Editing Traction engine (section)

===Portable engine===
{{main|Portable engine}}

A '''portable engine''' is a type of self-contained steam engine and boiler combination that may be moved from site to site. Although bearing a strong family resemblance, in both appearance and (stationary) operation, the portable engine is ''not'' classed as a traction engine as it is not self-propelled.  However, it is included in this list because the traction engine is a direct descendant.