Origin of the name "rocker panel"

What is the origin of the name “rocker panel”?

Good question to which I likely don’t have the correct answer but here goes anyway:
I’m going to hazard a guess (use my imagination) that the term came from old-timers (year??) off-roading and getting stuck on rocks while attempting to climb over them.

The lower body support being light metal would buckle and the result would be a ‘rocking’ motion.

There are rigid rocker panels (available aftermarket) that can be attached to the vehicle over the vehicle’s existing rocker panels.

I just so happen to have institutional access to the Oxford English Dictionary Online at the moment, so here goes…

They have the use of “rocker” as “the false bottom beneath the bottom framing, intended to give greater height” on a carriage going back to 1794 and it’s use in reference to an automobile in a body repair manual from 1921.

I’m suspecting that it’s origins have to do with the definition of “rocker” which means “one of the pieces of wood with a convex under-surface fixed to each end of a cradle, to the legs of a chair, or any other thing, in order to enable it to rock”.

So I’m imagining that the wood parts below the passenger area in a carriage looked like the “rockers” on a rocking chair, and the term was carried over to old “horseless carriage” type cars and then to more modern bodied cars.

Maybe the first one was used to prevent rocks from damaging a serious part of the body.

Totally correct answer.

The rocker is provided to give proportion to a horse driven carriage since the actual comfort dimensions for passengers were considered inelegant. Therefore the box was drawn first and curves sculpted (with French curves) to provide an eye appealing design. The rocker covered the full floor depth required for passengers in the center of the carriage.

The rocker term refers to a child’s cradle not a rocking chair, in original horse coach building terminology the side of the coach is called the front, it’s design axis therefore resembles that of a rocking cradle.

  • now only a Brit would know that…

For those referring the term back to the days of horse drawn carriages, let me suggest another possible explanation.

For centuries horse drawn carriages were coaches suspended using leather straps as hangers. The straps were attached to the undercarriage (what we’d now call the chassis) and the coach simply hung on top of the straps. The rocking motion produced by this design may have been the origin of the term rocker panel.

Scudder, with respect let me suggest that the hanging of the coach from the straps may have been the origin of the curved bottom design (elimination of stress points that would be in the straps with a flat bottom design) rather than simply aesthetics.

Just another theory.

I think it originated in the fifties when the first rock music festival was held. The adjudicators were called a “Rocker Panel”.

How did they migrate to under cars? Were they thrown under?

  • from “A Practical Treatise on Coach-building” by James W. Burgess published by Crosby Lockwood & Co London in 1881.

"Proportion in carriages applies to both form and colour; as regards form, it regulates the sizes of the various parts so that the whole may harmonise, and dictates the adoption of contrivances for lessening the apparent size of those parts
which would otherwise be unseemly. Thus, the total height which is necessary in the body for the comfort of the passengers is too great for the length which it is convenient to give it ; therefore the total height is reduced, and to give sufficient leg room a false bottom is affixed by means of convex rockers, and which, being thrown back and painted black, cease to form a portion of the elevation ; they are, -like a foundation, out of sight, and thus the proportion of the front view (the side is called the front in coach-builder’s parlance) is preserved. In painting the body of a coach or chariot, it is customary to confine the ground colour to the lower panels and to paint the upper ones black, all except some stripes on the upper part of the doors. Now, inasmuch as colour in…

Life’s way too short to type the whole book.

Cool. I bow to your research.

That would explain the term “rocker panels” currently used to hide those portions of the chassis under the passenger cabin.

Most terms applied to cars comes from the horse drawn carriage days. Dashboard was originally the board in front of the passengers that kept mud from the horses hooves from being slung on them when the horses started to dash. Cab is short for Cabriolet which was a type of carriage usually used for hire.

I suspect this thread has also uncovered the origin of the term “undercarriage”.

as well as coupe and phaeton