History of Anti-Two Block
A History of Anti-Two Block Prevention
LIMIT SWITCHES AS THE FORERUNNERS OF ANTI-TWO BLOCK DEVICES
Patents applied for as early as 1904, indicated the need for a safety device to stop the upward travel of a hook block on overhead crane like systems.
Otis Elevator Company was the assignee of a patent entitled “Automatic Stop for Whip-Hoists.” […]