A Brief Knowledge of Automobile Chassis

1. Backbone Chassis

Backbone tube chassis is a type of an automobile construction chassis that is similar to the body-on-frame design. Instead of a two-dimensional ladder type structure, it consists of a strong tubular backbone (usually rectangular in cross section) that connects the front and rear suspension attachment areas. A body is then placed on this structure.

It is almost a trademark design feature of Czech Tatra heavy trucks (cross-country, military etc.) - Hans Ledwinka developed this style of chassis for Tatra 11 in 1923 with the model Tatra 11. He further enhanced the design with 6x4 model Tatra 26 which had excellent offroad abilities.

This type of chassis is also often found on some sports cars. It also does not provide protection against side collisions, and has to be combined with a body that would compensate for this shortcoming.

Examples of cars using a backbone chassis include DeLorean DMC-12, Lloyd 600, Lotus Elan, Lotus Esprit and Europa, Škoda 420 Popular, Tatra T-87, Tatra T111, Tatra T148, Tatra T815 etc., as well as TVR S1. Some cars also use a backbone as a part of the chassis to strengthen it; examples include the Volkswagen Beetle and the Locost where the transmission tunnel forms a backbone.

Advantages

• Standard conception truck's superstructure has to withstand the torsion twist and subsequent wear reduces vehicle's lifespan.
• The half-axles have better contact with ground when operated off the road. This has little importance on roads.
• The vulnerable parts of drive shaft are covered by thick tube. The whole system is extremely reliable, however if a problem occurs, repairs are more complicated.

• Modular system is enabling configurations of 2, 3, 4, 5, or 6-axle vehicles with various wheel bases.

Disadvantages

• Manufacturing the backbone chassis is more complicated and more costly. However the more axles with all wheel drive are needed, the cost benefit turns in favor of backbone chassis.
• The backbone chassis is heavier for a given torsional stiffness than a uni-body.

    2.   Body on Frame



Body-on-frame is an old 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 (commonly ash), but steel ladder frames became common in the 1930s. It is technically not comparable to newer monocoque designs, almost no modern vehicle uses it (other than trucks).

In the USA the frequent changes in automobile design made it necessary to use a ladder frame rather than monocoque to make it possible to change the design without having to change the chassis, allowing frequent changes and improvements to the car's bodywork and interior (where they were most noticeable to customers) while leaving the chassis and driveline unchanged, and thus keeping cost down and design time short. It was also easy to use the same chassis and driveline for several very different cars. Especially in the days before computer-aided design, this was a big advantage.

Most small passenger vehicles switched to monocoque construction in the 1960s, but the trend had started in the 1930s with cars like the Opel Olympia, and Citroen Traction Avant leaving just trucks, some bus manufacturers and large cars using conventional frames. The switch continued for several decades - even small SUVs typically use this construction method today. Body-on-frame remains the preferred construction method for heavy-duty commercial vehicles, especially those intended to carry or pull heavy loads, such as trucks.

A halfway house to full monocoque construction was the 'semi-monocoque' used by the Volkswagen Beetle and Citroen 2CV. These used a lightweight separate chassis made from pressed sheet steel panels forming a 'platform chassis', to give the benefits of a traditional chassis, but with lower weight and greater stiffness. Both of these chassis were used for several different models. Volkswagen made use of the bodyshell for structural strength as well as the chassis - hence 'semi-monocoque'.

The Lincoln Town Car dominates the American limousine market because it is the last American luxury car made with body-on-frame, and therefore easily lengthened for livery work.

Advantages

• Easier to design, build and modify (less of an issue now that Computer-Assisted Design (CAD) is commonplace, but still an advantage for coach-built vehicles).
• Quieter, because the stresses do not pass into the body, which is isolated from the frame with rubber pads around the attachment bolts. Less significant lately, but earlier bodies would squeak and rattle, ever more as they rusted, lubricants drained, and fasteners loosened. Isolated bodies had a lesser degree of these modes of aging.
• Easier to repair after accidents. Grand-Am allows tubular spaceframe cars to replace their monocoque counterparts, as the cars can easily be repaired with new clips.
• Could allow a manufacturer to easily sub-contract portions of work, e.g. as when Austin subcontracted the aluminum body work of the Austin A40 Sports to Jensen Motors.

Disadvantages

•  Heavier than unibody - lower performance and/or higher fuel consumption.
• Far less resistant to torsional flexing (flexing of the whole car in corners) - compromising handling and road grip.
• No crumple zone - higher rate of death and serious injury. Some cars have adopted a "front clip" and "rear clip" format similar to what is used in NASCAR race cars where the car is split into three sections, and the clips absorb the impact, allowing the "clip" to be replaced when repairing the car.
• Structurally poor utilization of material.

