Since delving into Marmon’s history for the CC on the Marmon Sixteen of the depression years, I’ve come across several references to an earlier Marmon innovation, one that pretty much has been consigned to the dustbin of history: the Double Three-Point Suspension system. It is a fascinating and unique concept in the building of an automobile, and I simply cannot let it go without sharing it.
Howard Marmon was an engineer’s engineer, never content to take the simple or cheap way out. One vexing problem for early auto engineers was the need to accommodate harsh road conditions. The bad roads of the 20th Century’s first decade could exact a terrible toll on a car’s structure, particularly given the poor quality of contemporary metals.
Marmon’s solution was to build the car with two frames of a roughly triangular shape. The bottom frame mounted to both front wheels, and also to a central point on the structural differential case. The resulting rigid structure meant that the engine and differential were always aligned, thus eliminating the need for universal joints on the propeller shaft.
The second triangular frame, which supported the body, was mounted at both rear corners and to a central point on the front of the lower frame. There is a fabulous discussion of this innovation, accompanied by some wonderful demonstration pictures, in a Motor magazine from 1905, which you can read here.
Such an elegant, yet complicated and expensive, solution. I would imagine that the design became obsolete as the quality of American roads improved, since I’ve never heard of such a system being used anywhere else. I’d also think that body lean would become a problem at higher speeds. Might some of our readers know better? In any case, such an interesting concept is too good to be allowed to sink back into the depths of forgotten engineering innovations.
This may have been taken from steam locomotive practice. Modern steam locomotives almost all used a three-point suspension system that sounds like half of this setup.
Sounds like an overcomplicated X-frame to me, but can’t really tell without pictures. Would have given `frame flex’ a whole new meaning.
That is wild, and fascinating. The engine-transmission swings with respect to the cabin, if I understand correctly. The body around the engine must have had room to accommodate that? How about the gearshift? Crazy.
Only the rear of the body swings.
Engine, trans and rear end are all mounted on the upper frame, which does swing with the front wheels. See fig. 4 in the Motor article Jim linked to.
Cabin is mounted on the lower frame, which swings with the rear wheels.
The link only brings up 3 small text excerpts for me.
Interesting in principle, but it does raise a number of questions, like Mike’s. Sounds like it’s more suited to a serious off-roader. I’m not surprised that it didn’t get developed further.
This is like a modern design, the BugE, a very light electric three-wheeler made near Eugene by Mark Murphy, designer of the Nevco Gizmo (CC here).
BugE’s front chassis is a solid axle between the front wheels and long swing arms to the rear third of the car. The driver’s seat, power train and rear wheel are mounted on the rear frame. A single spring in front connects the two, suspending the front axle and allowing it to pivot. A bump on one side is divided by two by the axle, like Marmon’s chassis.
In later models (not shown on this picture) the rear wheel has a spring suspension at its attachment point. BugE has two body parts, fairing/fenders/roof attached to the front chassis, and a floor pan with rear fender mounted on the rear chassis.
How about that. (By the way, I test-drove a friend’s BugE even though its motor was running badly. It immediately convinced me I wanted a real car here in the Big City. Thus the electric Miata project.)
It sounds similar to the Model T suspension arrangement, and makes a lot of sense in that the chassis would not be subject to bending loads as they would simply pivot/rotate instead about the other 2 fixed points.
Rob Gray’s “Wothehellizat” (sp?) International 6×6-based motor home used the 3-point principle for mounting the motor home body behind the cab, with a single mount at the rear allowing the chassis to flex but not affect the body.
Being a Mopar guy, i recognized the Marmon frame immediately:
Wow – this one is completely new to me. And so cool! That must have been one whale of a center bearing to keep from breaking. I wonder what these felt like once that bearing started to wear?