"balance weight" meaning in English

{
  "forms": [
    {
      "form": "balance weights",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "balance weight (plural balance weights)",
      "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": "1961 February, \"\"Balmore\"\", “Driving and firing modern French steam locomotives - Part One”, in Trains Illustrated, page 109",
          "text": "The firehole door is made in three sections, hinged at the top and opening inwards to form a deflector plate, in a manner similar to the door of a Southern Region \"King Arthur\" class 4-6-0. Its operation, assisted by balance weights, is simple.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A weight that acts as a counterbalance."
      ],
      "id": "en-balance_weight-en-noun-MNpgB0k0",
      "links": [
        [
          "counterbalance",
          "counterbalance"
        ]
      ],
      "synonyms": [
        {
          "word": "balanceweight"
        }
      ]
    }
  ],
  "word": "balance weight"
}

{
  "forms": [
    {
      "form": "balance weights",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "balance weight (plural balance weights)",
      "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",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "1961 February, \"\"Balmore\"\", “Driving and firing modern French steam locomotives - Part One”, in Trains Illustrated, page 109",
          "text": "The firehole door is made in three sections, hinged at the top and opening inwards to form a deflector plate, in a manner similar to the door of a Southern Region \"King Arthur\" class 4-6-0. Its operation, assisted by balance weights, is simple.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A weight that acts as a counterbalance."
      ],
      "links": [
        [
          "counterbalance",
          "counterbalance"
        ]
      ]
    }
  ],
  "synonyms": [
    {
      "word": "balanceweight"
    }
  ],
  "word": "balance weight"
}