    3.    Exoskeleton

An Exoskeleton car has a visible external frame, being made of steel or carbon fiber tubes. The simplistic construction of the vehicle follows Colin Chapman's philosophy of maximising the power-to-weight ratio by minimising weight rather than simply adding power. Early monocoque racing cars such as the Lotus 25 had their chassis exposed but the term exoskeletal is more usually reserved for vehicles with an exposed spaceframe, such as sandrails, dune buggies or specialized light weight track cars.

Examples of exoskeleton cars

* Ariel Atom
* Deronda Type F
* Deronda Type G
* Rinspeed eXasis
* KTM X-Bow
* Kirkham Motorsports-Rush
* Race Car Replicas -Superlite Roadster
* SDR-VSTORM
* MEV Rocket, Atomic, tR1ke, Missile, Eco-Exo and Exocet

      4.      Monocoque : part 1


Monocoque (pronounced /ˈmɒnɵkɒk/ or /ˈmɒnɵkoʊk/) is a construction technique that supports structural load by using an object's exterior, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin or coachwork. The word monocoque comes from the Greek for single (mono) and French for shell (coque). The technique may also be called structural skin, stressed skin, unit body, unibody, unitary construction, or Body Frame Integral (BFI).
 Monocoque construction was pioneered in aircraft, with early designs appearing circa 1916, and entered wide use in the 1930s. Automobiles used monocoque designs as early as 1923 but widespread adoption did not begin until the second half of the 20th century. Today, a welded unit body is the predominant automobile construction technique. Monocoque designs also appear in motorcycles, boat hulls and architecture.
Automobile designs originally used body-on-frame construction, where a load-bearing chassis consisting of frame, powertrain, and suspension formed the base vehicle, and supported a non-load-bearing body or coachwork. Over time, this was supplanted by monocoque designs, integrating the body and chassis into a single unit. The external panels may be stressed, in such cases as the rocker panels, windshield frame and roof pillars, or non-stressed, as is often the case with fenders. Today, spot welded unit body is the dominant technique, although some vehicles (particularly trucks and buses) still use body-on-frame.

Early designs
The first automotive application of the monocoque technique was 1923's Lancia Lambda, but it was not a true monocoque because it did not have a stressed roof, it was akin to a boat and has been described as 'punt' type construction. In 1928 German motorcycle manufacturer DKW launched their first car, the P15 wood and fabric bodied monocoque car. The Airflow and Traction Avant steel partially monocoque cars (stressed panels on internal frames) were both launched in 1934. General Motors subsidiary Opel then followed with the Olympia in 1935. In 1936, Lincoln introduced the Zephyr, a monocoque design which was as strong as the Airflow yet much lighter.

A halfway house to full monocoque construction was the 'semi-monocoque' used by the 1930s designed Volkswagen Beetle. This used a lightweight separate chassis made from pressed sheet steel panels forming a 'platform chassis', to give the benefits of a traditional chassis, but with lower weight and greater stiffness. This chassis was used for several different models. Volkswagen made use of the bodyshell for structural strength as well as the chassis - hence 'semi-monocoque'.

Nash Motors introduced this type of construction in 1941 with the new 600, generally credited with being the first popular mass-produced unibody construction automobile made in the United States. The all-welded steel with sturdy bridge-like girders that arched front to rear made for improved strength, safety, and durability. Nash engineers claimed that about 500 pounds of excess weight was cut out (compared to body-on-frame automobiles) and the body's lower air drag helped it to achieve better fuel economy. The company's 1942 news release text attached to the X-ray drawing describes how "... all auto bodies will be built ... as this some day...".

Developments after 1945

After World War II the technique came into wider use. The Alec Issigonis Morris Minor of 1948 featured a monocoque body, as did the Hudson Motor range of the same period. General Motors-Holden in Australia built the monocoque-bodied Australian Holden of 1948. Other automakers incorporated this type of construction, and the terms unit body and unibody became more common in general use. The Ford Consul was the first Ford built in England using a unibody.
 In 1960, a major breakthrough in unibody construction was reached in mass-produced Detroit vehicles with over 99% of Chrysler vehicles produced that year being fully unitized; some of the basic designs surviving almost untouched through the mid 1970s (for example: Valiant, Dart, etc.) with tens of millions eventually produced. Convertible versions needed special supports welded underneath to compensate for the "missing" shape on the top.
American Motors (AMC) continued its engineering heritage from Nash and Hudson, in 1963 combining separate parts into single stampings. The Rambler Classic had "uniside" door-surrounds from a single stamping of steel: this reduced weight and assembly-costs, as well as increasing structural rigidity and improving door fitment.

        5.        Monocoque : part 2

Hybrid designs

In automobiles, it is now common to see true monocoque frames, where the structural members around the window and door frames are built by folding the skin material several times. In these situations the main concerns are spreading the load evenly, having no holes for corrosion to start, and reducing the overall workload. Compared to older techniques, in which a body is bolted to a frame, monocoque cars are less expensive, lighter, more rigid, and can be more protective of occupants in a crash when appropriately designed. The use of higher strength steels in panels at points of high stress has increased strength and rigidity without increasing weight.
In sophisticated monocoque designs, the windshield and rear window glass is bonded in place and often makes an important contribution to the designed structural strength of automobiles.

