Hydragas

From WOI Encyclopedia Italia

Hydragas is a type of automotive suspension system used in many cars produced by British Leyland and its successor companies.

Invented by famous British automotive engineer Alex Moulton, Hydragas is an evolution of the previous Hydrolastic system and was first introduced in 1973 in the Austin Allegro. 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 famous hydropneumatic system developed by Citroën, but without its attendant complexity.

The heart of the system are 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 teething problems (the Allegro version of Hydragas was found seriously wanting), it was gradually developed into a very effective and efficient alternative to steel springs on later BL/Rover Group models such as the Austin Metro and MGF.

Articles relating to Automobile configurations
Car body style and classification	2 plus 2 | Antique car | Cabrio coach | Cabriolet | City car | Classic car | Compact car | Compact performance car | Compact SUV | Convertible | Coupé | Coupé convertible | Coupe Utility | Crossover SUV | Custom car | Drophead coupe | Fastback | Full-size car | Grand tourer | Hardtop | Hatchback | Hot hatch | Hot rod | Large family car | Leisure activity vehicle | Liftback | Limousine | Luxury car | Microcar | Mid-size car | Mini SUV | Minivan | Multi-purpose vehicle | Muscle car | Notchback | Personal luxury car | Pickup truck | Retractable hardtop | Roadster | Sedan | Saloon | Small family car | Sport compact | Sports car | Sport utility vehicle | Spyder | Station wagon | Estate car | Supermini | Targa top | Taxicab | Touring car | Town car | T-top | Ute | Van | Voiturette
Specialised vehicles	Gyrocar | Flying car. Amphibious vehicle
Fuel technologies	Internal combustion engine | Electric vehicle | Neighborhood electric vehicle | Hybrid vehicle | Battery electric vehicle | Hydrogen vehicle | Fuel cell | Plug-in hybrid electric vehicle | Steam car | Alternative fuel cars | Biodiesel | Gasohol | Ethanol | LPG (Propane) | Homogeneous Charge Compression Ignition | Liquid Nitrogen | Gasoline Direct Injection
Driven wheels	Four-wheel drive | Front-wheel drive | Rear-wheel drive | All-wheel drive | Two-wheel drive
Engine positioning	Front engine | Rear engine | Mid engine
Layout	FF layout | FR layout | MR layout | MF layout | RR layout
Engine configuration	Internal combustion engine | Straight-6 | V engine | Wankel engine | Reciprocating engine | Inline engine | Flat engine | Flathead engine | Diesel engine | Two-stroke cycle | Four-stroke cycle | Pushrod engine | Straight engine | H engine | Turbodiesel | Hybrid vehicle | Rechargeable energy storage system | Electric vehicle | Hydrogen vehicle

