German Patent No. 867 057 (Deveson) — rotating shaft suspension for trucks

In this document

The fascicle is the German patent DE 867 057, published on 16 February 1953, entitled « Achsanordnung bei Lastwagen und ähnlichen Fahrzeugen » ("Axle arrangement for trucks and similar vehicles"). The designated inventor is Robert Ernest Deveson, residing in East Fremantle (Australia). The patent was filed on 23 December 1950, its application published on 4 October 1951, and the grant announced on 31 December 1952 p. 11.

The problem posed

The text notes that existing trucks "do not offer means to unload the wheels when the vehicle is immobilised" and therefore lack stability when at rest p. 11.

The proposed solution

The invention consists of arranging the axles so that, when parked, the wheels can be moved so that "the entire body of the vehicle can lower itself onto the ground and rest there," thus unloading the wheels p. 11.

Mechanically, each axle journal carrying a wheel is connected to an angled arm (12), itself connected to a rotating shaft (10). This shaft is coupled to a gear wheel (14), actuated by a toothed slide (15), itself moved by a sliding block (16) under the action of a hydraulic piston (17) housed in a cylinder (18) p. 12.

A locking pawl (20), held in engagement by springs (21), prevents any return movement once the position is set. To lower the vehicle, a release lever (26) actuates a cam (23) which disengages the pawl, allowing the vehicle to descend under its own weight, a movement braked by the "valve control of the hydraulic device" p. 12.

The text also specifies a complementary use: on bad roads, it is possible to raise the journals "higher than normal," which has the effect of reducing the flexibility of the chassis suspension p. 12.

Five claims (Patentansprüche) cover these elements: axle/arm/shaft/gear wheel connection (1), toothed slide in engagement (2), locking pawl with concave teeth (3), retention by springs and release by cam (4), and hydraulic actuation of the slide by piston-cylinder (5) p. 12. The patent cites German patent No. 636 972 as prior art p. 12. Page 13 reproduces the sheet of drawings (Fig. 1 to 3) with the references corresponding to the text.

Context

Placed in technical history, this patent belongs to the family of ground clearance adjustment and axle locking devices at rest, a concern shared by many heavy goods vehicle manufacturers in the post-war period — a period when Citroën was developing, for its part, the hydropneumatic suspension of the future DS, of which Paul Magès is the principal architect. This type of foreign patent illustrates the technical monitoring that engineers of the time conducted on competing suspension and hydraulic control solutions.

Archivist's perspective

This document probably belongs to a collection of patents gathered for technical monitoring purposes, as evidenced by the handwritten annotations (number "6", inscription close to "PG 1411") visible in the margins p. 11-12, which suggest an internal classification or numbering.

The mechanism described — rotating shafts, gear wheel, pawl and hydraulic jack — deals with a problem similar but distinct from that of Magès' hydropneumatic suspension: it is a matter here of immobilising a truck at rest rather than correcting the trim while driving. The comparison with Swiss Patent No. 291970 (Daimler-Benz) — automatic height correction device and German Patent No. 929 465 (Fox & Rice, GM) — pneumatic bellows suspension sheds light on the diversity of hydraulic and pneumatic approaches then explored on an international scale for ride height control.