German Patent No. 612843 (1935) — Hermine Lobinger's adjustable hydraulic suspension

In this document

This is the complete fascicle of German patent No. 612843, published by the Reichspatentamt on 6 May 1935, filed by Hermine Lobinger in Munich, in class "63c Gruppe 40" (reference "L 84635 II/63c"). The text specifies that the patent was granted in Germany as of 18 October 1933 and that its issuance was announced on 11 April 1935 p. 23.

The problem posed

The inventor starts from the observation that the load of motor vehicles is highly variable — "Ein viersitziger Personenwagen wird z. B. in vielen Fällen nur von einer Person benutzt" p. 23 — and that suspensions are only fully effective at full load. Previous attempts at mechanical adjustment (levers, joints, pushers, screws) are considered too complex and difficult to operate p. 23.

The claimed solution

The invention consists of adjusting hydraulically, from the driver's seat, the tension of additional springs (Zusatzfedern), in addition to the main springs p. 23. The device described includes:

• a pressure cylinder 1, accessible from the dashboard, operated by a handwheel 2 and a screw system 3, 4, which pushes a piston 5 returned by a spring 6 p. 23;
• a line 8 transmitting the liquid pressure to an adjustment jack 10 fixed to the chassis, acting on a piston 11 and a spring cup 12, in relation to the additional spring 14 and the axle 16 p. 23-24;
• a valve 24 allowing the rear suspension to be adjusted on both sides simultaneously, or on one side only p. 24;
• a variant with a locking pawl 27, 28, controlled by a cable 29, for heavy vehicles p. 24;
• the possibility of replacing the pressure cylinder with a pump, and housing it under the hood p. 24.

The text also mentions that a light or sound warning device can signal to the driver the need to adjust the suspension in case of overload p. 24.

Four claims (Patentansprüche) formalize these points p. 24. Pages 25 to 27 reproduce the sheet of drawings (Abb. 1 to 5) illustrating the chassis, the jacks, and the springs described.

Context

This patent belongs to the wave of interwar inventions seeking to improve automotive comfort through variable-adjustment suspensions — a concern found, in other forms, in contemporary patents such as that of Georges Messier (1930).

Historically, it is this same issue — the adaptation of the suspension to the load and the road — that Citroën and Paul Magès would solve twenty years later in a radically different way, with the hydropneumatic suspension of the DS (1955), based on pressurized fluid and nitrogen rather than mechanically adjusted springs.

Archivist's perspective

This document is of documentary interest for situating previous attempts at "intelligent" suspension in the history of the automobile. It does not come from Paul Magès's own collection but illustrates, it seems, an alternative technical path — the hydraulic adjustment of classic mechanical springs — that Citroën would not adopt.

The conceptual filiation with German Patent No. 502623 (1930) — Elastic chassis suspension by Georges Messier and with Swiss Patent No. 291970 (Daimler-Benz) — automatic height correction device deserves to be highlighted: these three pieces, despite different technical solutions, reflect the same search, pursued over several decades, for active control of vehicle trim and firmness.