Queen Essays

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.

Unit 2 Study Guide 2

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Guidelines

1. Legibly write on each piece of paper, green engineering pad with grid on the back preferred

· Your first and last names

· The course and section number, if applicable

· The assignment number

· The page number

2. Clearly present

· The given data

· The unknowns

· The formulas needed, and

· Sketches, where applicable

3. Write only on one side of the paper

4. Draw a long solid line to separate two different consecutive exercises/problems

5. Use consistent units

6. Round off final answers to proper degree of precision or accuracy

7. Underline your final answer

8. Staple multiple pages (for in seat only)

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Question 1

Which of the following is one of the three important considerations when analyzing or designing a hydraulic circuit?

A. Safety of operation.

B. Performance of desired function.

C. Efficiency of operation.

D. A, B, and C

E. None of the above

Answer D. “A, B, and C”

Question 2

Which of the following is the purpose of a regenerative circuit?

A. To regenerate the viscosity of the working fluid

B. To remove extra moisture from the working fluid

C. To speed up the extending speed of a double-acting cylinder

D. To control the temperature of the working fluid

E. None of the above

Answer C. “To speed up the extending speed of a double-acting cylinder”

Question 3

Which of the following is the purpose of fail-safe circuits?

A. Fail-safe circuits are designed to provide overload protection for system components

B. Fail-safe circuits are designed to regulate the flow rate of the working fluid

C. Fail-safe circuits are designed to control the bulk modulus of the working fluid

D. A, B, and C

E. None of the above

Answer A. “Fail-safe circuits are designed to provide overload protection for system components”

Question 4

Which of the following is one of the reasons for considering pneumatics instead of hydraulics?

A. Liquids exhibit greater inertia than do gases

B. Liquids exhibit greater viscosity than do gases

C. Hydraulic systems require special reservoirs and no-leak design components

D. There are no instances where pneumatics are considered instead of hydraulics

E. A, B, and C

Answer E. “A, B, and C”

Problem 1

A double-acting cylinder is hooked up in the regenerative circuit shown. The relief valve setting is 100 bars. The piston area is 120 cm2 and the rod area is 70 cm2. If the pump flow is 0.0018 m3/s, find the cylinder speed and load-carrying capacity for the

a. Extending stroke

b. Retracting stroke

Solution

Known data

Relief valve pressure p = 100 bars = 10,000,000 Pa

Piston area Ap = 120 cm2 = 0.012 m2

Rod area Ar = 70 cm2 = 0.007 m2

Pump flow rate Qp = 0.0018 m3/s

Unknown (s)

a. Extending stroke

· Cylinder speed VP ext?

· Load-carrying capacity Fload ext?

b. Retracting stroke

· Cylinder speed VP ret?

· Load-carrying capacity Fload ret?

Formula