You do not have permission to edit this page, for the following reasons:

This IP address has been blocked from editing Wikipedia.
This does not affect your ability to read Wikipedia pages.
Most people who see this message have done nothing wrong. Some kinds of blocks restrict editing from specific service providers or telecom companies in response to recent abuse or vandalism, and can sometimes affect other users who are unrelated to that abuse. Review the information below for assistance if you do not believe that you have done anything wrong.

The IP address or range 44.201.0.0/16 has been blocked (disabled) by ‪ST47‬ for the following reason(s):

The IP address that you are currently using has been blocked because it is believed to be a web host provider. To prevent abuse, web hosts may be blocked from editing Wikipedia.
You will not be able to edit Wikipedia using a web host provider because it hides your IP address, much like a proxy or VPN.
We recommend that you attempt to use another connection to edit. For example, if you use a proxy or VPN to connect to the internet, turn it off when editing Wikipedia. If you edit using a mobile connection, try using a Wi-Fi connection, and vice versa. If you are using a corporate internet connection, switch to a different Wi-Fi network. If you have a Wikipedia account, please log in.
If you do not have any other way to edit Wikipedia, you will need to request an IP block exemption.

How to appeal if you are confident that your connection does not use a web host's IP address:
If you are confident that you are not using a web host, you may appeal this block by adding the following text on your talk page: ((unblock|reason=Caught by a web host block but this host or IP is not a web host. My IP address is _______. Place any further information here. ~~~~)). You must fill in the blank with your IP address for this block to be investigated. Your IP address can be determined here. Alternatively, if you wish to keep your IP address private you can use the unblock ticket request system. There are several reasons you might be editing using the IP address of a web host (such as if you are using VPN software or a business network); please use this method of appeal only if you think your IP address is in fact not a web host.

Administrators: The IP block exemption user right should only be applied to allow users to edit using web host in exceptional circumstances, and they should usually be directed to the functionaries team via email. If you intend to give the IPBE user right, a CheckUser needs to take a look at the account. This can be requested most easily at SPI Quick Checkuser Requests. Unblocking an IP or IP range with this template is highly discouraged without at least contacting the blocking administrator.

This block will expire on 23:54, 31 July 2024.

Even when blocked, you will usually still be able to edit your user talk page, as well as email administrators and other editors.

For information on how to proceed, please read the FAQ for blocked users and the guideline on block appeals. The guide to appealing blocks may also be helpful.

Other useful links: Blocking policy · Help:I have been blocked
Your IP address is in a range that has been blocked on all Wikimedia Foundation wikis. The block was made by ‪AntiCompositeNumber‬. The reason given is Open proxy/Webhost: Visit the FAQ if you are affected .
- Start of block: 13:55, 18 August 2022
- Expiry of block: 13:55, 18 April 2025
Your current IP address is 44.201.28.123. The blocked range is 44.201.0.0/16. Please include all above details in any queries you make. If you believe you were blocked by mistake, you can find additional information and instructions in the No open proxies global policy. Otherwise, to discuss the block please post a request for review on Meta-Wiki. You could also send an email to the stewards VRT queue at stewards@wikimedia.org including all above details.

You can view and copy the source of this page:

((Short description|Automotive suspension system))
((More citations needed|date=June 2018))

'''Hydrolastic''' is a type of space-efficient automotive suspension system used in many [[Automobile|car]]s produced by [[British Motor Corporation]] (BMC) and its successor companies.

Invented by British rubber engineer [[Alex Moulton]], and first used on the 1962 [[British Motor Corporation|BMC]] project [[BMC ADO16|ADO16]] under designer [[Alec Issigonis]], later to be launched as the [[Morris 1100]].<ref>((cite book
|title=Creativity and Concept Design
|author=
|publisher=Open University Worldwide
|year=2004
|isbn=0-7492-5908-6
))</ref>

== Description ((anchor|Hydrolastic)) ==
The system replaces the separate springs and dampers of a conventional suspension system with fluid filled displacer units which are interconnected between the front and rear wheels on each side of the vehicle.

