idling speed

English

Noun

idling speed (plural idling speeds)

1. The speed, measured in revolutions per minute, of an internal-combustion engine when it is running, but is at rest and without power being applied, typically with transmission in neutral.
   • 1962 December, “The Oxted Line diesel-electric multiple-units”, in Modern Railways, page 383:

     Heating in the passenger sections is by electricity obtained from the main generator. When heating is dictated by the operation of a thermostat in the roof of the motor coach, engine idling speed is 600 r.p.m. instead of the normal 450 r.p.m. in order to produce a high enough generator voltage output at rest.

Related terms

• idle (verb, sense 3)