The various parts of the vehicle are
mounted on the chassis frame. The chassis frame must strong enough to withstand total weight of the vehicle. The chassis frame carries engine, clutch, gear box,Propeller shaft, rear axle, suspension,steering gear box and brake. Frame is fixed with two longitudinal bars and four or five cross bars by rivet or bolts.
• The skeleton of the vehicle is chassis
• Chassis frames are made up of alloy
steel and it is of high strength to make
the rigid structure.
• Based on the construction,application, load capacity of the vehicle, the chassis frame is made up of different size and shape.
• Chassis frame forms the backbone of
Functions of the chassis frame
1. To withstand the weight of the vehicle,passenger and goods.
2. To form the base to mount the engine,suspension, steering and power transmission system.
3. To build the vehicle body on the
4. To withstand the reaction due to
driving and braking force.
5. To absorb the ground reaction forces due to road undulations.
6. To withstand the static load and
dynamic load of a vehicle.
Types of chassis frame
Chassis frame are broadly classified
into three types, namely:
1. Conventional Frame
2. Semi Integral Frame
3. Integral or Unit Frame
Here the various components are
attached to frame and the vehicle body are superimposed on it. The total frame is mounted on the wheel axle by means of springs. This arrangement makes the body completely isolated from the frame
deflection. It is mostly used in heavy
vehicles like buses, trucks etc.
Semi Integral Frame
This type of frames is made up
of two or three sections and then it is
integrated. The particular portion of the frame can be replaced if any damaged happens during accident instead of replacing the entire frame.
In this type of construction, there is
no separate frame. All the assembly units are attached to the body. Heavy side members of the frames are eliminated and cross members
are combined with the floor of the body. The body of the vehicle gives a mounting for engine, transmission, suspension and other mechanical units. Weight of the vehicle is very much reduced and widely used in cars.
Various loads acting on the frame
1. Vertical loads when the vehicle
comes across a bump or pit and road
2. Engine torque and braking torque
3. Loads due to road camber, side wind,cornering force, Centrifugal force while taking a turn.
4. Aerodynamic forces at considerable
5. Weight of different components like
engine, transmission, passengers, fuel
tank, seats, exhaust acting at mounting points
6. Sudden impact loads during a collision