Each displacer unit contains a rubber spring, and damping is achieved by the displaced fluid passing through rubber valves.  The displaced fluid passes to the displacer of the paired wheel, thus providing a dynamic interaction between front and rear wheels. When a front wheel encounters a bump, fluid is transferred to the corresponding rear displacer, then lowers the rear wheel, hence lifting the rear, minimising pitch associated with the bump.<ref>Moulton, Alex. (1962). [http://copeland.id.au/?p=55 “Hydrolastic Springing”]. Automobile Engineer. September 1962</ref> Naturally the reverse occurs when it is a rear wheel that encounters a bump. This effect is particularly good on small cars as their shorter wheelbases are more affected by pitching.

However, the key improvement over conventional suspension is that the front/rear interconnection allows the vehicle to be stiffer in roll than in pitch.  Hence it is possible to design a compliant suspension - giving a comfortable ride - without suffering a penalty in terms of excessive roll when cornering. In roll, there is no transference of fluid from the displacers, and hence its internal pressure rises.  The only "give" in the suspension occurs because of the inherent flexibility of the rubber springs.  These are naturally stiff.

In pitch, as described above, fluid is displaced front to rear, and hence the pressure in the system stays effectively the same, and thus the suspension is much more compliant.

The design of the displacer units, and the way in which they are mounted means that as the suspension is compressed, the (roughly spherical) displacer deforms, and hence presents a larger area to the mounting plates.  The pressure in the system is thus acting over a larger area, and hence applying additional force.  This gives the suspension a sharply rising rate even in pitch, so that there is a strong tendency to return to equilibrium.  Without this rising rate there would be no effective pitch resistance at all.

Cars with Hydrolastic suspension do, however, have a marked tendency to squat under acceleration, and to dive under braking (and for the rear end to sag under heavy loads). This requires clever design of the suspension components to minimise these forces, and to maximise the rising rate characteristic.

== Influences ==
Jon Pressnell suggests in his book that the [[hydropneumatic suspension]] of the [[Citroën DS]] motivated Issigonis and Moulton, who were at the time of the launch of the DS working on a rubber and fluid suspension system themselves.  Pressnell also suggests that the complexity of the Citroën system encouraged Moulton to develop a much simpler system.<ref>((cite book
|title=Citroën DS: The Complete Story
|author=Jon Pressnell
|publisher=The Crowood Press
|year=1999
|isbn=1-86126-055-5
))</ref>

In a magazine interview for 'CAR' magazine in the late 1980s, Dr Moulton stated that he and Issigonis had also studied the [[Citroën 2CV]] in the 1950s, which featured fore/aft interconnected steel springs. They particularly wished to address the comical lack of roll stiffness of that car with the system that they were designing.

==Hydragas==
Hydragas is a type of automotive suspension system used in many [[Automobile|car]]s produced by [[British Leyland]] and its successor companies.

Invented by British automotive engineer [[Alex Moulton]], Hydragas is an evolution of the previous Hydrolastic system. Manufactured under licence by BTR AVS under the Dunlop brand at the historic Holbrook Lane site.  It was first introduced in 1973 in the [[Austin Allegro]] and was later fitted to the 1975 [[Princess (car)|Princess]] and its successor, the 1982 [[Austin Ambassador]].  Both systems attempt to address the ride-handling compromise of car suspension by interconnecting the suspension of the front and rear of the car in some way.  Hydragas attempted to perform the same function and advantages as the [[hydropneumatic]] system developed by [[Citroën]], but without its attendant complexity.

The heart of the system is the displacer units, which are pressurised spheres containing nitrogen gas. These replace the conventional steel springs of a regular suspension design.  The means for pressurising the gas in the displacers is done by pre-pressurising a [[hydraulic fluid]], and then connecting the displacer to its neighbour on the other axle.  This is unlike the Citroën system, which uses hydraulic fluid continuously pressurised by an engine-driven pump and regulated by a central pressure vessel.

