1200)
  3. Scaffolding, general requirements, construction (29 CFR 1926.451)
  4. Respiratory protection, general industry (29 CFR 1910.134)
  5. Control of hazardous energy (lockout/tagout), general industry (29 CFR 1910.147)
  6. Ladders, construction (29 CFR 1926.1053)]
  7. Powered industrial trucks, general industry (29 CFR 1910.178)
  8. Fall Protection–Training Requirements (29 CFR 1926.503
  9. Machinery and Machine Guarding, general requirements (29 CFR 1910.212)
  10. Eye and Face Protection (29 CFR 1926.102)

(Source: www.osha.gov/Top_Ten_Standards.html)

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Unguarded Shear Point on Force Tester Amputates Worker’s Finger

A worker was injured while testing gas springs similar to the type that hold the hatchback of an SUV open. The hazard that injured the worker was an unguarded shear point. The tester contained a mounting plate that was raised and lowered by a pneumatic cylinder.

The pneumatic cylinder lowered the mounting plate while the worker’s fingers were in the hazardous, unguarded shear point. Read More

Case Study: Fatality Servicing Unsupported Excavator Boom

A mini-excavator at a job site developed a leak at a hydraulic fitting at the base of the cylinder that raises and lowers the boom. A subcontractor foreman at the site raised the boom to search for the leak. The foreman found and attempted to tighten the leaking fitting. When he did, the fitting separated from the base of the cylinder, releasing the hydraulic pressure that held the boom aloft. The boom fell and the bucket struck a nearby superintendent for the general contractor.

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Testing As Part of Gas Appliance Incident Investigation

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Equipment and appliances supplied with fuel gases like natural gas, propane and butane are a common and convenient part of most of our lives.  Such devices as gas grills and ranges, ovens, furnaces, space heaters and water heaters usually perform without incident.  However, when they malfunction the potential for incidents such as fires and explosions, carbon monoxide (CO) poisoning and burn injuries may occur. These incidents may be due to design and manufacturing defects in the product, or improper installation or operation of the device.

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Defective Vertical Baler Causes Serious Crush Injury to Operator’s Arm

I recently worked on an interesting case involving a box baler. An employee of a butcher shop put some empty cardboard boxes in a vertical box baler and pushed the control switch to compact the boxes. After the 30 by 60 inch platen weighing 851 pounds returned to its raised position, the employee reached into the open space above the bottom door on the baler and began to clear cardboard from the bale tie slots in the bottom of the raised platen. Suddenly, and without warning, the steel pin attaching the platen to the raised hydraulic cylinder rod failed. The heavy steel platen fell and crushed his arm which was outstretched over the baler door into the compaction space.

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Should I Trust My Nail Gun?

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Can you imagine framing a house with the tools of our forefathers, using hand saws and hammers, rather than power saws and pneumatic nail guns? Power tools have made the job much easier and faster, that even the amateur is well equipped for this kind of work. Read More

Improper Design Leads to Fatigue Failure In Blower Shaft

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A blower used to exhaust air from an industrial process stopped functioning when the blower wheel drive shaft fractured.  The process, and thereby most of the plant, had to operate at a reduced volume until the blower wheel could be replaced.  The blower wheel had been installed during a shutdown a week before the incident.  The blower wheel was a spare installed when the existing blower wheel was sent for scheduled remanufacturing. Read More

Evolution of Narrow-Aisle Stock Picker Forklifts

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As the cost of warehousing has increased over time, material handling equipment has evolved to allow higher density storage capacities. Narrow aisle and order picker forklifts are among the innovations that have evolved over the past 50 years to accommodate this trend. Read More

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