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HANS ADOLPH MAUCH 1906-1984 BY EUGENE MURPHY A MAJOR CONTRIBUTOR TO rehabilitation engineering, a dis- tinguishec! engineer in several other areas, ant! a strong per- sonality, Hans Aclolph Mauch repeatedly predicted he would live to be a hundred years oIcI. Tall, tough, and an advocate of vigorous exercise, at age seventy-seven he worked long hours. Instead of quiet relaxation, he and his wife undertook such major adventures as a trip arounct the world, including some days and nights on the Trans-Siberian Express in 1983. He seemed in excellent health when he went to his labo- ratory as usual the morning of January 13, 1984. Yet, sud- cienly, he colIapse<1 from a massive stroke. After lingering a week in intensive care, he died on January 20, 1984. Fortunately, the S-N-S, his well-known hydraulic artificial knee designed to control both swing and stance phases of walking for above-knee amputees, was a well-establishecl product here and abroad (more than 12,000 had been sold). Voluntarily, Mauch had progressively lengthened the war- ranty perioc! to two years on this ingenious, complex, yet de- pendable mechanism. He had also made plans for three of his associates to attend regional meetings of the American Orthotic ant! Prosthetic Association in April 1984 to introduce new variants of the knee that might broaden the possibilities for prescription and especially to announce the availability of the long- 259
260 MEMORIAL TRIBUTES awaited Mauch multifunction hydraulic ankle joint. He had deliberately planned that the presentations by these younger men would emphasize the point that the future of Mauch Laboratories clici not depend solely on his own health. In- deed, Mrs. Mauch (Ion" a director of the company) has since taken over the presidency, employees have been purchasing stock, and the recently expandect plant building has been equipped with modern machinery that includes three computer-controlled machine tools. Hans Mauch was born in Stuttgart-Bad Cannstatt, Ger- many, on March 6, 1906. He was educated in mechanical, electrical, and electronic engineering at the technical univer- sities of Stuttgart ant! Berlin. He received the advancer! cie- gree of Diplom Ingenieur at Berlin in 1929, where he was in the top two percent of his class. One of his professors was Georg Schlesinger, who had con- tributed so much to German work in prosthetics cluring World War I, work that included writing a third! of the classic German text Erstozglieder und Arbeitshilfen. Yet the contact ap- pearect to have no immediate influence on Mauch's interests. He began his studies for the doctorate in engineering, but dropped them when he found that his choice of a thesis sub- ject had been preempted by another dissertation at a differ- ent university. He took a position with E. Zwietusch & Company in Berlin in 1930 and worked until 1935 on methods for the control of pneumatic conveyors, which were then widely used not only in department stores ant! hospitals but also to carry mail in large cylinders from one post office to another in many cities. He was in charge of research ant! development efforts involving automatic conveyors and sorters; these efforts in- cludec] the clevelopment of a method by which each cylinder would carry an easily changed, predetermined cocle that, de- spite unpredictable rotation and high velocity, could be read automatically and signalecl ahead to set switches that wouIcl divert the capsule to its correct destination. Mauch was employed as a civilian engineer in the German
HANS ADOLPH MAUCH 261 Air Ministry from 1935 to 1939. He left to establish his own consulting engineering office in Berlin, which he headed un- ti! the end of World War Il. He developed testing equipment and aviation and automotive engines and accessories; he also acted as a consultant to the German Air Ministry, where he was later placer! in charge of the terminal development of the V-l buzz bomb, the first guiclecl missile. He knew, and sometimes differed with, many of the top German engineers of the period, including Wernher van Braun. Mauch's thirc! major consulting activity was original re- search and development in the fields of aviation medicine and prosthetic crevices. In this bioengineering sector, Hans Mauch cooperated closely with UIrich K. Henschke, a racliol- ogist with a Ph.D. in physics. Head of the Aeromectical Insti- tute in Munich, Dr. Henschke worked on a variety of physi- ological problems. After WorIct War Il. the U.S. Air Force assemblect many top German scientists ant! engineers at Heidelberg. There, Henschke ant! Mauch collaborated on an important chapter, "How Man Controls," of a two-volume work, German Aviation Medicine World War ~ . This chapter was a pioneering effort in what later became known as the fields of cybernetics and human factors engineering. Henschke and Mauch also as- sembled an extensive bibliography of German work on arti- ficial limbs, designed a metal artificial leg that was intended for mass production of components and easy assembly to an individually fitted socket, ant! constructed! a series of moclels illustrating various concepts for stabilizing the knee joint of an above-knee prosthesis. In March 1946 the U.S. Army surgeon general sent a team to Europe to survey artificial limbs. In addition to important information on various crevices and procedures including the suction socket leg and cineplastic surgery to control arms, the team brought back the Henschke-Mauch bibliography and the concepts they developed involving knee control. Subse- quently, Henschke and Mauch went to Dayton, Ohio, late in 1946, to work as civilian employees at the Aeromedical I;ab-
