It is well known in the tree care industry that operators can become caught or snagged by material entering a wood chipper. The consequences can be devastating. On commercial wood chippers with mechanical infeed systems, a caught operator can be pulled into the machine by the infeed system. Due to the speed of the infeed system, once an operator has been caught there is a limited window of time before serious injury or death can occur. Commercial wood chippers commonly pull in branches at speeds of 20 inches per second (50.8 centimeters per second) or faster. Therefore, caught operators may have no more than a few seconds to either free themselves from the branches or activate a device to stop the feeding mechanism. As an operator is being pulled into the chipper toward the chipping mechanism, various factors can limit the caught operator’s ability to access or activate a feed-stop device. Consequently, operators are sometimes unable to save themselves from catastrophic injury or death. This paper analyzes the hazards associated with wood chipper accidents and assesses the effectiveness of various safety devices intended to protect operators from this danger. The investigation includes a historical review of wood chipper safety devices and ultimately reveals the importance and effectiveness of feed-stop devices that can be passively activated by an operator who has become caught. The paper addresses commercial wood chippers with mechanical infeed systems.

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This paper will examine the accelerations present during the operation of stand-up forklifts. Forklifts, or powered industrial trucks, are typically operated from 1 of 2 postures. Forklifts are either operated from a seated posture or a standing posture. Previous research has focused on the threshold of acceleration at which a standing forklift operator will be unable to maintain postural stability, but did not detail peak and average accelerations generated by forklifts during typical turning maneuvers. This paper will detail the accelerations generated by stand-up forklifts during typical operation from a theoretical examination of vehicle dynamics and present experimental data acquired during stand-up forklift testing. This paper will further examine performance required by consensus and industry standards, industry practice and the safety implications of stand-up forklift acceleration. The record of serious lower leg injury associated with stand-up forklifts, reports of ejection or loss of balance from the operator and data regarding acceleration present in the operator compartment support the use of a door for stand-up forklifts.

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In 2004, a report issued by the National Institute of Occupational Health and Safety (NIOSH) evaluated a fatal stand-up forklift accident where a warehouse forklift operator was crushed against a rack beam after it intruded into the operator’s compartment. One of the recommendations of the report was that “Manufacturers of stand-up reach forklifts should include vertical framing or posts at the rear corners of their machines, from the operator’s console to the overhead guard, to protect the operator from horizontal components entering the operator’s station 1.” Other published studies have also recognized the risk associated with the hazard of a horizontal rack beam entering the operator’s compartment of a stand-up forklift. It has been previously reported that there have been at least 250 incidences of horizontal intrusion as of June 2008 2. The ANSI B56.1 “Safety Standard for Low Lift and High Lift Trucks” has recognized such guarding as permissible since 1993, and almost all stand-up forklift manufacturers have made such guarding standard equipment. The evaluation that is the subject of this paper is related to the fatal horizontal intrusion incident involving a stand-up lift truck (forklift) operated by a 44-year-old male.