John Walter Christie (May 6, 1865 – January 11, 1944) was an American engineer and inventor. He is known best for developing the Christie suspension system used in several World War II-era tank designs, most notably the Soviet BT and T-34http://turcopolier.typepad.com/the_athenaeum/2013/01/the-soviet-command-economy-by-richard-sale.html, p. 5 tanks series, and the United Kingdom Crusader cruiser tanks, as well as the Comet heavy cruiser tank.

Early life and career Christie was born to Jacob Brinkerhoff Christie and Elizabeth Van Houten Christie in New Milford, New Jersey, in the Campbell-Christie House, on May 6, 1865. He started working at the age of sixteen at the Delamater Iron Works while attending classes at the Cooper Union in New York City. He eventually became a consulting engineer for several steamship companies and during his spare time did some work on early submarine designs. After the Spanish–American War he developed and patented an improved turret track for naval artillery.

At about the same time, he was working on designs for a front-wheel-drive car, which he promoted and demonstrated by racing at various speedways in the United States, including the Readville Race Track and the 1905 Vanderbilt Cup race. His car was knocked out of a race by a collision with Vincenzo Lancia who was at the time leading the race in a Fiat. Lancia was enraged, but presumably noticed the Christie car's vertical-pillar coil-based independent front suspension: the then unusual configuration was used subsequently for the Lancia Lambda.

He was the first American to compete in the 1907 French Grand Prix: the V4 engine of 19,891 cc that powered his vehicle was the largest ever used in a Grand Prix race, but the car was retired after four laps with "engine trouble". On September 9 of that same year, Christie was seriously injured by a crash when his car struck loose debris during a lap at Brunots Island Race Track in Pittsburgh, Pennsylvania. In a twelve-car endurance race earlier that day, scheduled to run 50 miles, the Haynes car of driver Rex Reinertson had lost its right front tire with disastrous results, catapulting into the air and landing on its roof. Reinertson was crushed beneath the car, suffering injuries (including a skull fracture) that proved ultimately fatal, and his mechanic Clarence Bastion was ejected from the vehicle and thrown through the air, breaking both of his arms and both of his legs. After ten more laps, the race was stopped so that the injured racers could receive medical treatment, and Reinertson's car was cleared off the track. Next was Christie, driving the car he had used at the Grand Prix only a few months before. He was attempting to exceed the track's lap record of 58 seconds, and due to receive a $500 prize if he was successful. Christie completed the second half of his warmup lap in only 24 seconds, so he was well on pace for a new record, but at the 1/8 mile marker of his real lap his right front wheel struck part of Reinertson's car that remained on the track. Christie was thrown from the car, traveling twenty feet in the air and fifty feet across the ground, before coming to earth. Mark Baldwin, a former Major League Baseball player who became a doctor after his retirement from professional sports, happened to be in the stands as a spectator, and he ran to Christie and administered first aid until Christie could be placed in an ambulance and taken to a hospital, a task that was complicated by the large number of spectators who had climbed down from the grandstands and moved onto the track. Christie had been knocked unconscious by the impact. He also sustained a broken left wrist, a cut on his right eye from the broken glass of his goggles, and a significant injury to his back. Doctors who treated Christie expressed concern that he might be crippled as a result of his injuries, or lose the sight of his damaged eye, and news of his accident was kept from his wife, who was herself seriously ill at their home in River Edge, New Jersey. Christie remained in the St. John's Hospital until September 19, at which time he was discharged and returned to New York."Walter Christie Coming Home", The New York Times, September 20, 1907, page 10. Walter Christie built the 1909 front wheel drive Christie Racer driven by Barney Oldfield, Master Driver of the World and America's Legendary Speed King, the first to lap the Indianapolis Speedway at more than 100 MPH. on May 28, 1916, speed: 102.623 MPH, time: 1.27.70.

Christie now switched his efforts from automobile racing to developing his front wheel drive New York taxicab design. With benefit of hindsight, the taxi design's importance came in large part from the fact that it incorporated a transversely mounted engine/transmission assembly, applying a basic architecture that would be greeted as revolutionary when applied by Alec Issigonis in the British Motors car BMC Mini fifty years later. However, in 1909 designs were less standardized than they would become by 1959, and for Christie the vehicle's more striking novelty was that the entire "forecarriage", incorporating all the major mechanical components, could be detached and replaced in "less than one hour". The car's radical design was to necessitate the manufacture of many complex components in-house, and problems encountered subsequently by other manufacturers, such as Cord L-29, producing or finding a dependable universal joint make it likely that the Christie design was difficult to maintain. Due to design limitations and a published unit price in 1909 of $2,600, sales of Christie taxis were poor.

