【单选题】
Gear pumps are （） because they discharge a near constant amount of liquid regardless of pressure.
A、negative displacement type
B、turbine type
C、positive displacement type
D、mixed-flow type
查看正确答案
A、A.stuffing boxes eliminate the leakage problems usually associated with other gear pumps B、B.it is not necessary to closely maintain design clearances with this pump C、C.they are essentially self-priming and produce a high suction lift D、D.these pumps are designed with extreme tooth angled
