SoE - Design Stage 2 - The Slider Crank -
Velocities, Accelerations, Forces and Moments

This note shows the approach needed (if computer software is not available) to determine the torque applied to a crank taking into account the gas pressure above the piston, the inertia of the piston and also that of the connecting rod.

The first diagram is the layout diagram:

The next two diagrams are the velocity and the acceleration diagrams:

The acceleration diagram, below, has had the centre of mass of the connecting rod (g') marked on it:

The diagrams below show the forces acting on the connecting rod, the accelerations of the connecting rod and the forces acting on the crank:

David Grieve, 27th November 2006.