This type of Grashof linkage is obtained when the shortest link is the input link (r2). The input link has full motion. The output link has a limited range of motion that is defined as follows:
lower limit: theta4 = 180 + theta1 - theta4''
upper limit: theta4 = 180 + theta1 - theta4'
where theta4' = acos [ ( r1^2 + r4^2 - ( r3 - r2 ) ^2 ) / ( 2 * r1 * r4 ) ]
and
theta4'' = acos [ ( r1^2 + r4^2 - (r3 + r2)^2 ) / (2*r1*r4) ]
To see animations of this linkage select the links below: