Treadmill entrapment injuries have been long-known and continue to make headlines today. These incidents can be prevented by the implementation of a relatively simple fixed barrier guard, which has also been long-known.
In this article, Industrial Engineer Harry Ehrlich discusses the inrunning nip point hazard that exists between the moving belt of the treadmill and the floor or other stationary object, and the manufacturer’s responsibility to protect people from that hazard.
TREADMILLS & CHILDREN: ENTRAPMENT INJURIES – EXPERT OVERVIEW
WHY THESE INJURIES OCCUR, AND HOW TO PREVENT THEM
If not adequately guarded, a treadmill designed for residential or commercial use can pose the same hazards that exist in industrial conveyor systems. The conveyors found in treadmills typically consist of a moving belt supported by a metal bed. The belt is looped around two pulleys (rollers); a drive pulley and a tail pulley, and is motor driven.
The hazard present on belt conveyor systems is the inrunning nip point hazard. Wherever parts rotate over, under, or near a stationary object, or wherever machine parts rotate in contact with or near each other, an inrunning nip is formed. The danger of an inrunning nip hazard is that it draws people in and makes it difficult to withdraw entrapped body parts.
While the configuration of treadmills and industrial conveyors is similar, the treadmill poses a unique hazard to children that is not present in industrial conveyors. The typical inrunning nip point hazard on conveyor systems is found between the moving belt and the pulley (roller). This hazard is illustrated below.
The treadmill industry is aware of the inrunning nip point hazard shown above and guarding is typically provided on each side of the pulley, denying access to the hazard. However, the treadmill poses a secondary inrunning nip point hazard, unique to this equipment. While industrial conveyors are typically installed at a height of 30 inches or greater, the conveyor mechanism of a treadmill is located just above floor level, thereby introducing the secondary in-running nip hazard between the moving belt and the stationary floor.
Absent an adequate guard that denies access to the hazard, hands, arms, or other body parts may become entrapped and pulled into and beneath the machine resulting in serious injuries including, but not limited to, friction burns, deglovings, and crush injuries. While some manufacturers provide a guard against this secondary hazard, many treadmills remain unguarded.
The illustration below shows the feasibility of a safer alternative through the provision of a relatively simple fixed barrier guard.
HAZARD EXPOSURE WITH RESPECT TO CHILDREN
Adults will generally avoid contact with this secondary hazard. However, it is foreseeable that children will play on the floor and find themselves in proximity to the hazard. Children are known to place their hands and fingers into openings and to squeeze into or through openings.i Given the serious nature of the hazard and the foreseeability of children present in the home, it is essential that manufacturers provide protection against the hazard.
TREADMILL & PRODUCT SAFETY INVESTIGATIONS
The experts at Robson Forensic have investigated incidents related to the use of treadmills and other consumer/industrial products. The experts involved in these investigations vary based on the specifics of each incident but may include mechanical and industrial engineers, electrical control experts, and scientists specializing in materials science.
Submit an inquiry to connect with one our in-house experts to discuss your case.
Harry has personally investigated conveyor mishaps, including treadmills. Having worked as an Industrial Engineer since 1978, he has been responsible for the design and manufacture of consumer products, as well as commercial and industrial equipment. Harry has had extensive experience in the area of compliance with safety standards. He has worked closely with Underwriters Laboratories, Canadian Standards Association, as well as overseas safety agencies. Harry is a voting member of ASTM and has served on ASTM and ANSI workgroups in the development of national consensus standards.
i. Human Factors Design Handbook, 2nd Edition, Woodson, Tillman and Tillman, Behavioral Expectancies for Children, McGraw Hill, 1992.