"detector bar" meaning in English

{
  "forms": [
    {
      "form": "detector bars",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "detector bar (plural detector bars)",
      "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"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A bar, connected with a switch, longer than the distance between any two consecutive wheels of a train, laid inside a rail and operated by the wheels so that the switch cannot be thrown until the entire train has passed the switch."
      ],
      "id": "en-detector_bar-en-noun-5YcfZrxH",
      "links": [
        [
          "switch",
          "switch"
        ],
        [
          "distance",
          "distance"
        ],
        [
          "consecutive",
          "consecutive"
        ],
        [
          "wheel",
          "wheel"
        ],
        [
          "train",
          "train"
        ],
        [
          "rail",
          "rail"
        ]
      ],
      "raw_glosses": [
        "(railways) A bar, connected with a switch, longer than the distance between any two consecutive wheels of a train, laid inside a rail and operated by the wheels so that the switch cannot be thrown until the entire train has passed the switch."
      ],
      "topics": [
        "railways",
        "transport"
      ]
    }
  ],
  "word": "detector bar"
}

{
  "forms": [
    {
      "form": "detector bars",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "detector bar (plural detector bars)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A bar, connected with a switch, longer than the distance between any two consecutive wheels of a train, laid inside a rail and operated by the wheels so that the switch cannot be thrown until the entire train has passed the switch."
      ],
      "links": [
        [
          "switch",
          "switch"
        ],
        [
          "distance",
          "distance"
        ],
        [
          "consecutive",
          "consecutive"
        ],
        [
          "wheel",
          "wheel"
        ],
        [
          "train",
          "train"
        ],
        [
          "rail",
          "rail"
        ]
      ],
      "raw_glosses": [
        "(railways) A bar, connected with a switch, longer than the distance between any two consecutive wheels of a train, laid inside a rail and operated by the wheels so that the switch cannot be thrown until the entire train has passed the switch."
      ],
      "topics": [
        "railways",
        "transport"
      ]
    }
  ],
  "word": "detector bar"
}