Types of frame construction PPT

This post covers the the types of frames construction.

Frame:

ž                          Main part of a chassis.

  ž  It is a rigid structure which forms a skeleton to hold all major parts together.

  ž  A vehicle frame is a high strength structure used to support all other parts of the vehicle.

Main functions (Importance) of Frame:

ž  To support the chassis components and the body.

ž  To withstand static and dynamic loads without distortion.

ž  To resist the effect of centrifugal forces when cornering a curve.

ž  To carry the load of passengers and goods in the body.

ž  To accommodate suspension system. 

Types of frames:

ž  Tubular Section

               Excellent resistance to torsion.

                Resistance increases as diameter is increased.

Other frame sections:

1.    Hat section (Not commonly used due to weakness)
2.     Double channel or I section (Good resistance to both bending    and torsion)
3.     Channel section (Excellent resistance to bending. Resistance increases as depth of section is increased)
4.     Box section (Good resistance to both bending and torsion)

Materials for frame:

Carbon                   0.25-0.35%

  Manganese          0.35-0.75%

ž   Silicon                     0.30 % maximum

ž   Nickel                      3%

ž              Phosphorous       0.05% maximum

       Sulphur                     0.5% maximum

Sub frames:

             Normally the various components are bolted directly to the main frame.

                But many a time, these components are mounted on a separate frame called “sub frame”.

                This sub frame is further supported by the main frame at three points. In this way the components are isolated from the effects of twisting and flexing of the main frame. 

Advantages of sub frames:

ž 

The mass of the sub frame alone helps to damp vibrations.

ž  

The provision of the sub frame simplifies production on the   assembly line and facilitates subsequent overhaul or repair. 

Frame Construction

ž     In order to provide good resistance to bending and torsional effect, the frame sections are made of proper forms.

ž

  There are three common types of frame sections such as channel, tubular and box sections.

        They are made from steel or heat treated alloy steel.

Types of frame construction:

ž  Conventional frame construction

ž  Semi-integral frame construction

ž  Integral or frameless construction 

Conventional frame construction:

ž  Also called “non load carrying frame”.

ž    The loads on the vehicle are transferred to the suspension by this type of frame.

ž  The body of the vehicle is made of flexible materials such as wood and mounted on the frame by using rubber mountings between body and frame.

ž  Mostly used in cars..

Semi Integral frame construction:

ž  The rubber body mountings are replaced by relatively stiff mountings.

ž  This arrangement also transfers a part of the frame load to the body structure.

ž  This type of frame is mainly used in American and European cars.

ž  But construction is heavy in nature compared to the conventional type. 

Integral or frameless construction:

 Also called “chassis less”, unitary or monocoque construction.

ž  Used in Passenger cars.

ž  It provides stiff light construction which is suitable for mass produced vehicles.

ž    All assembly parts are attached to the body.

ž  Heavy side members are eliminated and cross members are combined with the floor of the body. 

ž  This type of construction is led to much reduction of weight.

ž  All the members are welded together and form a single assembly.

ž  Here, the stresses are evenly distributed throughout the structure.