"big end" meaning in English

{
  "forms": [
    {
      "form": "big ends",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "big end (plural big ends)",
      "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": [
        {
          "text": "From the sound of that motor, I'd say yer big end's gone, mate.",
          "type": "example"
        },
        {
          "ref": "1951 July, “British Standard Locomotives”, in Railway Magazine, page 441",
          "text": "Except in the case of the largest 4-6-2, not yet in contemplation, use of two [outside] cylinders only was decided on for the following reasons:— […] 2. The split inside big end is a source of trouble at high speeds and powers unless exceptional integrity of maintenance can be guaranteed.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "In a piston engine, the larger end (crankshaft end) of the connecting rod that connects a piston to the crankshaft."
      ],
      "id": "en-big_end-en-noun-48xWv4Qe",
      "links": [
        [
          "piston engine",
          "piston engine"
        ],
        [
          "crankshaft",
          "crankshaft"
        ],
        [
          "connecting rod",
          "connecting rod"
        ]
      ]
    }
  ],
  "word": "big end"
}

{
  "forms": [
    {
      "form": "big ends",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "big end (plural big ends)",
      "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",
        "English terms with usage examples"
      ],
      "examples": [
        {
          "text": "From the sound of that motor, I'd say yer big end's gone, mate.",
          "type": "example"
        },
        {
          "ref": "1951 July, “British Standard Locomotives”, in Railway Magazine, page 441",
          "text": "Except in the case of the largest 4-6-2, not yet in contemplation, use of two [outside] cylinders only was decided on for the following reasons:— […] 2. The split inside big end is a source of trouble at high speeds and powers unless exceptional integrity of maintenance can be guaranteed.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "In a piston engine, the larger end (crankshaft end) of the connecting rod that connects a piston to the crankshaft."
      ],
      "links": [
        [
          "piston engine",
          "piston engine"
        ],
        [
          "crankshaft",
          "crankshaft"
        ],
        [
          "connecting rod",
          "connecting rod"
        ]
      ]
    }
  ],
  "word": "big end"
}