C-W indicator

This is my fairly simple concept that uses two lasers with sensors fixed to the housing. While the chain is under load it is at maximum length so measurement can be conducted in the following way: As you may notice while the first laser (on the left) is just about to quit sending its signal to the sensor, the second one is already 3.86mm on the appropriate chain link. That 3.86mm is the elongation that is critical to this setting. I used 7x20 chain so we have 9 (links) x 20 (pitch) + 7 (thickness of one link) + 6 (spacing in one link (20-7-7=6)) = 193mm. 193 x 0.02 = 3.86mm – critical elongation. The basic idea is that when sensor no. 1 is about to go OFF (not receive signal from laser), sensor no.2 should already be off. If that is not the case, if sensor no.2 is ON at that moment – that means that chain has reached its critical elongation of 3.86mm (in this case). Two sensors can be connected via logical circuits so that when the chain has reached critical elongation their outcome can be 1 (give electricity) or 0 (stop sending electrical signal). You can choose which signal to use (0 or 1) so you can later manipulate with it in such a way to automatically set the brake and stop the lifting process. Or, less dramatically, just to give operator a signal that chain should be replaced… P.S. Similar concept can be used if chain links are in linear order and not on the sprocket. Cheers