. It wasn't my intention to derail an interesting thread. 
I'll start a new thread up in the lounge section when I get the pics sorted out.This a 158 foot bridge girder and there is an 18 horsepower Kohler engine that operates the hydraulic system for the 4 axle trailer to oscillate. Operated by the driver with a toggle switch on the gearshift. Left, right and hopefully straight. I started hauling this stuff in 1977 thinking I was already an experienced big rig jockey. Got a lesson in humility.
Back on topic.