Height adjustable suspension
Encyclopedia
Height adjustable suspension is a feature of certain automobile suspension
systems that allow the motorist to vary the ride height
or ground clearance. This can be done for various reasons including giving better ground clearance over rough terrain, a lower ground clearance to improve fuel economy at high speed, or for stylistic reasons. Such a feature requires fairly sophisticated engineering
.
Height adjustment is most often achieved by air
or oil compression used for the "springs" of the vehicle - when the pressure is varied - the vehicle body rises or lowers.
The first instance of a production vehicle with adjustable suspension was on the 1954 Citroën 15CVH
. This vehicled featured a self-leveling, height adjustable hydropneumatic suspension
. Since this time, these systems have appeared continuously on Citroën
models, including the DS
and CX
.
Height adjustable suspension was banned in the United States
from 1974 to 1981, due to the stringent interpretation of passenger vehicle bumper height regulations by the U.S. government agency NHTSA
. Subaru was one of a few manufacturers who offered the feature after the ban was lifted on the Subaru XT
, the Subaru Leone
wagon and the Subaru Legacy
for a short time.
Many modern SUVs use height adjustability as part of active suspension
systems to improve the vehicle's versatility on and off road. The Range Rover offered this feature from 1993. New models of the Ford Expedition
have a computer-controlled system designed for convenience, which lowers automatically when the doors are unlocked by remote, returns to normal height when the vehicle is started, and (on 4-wheel-drive models), raises when the 4x4 system is engaged.
Some sports cars use these systems to improve the vehicle's handling by lowering the vehicle's height during higher speeds - a current example being the Mercedes-Benz
Active Body Control
system.
The new 2011 Jeep Grand Cherokee also includes adjustable suspension in the 4x4 model. It automatically lowers when the Park selection is engaged, and also lowers at high speeds to improve aerodynamics. It also allows drivers to manually raise the suspension for off-road situations.
Height adjustable air suspension
s are also equipped on some buses, mainly "Low-floor" city buses or "Kneeling Buses", however in recent years some high floor charter/intercity buses have been equipped with this feature as well. This allows the floor to be lowered when the bus is stopped, to allow people with large or bulky luggage, passengers with disabilities, or simply when stopping at stops with unusual curb arrangements to enter or exit the vehicle easily. It can also raise the bus more than normal, which is useful when navigating roads with large amounts of speed humps, crossing railway lines or in other unusual, but not always uncommon situations.
Adjustable suspensions have become intrinsically associated with lowrider
vehicles. The popular image of these vehicles is of one "hopping" on its suspension, or sitting with one wheel completely off the ground.
These systems were initially adapted from the hydraulic pistons, valves and pumps used to adjust the flaps on aircraft
. Today however, many aftermarket companies produce parts and equipment specifically designed for lowrider
s.
In recent years "air bag" systems (not to be confused with the air bag safety device) have been rapidly gaining popularity among car customizers. These air suspension
systems use heavy-duty custom rubber "bags" to replace the stock shocks and springs, with either a compressor or tank of compressed gas used to raise and lower the vehicle at will. Any light-duty truck, from a small suv Chevrolet S10 Blazer to a full-size truck such as Dodge Ram 3500, can be outfitted to adjust the vehicle so that the frame will lie on the ground when the air bags are deflated, or "Layed Out".
Trucks are also capable of "laying" the pinch weld of the body, or "Bodydrop" using a technique such as channeling the frame or building an entirely new frame.
Assistive technology
for persons with disabilities includes vehicles modified with height adjustable suspension, for example to allow wheelchair entry to the vehicle.
, allowing him to change the height of the car with a switch on the dashboard.
Certain modern layouts allow electronics alone to make this decision without the driver's control, especially if the car lowers at high speed.
Suspension (vehicle)
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...
systems that allow the motorist to vary the ride height
Ride height
Ride height is the amount of space between the base of an automobile tire and the underside of the chassis; or, more properly, to the shortest distance between a flat, level surface, and any part of a vehicle other than those parts designed to contact the ground...
or ground clearance. This can be done for various reasons including giving better ground clearance over rough terrain, a lower ground clearance to improve fuel economy at high speed, or for stylistic reasons. Such a feature requires fairly sophisticated engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
.
