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Old 06-22-2012, 01:24 AM
 
Location: SW France
13,699 posts, read 13,587,973 times
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For anyone interested I just found this video. Sadly the quality of the video itself is somewhat lacking, but the content is good;


Citroen DS Story Part 1 - YouTube

I had the pleasure of meeting the eccentric looking chap, LJK Setright, who features in the video. To my mind he was the best motoring journalist ever and makes most motoring journalists seem like comic book writers.
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Old 06-22-2012, 05:57 AM
 
5,666 posts, read 4,217,541 times
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Quote:
Originally Posted by Jezer View Post
For anyone interested I just found this video. Sadly the quality of the video itself is somewhat lacking, but the content is good;


Citroen DS Story Part 1 - YouTube

I had the pleasure of meeting the eccentric looking chap, LJK Setright, who features in the video. To my mind he was the best motoring journalist ever and makes most motoring journalists seem like comic book writers.
I met Setright at a classic car show in Shepton Mallet once, seemed a nice man. Top Gears James May (who is coincidentally a very good journalist when away from the show) rates Setright as being the best motoring journalist he's ever read.

On topic my Dad for many years had an Austin Princess 2.2HLS that had Hydropneumatic suspension and he loved it, he used to tow a fairly large caravan with it and it had a self leveling device that kept everything under control really well. He never had any trouble with it and like many British Leyland cars from the period it was rust that did for it in the end.

From Wikipedia:
Quote:
Suspension used BL's Hydragas system, and was very soft and smooth; the intention was to offer as smooth a ride as the CitroŽn CX and this was almost achieved. The Princess's ride was excellent, and comfort in general was a selling point; the car was roomy, reasonably well-appointed for the time, the seating was comfortable, and overall the driving experience Ė provided you didn't care that much about performance Ė was excellent.
Image of an Austin Princess: http://www.classicandperformancecar....re.php?id=3768
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Old 06-22-2012, 09:03 AM
 
Location: Londonderry, NH
41,505 posts, read 49,615,444 times
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LVD - FWIW - the Citroen Hydro suspension sat at the low point when the car was shut off. Watching one of these things "wake up" after the motor started was amusing. It was sort of like a horse getting up one foot at a time.
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Old 06-22-2012, 03:58 PM
 
Location: SW France
13,699 posts, read 13,587,973 times
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One thing that you did need to be careful about was where you left the car overnight, when it would gradually sink down. Leaving it over something like a kerb would not be a good idea!

The other thing that could happen was if you left your foot on the brakes for any length of time, say in a traffic jam.

One time I did this and the pressure would build up. This would be released through the suspension and I remember looking out the rear view mirror at the driver behind me at the very second that the car lurched upwards by about a foot.

The look on that driver's face was priceless!
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Old 06-23-2012, 04:46 AM
 
Location: Prepperland
13,144 posts, read 9,223,353 times
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Car Bibles : The Car Suspension Bible page 3 of 5
Quote:
CitroŽn's hydropneumatic suspension uses a hydraulic pump that raises and lowers the car to different heights. Sure it's a superior system but it's also a lot more costly to manufacture and maintain. That's due in part to the fact that they don't use o-rings as seals; the pistons and bores are machined to incredible tolerances (microns), that it makes seals unnecessary. Downside : if something leaks, you need a whole new cylinder assembly.
Was there some engineering reason why CitroŽn wouldn't make a more economical suspension using o-rings?
(No comments about Shuttle disasters, please !)

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Old 06-23-2012, 07:27 AM
 
Location: Austin, TX
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Citroen has adapted their system for small cars (the GS). I guess the price differential must not have been that high if they could use it on a small car.
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Old 06-23-2012, 08:42 AM
 
Location: SW France
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I fancied having a GS when I was young. I used to go around in a friend's GS and I thought that it was a great car- stylish, comfortable and different.

I had a Fiat 127 at the time and the GS was probably around 33% more expensive than mine.

That said it competed with pretty mundane cars and had a reasonable following.
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Old 11-04-2016, 01:42 PM
 
Location: Prepperland
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Hybrid hydraulic powered vehicles might represent an ideal platform for hydropneumatic suspensions.

https://en.wikipedia.org/wiki/Hydraulic_hybrid_vehicle
Hydraulic hybrid vehicles, or HHVs use a pressurized fluid power source, along with a conventional internal combustion engine (ICE), to achieve better fuel economy and reductions in harmful emissions. They capture and reuse 70%-80% of the vehicle's braking/decelerating energy compared to 25% for electric hybrids. For trucks and buses, this can also be less expensive than electric systems, due to the price of batteries required for the latter. Hydraulic hybrid vehicle systems can also weigh less than electric systems, due to the high weight of the batteries. This can lead to a lower impact on payload capacity, especially for heavy vehicle classes.
The UPS Hydraulic Hybrid - How Hydraulic Hybrids Work | HowStuffWorks
A gas/electric hybrid recovers 30 percent of braking energy, while a hydraulic hybrid can recover 70 percent, contributing to better efficiency [source: NextEnergy]. The EPA estimates that CO2 emissions from hydraulic hybrid UPS trucks are 40 percent lower than conventional UPS trucks, and a fleet of trucks could save 1,000 gallons of fuel a year. The EPA also estimates that with less maintenance than a gas/electric hybrid and less fuel then a conventional truck, UPS could save up to $50,000 over the lifespan of each hydraulic hybrid truck [source: EPA].

The 1955 CitroŽn DS had suspension, power steering, brakes and gearbox/clutch assembly powered by high pressure hydraulic assistance. One can imagine the benefits of conversion to a hybrid hydraulic propulsion system.

Off road Recreational Vehicles and Motor Homes would be one market for such hybrid hydraulic + suspension systems. They could use the adjustable suspension for additional clearance, and benefit from any improvement in fuel economy.
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Old 11-04-2016, 02:22 PM
 
10,875 posts, read 41,221,323 times
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Quote:
Originally Posted by Sayantsi View Post
I think GM's magnetorheological system is a simpler system that works very effectively. The centralized systems German companies tried out in the past didn't work too well if I remember correctly, but they used air as the central fluid.
Nope.

"air suspension" systems using individual airbags and ride height sensing control valves at the corners went out of production with cars such as the early 1970's 300SEL MB's.

MB changed over to hydraulic fluid systems after that. The USA models saw 300TDt wagons with a hydraulic ride height system for the rear suspension (to compensate for load weight in the vehicle), but many other euro delivered models had active 4-corner hydraulic systems. I worked on a lot of euro ("gray market") MB's (and BMW's) that had these systems in various iterations.

A common failure on the MB's suspension system was to see damaged components when a tire shop put such a car on a lift and raised it without first selecting the ride height control valve "locked suspension" position. When the raised the car, then lowered it, the suspension was collapsed and frequently would not recover without replacing the control valve or other components.

Agreed, however, that the "centralized systems" were maintenance hogs, often developing serious leaks which required frequent additions of their specified hydraulic fluid. Early failures of components complicated these systems, too ... making them fairly expensive per mile to use.
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