单项选择题
In a fixed displacement axial piston hydraulic motor, the speed is varied by（）
A.regulating the ratio between torque and speed via the torque limiter at the motor
B.directing the motor output flow through a bypass line
C.maintaining a constant flow and pressure input
D.controlling the input flow rate
相关考题
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单项选择题
In a shell-and-tube type hydraulic fluid cooler, the amount of heat transferred from the hydraulic fluid to the cooling water depends upon（）
A.the temperature of the hydraulic fluid
B.the flow rate of the hydraulic fluid
C.the temperature of the cooling water
D.all of the above -
单项选择题
An orifice-check valve placed in a hydraulic system is used to（）
A.regulate the fluid flow in either direction
B.restrict movement of hydraulic fluid in one direction, but allow free movement in the other direction
C.allow free movement of hydraulic fluid in both directions
D.allow a restricted fluid flow in one direction only -
单项选择题
Purging air from a hydraulic system is necessary when（）
A.adding small amounts of oil to the system
B.the system has been overheated
C.the system has been drained and then filled with new oil
D.the system has been idle for a long period of time
