The mechanism shown is a safety device for an elevator. If the cable breaks, the two helical compression springs push the steel rods upwards to the horizontal position to force the pads on the wall and stop the elevator. At the operation position, the rods are at an angle of 20 to the horizontal, The distance /- 300mm, and the spring is made of a steel AISI 4130 Q&T at 425C with a natural frequency of 40.81 Hz. Determine the spring dimensions (d and D), number of turns and the free length if at the compressed position it is fully compressed and when the rods are horizontal, it is half-way released. (Note: The total spring deflection A= 2/ tan a)