Existing comment:
Sheaves, Ropes, and Gears:
The gears, sheaves, carriage, and other fittings were the heart of the engine house. These actually pulled the endless rope which hauled the trains up the incline.
The machinery for working the rope is placed in a pit, under the railway, at the head of the inclined plane. The cast iron sheaves, or wheels, that give motion to the rope,. are placed, the one 91-1/2 feet, and the other 87-1/2 feet from the head of the plane, ... These sheaves are ... 8-1/2 feet in diameter ... These sheaves are placed vertically, and revolve in opposite directions. The end of the shaft of each sheave opposite the engine which works its, has a cogwheel four feet in diameter, strongly secured upon it. The teeth of these wheels work into each other and regulate the motion of the vertical sheaves. A cast iron sheave, nine feet seven inches in diameter, is fixed on a movable carriage between the vertical wheels and the commencement of the descent of the plane... The machinery is designed for two engines -- one of each side of the railroad.
-- Sylvester Welch, Report on the Allegheny Portage Railroad, 1833
Whenever the descending train of cars preponderates in weight, over the ascending train... the engine is disengaged, and the sheaves and rope are put in motion, by the gravity of the descending load. The velocity of the descending train of cars is regulated in the following manner: A cylinder fourteen inches in diameter and about six feet long, with a small air vessel upon each end, and a pipe upon one side, is placed upon a cast iron frame, secured to the walls, between the engine and the large sheaves. The cylinder is filled with water, and the piston... drives the water backwards and forwards through the side pipe. In the centre of the side pipe a sliding valve is fixed by which the engine tender can regulate the size of the aperture through which the water must pass, and by this regulate the velocity of the cars.
-- Sylvester Welch, Report on the Allegheny Portage Railroad, 1833 |