Air suspension
Air suspension is a type of vehicle suspension powered by an engine driven or electric air pump or compressor. This pump pressurizes the air, using compressed air as a spring. Air suspension replaces conventional steel springs. If the engine is left off for an extended period, the car will settle...
or oil compression used for the "springs" of the vehicle - when the pressure is varied - the vehicle body rises or lowers.
Factory systems
Citroën Traction Avant
The Citroën Traction Avant is an automobile which was produced by the French manufacturer Citroën from 1934 to 1957. About 760,000 units were produced.-Impact on the world:...
. This vehicled featured a self-leveling, height adjustable hydropneumatic suspension
Hydropneumatic suspension
Hydropneumatic suspension is a type of automotive suspension system, invented by Citroën, and fitted to Citroën cars, as well as being used under licence by other car manufacturers, notably Rolls-Royce, and Peugeot. It was also used on Berliet trucks and is since recently used on Mercedes-Benz...
. Since this time, these systems have appeared continuously on Citroën
Citroën
Citroën is a major French automobile manufacturer, part of the PSA Peugeot Citroën group.Founded in 1919 by French industrialist André-Gustave Citroën , Citroën was the first mass-production car company outside the USA and pioneered the modern concept of creating a sales and services network that...
models, including the DS
Citroën DS
The Citroën DS is an executive car produced by the French manufacturer Citroën between 1955 and 1975. Styled by Italian sculptor and industrial designer Flaminio Bertoni and the French aeronautical engineer André Lefèbvre, the DS was known for its aerodynamic futuristic body design and innovative...
and CX
Citroën CX
The Citroën CX is an automobile produced by the French automaker Citroën from 1974 to 1991. Citroën sold nearly 1.2 million CXs during its 16 years of production. The CX was voted European Car of the Year in 1975....
.
Height adjustable suspension was banned in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
from 1974 to 1981, due to the stringent interpretation of passenger vehicle bumper height regulations by the U.S. government agency NHTSA
National Highway Traffic Safety Administration
The National Highway Traffic Safety Administration is an agency of the Executive Branch of the U.S. government, part of the Department of Transportation...
. Subaru was one of a few manufacturers who offered the feature after the ban was lifted on the Subaru XT
Subaru XT
The Subaru XT, XT6, Vortex, and Alcyone is a 2-door coupé that sold from 1985 to 1991. The name Alcyone was used in Japan, the Vortex name was used in Australia and New Zealand, and the name XT or XT6 , was sold in North America and Europe...
, the Subaru Leone
Subaru Leone
The Subaru Leone was a compact car produced by the Japanese car manufacturer Fuji Heavy Industries from 1971 to 1994. The word "leone" is Italian for lion....
wagon and the Subaru Legacy
Subaru Legacy
The Subaru Legacy is a mid-size car built by the Japanese company Fuji Heavy Industries, and manufactured by its division Subaru since 1989, and is available as a sedan or wagon. Part of the original design goals for the Legacy model was to provide Subaru a vehicle in which they could compete in...
for a short time.
Many modern SUVs use height adjustability as part of active suspension
Active suspension
Active or adaptive suspension is an automotive technology that controls the vertical movement of the wheels with an onboard system rather than the movement being determined entirely by the road surface...
systems to improve the vehicle's versatility on and off road. The Range Rover offered this feature from 1993. New models of the Ford Expedition
Ford Expedition
The Ford Expedition is a full-size SUV built by the Ford Motor Company. Introduced in 1997 as a replacement to the Ford Bronco, it was previously slotted between the smaller Ford Explorer and the larger Ford Excursion, but as of the 2005 model year, it is Ford's largest and last truck-based,...
have a computer-controlled system designed for convenience, which lowers automatically when the doors are unlocked by remote, returns to normal height when the vehicle is started, and (on 4-wheel-drive models), raises when the 4x4 system is engaged.
