MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES

**Definition:** This place covers:

Machines or engines, in general or of positive-displacement type.

**Limiting references (this place does not cover):** - Rotary-piston or oscillating-piston machines or engines -> F01C - Non-positive-displacement machines or engines, e.g. steam turbines -> F01D - Internal-combustion engines -> F02B - Combustion-product engine plants -> F02G - Machines or engines, other than of positive-displacement type, for liquids -> F03B - Positive-displacement engines driven by liquids -> F03C - Wind motors -> F03D - Positive-displacement machines for liquids -> F04B - Rotary-piston, or oscillating-piston, positive-displacement machines for liquids -> F04C

**Glossary:** - engine: a device for continuously converting fluid energy into mechanical power, thus, this term includes, for example, steam piston engines or steam turbines, per se, or internal-combustion piston engines, but it excludes single-stroke devices. - machine: a device which could equally be an engine and a pump, and not a device which is restricted to an engine or one which is restricted to a pump. - pump: a device for continuously raising, forcing, compressing, or exhausting fluid by mechanical or other means. Thus, this term includes fans or blowers. - positive displacement: the way the energy of a working fluid is transformed into mechanical energy, in which variations of volume created by the working fluid in a working chamber produce equivalent displacements of the mechanical member transmitting the energy, the dynamic effect of the fluid being of minor importance, and vice versa. - non-positive displacement: the way the energy of a working fluid is transformed into mechanical energy, by transformation of the energy of the working fluid into kinetic energy, and vice versa. - oscillating-piston machine: a positive-displacement machine in which a fluid-engaging work-transmitting member oscillates. This definition applies also to engines and pumps. - rotary-piston machine: a positive-displacement machine in which a fluid-engaging work-transmitting member rotates about a fixed axis or about an axis moving along a circular or similar orbit. This definition applies also to engines and pumps. - rotary piston: the work-transmitting member of a rotary-piston machine and may be of any suitable form, e.g., like a toothed gear. - free piston: a piston of which the length of stroke is not defined by any member driven thereby. - cylinders: positive-displacement working chambers in general. Thus, this term is not restricted to cylinders of circular cross-section. - main shaft: the shaft which converts reciprocating piston motion into rotary motion or vice versa. - plant: an engine together with such additional apparatus as is necessary to run the engine. For example, a steam engine plant includes a steam engine and means for generating the steam. - working fluid: the driven fluid in a pump or the driving fluid in an engine. The working fluid can be in a compressible, gaseous state, called elastic fluid, e.g. steam; in a liquid state; or in a state where there is coexistence of an elastic fluid and liquid phase.