Editing Traction engine (section)

==Terminology==
* ''spud'' or ''lug'' &ndash; strip of angled metal that could be bolted to the driving wheels to provide greater traction on soft or heavy ground.  Spuds were often required on ploughing engines when moving across farmland.
* ''strake'' &ndash; name for the diagonal strips cast into or rivetted onto the wheel rims to provide traction on unmade ground (similar to the tread on a pneumatic tyre).
* ''Nominal horse power'' &ndash; nhp is the typical way that traction engines are rated. However, it has long been accepted that [[Nominal horsepower|nominal horse power]] greatly understates the actual power of the engine. There are many ways to estimate the actual horse power but none of them gives an accurate answer; for example, a 4&nbsp;nhp engine is said to be approximately {{convert|36|hp|abbr=on}}; however a 4&nbsp;nhp engine can easily pull a laden 8-wheeler lorry, while a diesel engine of {{convert|36|hp|abbr=on}} cannot. Thus, many{{who|date=November 2011}} have resigned themselves that this debate will never be settled and, while nominal horsepower gives a convenient way of rating traction engines, it may never be converted accurately into diesel HP.

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