High-Pressure Hydraulics by Citro?n

[jeanlouis]

Roger Brioult, journalist and mechanic


If I open his books at the evening, the night is over ! Same to Gabriel Voisin or Jean-Albert Grégoire

In 1946, Roger Brioult created the "Revue Technique Automobile" (RTA), you know these books that, in theory, help you to repair your car. :worried:
He was the first to dismantle entirely a DS for his review at the time where nobody knew this car.

Roger Brioult behind his Cord 810

This Citroën specialist who ordered a DS at the motorshow 55 and bought the last 2CV made at Levallois, travelled in Opel Commodore !

Left, Roger Brioult, right, Jacques Né the "father" of the SM beside his own car.

Roger Brioult and Paul Mages, Mister hydraulics at Citroën.

 

[jeanlouis]

Experimental SM







From 1970 to 1974, Citroën used several SM to test the speed limits for a front wheels drive. At this age many constructors (Simca, Peugeot, Fiat...) thinked that this kind of transmission was reserved to small and middle cars only. Maybe Citroën expected to creat a prestigious coach still more performant than a SM? A french Ferrari? Maserati engine, hydropneumatic suspension and the new power steering allowed it.


Unfinished prototype. Peugeot got majority at Citroën in 1974, left the SM and sold Maserati the next year. With these SM-laboratory, that were used also in some rallies, the constructor was near of 300 km/h!

 

[dargelos]

I wonder how you feel about electricfication? Probably not too happy. Whether we like it or not, emission regulations are going to get ever more strict, making it difficult to continue driving old cars, first in cities, then in most other places too. Battery conversions are a way to keep classic cars legal for the long term future, though at a hefty price. This is an example of a nicely done job.


1971 model.

34 lithium batteries each 3.2 volt giving 108 volt bus powering a 30kw ac motor.

Half the batteries under the rear seat, half where the engine used to be, keeping the weight balance about right. The normal car battery is retained for the lights, wipers radio and so on. Behind that, hard to see, is a small electric motor to drive the hydraulic pump for the suspension, brakes and steering. Which work as amazingly well as they did before.

I don't like the new lettering, it is unnecessary.

LCD screen for battery controller, needs a little more work for neatness.

The Dutch owner spent 20k euro and two and a half years to do this, he is happy with it. I would be too.

 

[jeanlouis]

So beautiful ! It is amazing what guys are able to do for allways driving a DS. He is really addicted. However hydraulic high pressure systems waste a few more energy than a classic mechanic. Today it is not interesting. In my opinion electric propulsion or not, it is not the main question. The real issue is energy and raw material savings.
2 CV is nearer of the car of the future than DS.

 

[dargelos]

You are right, today's designers can learn a lot from the two little horses. Cars of tomorow won't look like that or work like that, but the lesson is one of design philosophy. No other car has ever managed to acheive such a tight fit to a tight brief. It did precisely what it was required to do, not a drop more, not a drop less.
The Ford T, VW Beetle, Fiat 500 and Austin Mini were all succesful solutions to the problem of providing affordable cars for the masses but none managed the same combination of low purchase price and low materials consumption and low fuel consumption and indestrucability and ease of repair. The others got most of that right but only the 2CV got it all right.
That does not mean I would want to drive one today, with zero safety features and minimal acceleration, they are too vunerable when the roads are full of 4X4 drivers with a coffee in one hand and a cellphone in the other.

 

[jeanlouis]

High pressure pump, the heart of any hydraulics Citroën




Technical drawings as I learned it at school.
2 kinds of high pressure pump :
- single cylinder for ID19 with mechanical steering driven by a specific cam of the camshaft
- seven axial piston pump for DS19 driven by two belts









Same to CX, I added drawing and functioning of the pressure regulator with pilot slide valve that was an important development of the hydraulics circuit (DS starting 1969). Assisted steering is a big energy consumer. Until the BX, the constructor used single piston pump or seven piston pump according the presence of this equipment.

 

[jeanlouis]

The GS, it is hydraulics for everyone! :thumbs up:
No assisted steering and a small single cylinder pump incorporated to the beautiful (I don't hide my opinion) flat-four air-cooled engine. The pump is driven by excentric.

 

[jeanlouis]

A new five piston high pressure pump appears on BX in 1982 and it is straight away assembled on CX.
Its flow rate is 33% better than the one of the old seven piston. Some customers of these new models are surprised to feel their car climbing in only some seconds. Today some seconds it would be still too many !
In 1993, Xantia got a new high pressure pump with several (5 ?) radial pistons but I have no information about it.

