Jacobs Ladder

[jaybee]

First of all let's specify I'm reinventing the wheel and know it. Last weekend at Iowa Speedway I had time to kill before the Xfinity race I had time to kill and had a long conversation with a guy who was stationed at a sprint car display. As I've never been around dirt cars a lot but know some of the technology I asked him about the Jacobs Ladder. He quickly replied "ah, the Watt's Link" and headed for the back of the car. That made my ears perk up, though after looking at the thing I still don't think that's the right term. Here's a video of the thing in action. The JL is the trapezoidal contraption which hooks back to the rr wheel with something akin to a ladder bar. https://www.youtube.com/watch?v=uWjq0KbsNKQ

The thing is made to be extremely light and compact, and make the axle travel almost vertically in a very narrow chassis without room for a panhard bar of any significant length, and a quick change which sits right where a traditional Watts Link should be. It works because the straps (the shiny links in the video) tilt the paddle (the ladder bar thingy) up and down at the axle mount as they cycle. The lower link points up and swings the bottom link of the paddle outward on bump, the top link does the opposite. The links are oriented to cross right in the center of the car at roll center height.



One serious issue for anything other than a circle track car...they're set up so the roll center moves up pretty dramatically as the car rolls right in order to load up the right rear. If that's inherent to the design you'd get a car which would oversteer on left turns, understeer on right turns...Great if you're Donny Schatz, not so good for anyone else. Is this necessarily the case, or can it be tamed? I ask because the positives...a compact, lightweight locating device which basically "hides" right around the axle...hold promise. Plus I just like thought experiments.

[UMI Tech]

There's a lot of adjustments on a sprint car that can't really be done to a street car. They run anywhere between 6 - 15" of stagger in the rear tires, both rear wheels can be moved in and outward on the axle and There is a separate torsion bar for each corner of the car. A sprint car drives off the turns on the left rear tire unlike most other circle track applications and has a panel on the top wing that loads the left rear tire at corner entry. In a nutshell there's enough adjustments that you can overcome that jacobs ladder design to make a car tight or loose on corner entry depending on driver preferences.

Craig