The strap is usually of iron, and the pulley of hard wood.
Then to the paying-out drum P, from it to the dynamometer D, and finally to the stern pulley, over which it passes into the sea.
When the a,ces of a pair of pulleys are not parallel, the pulleys should be so placed that the part of the belt which is approaching each pulley shall be in the plane of the pulley.
A recording drum or integrating apparatus may be arranged on the pulley frames.
The pitch-line of a pulley or drum is a curve to which the line of connection is always a tangentthat :s to say, it is a curve parallel to the acting surface of the pulley or drum, and distant from it by half the thickness of the wrapping con nector.