question: For sudden surges in pressure above the cab , what is used as a `` brake '' ?
answer: a diaphragm or a piston
turker_answer: For sudden surges in pressure above the cab , a diaphragm or a piston is used as a `` brake '' .
rule-based: For sudden surges in pressure above the cab , a diaphragm or a piston is used as a `` brake '' .