Other Makers Copy the Axle
Early motorists typically carried spare axles when travelling to remote places: Firmin Bruner, recalling life in Central Nevada mining camps, describes a journey in 1916, that took a day longer than planned when an axle broke and had to be replaced by the spare with a farmer's help. Unlucky motorists might break several axles in succession on a long trip and be stranded till fresh axles could be despatched to them by train. Alongside tire punctures and engine failures, axle weakness was a blot on the saleability of many early cars and trucks. Plainly this was not a situation customers were happy to accept.
In 1917, Everybody's Magazine listed the various drives available for US trucks: a few direct-shaft and Hotchkiss setups, many chain drives and internal-gear drives and the occasional friction and roller drives (list reproduced in BARBER, some only specified as "worm" or "bevel" gearing). The Piggins was the only make in the list with an enclosed spur-gear drive. Although Piggins Motor Truck was not a commercial success, the company's novel drive system helped to advance a technological race to adapt and improve the dead-axle-and-jackshaft concept as a possible solution to axle failures.
While we have barely any documentation on the Piggins' engineering ideas, we can discover a great deal from reading praise, and criticism, of their ideas in the pages of later US patents. Examining the development of the idea reveals the mechanical genius of the Piggins brothers, a tiny two-man partnership who challenged a design by Clément, one of the fathers of the French automobile industry, and who were in competition with far larger and better-resourced engineering bureaus in Detroit and the rest of the Mid-West.
The evolution of the Piggins and Clément axles helps to explain why one of the most difficult problems in the early history of automotive engineering took so long to solve: solutions were sought by experimentation, producing cars which the customers had to road-test.
Just as the brothers took an idea which had its beginnings in Paul Synnestvedt's 1899 patent for an all-electric car and applied it to a fundamentally different type of vehicle, other inventors were soon thinking hard about how to modify and improve Adolph Clément's and the Piggins Brothers' designs. Those efforts can be traced on a monthly basis in the publications of the US patent office. The Clément design attracted the most attention from inventors and it was only in 1918 that the distinctive and less-used Piggins design found a name, the "external-gear" drive:
|Filing Date||Invention||Inventors||US Patent|
|1917-03-08||Placement of pinion external to the hub gear for easy wheel changes||Alanson P. Brush||1401580|
|1918-08-23||Internal or external gear drive in which all gears run in a bath of oil; joints to remain oil-tight even with wobbling or improper maintenance (the first patent to use the term of art "external gear")||Adolph P. Herff||1305103|
|1919-07-25||An oil bath and felt seals are put around internal or external drives||Stephen I. Fekete and Stuart G. Baits, Essex Motors||1319519|
As has already been pointed out, the Piggins axle was one of the two distinct subtypes in the hybrid-axle world: the internal and the external. This distinction has to do with the location of the pinion gear, either inside the circumference of the road-wheel hub or outside of it:
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© Jean-Baptiste Piggin 2000-2009
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