Some sports cars use these systems to improve the vehicle's handling by lowering the vehicle's height during higher speeds - a current example being the Mercedes-Benz
Mercedes-Benz
Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...
Active Body Control
Active Body Control
Active Body Control, or ABC, is the Mercedes-Benz brand name used to describe fully active suspension, that allows control of the vehicle body motions and therefore virtually eliminates body roll in many driving situations including cornering, accelerating, and braking.In the ABC system, a computer...
system.
The new 2011 Jeep Grand Cherokee also includes adjustable suspension in the 4x4 model. It automatically lowers when the Park selection is engaged, and also lowers at high speeds to improve aerodynamics. It also allows drivers to manually raise the suspension for off-road situations.
Height adjustable air suspension
Air suspension
Air suspension is a type of vehicle suspension powered by an engine driven or electric air pump or compressor. This pump pressurizes the air, using compressed air as a spring. Air suspension replaces conventional steel springs. If the engine is left off for an extended period, the car will settle...
s are also equipped on some buses, mainly "Low-floor" city buses or "Kneeling Buses", however in recent years some high floor charter/intercity buses have been equipped with this feature as well. This allows the floor to be lowered when the bus is stopped, to allow people with large or bulky luggage, passengers with disabilities, or simply when stopping at stops with unusual curb arrangements to enter or exit the vehicle easily. It can also raise the bus more than normal, which is useful when navigating roads with large amounts of speed humps, crossing railway lines or in other unusual, but not always uncommon situations.
Aftermarket systems
Lowrider
]A lowrider is a style of car originated by Chicano communities that sits lower to the ground than most other cars. Many lowriders have their suspension systems modified so that their ride can change height at the flip of a switch...
vehicles. The popular image of these vehicles is of one "hopping" on its suspension, or sitting with one wheel completely off the ground.
These systems were initially adapted from the hydraulic pistons, valves and pumps used to adjust the flaps on aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
. Today however, many aftermarket companies produce parts and equipment specifically designed for lowrider
Lowrider
]A lowrider is a style of car originated by Chicano communities that sits lower to the ground than most other cars. Many lowriders have their suspension systems modified so that their ride can change height at the flip of a switch...
s.
In recent years "air bag" systems (not to be confused with the air bag safety device) have been rapidly gaining popularity among car customizers. These air suspension
Air suspension
Air suspension is a type of vehicle suspension powered by an engine driven or electric air pump or compressor. This pump pressurizes the air, using compressed air as a spring. Air suspension replaces conventional steel springs. If the engine is left off for an extended period, the car will settle...
systems use heavy-duty custom rubber "bags" to replace the stock shocks and springs, with either a compressor or tank of compressed gas used to raise and lower the vehicle at will. Any light-duty truck, from a small suv Chevrolet S10 Blazer to a full-size truck such as Dodge Ram 3500, can be outfitted to adjust the vehicle so that the frame will lie on the ground when the air bags are deflated, or "Layed Out".
Trucks are also capable of "laying" the pinch weld of the body, or "Bodydrop" using a technique such as channeling the frame or building an entirely new frame.
Assistive technology
Assistive technology
Assistive technology or adaptive technology is an umbrella term that includes assistive, adaptive, and rehabilitative devices for people with disabilities and also includes the process used in selecting, locating, and using them...
for persons with disabilities includes vehicles modified with height adjustable suspension, for example to allow wheelchair entry to the vehicle.
History of aftermarket systems
Ron Aguirre is commonly accepted as the first person to create a custom car with hydraulically adjustable suspension. In 1959 he scavenged the Pesco pumps and valves from a B-52 Bomber and adapted them to the front suspension of his X-Sonic bubble-topped custom CorvetteCorvette
A corvette is a small, maneuverable, lightly armed warship, originally smaller than a frigate and larger than a coastal patrol craft or fast attack craft , although many recent designs resemble frigates in size and role...
, allowing him to change the height of the car with a switch on the dashboard.
User control
Traditional height adjustable suspension is controlled by the driver manually.Certain modern layouts allow electronics alone to make this decision without the driver's control, especially if the car lowers at high speed.