In 1912 Christie began manufacturing wheeled fire engine tractors which also utilized a front-wheel-drive system, and subsequently sold scores of them to fire departments around the country, most notably the New York City Fire Department. The tractors allowed the departments to keep their steam-powered pumps while ending the use of horses to pull them to the scene of a fire.

In 1916, during the First World War, he developed a prototype four-wheeled gun carriage for the US Army Ordnance Board. But the Ordnance board had specified strict guidelines for weapons, and Christie refused to revise his designs to suit their requirements. Christie's stubbornness and his tendency to offend the US Army bureaucracy would have consequences for the rest of his career.

Amphibious tank

Christie's first important sympathizer was not with the Army, but with the United States Marine Corps: Major General Eli K. Cole, who was an advocate of developing the amphibious capability of the Marine Corps. Christie had built an amphibious light tank a decade before Donald Roebling's Alligator, and this was to be displayed during the military's Winter Maneuvers of 1924 at Culebra, Puerto Rico. In overall command of the exercise was Admiral Robert Coontz, USN. Along with testing the "Beetle Boat", a copy of the armoured lighter barges used as landing craft by the British during the Gallipoli landings in 1915, Christie presented his amphibious tank, first recommended by Brigadier General Smedley Butler.Daugherty, Leo J. III, Pioneers of Amphibious Warfare, 1898–1945, McFarland & Company, Inc., Jefferson NC., 2009, p.116 The tank was transported to the exercise area aboard the , and designated as "Marine Corps Tank (GC-2)". It was then hoisted aboard a waiting submarine prior to its launch toward the shore, then "As the "mother ship" submerged, the Christie tank proceeded to shore. Unable to maneuver through the heavy surf, the vehicle returned to the Wyoming without landing. The next day, when the surf had subsided, the Christie amphibian once again left its mooring aboard the submarine and made a perfect landing. Despite the fact that the vehicle came ashore after the exercise had been declared officially finished, Cole stated that the tank possessed the capability of being developed into an extremely valuable weapon, especially in association with landing operations."Daugherty, p.117

Later innovations and bureaucratic frustrations

Christie continued to submit designs to the Ordnance board, but none was deemed acceptable. A major reason was poor cross-country performance, due to limited suspension capabilities. He attended to this problem, and after five years of development (for $382,000) he produced the innovative prototype tank chassis M1928 (Model 1928) design. He proudly referred to it informally as the "Model 1940" because he considered it to be 12 years ahead of its time. The M1928 still retained large road wheels with no return rollers for the tracks from his earlier designs, so that the tracks could be removed for road travel, allowing for greater speed and range. What made this prototype innovative was its new "helicoil" suspension system, whereby each wheel had its own spring-loaded assembly. This reduced space in the interior of the tank, but (combined with a very light overall weight) allowed for unprecedented high-speed cross-country mobility, albeit at the cost of extremely thin armor. Another feature of the M1928 and later Christie designs was sloped armor in front, which could better deflect projectiles. The sloped armor helped to compensate for its thinness. The Army purchased several of Christie's tank prototypes for testing purposes and Christie's patent,U.S. Patent 1836446 http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=1836446.PN.&OS=PN/1836446&RS=PN/1836446 allowing them to produce prototypes based on his design.

In October 1928, the M1928 was demonstrated at Fort Myer, Virginia. There the Army's Chief of Staff, General Charles P. Summerall, and other high-ranking officers were impressed and strongly recommended that the Infantry Tank Board conduct further, official tests of the new vehicle. However, the Tank Board was less enthusiastic. They noted that the vehicle's armor was very thin and could not survive penetration by the smallest armor-piercing antitank rifle or artillery piece. The Board also differed with Christie on its guidelines for tank capabilities, which were based on a radically different theory of armored warfare than that used by Christie. While Christie advocated the use of lightweight tanks with long range and high speed, designed to penetrate enemy lines and attack their infrastructure and logistics capabilities, they considered the tank as simply an auxiliary weapon to help protect the infantry, and to help isolate and reduce enemy strongpoints near the front lines, much as they had been used during the previous world war. For the Infantry Tank Board, armor and firepower were more important design criteria than mobility, and the M1928 prototype was passed to the Cavalry for further evaluation.

The Cavalry's thinking at that time was based on armored cars, and it wanted to develop the M1928 as an armored car chassis. Once again, Christie's concept of how his vehicles should be used, together with his difficult nature, resulted in disputes with Army officials. One member of the Cavalry Evaluation Board who appreciated both Christie's design and tank warfare concepts was Lt. Colonel George S. Patton. Patton, and his friend Major Clarence C. Benson, strongly endorsed the adoption of the M1928 as the basis for a Cavalry tank.George S. Patton Papers