1. Which of the following is not a characteristic of a fluid coupling?
a) Variable torque ratio
b) Variable speed ratio
c) Slip-free operation
d) High efficiency
Answer: b) Variable speed ratio
Explanation: Fluid couplings provide a variable torque ratio but maintain a constant speed ratio between the input and output shafts. They operate without slip and typically exhibit high efficiency.
2. What is the function of a velocity diagram in fluid machinery?
a) To determine slip
b) To visualize the flow velocity
c) To calculate efficiency
d) To measure torque
Answer: b) To visualize the flow velocity
Explanation: Velocity diagrams help engineers visualize the flow velocity and direction within fluid machinery, aiding in design and analysis.
3. What is the primary distinction between positive displacement machines and turbo machines?
a) Positive displacement machines operate at constant speed
b) Turbo machines have variable displacement
c) Positive displacement machines have fixed displacement
d) Turbo machines operate with constant torque
Answer: c) Positive displacement machines have fixed displacement
Explanation: Positive displacement machines displace a fixed volume of fluid per cycle, while turbo machines impart energy to the fluid continuously.
4. Which type of pump has a variable displacement?
a) Centrifugal pump
b) Axial-flow pump
c) Gear pump
d) Piston pump
Answer: d) Piston pump
Explanation: Piston pumps are positive displacement pumps that can have variable displacement by adjusting the stroke length or rotational speed.
5. In a hydrostatic system, what is the function of an accumulator?
a) Stores excess fluid
b) Regulates pressure fluctuations
c) Converts mechanical energy into hydraulic energy
d) Controls flow direction
Answer: b) Regulates pressure fluctuations
Explanation: Accumulators store fluid under pressure and help regulate pressure fluctuations within a hydraulic system, providing a source of stored energy.
6. What is the purpose of a hydraulic intensifier?
a) To increase the flow rate
b) To amplify hydraulic pressure
c) To reduce fluid viscosity
d) To regulate temperature
Answer: b) To amplify hydraulic pressure
Explanation: Hydraulic intensifiers increase hydraulic pressure by using a small force to act on a small area and transmit a larger force to a larger area, effectively amplifying pressure.
7. Which type of machine is best suited for high-pressure applications in hydraulic systems?
a) Positive displacement pump
b) Turbo machine
c) Centrifugal pump
d) Axial-flow pump
Answer: a) Positive displacement pump
Explanation: Positive displacement pumps are capable of generating high pressures because they deliver a fixed volume of fluid per cycle, regardless of system resistance.
8. What is the characteristic feature of a torque converter?
a) Variable torque ratio
b) Fixed speed ratio
c) Slip-free operation
d) Low efficiency
Answer: a) Variable torque ratio
Explanation: Torque converters provide a variable torque ratio between the input and output shafts, allowing for smooth power transmission in automotive applications.
9. What distinguishes a turbo machine from a positive displacement machine?
a) Turbo machines operate with variable displacement
b) Positive displacement machines operate with constant torque
c) Turbo machines have fixed displacement
d) Positive displacement machines have variable speed
Answer: a) Turbo machines operate with variable displacement
Explanation: Turbo machines, such as turbines and compressors, operate with variable displacement, while positive displacement machines maintain a fixed displacement.
10. Which component of a hydrostatic system is used to store hydraulic energy?
a) Hydraulic intensifier
b) Accumulator
c) Positive displacement pump
d) Torque converter
Answer: b) Accumulator
Explanation: Accumulators store hydraulic energy in the form of pressurized fluid, which can be used to supplement system power during peak demands or absorb shocks.
11. What does slip refer to in fluid machinery?
a) Loss of pressure
b) Loss of speed
c) Loss of torque
d) Loss of efficiency
Answer: b) Loss of speed
Explanation: Slip in fluid machinery refers to the difference between the theoretical speed and the actual speed of the machine, typically caused by factors such as fluid viscosity or mechanical losses.
12. Which type of pump is commonly used in high-pressure hydraulic systems?
a) Gear pump
b) Centrifugal pump
c) Axial-flow pump
d) Piston pump
Answer: d) Piston pump
Explanation: Piston pumps are well-suited for high-pressure hydraulic systems due to their ability to generate significant pressure by displacing fluid with reciprocating or rotating pistons.
13. What is the primary advantage of a variable displacement pump over a fixed displacement pump?
a) Higher efficiency
b) Lower cost
c) Greater reliability
d) Adjustable flow rate
Answer: d) Adjustable flow rate
Explanation: Variable displacement pumps allow for the adjustment of flow rate, making them versatile for applications where varying fluid flow requirements are needed.
14. Which component of a fluid coupling contributes to its slip-free operation?
a) Impeller
b) Turbine
c) Stator
d) Shaft
Answer: c) Stator
Explanation: The stator in a fluid coupling redirects the fluid flow exiting the turbine back to the impeller, reducing slip and improving the efficiency of power transmission.
15. What distinguishes a positive displacement pump from a turbo machine?
a) Positive displacement pumps have fixed displacement
b) Turbo machines have variable displacement
c) Positive displacement pumps operate with constant speed
d) Turbo machines have fixed speed
Answer: a) Positive displacement pumps have fixed displacement
Explanation: Positive displacement pumps displace a fixed volume of fluid per cycle, while turbo machines continuously impart energy to the fluid without necessarily displacing a fixed volume.