Tayco Note: comparing the "Liquid Spring" to the Citroën suspension, "best in the world"

In this document

The context of the Tayco / Rabinow project

Page 24 recounts how TAYCO previously combined its Liquid Spring system with Dr. Rabinow's (formerly of the National Bureau of Standards) magnetic and hydraulic clutch, as part of a missile project led with Robert Kemelhor (Bureau of Aeronautics, then Johns Hopkins University). The initial contract is presented as a success, proving the compatibility of the two techniques p. 24. The note specifies that "certain aspects" remain unpublished for security reasons p. 24.

The comparison with the Citroën suspension

The note sets out three goals for the "test program": to apply the Liquid Spring system and the central accumulator to a vehicle, truck, or bus; or to develop suspensions for heavy goods vehicles p. 25-26.

The text describes the Citroën suspension as a system with "hydraulic units on each wheel that compress liquid against a gas sphere", connected to a "central accumulator" serving as a power source to raise or lower the vehicle p. 25. By contrast, the Tayco Liquid Spring "does not require an air tank" and would be "less expensive to manufacture" p. 25.

TAYCO announces that it has purchased a Citroën estate car to compare it to a 1958 Chevrolet Station-Wagon equipped with the Liquid Spring, with electronic equipment intended to record "shocks and vibrations" p. 25. The Citroën suspension is described there, "at the present time, it must be admitted", as the "best suspension in the world" p. 25. The project then plans to install the Tayco accumulator on the Citroën itself, followed by demonstrations in Detroit, with a system deemed commercially viable "in 1962" p. 25.

Comparative technical calculations

Page 26, which is very damaged, contains calculations comparing the DS gas spring and an equivalent liquid spring, at an operating pressure of 100 kg/cm²:

The document also mentions the reference to "figure 6 of the Taylor document", deemed less favourable, and explicitly cites the source of Comproil oils: "Hydra Spring Division, Wales-Strippit C°, North Tonawanda NY" p. 26.

Context

The suspension mentioned is the Citroën hydropneumatic, implemented on a large scale on the DS presented in 1955, the work notably of Paul Magès. Its principle—gas spheres under pressure separated from the liquid by a membrane, connected to a central hydraulic circuit providing suspension, braking, and steering—aroused keen technical interest in the United States from the late 1950s.

Tayco Developments (Taylor Devices) was an American manufacturer of "Liquid Springs", hydraulic springs without gas, positioned as a less expensive alternative to gas sphere systems. The commercial rivalry between these approaches—gas spring versus liquid spring—gave rise to several documented exchanges between Tayco and Citroën at the turn of the 1960s.

Archivist's perspective

This document illustrates, seen from the United States, the recognition of the Citroën suspension as a global benchmark—a judgment all the more notable as it comes from a direct competitor p. 25. It also sheds light on the view that Magès may have taken in return of rival solutions: the calculations on page 26, precisely comparing gas spring and liquid spring at equal performance, seem to announce or echo the work that Magès would carry out himself on this question, as evidenced by his note of 6 March 1961 and his manuscript drafts of 1961.

The presence of the reference to Comproil oils also refers to the Wales-Strippit collection held elsewhere, notably the Hydra Springs bulletin annotated by Magès. The very degraded material state of page 26 (faint text, cuts) unfortunately limits the complete reading of the reasoning, but the preserved figures are sufficient to situate this document within the constant technological monitoring that Magès seems to have exercised over the solutions competing with his own invention.