Chapel inclined plane the tower. In spite of the large mechanical advantage provided by the brake lever, the brakeman was unable to apply the brake unaided. To further increase the mechanical advantage, a pulley block was fitted to the lever and the brakeman used this to apply the brake. When the tramway opened in 1796, a hemp rope was used on the incline but it was found that this was too weak and a wrought-iron chain soon replaced it. This also proved not to be strong enough and in 1809 it was replaced. The new chain had links 5 inches (127 mm) long
Block and tackle more precise estimate of efficiency is possible by use of the sheave friction factor, formula_12 (which may be obtainable from the manufacturer or published tables). The relevant equation is: Typical formula_12 values are 1.04 for roller bearing sheaves and 1.09 for plain bearing sheaves (with wire rope). The increased force produced by a tackle is offset by both the increased length of rope needed and the friction in the system. In order to raise a block and tackle with a mechanical advantage of 6 a distance of 1 metre, it is necessary to pull 6 metres of rope through the