Despite early problems (the Allegro version of Hydragas was found seriously wanting), it was gradually developed into an effective and efficient alternative to steel springs on later BL/Rover Group models such as the [[Austin Metro]] and [[MG F|MGF]]. The Metro originally featured independent Hydragas units, with no fore/aft interconnection (the pipework was deleted on cost grounds, against the advice of Moulton). While the Metro was praised for its handling, and offered a significant improvement in ride quality over the [[Mini]], it was criticised for its tendency to pitch and bounce on uneven roads - precisely the characteristics the interconnection was intended to remove. The revised [[Austin Metro#Rover Metro|Rover Metro]] had its suspension interconnected and went on to receive plaudits for the quality of its ride.

The [[Austin Maxi]] was the only in production car to feature both systems. The Maxi featured 1100 designed Hydrolastic units with the regulator valve fitted with the interconnection pipe. However, in 1978 production of Hydrolastic bottles at Dunlop came to an end and BL modified the [[Princess (car)|Princess]] Hydragas bottles to fit. This involved fitting a new front subframe design, with a larger diameter horizontal chamber in the subframe. MGF was the last vehicle platform to use this design. The Hydragas system was dropped in favour of conventional suspension by Rover when BTR AVS sought to increase the price of the units substantially. After servicing the spares market for some years a buyer was found and the production line was sold.

== Cars ==
((col-float))
'''Cars using the [[#Hydrolastic|Hydrolastic]] suspension system:'''
* ADO16 [[BMC ADO16|Morris / Austin / Wolseley / MG 1100 / 1300, Riley Kestrel / 1300 & Vanden Plas Princess 1100 / 1300]]
* ADO16 [[BMC ADO16|Innocenti IM3 / IM3S / I4 / I5]] (IT)
* ADO16 [[Austin Apache|Austin Apache / Victoria]] (ZA/ES)
* ADO16 [[Morris Nomad|Morris 1500 / Nomad]] (AU/NZ)
* ADO15 [[Mini|Austin / Morris Mini & Wolseley Hornet / Riley Elf]] (from 1964 to 1971)
* ADO17 [[BMC ADO17|Austin / Morris 1800 / 2200 & Wolseley 18/85 / Six]]
* ADO17 [[Austin Kimberley|Austin / Morris Kimberley / Tasman]] (AU/NZ)
* ADO14 [[Austin Maxi]] (until March 1978)
* ADO61 [[Austin 3-Litre]]
* Huffaker Indianapolis cars 1964-1969 "MG Liquid Suspension Special"

((col-float-break))
'''Cars using the [[#Hydragas|Hydragas]] suspension system:'''
* ADO67 [[Austin Allegro|Austin Allegro & Vanden Plas 1500 / 1750]]
* ADO71 [[Leyland Princess|Austin / Morris / Wolseley 18–22, Princess]] & [[Austin Ambassador]]
* ADO14 [[Austin Maxi]] (from March 1978 onwards)
* ADO88 / LC8 [[Austin Metro|Austin / MG Metro]] (not interconnected front to rear) & [[Rover Metro|Rover Metro / 100]]
* [[MG F|MGF]]

((col-float-end))

== Bicycles ==

In 1962 Alex Moulton founded the [[Moulton Bicycle]] company to build his innovative design for [[small wheel bicycle]]s. To ensure a safe and comfortable ride whilst using small wheels with high-pressure [[tire|tyre]]s Moulton fitted his bicycles with rubber suspension units similar to those used on the original Mini.

Later 'New Series' Moulton bicycles are fitted with rear suspensions systems marketed as 'Hydrolastic'. These are, in essence, miniaturised versions of the displacers used on Hydrolastic-equipped cars being a rubber cone spring with an internal fluid chamber to provide damping.

