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VARIOUS TERMINOLOGY USED IN I.C ENGINES





Bore :

The inside diameter of  the cylinder is called as bore (D).

Stroke :

It is the maximum distance travelled by a piston in one direction. It is equal to twice the crank radius. It is denoted by L. 

Piston area :

The area of the circle of diameter is equal to cylinder bore. 

Dead Centre :

It is the extreme position of the piston in the one direction before its reversal.

Top Dead Centre (TDC) :

The extreme position of the piston at the top of the cylinder is called Top Dead Centre (TDC).

Bottom Dead Centre ( BDC) :

The extreme position of the piston at the bottom of the cylinder is called Bottom Dead Centre ( BDC ) .

Clearance volume ( Vc ) :

The Volume of the cylinder when the piston is at TDC is known as clearance Volume.

Swept Volume or Displacement Volume (Vs) :

It is the volume generated by the working piston when it is travelling from one dead Centre to next one. It is the product of piston area and stroke. 

Vs = A * L 

Cylinder Volume :

It is the sum of  swept volume and clearance volume.

V = Vc + Vs 

Compression Ratio (r) :

It is the ratio of volume when the piston is at BDC to the volume when the piston is at TDC. 

r = V1 /  V2 = V1 /  Vc  = ( Vs + Vc ) / Vc 


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