当今国际公认，被称之为现代文明三大支柱的技术是（）。

A.slide block

B.tilting box

C.pintle

D.reaction ring

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

A variable displacement system of hydraulic drives consists of _____.

A.a variable displacement axial piston pump

B.a constant displacement axial piston pump

C.a reciprocating piston pump

D.a centrifugal pump

A.cause loss of hydraulic oil from the system

B.result in extreme damage to the pump

C.cause damage to the pump ff not continually drained from the pump casing

D.result in the system high side pressure to substantially drop off

A.radially from the shaft

B.parallel to each other and to the shaft

C.parallel to each other but at a right angle to the shaft

D.at an angle to each other and to the shaft

A.Variable volumes can be obtained with gear pumps only by variation of the pump drive speed

B.A radial piston pump houses sliding pistons in a stationary cylinder block through which passes a rotating pintle or ported shaft

C.The amount of fluid displaced per revolution of an axial piston rotary pump is dependent on the angle formed between the cylinder block and valve plate

D.All of the above

With reference to an axial piston pump, which one of the following statements is true？

A.The cylindrical barrel is coupled to the motor

B.The cylindrical barrel has an odd number of bores

C.The bores end in sockets

D.The sockets fit in the swash plate

Hydraulic pumps most commonly used in steering systems are of the ______.

A.lobe type

B.screw type

C.axial piston type

D.volute type

Which of the following types of hydraulic pumps would be used in a steering system？

A.Lobe

B.Screw

C.Radial piston

D.Volute

A.accumulator spring compression

B.balance piston

C.compensating(补偿) needle valve

D.proportional piston