Correct Answer - Option 3 : throw of the switch
Throw of switch: It is the distance between the running face of the stock rail and the toe of the tongue rail.
The specified throw of a switch on BG is 95 mm and on MG it is 89 mm.
Some other important terms are as follows:
Heel clearance: It is the distance between the running edge of the stock rail and the switch rail at the switch heel.
Its recommended value on BG is 133 mm, 121 mm to 117 mm for MG and 98 mm for NG track respectively.
Switch angle: It is the angle between the gauge faces of the stock rail and the tongue angle.
Check rails: These are the rails provided to guide the wheel flanges, while the opposite wheel is jumping the gap.
Flange way clearance: It is the distance between the adjacent faces of the stock rail and the check rail. Its minimum value is 60 mm.