# Number of degrees of freedom of a double toggle mechanism for punching

1. Aug 5, 2013

### marellasunny

This is a mechanism used for crushing rocks/punching holes(when horizontal). When I use the Kutzbach criterion to find the number of degrees of freedom,I get 2. Is this because of the failure of Kutzbach criterion to recognize the geometry of the mechanism or did I go wrong somewhere?

Kutzbach criterion:
$$d.o.f=3(n-1)-2 j_1-j_2$$
where n-number of links(=5 in this case)
j_1- number of lower pair joints(=5 in this case)
j_2-number of higher pair joints(=0 in this case)

P.S: The d.o.f is obviously 1 realistically speaking as there is just 1 input given i.e the shaft torque to rotate link1.

2. Apr 29, 2015

### Myron Dietrich

Im actually having the same problem. Any help would be appreciated.