Difference Between Conventional Frame and Frameless construction

Comparison of Conventional Frame and Frameless construction

Difference Between Conventional Frame and Frameless construction

Comparison Chart

Conventional frame construction Frameless construction
It is used for commercial heavy vehicles. It is used for light vehicle and mostly for cars.
In this type of frame construction, the frame and body are a seperate part. The chassis components and body are fitted on the frame. In this type of frame construction, the frame and body are integrated part.and on it the different chassis components are fitted.
The heavy side members are used. Light side members are used.
This construction is better for low volume produced a vehicle. This construction is very much suitable for light and mass-produced vehicles.
There is flexibility to fitting a variety of bodies to the same chassis. It is designed for a specific vehicle and there is no flexibility to change the body design for the corresponding chassis.
The localized accident damage is easy to repair in comparison to the integral chassis. In case of accident, it becomes difficult to repair, set it right and properly align the same.
The height of the chassis is increased or decreased depending upon the techniques of mounting the chassis frame to the axle. The height of the chassis does not change once it is designed.
The dead weight of a vehicle is greater as the frame required long and heavy side and cross members. The dead weight of the vehicle is less as body floor works as a chassis and extra cross members are eliminated.
Due to the heavy frame, the C.G. of vehicle higher compared to the frameless body. Hence vehicle at high speed the stability is reduced. Due to the elimination of frame C.G. of a vehicle is lowered which gives more ty stability specially for a fast moving vehicle
The cost of a vehicle is increased due to a heavy frame. Cost is less as body floor works as long side and cross members.

Conventional frame construction

  • This type of frame is used on most heavy vehicles. For different types of vehicle, the construction details are different and varying. Chassis frames are made of steel section so that they are strong enough to withstand the load and at the same time are also light in weight to reduce dead weight on the vehicle. This type of frame has two long members and 5 to 6 cross members joined together with the help of rivets or bolts as shown in Image The cross members are used to increase the strength of frame side members may be paralleled with both horizontal and vertical planes. But more commonly taper inwards(They are inswept (narrowing) at the front and are upswept at the rear. the frame is narrowed down at the front to have a better steering lock which gives smaller turning circle and provides space for the pivoting and swinging of the front wheels. The upswept at the rear in primarily to give room for the vertical movement of the rear axle as the travels over road bumps and other surface inequalities. The body brackets are provided to support the body of the vehicle. The spring brackets are provided for mounting the spring. The extension of the chassis frame ahead of the front axle is known as front overhang, while its extension beyond the rear axle is called rear overhang.
  • The engine, clutch, gearbox, and steering are all bottled together to form a rigid assembly which is mounted usually on the front end of the frame. It is necessary that chassis must maintain the working assemblies in their correct positions and provide a mounting for the body although it adds little for the strength of the structure.

Integrated frame chassis or Frameless chassis

  • This frame construction, nowadays used in most of the motor cars is called frameless or chassisless or mono or unit construction in which the floor assembly and a part of the frame form one integral unbias shown in images. In this type of construction heavy side members used in conventional frame construction are eliminated and the floor is strengthened by cross members and the body, all welded together some cases subframes are also used on which various chassis components are mounted.

  • This sub-frame is further supported by the main frame at three points.
  • The main purpose of using sub-frame is to provide isolation. flexibility and simplified production. Normally the structure includes an underframe or floor structure having light side member, cross members, floor and other components. They are welded together as one assembly The surface is ribbed and dished for added strengths and rigidity The pressed steel body shell is attached to the chassis frame by welding or bolting.