## Side or Overhung Crankshaft- When the crank is at an angle of maximum twisting moment

**Introduction:**

Considering a position of the crank at an angle of maximum twisting moment. The design of a centre crankshaft that the thrust in the connecting rod (FQ) gives rise to the tangential force (F_{T}) and the radial force (F_{R}).

**When the crank is at an angle of maximum twisting moment:**

Consider a position of the crank at an angle of maximum twisting moment as shown in Fig. In the design of a centre crankshaft that the thrust in the connecting rod (F_{Q}) gives rise to the tangential force (F_{T}) and the radial force (F_{R}).

Due to the tangential force (F_{T}), there will be two reactions at the bearings 1 and 2, such that

** Fig.Crank at an angle of maximum twisting moment.**

The reactions at the bearings 1 and 2 due to the flywheel weight (W) and resultant belt pull (T_{1} T_{2}) will be same as discussed earlier.

Now the various parts of the crankshaft are designed as discussed below:

**(a) Design of crank web.**

The most critical section is where the web joins the shaft. This section is subjected to the following stresses :

(i) Bending stress due to the tangential force F_{T} ;

(ii) Bending stress due to the radial force F_{R} ;

(iii) Direct compressive stress due to the radial force F_{R} ; and

(iv) Shear stress due to the twisting moment of F_{T}.

We know that bending moment due to the tangential force,

d_{1} = Diameter of the bearing 1.

Now the total or maximum stress is given by

This total maximum stress should be less than the maximum allowable stress.