 

[jeanlouis]

First Paris motorshow for GS and SM in october 1970









First test of the GS in Ireland (L'Automobile - September 1970)

 

[jeanlouis]

GS and SM, my two Mont-Blanc models

 

[jeanlouis]

With the appearance of Citroën GS, it begin a new age for the constructor, the factory of Rennes la Janais and Britanny :10.500 workers in 1970, 3.500 today (assembly of C5 Aircross and Peugeot 5008). The site was inaugurated in 1961 with the Ami 6.









Beside GS the manufacture of Ami 8 is going on until 1978.

 

[jeanlouis]

How to identify a DS ?



Except DS 19 and ID 19, in theory, you have the logotype at the rear right of the car.

 

[jeanlouis]

If it is easy to distinguish a DSpécial from a DS Pallas, it is less obvious for a DSuper 5 from a DS 21 mechanical gearbox 5 speeds. Same engine, same gearbox, same dashboard, same finition ...
Look at the photo above : wheel trim covered the whole wheel on the DS, gold logo Citroën on the DS, silver on the DSuper 5. But after 50 years, often logos and wheel trims have been changed, after a new paint for example. The best way is to look at the brake control : it's allways a classic pedal on DSuper 5 (or other ID) and a rubber "mushroom" on all the DS. See the post above about high pressure brakes.

 

[dargelos]

This is a little off topic but there is a Citroen that I am particularly interested in finding out about, the Currus tourist bus, as seen in the film Zazie Dans Le Metro. Probably conventional in it's engineering, but styled like nothing else on earth. Do you have any information about this unique vehicle?

 

[jeanlouis]

I did not see this movie, I presume it is from the novel of Raymond Queneau ?
This bus has maybe the same front face than the Citroën truck of the first photo #6 ?
It is not off topic, this bus would have the high pressure brakes of the DS.
Could you tell me if it is really this ? If yes, I have some pics of this bus.

 

[dargelos]

The movie is faithful to the book, very witty, with some interesting old cars, you will enjoy it. Made in 1960 so the bus must be based on an earlier truck chassis than in #6.

​

The citizens of Paris must have thought aliens had landed when these things appeared on their streets.

 

[jeanlouis]

Great work of Currus, it is like a boat on wheels

 

[jeanlouis]

All what I found about the Cityrama, the name of the bus that was also the name of the tour operator, I presume.
It was realized in 1959 on a Citroën type 55 frame, by Currus.

 

[jeanlouis]

Chapron is another bodyworker who worked a lot for Citroën


Recent photo of a SM Opéra, saloon 4 doors 1973, at the stand SM Club de France

Henri Chapron himself behind his model SM convertible Mylord (1972).


Convertible DS, "factory" model of the catalog Citroën, appeared in 1960, designed by Flaminio Bertoni and made by Chapron.

Convertible La Croisette - 1960

Coach Le Dandy - 1961

Convertible Le Caddy - 1963

Convertible Palm Beach - 1963

Le Dandy and Palm Beach side by side, notice the new rear fenders of all Chapron models starting 1964. A modification that allow to distinguish easily Chapron convertible from the "factory" convertible.

Saloon Majesty - 1964

Coach Concorde - 1964

Convertible Le Caddy - 1966

Coach Le Dandy - 1966

Coach Le Léman - 1966

Coach Le Dandy - 1967

Coach Le Dandy - 1968

Saloon Lorraine - 1970

Convertible Palm Beach - 1972

The production is very low even beside the production of the convertible "factory" : 1365 units. Henri Chapron was a true conservative craftsman at the opposite of Andre Citroën.

 

[jeanlouis]

DS Prestige was another model of the catalog Citroën made at Chapron


Presented at Paris motorshow 1958, DS Prestige is the answer to Simca that had exposed previous year its "Presidence", the up'market model of the V8 range (Beaulieu, Chambord...)
Special feature of the DS Prestige : an internal glass partition and a large leather front seat for the driver.

For the first time in Europe, DS Prestige had phone in board, an expensive option that costed half the price of a 2CV. Following year, Simca installed the phone more a television set at the rear of the "Presidence".

An austere ID 19 "voiture de maitre", only 46 units sold !


Phone, interphone and double control of the radio set are in option

Starting 1965, the finition Pallas is available in option for DS Prestige. In 1972 only, Prestige became Prestige-Pallas.

DS Prestige - 1967