This workshop requires the reader to consider the CG (center of gravity) of a load and the desired weight distribution to the tractor and trailer axles respectively. Often a rigger and truck driver must work together to land a load which produces a desired axle loading allowing the truck and trailer to legally travel over the road. In this example, the truck driver would like to end up with 22,000 lb on the driving axes and 18,000 lb on the trailer axles. The question is: Where do you place the load and in which orientation to achieve the loading requirements?
Study the information in the diagram, referring to the panels from the Journeyman and Master Rigger Reference Cards pictured below. Assume a frictionless system. See if you can arrive at the best solution of the three loading options provided. The answer is provided below.
Journeyman Rigger's Reference Card Panel 2:
Master Rigger's Reference Card Panel 9:
Assignment: Place the package where it produces proper loading for the rear and driver axles.
Loading Options:
A) Place the electric motor end of the package 1.5 ft from the trailer's rear bumper.
B) Place the pump end of the package 2.5 ft from the trailer's forward end.
C) Place the electric motor end of the package 4.5 ft from the trailer's rear bumper.
The best solution to achieve proper axle loading is Option # _____ .
Happy trails to all my crane and rigging friends,
Mike Parnell
ITI-Field Services
P.S. This article was originally published in The Professional Rigger Newsletter - Rig Right, Load Right!.
Workshop Solution:
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