Engineering - Electronic Engineering Review Assignment Hydraulic Motors and Circuits

Question 1

Which of the following statements is true about limited rotation hydraulic motors?

A. They are also called oscillating motors

B. They can rotate in both clockwise and counter clockwise direction

C. They are classified as rotary actuators

D. They rotate through less than one complete cycle

E. All of the above

Answer E. “All of the above”

Question 2

Which of the following statements list the main advantage (s) of gear motors?

A. Long expected life in all weather conditions

B. Highest overall efficiencies

C. Light weight

D. High power and torque at high speed

E. Low cost and from simple design

Answer E. “Low cost and from simple design”

Question 3

A. Volumetric efficiency is the theoretical flow rate the motor should consume, divided by the torque the motor should theoretically deliver.

B. Volumetric efficiency is the theoretical flow rate the motor should consume, divided by the actual power delivered to the motor.

C. Volumetric efficiency is the theoretical flow rate the motor should consume, divided by the actual flow rate consumed by the motor.

D. The volumetric efficiency of a motor can be greater than 1

E. None of the above

Answer C. “Volumetric efficiency is the theoretical flow rate the motor should consume, divided by the actual flow rate consumed by the motor.”

Question 4

Which of the following statements is true about different efficiencies of a hydraulic motor?

A. The overall efficiency of a hydraulic motor is, as in the case of pumps, equals to the product of the volumetric and mechanical efficiencies

B. The mechanical efficiency of a hydraulic motor is the inverse of that of a pump.

C. The volumetric efficiency of a hydraulic motor is the inverse of that of a pump.

D. A, B, and C

E. None of the above

Answer D. “A, B, and C”

Question 5

Which of the following statements is NOT true about different efficiencies of a hydraulic motor?

A. The volumetric efficiency of a hydraulic motor is the inverse of that of a pump.

B. The mechanical efficiency of a hydraulic motor is the inverse of that of a pump.

C. The overall efficiency of a hydraulic motor is, as in the case of pumps, equals to the product of the volumetric and mechanical efficiencies

D. Volumetric, mechanical, and overall efficiency of a motor are always greater the volumetric, mechanical, and overall efficiency of a pump respectively

E. None of the above

Answer D. “Volumetric, mechanical, and overall efficiency of a motor are always greater the volumetric, mechanical, and overall efficiency of a pump respectively.”

Question 6

Which of the following is true about hydraulic motors?

A. A motor uses more flow than it theoretically should

B. A hydraulic motor delivers less torque than it theoretically should

C. Hydraulic motors extract energy from a fluid and convert it to mechanical energy

D. In vane motors, vanes are held in contact with cam ring by springs or by being pressure-loaded

E. All of the above

Answer E. “All of the above”

Question 7

Which of the following is true about hydraulic motors?

A. A motor uses more flow than it theoretically should

B. A hydraulic motor delivers less torque than it theoretically should

C. Hydraulic motors extract energy from a fluid and convert it to mechanical energy

D. In vane motors, vanes are held in contact with cam ring by springs or by being pressure-loaded

E. All of the above

Answer E. “All of the above”

Question 8

Which of the following is true about hydraulic valves?

A. Directional control valves determine the path if a fluid in a given circuit

B. Pilot check valves can permit flow in the normally blocked opposite direction

C. A pressure relief valve is used to limits the maximum pressure in a hydraulic system

D. A pressure reducing valve is used to maintain reduced pressures

E. All of the above

Answer E. “All of the above”

Question 9

Which of the following is one way of actuating a directional control valve?

A. Solenoid actuated

B. Manually actuated

C. Piloted actuated

D. Mechanically actuated

E. All of the above

Answer E. “All of the above”

Question 10

Which of the following is true about hydraulic valves?

A. Directional control valves determine the path of a fluid in a given circuit

B. Pressure control valves protect the system against overpressure

C. Flow control valves control fluid flow rate in hydraulic circuit lines

D. Check valves permit fluid flow in only one direction regardless

E. All of the above

Answer E. “All of the above”

Question 11

Which of the following symbols represent a shuttle valve?

A.

B.

C.

D.

E. None of the above

Answer D.

Question 12

Which of the following symbols represent a two position, four-way directional control valve?

A.

B.

C.

D.

E. None of the above

Answer A.

Question 13

Which of the following is NOT a directional control valve?

A. Check valve

B. Shuttle valve

C. Solenoid actuated, spring return, two-position, three-way valve

D. Counterbalance valve

E. None of the above

Answer D. “Counterbalance valve”

Question 14

Which of the following is NOT a pressure control valve?

A. Pressure relief valve

B. Pressure reducing valve

C. Sequence valve

D. Unloading valve

E. None of the above

Answer E. “None of the above”

Question 15

Which of the following is NOT a flow control valve?

A. Needle valve

B. Non-pressure-compensated valve

C. Pressure compensated valve

D. Servo valve

E. None of the above

Answer D. “Servo valve”

Problem 1

A rotary actuator has the following physical data:

Outer radius of rotor = 0. 5 in

Outer radius of vane = 1.25 in

Width of vane = 1 in

If the torque load is 800 in∙lb, what pressure must be developed to overcome the load?

Solution

Known Data

Outer radius of rotor RR = 0.5 in

Outer radius of vane RV = 1.25 in

Width of vane L = 1 in

Torque T = 800 in∙lb

Unknown (s)

Pressure p?

Needed

Volumetric displacement VD

Formula

Detailed Calculation

First, solve for the volumetric displacement.