Evolution of Narrow-Aisle Stock Picker Forklifts


Expertise Includes:

    • Aerial Lifts
    • Failure Analysis
    • Industrial Accident Reconstruction
    • Machine Safeguarding
    • Products Liability
    • Vehicle Mechanical Failure
    • Water & Sewer Systems

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.

As the technology has changed, the challenges for operator safety must be a foremost consideration in the operation of the warehouse and the design of the equipment. Some of these considerations are:

  • Higher storage rack heights have a great effect on the stability of lift trucks. Racks should be designed and consistently utilized with higher weight items reserved for lower racks. Know the weight of your load before lifting.
  • For lift trucks where the operator is elevated with the forks, the operator must utilize fall protection. Since 2013, fixed length, non-absorbing lanyards are no longer allowed; additionally, a body belt is no longer allowed for operators weighing more than 220 lbs. OSHA has stated a strong preference for harnesses over belts for all operators in these applications. If the operator weight exceeds 220 lbs., the lift capacity of the lift truck must be reduced by his weight.
  • Collision avoidance devices greatly enhance the safety of lift trucks operating in confined operating spaces. Devices are commercially available for avoiding collisions with overhead doors or fixed objects in aisle spaces. For multiple lift trucks operating in the same space, additional devices are now available for collision avoidance with other trucks. Whereas in the past, truck collision avoidance relied upon flashing beacons or the diligence of the operator in sounding his horn at blind intersections, drive-by-wire technology may be employed to reduce reliance on the operator. Collisions involving an operator on an elevated load can have tragic results.


It is important to view the technology selected for operator protection as a system. For example, if the lift trucks in a very narrow-aisle warehouse are retrofitted with drive-by -wire steering, the operator will gain confidence that watching where he is going is not quite so critical. If those same lift trucks are equipped with seats that swivel to match the direction of travel, the operator may be even less likely to focus on travel direction. If these trucks were additionally fitted with brake-by-wire technology, collision avoidance would be enhanced, and perhaps avoid the fatalities such as occurred in a case investigated by the Warren Group where steering-by-wire was employed without brake-by wire.

Roger Davis, a senior consulting engineer at The Warren Group, is a licensed professional engineer in South Carolina, North Carolina, Alabama, Georgia and Mississippi. He holds a Bachelor of Science in Mechanical Engineering and a Master of Business Administration from the University of South Carolina. Roger is a certified fire and explosion investigator and certified vehicle fire investigator. He is an accomplished gas and diesel engine mechanic and has more than 30 years of experience with hydraulic plumbing and piping issues.  His expertise also includes property damage and personal injury investigations involving municipal utilities.  Roger has investigated claims and injuries ranging from pressure piping system failures and material and personnel handling equipment to large engine failures and fires involving machinery, generators and vehicles.

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