Port·a·ble a.
  1. Capable of being borne or carried; easily transported; conveyed without difficulty; as, a portable bed, desk, engine.
  2. Possible to be endured; supportable. [Obs.]
     How light and portable my pain seems now!   --Shak.
  Portable forge. See under Forge.
  Portable steam engine. See under Steam engine.
  ◄ ►
  Steam en·gine An engine moved by steam.
  =
  nder. A marine engine, or the engine of a locomotive, is said to run forward when its motion is such as would propel the vessel or the locomotive forward. Steam engines are further classified as double-cylinder, disk, semicylinder, trunk engines, etc. Machines, such as cranes, hammers, etc., of which the steam engine forms a part, are called steam cranes, steam hammers, etc. See Illustration in Appendix.
  Back-acting steam engine, or Back-action steam engine, a steam engine in which the motion is transmitted backward from the crosshead to a crank which is between the crosshead and the cylinder, or beyond the cylinder.
  Portable steam engine, a steam engine combined with, and attached to, a boiler which is mounted on wheels so as to admit of easy transportation; -- used for driving machinery in the field, as thrashing machines, draining pumps, etc.
  Semiportable steam engine, a steam engine combined with, and attached to, a steam boiler, but not mounted on wheels.
  ◄ ►