Piston. 1. That part of a steam-engine that moves under steam pressure. 2. A disc that fits a bore and slides therein.
Pitch. The distance apart of two pieces.
Pitch-circle. A circle drawn through these parts in a gear wheel where the face of the tooth meets the flank, this circle representing the diameter of the wheel for calculations involving its velocity.
Pitch-line. A part of a pitch circle.
Pitman. A name sometimes given to a connecting rod.
Planer-shaper. A metal-cutting machine in which the ram or slide carrying the tool is moved after the manner of a planing machine.
Planimeter (pla-nĭm′-e-ter). An instrument for finding the area of irregularly shaped plane surfaces.
Planing-machine. 1. For iron. A machine having a travelling work-table sliding in guideways, the tool being carried in a slideway that spans the table, two or more slide-rests are used in the larger-sized machines. 2. Wood-planing machine. A machine in which the work is fed to a revolving shaft or head carrying long planing knives.
Platen. 1. A work-holding table. 2. The plane surfaced plate which presses on the type in printing.
Play. Looseness of fit.