1、Riding on Air A History of Air Suspension Jack GieckRIDING ON AIR A History of Air Suspension Jack Gieck, P.E. Society of Automotive Engineers, Inc. Warrendale, Pa. Copyright 1999 Society of Automotive Engineers, Inc. eISBN: 978-0-7680-3800-2Library of Congress Cataloging-in-Publication Data Gieck,
2、Jack. Riding on air : a history of air suspension / Jack Gieck. p. cm. Includes bibliographical references and index. ISBN 0-7680-0454-3 1. Motor vehiclesAir suspensionHistory. I. Title. TL257.3.G54 1999 629.243dc21 99-33364 CIP Copyright 1999 Society of Automotive Engineers, Inc. 400 Commonwealth D
3、rive Warrendale, PA 15096-0001 U.S.A. Phone: (724)776-4841 Fax:(724)776-5760 E-mail: publicationssae.org http:/www.sae.org ISBN 0-7680-0454-3 All rights reserved. Printed in the United States of America Permission to photocopy for internal or personal use, or the internal or personal use of specific
4、 clients, is granted by SAE for libraries and other users registered with the Copyright Clearance Center (CCC), provided that the base fee of $.50 per page is paid directly to CCC, 222 Rosewood Dr., Danvers, MA 01923. Special requests should be addressed to the SAE Publications Group. 0-7680-0454-3/
5、99-$.50. SAE Order No. R-235To my collaborators on this book, Tom Bank and Art Hirtreiter who made air suspension possibleCONTENTS Preface vii 1. The Medium 1 2. Reduction to Practice 19 3. Model Trains . 55 4. Complying with the Gas Laws 67 5. Mutations 79 6. Wild Ride 121 7. New Era 131 8. Prolife
6、ration 157 9. The French Connection 199 10. Renaissance 209 11. Next 219 Notes 235 Index 247 About the Author 261 vPREFACE G recian chariots rode hard. As these ancient war machines rumbled over the rugged roads of Babylonia and Egypt, and later raced across the wooden floor of the Roman Colosseum,
7、every minor irregularity encountered by their solid wooden wheels was faithfully transmitted through their solid axles to the bed of the vehicle, some of the bumps imparting several gswhich may account for their drivers electing to stand rather than attempting to sit down. The first recorded efforts
8、 to achieve a modicum of ride comfort were literally “suspensions.“ The passenger compartments of seventeenth century coaches in France and England were suspended by long leather straps attached to four vertical wooden posts anchored to the box frame of the horse-drawn vehicle. The date of conceptio
9、n of this invention is said to be circa 1430, when, in the town of Kocs (from which the word “coach“ is derived), in what is now southwestern Czechoslovakia, a royal personage is said to have complained about the rough ride afforded by the wagons in which she was transported.1 Eighteenth century sta
10、gecoach passengers gratefully accepted the introduction of wooden springs (hickory was the preferred raw material), frequently in combination with leather straps, and later S-shaped iron or steel springs forged by blacksmiths of the time. By 1796, builders of a two-horse English curricle had inserte
11、d coil springs as spreaders between the tensioned leather straps to further soften the ride. Eventually, as steel became commercially available in the mid-nineteenth century, multi-leaf elliptical springs appeared on horse-drawn coaches in both England and the United States.2 But some of the authors
12、 of what passed for the technical literature of the time wrote about the promise offered by “the springiness of air itself“ as a potential medium to isolate the passenger from the road. And it wasnt long before the idea appeared in a series of patents. viiRiding on Air I first heard of air suspensio
13、n in 1947, shortly after I joined Firestone, having read Roy W. Browns SAE technical paper, “Air SpringsTomorrows Ride,“ which he had presented to the annual meeting of the Society of Automotive Engineers a decade earlier.3 Browns ingenious but hopelessly complex pneumatic system for passenger cars
14、had generated little enthusiasm in the Depression-era economy of 1936. But, unknown to me at the time, Brown and Firestone engineer Fred Haushalter were already at work with engineers of General Motors Truck Charlie Slemmons of General; as well as Herb Deist, Jack viiiPreface Hollis, Dave Thomas, Ga
15、ry Reynolds and Steve Lindsey of Firestone. Many of the books vintage illustrations are the product of the invaluable pack-rat tendencies of self- appointed historical archivists John Grafton of Goodyear and Larry Wilson of Firestone. I am also indebted to George Villec (SAEs reviewer for this book)
16、, and to Michael Soltis of Ford Motor Company for their substantial contributionsand of course, to my friends at Firestone Industrial Products, who made a major industry out of the modest business that Fred Haushalter, Tom Bank, Mike Kray, Gerry Marsh, Herb Deist, Bob Weir, Al Boyer, Mary Jean Hosie
17、r, and I started half a century ago. The history of air suspension goes back more than a century and a half, which will become apparent as we review concepts that have periodically emerged to advance the technol- ogy. It is often easy to see how one idea led to another. But in offering a chronology