262 MEMORIAL TRIBUTES oratory of the Wright Air Force Development Center. Yet, they were able to devote only a small portion of their efforts to prosthetics. Later, Mauch and several others workoct eve- nings and weekends in the basement of his small home with support by the Veterans Administration through its National Academy of Sciences' contract. Hans Mauch became a naturalized U.S. citizen in June 1955. He left the Aeromedical Laboratory in 1957 to set up his own organization, which was incorporated in 1959 as Mauch I,aboratories, Inc. The company engaged in research, development, ant} manufacturing in the biomedical engi- neering field. Except for a ciassifie(1 project to develop a novel space suit for the Air Force ant! NASA, which the company performed from 1959 to 1964, all of Mauch's work until the micI-1970s was devotect to rehabilitation projects sponsored by the Vet- erans Administration in coordination, through various Na- tional Research Council committees, with projects of other agencies. In recent years, after termination of his VA con- tracts, further improvements in the company's devices were made by Mauch as proprietary (developments. After exhaustive development and evaluation efforts that culminated in a nationwide clinical trial, the original Henschke-Mauch Model A semivoluntary stance-and-swing hydraulic leg for above-knee amputees was shortened, re- finecI, and renamed the S-N-S. A simpler Mocle} B to control only the swing phase was producer! briefly in 1963; it has been refined and is currently soil! as Mode} S. Several other companies procluced swing-phase units under the Mauch patent, which was assigned to the VA and licensed to others without royalties after training at Mauch Laboratories. The Mauch swing control provides programmed resis- tance that automatically varies with knee angle and walking speed, plus the possibility of independent adjustment of re- sistances to flexion anal extension. The stance phase control always allows extension, but automatically imposes a high (but acljustable) resistance to knee flexion except after a brief
HANS ADOLPH MAUCH 263 application of a hyperextension moment, normally after the heel leaves the ground. The rigid locking of the device is normally undesirable (the residual limb could be injured after stumbling), but it can be obtained voluntarily if desirer! for example, for pro- longed stancling or for driving an automobile with flexed knee. Conversely, very low resistance to flexion can also be ensured for bicycling. These knee control features are supe- rior to other brakes and locks that have been clisclosecl in literature and patent applications here and abroad for well over a century. The S-N-S is the sole survivor of many years of effort by numerous capable engineers ant] interdisciplinary teams supported by substantial government projects. The genius, persistence, anct vision of Hans Mauch are demonstrated by his eventual success with the S-N-S, the recent acceptance of the hydraulic ankle, and his yearning to attain a truly volun- tary yet subconscious control of swing-and-stance phase movement. Although this memoir focuses on Mauch's contributions to hydraulic lower limb prostheses, he made thoughtful, inge- nious contributions in many fields, including aviation anc! aviation medicine, space suits, and the human factors aspects of displays and controls. Mauch was the inventor or coinven- tor of more than eighty patented inventions in nine countries and the author or coauthor of numerous papers and reports. Uncler VA contract, he cleveloped several types of personal reading machines for the blind, another area he ant! Dr. Henschke hac! explores! in Heidelberg. His audible-output Stereotoner clirect-translation reacting aid, which was smaller, lighter, and lower in price than the wiclely known tactile-output Optacon, reached limited commercial procluc- tion. Hans Mauch was elected to the National Academy of En- gineering in 1973. He served on its General Engineering Peer Group from 1976 to 197S, and he consistently attended the academy's annual meetings. He also served for a quarter
264 MEMORIAL TRIBUTES of a century on many National Research Council committees and working groups in prosthetics. He was a consultant to the U.S. Air Force and to the U.S. Department of Health, Education, and Welfare. In 1944 he received the Knight Cross to the Merit Cross from the German Air Ministry, the highest nonpolitical dec- oration for civilians. The U.S. Air Force awarded him the Outstanding Civil Service Commendation in 1956 and the Outstanding Inventor Award in 1960. Hans Mauch married Austrian-born Tatjana Schmitt in 1948. She also came to the United States to work for the U.S. Air Force. They hac! three daughters. A brilliant, well-educated, cultured man, Mauch was a cre- ative inventor and developer, a valuable member of commit- tees and councils, and a clelightful friend. Sometimes a naive suggestion to him wouIct bring the rebuff, "We already thought of that in Heidelberg!" or he would produce an old notebook containing a similar sketch and the record of the notion's failure. Nevertheless, he would explore suggestions carefully and accept good ideas or clata. Another able engi- neer once observed, "The trouble with Mauch is that he's a perfectionist!" Well, what's so back about that, especially when his work was offered to the consumer at such a surprisingly reasonable cost?