Dymech became involved with this trailer upgrade program as a design-build contract for the Department of National Defence. To increase versatility in the field, the original equipment, a fleet of 18 flatbed gooseneck semi-trailers, needed to be upgraded from 25 tonne capacity to 35 tonne capacity.

The on-road/off-road capabilities of the trailers had to be preserved, as well as the ability to work with both the standard transport hitch height of 49 inches and the higher hitch height of 64 inches found on DND’s HLVW 6x6 off-road trucks.

A 3D model of the original trailers was done using Pro/Engineer modeling software and a DND supplied drawing package. The assembly consisted of over 300 parts in over 75 sub-assemblies.

The model was used to run Finite Element Analysis to study how the increased load would affect the trailers structurally. Stress distribution diagrams were produced from these studies to identify weak areas in need of reinforcement or replacement.

An added source of complexity was the fact that the gooseneck trailers are hydraulically controlled to allow positioning in several configurations. Dynamic analysis to determine the load conditions during movement was done using Pro/Mechanica software.

Once redesign was complete, Dymech built a prototype and completed several real world tests that closely mirror the anticipated field use of the equipment. Real time data was collected through bi-axial strain gauges and analysis software.

The entire fleet of trailers was upgraded with new suspensions, axles, wheels and tires. The hydraulic system was overhauled and new diesel engines were installed along with new valves and cylinder rod-ends. The electrical system was completely replaced. Structurally, additional links in the gooseneck, as well as reinforcement plates and gussets were fabricated and installed as required.