11-04-2012, 12:31 PM
TYPES OF FRAMES
types of frame.pptm (Size: 651.75 KB / Downloads: 40)
FUNCTION OF FRAMES
Frame is provided with cross members to increase the rigidity and
to withstand the shock blows, twists and vibrations coming during
operations.
A frame is required to carry the weight of the vehicles and its
passengers to withstand the engine torque, thrust stress, acceleration
and breaking torque, to resist the effect of centrifugal forces when
cornering and to withstand bending and twisting stresses due to
fluctuating of front and rear axles.
Ladder Type Frame
They are mostly used in commercial vehicle. The frame is not designed to be a rigid structure, but to combine strength and flexibility. This allows frame to weave or twist and hence relieves stresses on spring and other chassis parts. It consists of two parallel side members connected to each other by several cross-members. The side members support the load, and the cross member give the torsional rigidity to the frame. The steel channel section used for side members has a vertical web with a horizontal flange top and bottom. In the middle part of the frame the side members has maximum heights and width of the flanges.
Perimeter Type Frame
In the middle part the frame expands and at the end it narrows. At the front the distance between the side members is determined by the track and minimum angle of turn of front wheel, and at the rear by the track of rear wheel. The side members are connected by several cross-members. The front ‘shoulders’ of side members are placed ahead of the inclined part of the floor in the zone of the engine compartment partition.
REQUIREMENT FOR A GOOD FRAME
It should be strong and stiff enough to resist the severe twisting and bending forces to which it is subjected particularly when vehicle is travelling at high speed over a rough road