"idling speed" meaning in English

{
  "forms": [
    {
      "form": "idling speeds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "idling speed (plural idling speeds)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1962 December, “The Oxted Line diesel-electric multiple-units”, in Modern Railways, page 383",
          "text": "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.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "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."
      ],
      "id": "en-idling_speed-en-noun-3CUGPRve",
      "related": [
        {
          "english": "sense 3",
          "tags": [
            "verb"
          ],
          "word": "idle"
        }
      ]
    }
  ],
  "word": "idling speed"
}

{
  "forms": [
    {
      "form": "idling speeds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "idling speed (plural idling speeds)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "english": "sense 3",
      "tags": [
        "verb"
      ],
      "word": "idle"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "1962 December, “The Oxted Line diesel-electric multiple-units”, in Modern Railways, page 383",
          "text": "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.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "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."
      ]
    }
  ],
  "word": "idling speed"
}