At the head of the plane is mounted a drum or sheave, and around it passes a rope, one end of which is attached to the loaded cars at the top, the other to the empty cars at the foot.
The loaded train is coupled to the main rope, and to the rear end is attached the tail-rope; which reaches to the end of the line, passing there around a large grooved sheave and thence back to the engine.
In the endless rope system the rope runs from a grip wheel on the driving engine to the end of the line, round a return sheave, and thence back to the engine.
To prevent excessive bending stresses the diameter of drum and sheave must bear a proper ratio to that of the rope.
Arrived at the farther sheave C, the now cool pigs are dumped into a railway car.
The pulley or sheave FG has a weight W
A cord has one end made fast a to and wrapped round the barrel AE; it passes from A under the sheave FG, and has the other end wrapped round and made fast to the barrel BD.
Transmitted by wrapping connectors to FG, and combined by that sheave so as to act on the fol w lower W, whose motion is the same with that of the centre of FG.
Hence the instantaneous axis of the sheave FG is in the diameter FG, at the distance FG ACBC
From the centre towards G; the angular velocity of the sheave is AC + BC