German Patent No. 929 465 (Fox & Rice, GM) — bellows-type pneumatic suspension

In this document

This fascicle is the full text of German patent No. 929 465, issued by the Deutsches Patentamt (German Patent Office) to the General Motors Corporation (Detroit), with the designated inventors being Harold E. Fox (Pontiac) and William E. Rice (Lakeville, Michigan) p. 5.

Administrative elements

The patent was published on 27 June 1955, with effect in the Federal Republic of Germany from 26 September 1950; the application claims an American priority of 2 July 1949 p. 5. It is classified as "Klasse 63c Gruppe 41".

Object of the invention

The patent concerns a pneumatic suspension (Luftfederung) for vehicles, particularly automobiles, in which flexible bellows (Druckluftbalgen) are connected to rigid air reservoirs by pipes with a deliberately large diameter and without any throttling device, which allows for a long suspension travel and avoids excessive pressures p. 5.

The example described is a three-axle public transport vehicle, with bellows of different volumes at the front and rear, mounted on specific axles and housings p. 6-7.

Level correction

The device incorporates control valves (Steuerventile, referenced 40 and 42), placed between the axles and the body, which open a compressed air supply when the body lowers under load, or exhaust the air when it rises, in order to maintain a constant floor height p. 6-8. A timer system (Verzögerer) prevents the valves from reacting to road shocks, with only the static load triggering the correction p. 6, 8.

Claims (Patentansprüche) 1 to 4 reiterate these principles: bellows/reservoirs without throttling, control valves slaved to the body-axle distance, time delay, and separate valves for front/rear axles p. 8.

The fascicle also cites German, French, American, and British prior art p. 8 and includes two plates of technical drawings (Fig. 1 to 6) illustrating the chassis, axles, and bellows p. 9-10.

Context

This patent belongs to the lineage of bellows-type pneumatic suspensions developed in the United States in the automotive and heavy goods vehicle industry in the late 1940s, of which General Motors was a notable player — these systems already aimed, like the future Citroën hydropneumatic suspension, to combine comfort and automatic body height maintenance.

A commercial stamp visible on the first page mentions the Office Flutry, J. & G. Ruef Fluid Industry in Paris, a company probably responsible at the time for the distribution or translation of technical documentation of foreign patents in France.

Archivist's perspective

This document illustrates the technological monitoring work carried out around Paul Magès at the time when the Citroën hydropneumatic suspension was being developed: understanding competing solutions for height correction and air suspension, here via bellows and timed valves, undoubtedly helped to situate the originality of the hydraulic approach adopted at Citroën.

Handwritten annotations ("figure 4-5-6", mention of "preliminary pneumatic suspension", p. 5) suggest an active and targeted reading of the document, probably to extract the principles of level regulation.

This patent can be usefully compared with other items from the same monitoring collection, such as the Swiss Daimler-Benz patent on automatic height correction or the Hermine Lobinger patent on adjustable hydraulic suspension, which all testify to the same effort to explore technical alternatives at the time.