Cold weather test on DS (Dec. 1955) — Citroën Laboratory report no. 222 995

In this document

This report from the André Citroën Laboratory (53, rue Balard), dated 4 January 1956 and registered under no. 222 995, covers a test entitled "Influence of cold on DS", conducted "on the road on 28, 29, 30 December 1955" p. 134. It is addressed to "STUDIES" for the attention of "Mr. MAGES" p. 134.

Vehicles and conditions

Three cars participated in the test: two production DS (ELV 563, ELV 564) and one non-production DS (ELV 540). The ELV 564 was instrumented with thermometers measuring the temperatures of the main radiator, heating radiators, passenger compartment, and under the bonnet (hydraulic block, engine oil filter, Lockheed reservoir) p. 134. The outside temperatures recorded were approximately 5° on the first day, then 2° to 3° on the second p. 134.

Mechanical behaviour

The gear shifting time was "clearly increased at the start", requiring "8 to 10 minutes of running to return to the usual shifting" p. 134. The ELV 563 saw its gear shifting "lengthen very significantly" at the end of the journey, unlike the ELV 564. The Lockheed fluid temperature rose abnormally in the ELV 564 reservoir p. 134. A "new gear shifting corrector" is mentioned as providing an effective remedy, with shifting remaining as fast at +40° as at +6° in the reservoir; the report also notes that "the steering and suspension do not show signs of the cold" p. 135.

Equipment and incidents

Several points are reviewed: ventilation (correct sealing on the ELV 564, broken stop notch on the ELV 563, p. 134); heating (25° reached in the passenger compartment in cold weather, weaker hot air in the rear, p. 135); defrosting deemed "long" and "noisy" p. 135; windscreen wipers "gripping", manual control broken, windscreen washer not very effective, and a remark on the ergonomics of the control buttons p. 135; windows difficult to operate, doors closing poorly if the car is "warped", unstable dashboard, warning light turning on for no apparent reason p. 135. A faulty indicator on the ELV 563, a water pump leak on the ELV 540, rear brakes that "squeak", and above all a hydraulic incident: rupture at the brazing of the reverse gear tube on the gearbox cylinder, which occurred after the return p. 135.

Context

The DS, presented by Citroën in 1955, incorporates the hydropneumatic suspension developed under the direction of Paul Magès. Winter tests in extreme cold were part of the classic validation campaigns in extreme conditions conducted by manufacturers, in order to detect weaknesses in hydraulic systems, heating, and electrical equipment before large-scale industrialisation — this general context is, however, not detailed in the document itself.

Archivist's perspective

This report illustrates the meticulous work of fine-tuning the DS in the months following its commercial launch: it seems that each subsystem (hydraulic, heating, windscreen wiper, braking) was subject to rigorous monitoring by the Laboratory, with direct reporting to Paul Magès p. 134. The hydraulic tube rupture incident p. 135 recalls the technical challenges specific to the early days of the hydropneumatic system, the precursors of which can be found in the Hydropneumatic suspension plans with differential interaction resulting from pre-war research. This document probably belongs to the same collection as the Summary of folder 41-59, dedicated to the developments of the DS and its suspension.