question: How does it enable the cab to go down by it 's own weight ?
answer: it opens the valve so that the air can pressurize the top of the `` shaft ''
turker_answer: Opening the valve so that the air can pressurize the top of the `` shaft '' , enables the cab to go down by it 's own weight .
rule-based: It enables the cab to go down by it 's own weight by it opens the valve so that the air can pressurize the top of the `` shaft .