== External links ==
*[http://www.hydragas.co.uk/ The Hydragas Register] ((Webarchive|url=https://web.archive.org/web/20080129082018/http://www.hydragas.co.uk/ |date=2008-01-29 )) - a website helping owners of hydragas and hydrolastic cars to find a garage or individual who can carry out a pump up service in their area.

== Notes ==
((reflist))

((Powertrain))

[[Category:Shock absorbers]]
[[Category:Automotive suspension technologies]]
[[Category:Automotive technology tradenames]]

Pages transcluded onto the current version of this page (help):

Hydrolastic (edit)
Template:Ambox (view source) (template editor protected)
Template:Anchor (view source) (template editor protected)
Template:Cite book (view source) (protected)
Template:Col-float (view source) (extended confirmed protected)
Template:Col-float-break (view source) (extended confirmed protected)
Template:Col-float-end (view source) (extended confirmed protected)
Template:Col-float/styles.css (view source) (extended confirmed protected)
Template:Find sources mainspace (view source) (template editor protected)
Template:Hlist/styles.css (view source) (protected)
Template:Icon (view source) (template editor protected)
Template:Main other (view source) (protected)
Template:More citations needed (view source) (template editor protected)
Template:Navbox (view source) (template editor protected)
Template:Pagetype (view source) (protected)
Template:Powertrain (edit)
Template:Reflist (view source) (protected)
Template:Reflist/styles.css (view source) (protected)
Template:SDcat (view source) (protected)
Template:Short description (view source) (protected)
Template:Short description/lowercasecheck (view source) (protected)
Template:Webarchive (view source) (template editor protected)
Module:Anchor (view source) (template editor protected)
Module:Arguments (view source) (protected)
Module:Category handler (view source) (protected)
Module:Category handler/blacklist (view source) (protected)
Module:Category handler/config (view source) (protected)
Module:Category handler/data (view source) (protected)
Module:Category handler/shared (view source) (protected)
Module:Check for unknown parameters (view source) (protected)
Module:Citation/CS1 (view source) (protected)
Module:Citation/CS1/COinS (view source) (protected)
Module:Citation/CS1/Configuration (view source) (protected)
Module:Citation/CS1/Date validation (view source) (protected)
Module:Citation/CS1/Identifiers (view source) (protected)
Module:Citation/CS1/Utilities (view source) (protected)
Module:Citation/CS1/Whitelist (view source) (protected)
Module:Citation/CS1/styles.css (view source) (protected)
Module:Disambiguation/templates (view source) (protected)
Module:Find sources (view source) (template editor protected)
Module:Find sources/config (view source) (template editor protected)
Module:Find sources/links (view source) (template editor protected)
Module:Find sources/templates/Find sources mainspace (view source) (template editor protected)
Module:Icon (view source) (template editor protected)
Module:Icon/data (view source) (template editor protected)
Module:Message box (view source) (protected)
Module:Message box/ambox.css (view source) (protected)
Module:Message box/configuration (view source) (protected)
Module:Namespace detect/config (view source) (protected)
Module:Namespace detect/data (view source) (protected)
Module:Navbar (view source) (protected)
Module:Navbar/configuration (view source) (protected)
Module:Navbar/styles.css (view source) (protected)
Module:Navbox (view source) (template editor protected)
Module:Navbox/configuration (view source) (template editor protected)
Module:Navbox/styles.css (view source) (template editor protected)
Module:Pagetype (view source) (protected)
Module:Pagetype/config (view source) (protected)
Module:Pagetype/disambiguation (view source) (protected)
Module:Pagetype/setindex (view source) (protected)
Module:Pagetype/softredirect (view source) (protected)
Module:SDcat (view source) (protected)
Module:String (view source) (protected)
Module:TableTools (view source) (protected)
Module:Unsubst (view source) (protected)
Module:Webarchive (view source) (template editor protected)
Module:Webarchive/data (view source) (template editor protected)
Module:Wikitext Parsing (view source) (protected)
Module:Yesno (view source) (protected)

Return to Hydrolastic.

Retrieved from "https://en.wikipedia.org/wiki/Hydrolastic"