History to Houdaille Shocks
Maurice Houdaille (1880 - 1953) invented the double-action rotary shock absorber that bears his name. Exactly when he began his experimental work is unclear, but we do know that he was far enough along in 1907 to patent the two-vane pressure-balanced rotor. (Possibly because of this patent, some competitive shocks used unbalanced rotors as illustrated here.)
The concentric fluid reservoir, sealed against working pressure by a check valve, was patented two years later. The last definitive patent was issued in 1914 for the striated plugs that vent the working chambers.
The remarkable thing is that the shocks employ no high pressure seals, either at the rotor/body interfaces or at rotor shaft. Sealing is a entirely a function of the precision of mechanical fit. In comparison, a piston-type pump represents a much easier sealing problem, since the piston can be fitted with expansion rings or, as in the case of diesel injection pumps and some model aircraft engines, lapped to fit. It is interesting that the modern Kayaba rotary shock, used on certain Suzuki motorcycles, seals the rotor with elastomer pads.
Designers of most pre-1914 passenger cars assumed that the friction between spring leaves gave adequate damping at the moderate speeds these vehicles were capable of. Sports and racing cars generally were fitted with friction shocks, such as the American Hartford. Frequent adjustments were required to compensate for pad wear and changing driving conditions. Once set, the amount of damping was constant, regardless of the rate of suspension acceleration.
Hydraulic shocks appeared early and, according to one account, were fitted on the Mors car that was declared winner of the aborted 1903 Paris-Madrid race. Some form of sophisticated shock absorber would have been appropriate: the giant 10-liter machine average 65.3 mph for 342 miles before authorities intervened to halt the race. By then, more than a dozen spectators had been killed. In view of its late starting position and the frequent stops for tire changes, the Mors probably achieved burst speeds of 90 mph.
Factory racing teams were among the Houdaille’s first customers. The Sunbeam that won the 1915 Isle of Man event and the Benz that took honors in the Paris-Moscow race helped to publicize the new dampers. The French army used them on ambulances and staff cars. By the late 1920’s, Houdaille dominated the domestic market. Rolls Royce, which tested its vehicles on the excellent French road system, fitted the shocks on certain export models. A world-wide network of agents was established to serve the aftermarket. Even the lowly Model T could be retrofitted with the hydraulic shocks.
Today the automotive market has been lost, but Houdaille Lelaurin continues to manufacture rotary dampers for railcars, industrial washing machines and military applications. The Paris-based company also rebuilds shocks for vintage cars.
Domestic manufacture began in 1915 with OEM shocks for Mercer and Cunningham cars, but soon ended because of the shortage of alloy steel resulting from America’s entry into the First World War. A. B. Shutz, a well-known automotive engineer of the period, purchased the rights and resumed limited production in 1919 at his Houde Engineering plant in Buffalo, New York. The first major breakthrough came in 1923 with a contract to supply Lincoln. Pierce-Arrow, Jordan and Sterns-Knight followed.
In 1927 Henry Ford electrified the automotive world by announcing that these sophisticated appliances would be standard on the upcoming Model A. This order alone was worth an estimated 21.5 million units. Another 2 million or so Houdailles would used on the front axles of Model B and V-8 Fords until 1934 The great majority were built by Houde Engineering, although both National and Spicer made complete units and may have supplied wing shafts and other parts.
The Ford contract was followed by orders from Chrysler, Studebaker, Graham Paige, Hudson and Nash.
There are no interchangeable parts in a Houdaille shock, which probably makes it the first mass-produced automotive component to be built in this expensive and, in one sense, retrograde fashion. Rebuilding Houdaille shocks with their custom-tailored parts was not theoretically possible, although some Ford dealers tried.
Houde Engineering conducted a sophisticated marketing campaign that equated shock absorbers with social status. “And you, “ said one of the magazine ads reprinted by George Sprotte The Restorer for May-June 1979, “can have this amazing liquid-smooth comfort -- formerly the privilege of the wealthy -- for less than the cost of many make-shift devices.” Another company promotion exclaims that Houdailles give “the elite a taste of riding comfort as it ought to be!”
The manufacturer boasted that the “modern perfected Houdaille” with its “watch-like precision” was “hardly improved beyond its basic design.” In other words, the product, which had hardly changed since 1915, was too good to require development.
According to a brochure published by Houde in 1929, Maurice Houdaille “went to work in 1909 as an experimental engineer for the Rochet-Schneider Words. His hydraulic device for eliminating the recoil shock on the great 75 mm French cannons was an idea he further developed for use as a shock absorber on motor cars.” The supposed connection was reiterated in magazine advertising.
It is quite possible that M. Houdaille contributed to the later development of the weapon: he was an hydraulics expert and active during the period when France was rearming. But he could hardly have invented the technology, since the field piece was adopted in 1893, when Maurice was still a school boy. Nor does his rotary shock absorber have much in common with the double-piston, air-over-oil muzzle brake. The mention of Rochet-Schneider in the material quoted above may also be misleading, since it would be easy enough for readers to confuse the Lyons-based auto manufacturer with Schneider-Creusot, which did indeed make weaponry. As far as I can determine, there was no connection between these two companies other than the coincidence of their names. Until reorganized in 1908, Rochet-Schneider had been owned by British investors, which makes it even less likely to have been part of the French military-industrial complex.
The brochure concludes with a brief description of the manufacturing process, which was the center of gravity of the whole operation. The immediacy of the account makes one think that some production veteran sat down with the writer and explained what had been done and at what cost:
The simplicity of the Houdaille instrument might erroneously imply simplicity of manufacture. It is a fairly easy task for a good mechanic to complete a piece of work to very accurate measurements, but it takes genius to make another one just like it. And Houdaille production has progressed from a dozen a day to thousands an hour.
The challenge faced by management was to get millions of the high-precision instruments out the door in the shortest possible time. That required organization and dedicated tooling. By the late 1940s, when the market for rotary shocks dried up, the Buffalo plant was able to use its expertise to transform itself into a manufacturer of specialized machine tools.
The emphasis on production probably explains why the endemic leaks were never fixed, why steel-on-steel rotor bushings continued to be used, and why shocks were shipped with glycerin after hydraulic oils became available.
Theory of Operation