18、of these developments, it is never my intention to suggest that any of these inventors deliberately plagiarized innovations from prior art. Rather, I think we see examples of technological evolutionideas whose time had inevitably comejust as similar scien- tific discoveries are often simultaneously
19、announced half a world apart. Many of these innovators might honestly confess, however, as Isaac Newton did in a rare moment of modesty, “If I have seen farther than others, it is because I have stood on the shoulders of giants.“ Jack Gieck Akron, Ohio ixCHAPTER ONE THE MEDIUM H alf a century before
20、 automobiles emerged on American and European roads, engineers dreamed of floating their vehicles on cushions of air. In 1847, the year Thomas Edison was born, only three years after Charles Goodyears rubber vulcanization patent was issued,1 inventor John Lewis was granted U.S. Patent No. 4,965 for
21、“Pneumatic Springs for Railroad Cars, Locomotives, Burden-Cars, Bumpers but the application it described was not exactly an air spring. In its May, 1847, issue, the neonate Scientific American reported that: A number of horse-drawn cabs with newly invented wheels have just been put on the road in Lo
22、ndon. Their novelty consists in the entire absence of springs. A hollow tube of India rubber about a foot in diameter, inflated with air, encircles each wheel in the manner of a tire, and with this simple but novel appendage the vehicle glides noiselessly along, affording the greatest possible amoun
23、t of cab comfort to the passenger.3 A “tire,“ at the time, was understood to mean a band of iron wrapped around the circumference, or rim, of a (wooden) wheel to reduce road wear. The very fat twelve-inch section of this original, truly “balloon“ tire suggests that it must have had a very low inflat
24、ion pressure, if any. It would be almost half a century (1888) before the Scottish 1Riding on Air Fig. 1.1 In 1847, John Lewis of New Haven, Connecticut, was issued U.S. Patent 4,965 for the first air spring made of a flexible rubber materiala “Pneumatic Spring for Railroad Cars.“ 2The Medium veteri
25、narian, John Boyd Dunlop, would develop a practical pneumatic tirewhich he initially intended for bicycles.4 Floating a vehicle on cushions of air sounds like a marvelous idea. Air suspension invokes an image of passengers and cargo flying above the road, completely isolated from any bumps on its su
26、rface. Indeed, trade journal advertisements announcing the Firestone innovation on General Motors buses in 1953 pictured a Greyhound luxury coach that had sprouted wings. Knowledgeable engineers were not impressed by the ad. Vehicle ride, they knew, is independent of the spring medium. It is a funct
27、ion of the stiffness of the springs of the vehicle (whatever they are made of), the load resting on them, and any damping devices in the suspension, such as hydraulic shock absorbersand the vehicles tires, of course. What air suspension really offers is adjustable, variable-rate springs whose stiffn
28、ess can be fine-tuned as the load in the vehicle changes. This unique advantage of air springs one that would not be realized until the twentieth centurywas disclosed in another Scientific American article, this one in June, 1861, which reported an invention by I. W. Hoagland of New Brunswick, New J
29、ersey: a “New and Improved Pneumatic Spring for railway Carriages,“ which, the magazine explained, “is easily adjustable to any degree of compression desired“ (see Fig.1.2).5 “The mechanical engineer who devised these ingenious modifications,“ the magazine article continues, “is satisfied that he ha
30、s overcome all the difficulties encountered in the use of the air spring, and . by the adoption of his improvements, the great advantages of that most perfect of all springs can be practically realized.“ Hoaglands confidence notwithstanding, those of us who struggled with the first practical applica
31、tions of air springs on buses and passenger cars in the 1950s would not have agreed. That Lewiss and Hoaglands dreams were a century ahead of rubber technology is evident in the language of their own patents. Lewiss proposal, with its deliberate redundancy of two, or even three, nesting rubberized f
32、abric diaphragms between his “respiratory chambers“ was a hedge against leakageas was his “interposing alcohol or water“ on both sides of the flexible joint, “the more effectually to prevent the escape of the air.“ Other inventors, e.g., William R. Fee, with his pneumatic “Car Spring“ (Fig. 1.3) and
33、 George. M. Alsops “Carriage Spring“ (Fig. 1.4) picture “vessels“ partially filled with water, oil, or other liquids.6 I. W. Hoaglands pneumatic spring for railroad cars, “about nine inches 23 cm in diameter, and nine inches in height“ offered a more complex solution to the “difficulty of preventing
