The lengths of the links comply with the conditions: A͞B=D͞C and B͞C=A͞D, i.e. figure ABCD is a parallelogram. Link 2 rotates about fixed axis x-x and is connected by screw pair E to the fixed link and by a turning pair to link 8. Link 5 is connected by turning pair F to link 8 and by turning pair C to link 3 which mounts bearing a. Pulley 7 rotates about axis G. The tension of belt 4 is adjusted by translational displacement of link 3 for which purpose point F is adjusted along axis x-x. This is done by rotating link 2 about axis x-x.
$2287$LS,FD$