Mechanical Engineering Flashcards

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Questions and Answers

What is the usual cause of overheating in high speed, grease-lubricated antifriction bearings?

Faulty mounting practices

How can too much wear in gears be reduced?

Proper meshed

Why are timing belts made with teeth?

Doesn't slip

What is the purpose of the insert, or spider, used in flexible jaw couplings?

Transmit torque and accept misalignment Signup and view all the answers

What do clutches on machinery provide?

Disengaging and may also interrupt the power supply Signup and view all the answers

What determines the selection of gear reducer size?

Torque and speed Signup and view all the answers

Why do metal parts seize when there is a lack of lubrication?

Metal to metal contact (lube protects the bearing against corrosion) Signup and view all the answers

What causes lubrication oil to get milky?

Mixing incompatible oils, contamination Signup and view all the answers

Why are heavy oils used?

To reduce the friction from heat and wear Signup and view all the answers

What is viscosity?

The resistance of a liquid to flow Signup and view all the answers

Which machine condition can be determined by using oil analysis?

Various types of wear and take corrective action before failure Signup and view all the answers

Acids that form in lubricants affecting performance are a result of?

Oxygen from the air and high temperatures Signup and view all the answers

What will shutting the fluid discharge of an air-operated reciprocating pump cause?

Overstroke Signup and view all the answers

What is the pressure on a fluid?

Measurement of force per unit area on an object in the fluid Signup and view all the answers

What can you use to meet peak hydraulic system demands?

A variable displacement pump Signup and view all the answers

Pressure in the hydraulic system can be controlled electrically by the use of?

Metering the flow of fluid into or out Signup and view all the answers

Hydraulic valves are typically adjusted by?

Flow control valve and adjustment of the control Signup and view all the answers

Why can hydraulic reservoir suction lines be raised?

To create enough vacuum Signup and view all the answers

When air is compressed, what else increases besides temperature?

The pressure and temperature of the air increases Signup and view all the answers

What determines the speed of a piston?

Crankshaft stroke and the engine RPM Signup and view all the answers

What controls the safe operating speed of an air motor?

Air supply pressure Signup and view all the answers

Where should air line filters and lubricators be installed?

Closer where it is going to be used Signup and view all the answers

If a solenoid valve fails to open, what should you check?

Normally closed (power to open) Signup and view all the answers

What can result from cavitation in centrifugal pumps?

Pump performance deterioration, mechanical damage, noise, and vibration Signup and view all the answers

What can cause a compressor to run too hot?

Build up internal moisture and condensation Signup and view all the answers

What can a pilot flame detector indicate?

If the flame is actually lit Signup and view all the answers

Air cooled condensers generally have?

Fan, ambient air Signup and view all the answers

What tool is used to measure threads?

Screw gauge, thread gauge, pitch gauge Signup and view all the answers

How do you put a bearing onto a shaft?

Press fit Signup and view all the answers

What is the main purpose of a rectifier?

Convert AC to DC Signup and view all the answers

What do variable frequency drives control?

The speed of AC motor by varying the frequency Signup and view all the answers

What does regulation of a power supply refer to?

Output Signup and view all the answers

What are the four basic components of control systems?

Controller, amplifier, actuator, and feedback Signup and view all the answers

What device does not require an analog input module on a PLC?

Thermocouple Signup and view all the answers

What is the final element in a control loop?

Control valve Signup and view all the answers

What does an I/P transducer convert?

An electronic signal to a pneumatic signal used to control a valve Signup and view all the answers

What is the first thing to do after you Meg a motor?

Disconnect power or test megohmeter Signup and view all the answers

What is a Megger?

The instrument used for measuring the resistance of insulation Signup and view all the answers

What is trending?

The process of monitoring and analyzing data over time Signup and view all the answers

Study Notes

Overheating and Gears

Overheating in high-speed, grease-lubricated antifriction bearings typically results from faulty mounting practices.
Proper gear meshing can significantly reduce wear on gears.

Timing Belts and Couplings

Timing belts are designed with teeth to prevent slipping during operation.
The insert, or spider, in flexible jaw couplings transmits torque while accommodating misalignment.

Machinery and Power Control

Clutches in machinery are used to disengage components and can also interrupt the power supply.
The size selection of a gear reducer depends on the required torque and speed.

Lubrication and Oil Analysis

Metal parts may seize due to lack of lubrication, leading to direct metal-to-metal contact.
Lubrication oil can become milky due to mixing incompatible oils or contamination from external sources.
Heavy oils are utilized to minimize friction caused by heat and wear.
Viscosity measures a liquid's resistance to flow and affects lubrication performance.

Fluid Dynamics and Pump Operations

Oil analysis can identify various wear types in machinery, allowing preemptive corrective measures.
Acids forming in lubricants due to oxygen and high temperatures can adversely affect performance.
Shutting off fluid discharge from an air-operated reciprocating pump may cause the pump to overstroke.
Pressure in a fluid is defined as the measurement of force exerted per unit area.

Hydraulic Systems and Control

Variable displacement pumps can meet peak demands in hydraulic systems.
Hydraulic system pressure can be controlled electrically by adjusting fluid flow.
Flow control valves in hydraulic systems facilitate the adjustment and management of pressure.

Air Compression and Piston Speed

Compressing air increases both its temperature and pressure.
The speed of a piston is influenced by the crankshaft stroke and engine RPM.

Air Motors and Filtration

Safe operational speed for air motors is regulated by air supply pressure.
Air line filters and lubricators should be positioned close to their point of use for optimal effectiveness.

Mechanical Failures and Pumps

When a solenoid valve fails to open, checking if it is normally closed can be a solution.
Cavitation in centrifugal pumps can lead to performance deterioration, mechanical damage, along with noise and vibration.
High running temperatures in compressors may indicate internal moisture and condensation issues.

Control Systems and Measurements

A pilot flame detector ensures that the flame is genuinely lit.
Air-cooled condensers generally use fans to facilitate ambient air cooling.
Screw gauges and thread gauges are tools used for measuring threads.

Bearings and Power Conversion

A press fit is the recommended method for installing bearings onto shafts.
Rectifiers primarily convert alternating current (AC) to direct current (DC).
Variable frequency drives regulate AC motor speed by varying frequency outputs.

Control Loop Components

Regulation of a power supply focuses on its output stability.
Control systems incorporate four essential components: controller, amplifier, actuator, and feedback mechanism.
Thermocouples do not require an analog input module on a PLC for operation.
The final element in a control loop is typically the control valve.

Signal Conversion and Motor Testing

I/P transducers convert electronic signals from control systems into pneumatic signals for valve control.
After measuring insulation resistance with a megohmmeter, the first action should be to disconnect the power supply.
A Megger is the instrument used for measuring the resistance of electrical insulation.

Trending refers to observing the general direction of changes in process data over time, which aids in diagnostics.

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Description

Test your knowledge on mechanical engineering concepts with these flashcards. Each card covers important definitions and principles related to bearings, gears, and couplings. Ideal for students and professionals looking to refresh their understanding of the subject.