34、 air from leaking out, either around the piston or through the walls.“ The magazine pictured a kind of boot-strap arrangement which captured the energy available in the bouncing of the suspension. In the center of Hoaglands large, primary air spring 3Riding on Air Fig. 1.2 I. W. Hoaglands 1861 air s
35、pring patent, also intended for railway carriage suspensions, had its own built-in air compressor to compensate for leakage. The bouncing motion of the suspension pumped a miniature air spring which kept the primary spring inflated. 4The Medium Fig. 1.3 To limit air leakage, William Fee partially fi
36、lled his 1858 air spring for rail cars with water. 5Riding on Air Fig. 1.4 Below the flexible diaphragm of inventor George Alsops 1859 carriage spring, the axle of the rail car was surrounded by water. 6The Medium supporting the vehicle (yet another rubberized fabric diaphragm which rolled up and do
37、wn between two concentric metal cylinders) was a tiny air spring of similar design a self-contained, jounce-actuated air compressor which kept the unit pumped up. Later inventors continued to focus on the use of liquids to prevent the escape of air. In their “Improvement in Pneumatic Springs,“ in 18
38、71, John Bevan and Benjamin Hitchcock of New York state devised a thick-walled two-convolution “India-rubber shell“ filled with “a fluid incapable of freezing“ (they suggest a mixture of glycerine and water), containing a hollow rubber ball. When the spring was deflected, the incompressible fluid sq
39、uashed the rubber ball, compressing air into a metal cylinder to which it was attached (Fig. 1.5).7 The multiplicity of precautions against leakage, graphically documented by early designers, reflects their (justifiable) doubt about the quality of the raw materials available at the time. Long before
40、 the development of multi-roll rubber calenders which uniformly “friction and skim“ high-tensile-strength nylon tire cord today, cotton fabric was rubberized (to make raincoats) by spreading a solution of rubber cement on the cloth. The coating was less than uniform, and it was often inadequately cu
41、red, because Charles Goodyear was still experimenting with his “vulcanization“ recipe. Rejecting the unreliable technology of the infant rubber industry at that time, some air spring inventors conservatively chose a sliding metal piston in a cylinder. In his 1867 patent,8 following the lead of Lewis
42、 and Fee, W. A. Dripps further hedges against leakage of his assembly by providing a liquid interface with his sliding seal. Drippss design (Fig. 1.6) is actually an early hydropneumatic spring, in which liquid is displaced into an adjacent chamber, where it rises to compress air above the liquid su
43、rface as the suspension goes into compression. To adjust the air pressure to tailor the spring to the supported load, liquid in the displacement chamber could be pumped in or bled out through a petcock at the bottom of the chamber. Prototypes of these early air springs may have been produced to fulf
44、ill U.S. Patent Office requirements of the time, but there is no evidence in the literature that any of them saw the light of day in a commercial application. The bicycle age of the 1880s and 1890s produced a complex pneumatic bicycle seat with “hollow cushions divided into communicating compartment
45、s Fig. 1.79 capable of being inflated.“ The cushions were stacked on top of each other so that compression of the top one displaced air into the lower chamber. Richard Aronstein of Goldfield, Colorado, designed a set of pneumatic bicycle springs (in combination with encircling coil springs) under bo
46、th the seat and the handlebars, with provision for displacing the air into two “air reservoirs“the interiors of tubular members of the bicycle frame. The language in Aronsteins patent reflects the need for a solution to the endless puncture problems familiar to bicyclists at the time (a vexation tha
47、t has yet 7Riding on Air Fig. 1.5 This 1871 hydropneumatic spring designed by John Bevan and Benjamin Hitchcock employed a thick, two-convolution rubber envelope filled with a mixture of glycerine and water (to prevent freezing). When the spring was deflected, the fluid squashed an air-filled rubber
48、 ball, compressing the air into a metal cylinder to which it was attached. 8The Medium Fig. 1.6 Rejecting leak-prone rubber diaphragms of the time, W. A. Dripps resorted to a metal piston with a sliding seal for his hydropneumatic spring. When the spring was compressed into the liquid-filled cylinde
49、r, the liquid was displaced into an adjacent chamber, where it rose to compress a column of air. 9Riding on Air Fig. 1.7 During the bicycle age of the 1890s, B. W. Davis designed a “pneumatic bicycle saddle“ which had “hollow cushions divided into communicating compart- ments capable of being inflated.“ The cushions were stacked on top of each other so that compression of the top one displaced air into the lower reservoir chamber. 10The Medium to disappear a century laterparticularly in California, and in other parts of the country where thor
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