Wales “Hydra News” No. 3: the flexibility of identical Hydra Springs (1953)

In this document

This Hydra News bulletin No. 3, published by the Wales-Strippit Corporation (North Tonawanda, N.Y.), presents an order for 26 dimensionally identical Hydra Springs intended for “an Armed Forces installation” (a military installation, not otherwise specified) p. 19.

The principle: same size, different forces

The text explains that these tension springs, all of identical dimensions (2'' x 4'' x 5''), can provide 26 different forces ranging from 1,500 to 7,000 pounds p. 19. This variation is obtained not by changing the size of the spring, but by adjusting three parameters: the use of Comproils (Wales fluids) of different compressibilities, the variation of volumes, or that of piston surfaces p. 19.

Origin of the order

The document specifies that this order of 26 units was placed after a comparative test between two initial Hydra Springs—presented in the previous bulletin, Hydra News No. 1—and “the old hydraulic system” comprising cylinders, hydraulic piping, and accumulators p. 19.

Mechanical comparison

An equivalence is given for comparison: each spring, offering a stroke of 2-7/8'', would be equivalent to a classic helical spring 18'' long, 6'' in diameter, made of 1'' wire p. 19.

The document is dated by the mention “© 1953” p. 19.

Context

In the 1950s, the engineer Paul Magès, tasked at Citroën with developing the hydropneumatic suspension applied in particular to the future DS, closely followed American innovations in liquid springs—hence the preservation in his archives of several bulletins from the Wales-Strippit firm.

These Hydra Springs, designed for American industrial and military uses, are based on a principle close to that explored by Magès: replacing a classic mechanical spring with a volume of compressed liquid, offering compactness and modularity.

Archivist's perspective

This issue No. 3 of the Hydra News series seems to have interested Magès for its very concrete demonstration of the modularity of a liquid spring: the same spring body, without changing dimensions, can cover a considerable range of forces simply by modifying the fluid or the internal proportions p. 19.

This document is part of a coherent collection preserved by Magès: it follows the Wales “Hydra News” No. 1: tension springs with damped return, explicitly cited as a reference in this issue No. 3 p. 19, and precedes the Wales Hydra News No. 2 devoted to compression springs. It seems that Magès systematically followed this series of bulletins to fuel his comparative reflection between liquid springs and classic mechanical springs, a reflection he would deepen himself in his notes from the 1960s.