Hydraulics Quiz No. 5 — DIRASS, DIRAVI and pressure regulator

Fifth quiz from the internal Citroën hydraulics training course: questions on DIRASS and DIRAVI steering, the pressure regulator, with a diagram to label and a table of components to complete.

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Understanding this document

In this document

A multiple-choice questionnaire on DIRASS, DIRAVI and the pressure regulator

This document is the fifth of six "Hydraulics Quizzes" from an internal training course. It must be "returned no later than fifteen days after receipt" in a stamped envelope p. 14.

The first questions ask to distinguish the functions of DIRASS and DIRAVI — assistance, speed-sensitive hardening, return centering (questions 1 and 2, p. 14) — then to identify the elements of a DIRASS steering circuit: pressure regulator, cylinder, priority valve, rotary valve, front height corrector (question 3, p. 14).

Operation by pressure or by flow

Several questions contrast "pressure-based" and "flow-based" operation, applied to the suspension (question 4) and to DIRASS (question 5), p. 14.

The pressure regulator: conjunction and disjunction

Questions 6 to 10 concern the role of the flow distributor according to the conjunction and disjunction phases: distribution of fluid between the reservoir, steering circuit and main circuit p. 14, as well as variations in flow and pressure in the steering circuit when driving straight or cornering p. 14.

Diagram and table exercises

Question 11 p. 15 is a practical exercise: based on a hydraulic diagram (rack, RD, CD, AC, HP blocks, rotor R, VP, conduits A to F), one must indicate the direction of fluid circulation in six conduits when the pressure regulator is in the disjunction phase p. 15.

Question 12 p. 15 proposes a tick-box table associating components — assistance cylinder, TC distributor, cam/roller system, variable flow regulator, centrifugal regulator, TR distributor — with the three functions: assistance, speed-sensitive hardening, return centering.

Component	Assistance (1)	Hardening (2)	Return centering (3)	Page
Assistance cylinder	12a	12g	12m	p. 15
TC distributor	12b	12h	12n	p. 15
Cam/roller system	12c	12i	12o	p. 15
Variable flow regulator	12d	12j	12p	p. 15
Centrifugal regulator	12e	12k	12q	p. 15
TR distributor	12f	12l	12r	p. 15

The document concludes with a space for remarks, study time, signature and date, with the note "Keep the carbon copy" p. 15.

Context

The acronyms DIRASS (power steering) and DIRAVI (variable-assist power steering, which appeared on the SM then the CX/DS) designate, in the history of Citroën, two generations of hydraulic steering systems linked to the inventions of Paul Magès. The pressure regulator, a key part of the Citroën high-pressure hydraulic circuit, regulates the priority between circuits (steering, brakes, suspension) depending on whether the pressure is sufficient (conjunction) or not (disjunction). These concepts are not explained in this document, which assumes prior knowledge — probably acquired in the previous modules of the training.

Archivist's perspective

This fifth quiz follows on from the previous ones, with increasing technical difficulty: it is no longer just a matter of recalling definitions, but of manipulating a complex hydraulic diagram (question 11) and a cross-reference table of components/functions (question 12), a sign of a progressive and demanding training course.

It usefully complements Quiz No. 1 and No. 2, devoted to the basics of pressure and the accumulator, by addressing here power steering and the pressure regulator, two key pieces of Paul Magès' technical legacy.

The subject can be clarified by the technical notebook excerpt on steering return centering, which details certain components mentioned here (variable flow regulator, cam/roller system).

The existence of a second copy of this same quiz probably suggests distribution to several trainees or the retention of multiple copies by the training department.