Disadvantages

Unfortunately, when a vehicle with a unibody design is involved in a serious accident, it may be more difficult to repair than a vehicle with a full frame. Rust can be more of a problem, since the structural metal is part of the load-bearing structure (of metal that is much thinner than a conventional chassis) making it more critical, and must be repaired by cutting-out and welding rather than by simply bolting on new parts (as would be the case for a separate chassis). Structural rust of monocoque cars was a serious problem until the 1990s. Since then, more and more car makers have adopted protection techniques such as galvanizing for structural areas or for the whole body.

          6.          Spaceframe

A space frame or space structure is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports. Like the truss, a space frame is strong because of the inherent rigidity of the triangle; flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut.

Overview

The simplest form of space frame is a horizontal slab of interlocking square pyramids built from aluminium or tubular steel struts. In many ways this looks like the horizontal jib of a tower crane repeated many times to make it wider. A stronger form is composed of interlocking tetrahedral pyramids in which all the struts have unit length. More technically this is referred to as an isotropic vector matrix or in a single unit width an octet truss. More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes.

History

Space frames were independently developed by Alexander Graham Bell around 1900 and Buckminster Fuller in the 1950s. Bell's interest was primarily in using them to make rigid frames for nautical and aeronautical engineering. Few of his designs were realised. Buckminster Fuller's focus was architectural structures; his work had greater influence.

Application in Vehicles

Space frames are sometimes used in the chassis designs of automobiles and motorcycles. In a space-frame, or tube-frame, chassis, the suspension, engine, and body panels are attached to a skeletal space frame, and the body panels have little or no structural function. By contrast, in a unit-body design, the body serves as part of the structure. Tube-frame chassis are frequently used in certain types of racing cars. British manufacturers TVR were particularly well known for their tube-frame chassis designs, produced since the 1950s. Other notable examples of tube-frame cars include the Lotus Seven, Ferrari 360, Lamborghini Gallardo, and Mercedes-Benz SLS AMG.
Space frames have also been used in bicycles, such as those designed by Alex Moulton.

            7.            Superleggera

Superleggera (translation: super light) is an automobile chassis construction technology developed by Felice Bianchi Anderloni of Italian coachbuilder Carrozzeria Touring. The company was located just north of Milan, near Alfa Romeo, Italian Citroen, and the former Isotta-Fraschini plant. First bodyworks were naturally made for these companies.

Touring licensed Charles Weymann's system of fabric-covered lightweight frames, which led to Touring’s own Superleggera construction. Patented by Carrozzeria Touring in 1936, the superleggera system consists of a structural framework of small diameter tubes that conform to an automobile body's shape and are covered by thin alloy body panels that strengthen the framework. Aside from light weight, the superleggera construction system allows great design and manufacturing flexibility, enabling coachbuilders to quickly construct innovative body shapes.
The superleggera system was primarily based on the use of 'Duraluminium', a material that originated in the zeppelin industry prior to World War I.

The superleggera system is no longer used in volume automobile production for a number of reasons. Primarily, a superleggera chassis can not meet modern impact resistance standards, and the cost of manufacture and galvanic corrosion between the aluminum body panels and the steel tubular frame are also prohibitive factors. Additionally, the frame tubes used to construct a superleggera chassis are too small and of unsuitable material for mounting suspension components, a disadvantage not found in spaceframe and other chassis systems. Car makers such as Bristol, who had aircraft industry experience, were more successful in countering galvanic corrosion than other manufacturers.

Superleggera is a trademark owned by Carrozzeria Touring Superleggera s.r.l., the modern incarnation of the firm that patented the system in 1936.

Notable automobiles

Carrozzeria Touring licensed the superleggera construction system to Aston Martin, who designed and manufactured superleggera chassis for the DB4 and DB5. Several other manufacturers created automobiles that utilized Carozzeria Touring's superleggera chassis construction technology. Notable examples include:

* Alfa Romeo 8C 2900 Mille Miglia
* Alfa Romeo 1900 Super Sprint
* Alfa Romeo 2600
* Aston Martin DB4 and DB5
* BMW 328 Touring Roadster
* Bristol Cars
* Ferraris 166, 195, 212 and 340 models
* Lamborghini 350GT
* Lancia Flaminia Convertible
* Pegaso Z-102

Akhirnya selesai juga tentang chassis ini, maaf tidak saya translate ke bhs. Indonesia, karena akan membuat pengertiannya menjadi beda. Thanks juga untuk Kaskus dan agan Purrfect yang memberi sumber bahasan ini.