Subframe
Encyclopedia
A subframe is a structural component of a vehicle, such as an automobile
or an aircraft
, that uses a discrete, separate structure within a larger body-on-frame
or unit body
to carry certain components, such as the engine
, drivetrain, or suspension
. The subframe is bolted
and/or welded
to the vehicle. When bolted, it is sometimes equipped with rubber
bushings
or springs
to dampen
vibration
.
The principal purposes of using a subframe are, to spread high chassis loads over a wide area of relatively thin sheet metal of a monocoque body shell, and to isolate vibration and harshness from the rest of the body. For example, in an automobile with its powertrain contained in a subframe, forces generated by the engine and transmission can be damped enough that they will not disturb passengers. As a natural development from a car with a full chassis, separate front and rear subframes are used in modern vehicles to reduce the overall weight and cost. In addition a subframe yields benefits to production in that subassemblies can be made which can be introduced to the main bodyshell when required on an automated line.
There are generally three basic forms of the subframe.
A subframe is usually made of pressed steel panels that are much thicker than bodyshell panels, which are welded or spot welded together. The use of Hydroformed tubes may also be used.
The revolutionary monocoque
transverse engined front wheel drive 1959 Austin Mini, that set the template for modern front wheel drive cars, used front and rear subframes to provide accurate road wheel control while using a stiff lightweight body. The 1961 Jaguar E-type
or XKE used a tubular spaceframe type front subframe to mount the engine gearbox and long bonnet / hood, to a monocoque 'tub' passenger compartment.
The sub frame saw regular production in the 60's and 70's General Motors X and F cars.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
or an 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...
, that uses a discrete, separate structure within a larger body-on-frame
Body-on-frame
Body-on-frame is an automobile construction method. Mounting a separate body to a rigid frame that supports the drivetrain was the original method of building automobiles, and its use continues to this day. The original frames were made of wood , but steel ladder frames became common in the 1930s...
or unit body
Monocoque
Monocoque is a construction technique that supports structural load by using an object's external skin, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin or coachwork...
to carry certain components, such as the engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...
, drivetrain, or suspension
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...
. The subframe is bolted
Screw
A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
and/or welded
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...
to the vehicle. When bolted, it is sometimes equipped with rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
bushings
Bushing (isolator)
A bushing or rubber bushing is a type of vibration isolator. It provides an interface between two parts, damping the energy transmitted through the bushing. A common application is in vehicle suspension systems, where a bushing made of rubber separates the faces of two metal objects while allowing...
or springs
Spring (device)
A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...
to dampen
Damping
In physics, damping is any effect that tends to reduce the amplitude of oscillations in an oscillatory system, particularly the harmonic oscillator.In mechanics, friction is one such damping effect...
vibration
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
.
The principal purposes of using a subframe are, to spread high chassis loads over a wide area of relatively thin sheet metal of a monocoque body shell, and to isolate vibration and harshness from the rest of the body. For example, in an automobile with its powertrain contained in a subframe, forces generated by the engine and transmission can be damped enough that they will not disturb passengers. As a natural development from a car with a full chassis, separate front and rear subframes are used in modern vehicles to reduce the overall weight and cost. In addition a subframe yields benefits to production in that subassemblies can be made which can be introduced to the main bodyshell when required on an automated line.
There are generally three basic forms of the subframe.
- A simple "axle" type which usually carries the lower control arms and steering rack.
- A perimeter frame which carries the above components but in addition supports the engine.
- A perimeter frame which carries the above components but in addition supports the engine, transmission and possibly full suspension. (As used on front wheel drive cars)
A subframe is usually made of pressed steel panels that are much thicker than bodyshell panels, which are welded or spot welded together. The use of Hydroformed tubes may also be used.
The revolutionary monocoque
Monocoque
Monocoque is a construction technique that supports structural load by using an object's external skin, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin or coachwork...
transverse engined front wheel drive 1959 Austin Mini, that set the template for modern front wheel drive cars, used front and rear subframes to provide accurate road wheel control while using a stiff lightweight body. The 1961 Jaguar E-type
Jaguar E-type
The Jaguar E-Type or XK-E is a British automobile, manufactured by Jaguar between 1961 and 1975. Its combination of good looks, high performance, and competitive pricing established the marque as an icon of 1960s motoring...
or XKE used a tubular spaceframe type front subframe to mount the engine gearbox and long bonnet / hood, to a monocoque 'tub' passenger compartment.
The sub frame saw regular production in the 60's and 70's General Motors X and F cars.