Body	Framework	A-pillar | Bumper | Cabrio coach | Chassis | Crumple zone | Body-on-frame | Dagmar bumpers | Fender | Fender skirts | Grille | Hood | Hood scoop | Monocoque construction | Pontoon fenders | Quarter panel | Shaker scoop | Spoiler | Subframe | Tonneau
Doors	Butterfly doors | Gull-wing door | Scissor doors | Suicide door
Glass	Sunroof | Greenhouse | Windshield
Other	Antenna ball | Hood ornament | Japan Black paint | Nerf bar | Truck accessory | Bumper sticker
Exterior Equipment	Lighting	Daytime running lamp | Headlamp | Headlight styling | Hidden headlamps | Retroreflector | Sealed beam | Trafficators | High intensity discharge
	Other	British car number plates | Distance sensor | US and Canadian license plates | Vanity plate | Vehicle registration plate | Windscreen wiper | Windshield washer fluid
Car engine	Air/Fuel	Air filter | Automatic Performance Control | Blowoff valve | Boost | Boost controller | Butterfly valve | Carburetor | Charge cooler | Centrifugal type supercharger | Cold air intake | Engine management system | Engine Control Unit | Forced induction | Front mounted intercooler | Fuel filter | Fuel injection | Fuel pump | Fuel tank | Gasoline direct injection | Indirect injection | Intake | Intercooler | Manifold | Manifold vacuum | Mass flow sensor | Naturally-aspirated engine | Ram-air intake | Scroll-type supercharger | Short ram air intake | Supercharger | Throttle body | Top mounted intercooler | Turbocharger | Turbocharged Direct Injection | Twin-turbo | Variable Length Intake Manifold | Variable geometry turbocharger. Warm air intake
	Exhaust	Catalytic converter | Emissions control devices | Exhaust pipe | Exhaust system | Glasspack | Muffler | Oxygen sensor
	Cooling	Aircooling | Antifreeze | Ethylene glycol | Radiator | Thermostat
	Ignition system	Starter | Car battery | Contact breaker | Distributor | Electrical ballast | Ignition coil | Lead-acid battery | Magneto | Spark-ignition | Spark plug
	Other	Balance shaft | Block heater | Crank. Cam | Camshaft | Connecting rod | Combustion chamber | Crank pin | Crankshaft | Crossflow cylinder head | Crossplane | Desmodromic valve | Engine knocking | Compression ratio | Crank sensor | Cylinder | Cylinder bank | Cylinder block | Cylinder head | Cylinder head porting | Dump valve,Engine balance | Oil filter | Firing order | Freeze plug | Gasket | Head gasket | Hypereutectic piston | Hydrolock | Lean burn | Main bearing | Motor oil | Multi-valve | Oil sludge | Overhead camshaft | Overhead valve | PCV valve | Piston | Piston ring | Pneumatic valve gear | Poppet valve | Power band | Redline | Reverse-flow cylinder head | Rocker arm | Seal | Sleeve valve | Starter ring gear | Synthetic oil | Tappet | Timing belt | Timing mark | Top dead centre | Underdrive pulleys | Valve float | Variable valve timing
Interior equipment	Instruments	Backup camera | Boost gauge | Buzzer | Car computer | Carputer | Check Engine light | Fuel gauge | Global Positioning System | Idiot light | Navigation system | Odometer | Speedometer | Tachometer | Trip computer
	Controls	Bowden cable | Cruise control | Electronic throttle control | Hand brake | Manettino dial | Steering wheel | Throttle | Gear stick
	Motor vehicle theft deterrence	Car alarm | ESITrack | Immobiliser | Klaxon | Vehicle tracking system | VIN etching
	Passenger safety & seating	Airbag | Armrest | Automatic seatbelt | Bench seat | Bucket seat | Child safety lock | Dicky seat | Passive safety | Rumble seat | Seat belt
	Other	Air conditioning | Ancillary power | Car audio | Car phone | Center console | Dashboard | Motorola connector | Power window | Rear-view mirror | TripSense
Powertrain	Wheels and Tires	All-terrain tyre | Bias-ply tire | Contact patch | Custom wheel | Drive wheel | Hubcap | Magnesium alloy wheel | Mud-terrain tyre | Paddle tires | Radial tire | Rostyle wheel | Run flat tires | Schrader valve | Slick tire | Spinner | Tire code | Tread | Treadwear rating | Whitewall tire | Wire wheels
	Transmission	Automatic transmission | Clutch | Continuously variable transmission | Differential | Driveshaft | Electrorheological clutch | Epicyclic gearing | Fluid coupling | Fully-automatic transmission | Gear stick | Gearbox | Hydramatic | Limited slip differential | Locking differential | Manual transmission | Roto Hydramatic | Saxomat | Semi-automatic transmission | Semi-automatic transmission | Super Turbine 300 | Tiptronic Torque converter | Transmission (mechanics) | Transmission Control Unit | Turbo-Hydramatic | Universal joint
	Steering	Ackermann steering geometry | Anti-lock braking system | Camber angle | Car handling | Caster angle | Oversteer | Power steering | Rack and pinion | Toe angle | Torque steering | Understeer
	Suspension	Axle | Beam axle | Coil spring | De Dion tube | Double wishbone | Electronic Stability Control | Hydragas | Hydrolastic | Hydropneumatic suspension | Independent suspension | Kingpin | Leaf spring | Live axle | MacPherson strut | Multi-link suspension | Panhard rod | Semi-trailing arm suspension | Shock absorber | Sway bar | Swing axle | Torsion beam suspension | Transaxle | Trailing arm | Unsprung weight | Watt's linkage | Wishbone suspension
	Brakes	Anti-lock braking system | Disc brake | Drum brake | Hand brake | Hydraulic brake | Inboard brake | Brake lining | Brake fade | Brake fluid | Hydraulic fluid | Brake bleeding | Engine braking | Electronic brakeforce distribution | Regenerative brake