Mechanical Engineering Flashcards

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 and Diagnostics

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