This assembly was used for AC traction masts in the early 70s (or before) - such as Howrah-Tundla/Durg, Igatpuri-Bhusaval, Virar-Ahmedabad. Since then, they changed the orientation of the register arm dropper so that it originates from the middle of...

This assembly was used for AC traction masts in the early 70s (or before) - such as Howrah-Tundla/Durg, Igatpuri-Bhusaval, Virar-Ahmedabad. Since then, they changed the orientation of the register arm dropper so that it originates from the middle of the bracket tube instead of the top. As an illustration, take a look at the left mast in http://www.irfca.org/gallery/openline/IMG_5833.jpg.html and note the orientation of the register arm dropper - the length gets cut down by half, resulting in huge savings in raw material.

Many more can be found at this very informative site - http://www.indianrailways.gov.in/financecode/ACTraction-II-P-II/AcTractionIIAppendix10.htm .

Can someone explain this? Where is Cantilever Assembly used?