# Can anyone explain the Grashof Criterion ?

1. Feb 28, 2012

### M110020

Hi, I'm a university second year Mechanical Engineering student and I'm new to this module of Kinematics and Dynamics of Machinery and I've just learned the concept of the Grashof Criterion where "The sum of the shortest and longest link of a planar four-bar linkage cannot be greater than the sum of remaining two links if there is to be continuous relative motion between the links."

L$_{max}$+L$_{min}$$\leq$L$_{a}$+L$_{b}$

Can anyone explain to me why is it so? Why must the sum of the max and min linkages be longer than the other 2?? Is there a mathematical equation to prove this? Thanks for the assistance :)

2. Feb 29, 2012