More Tech Flashcards
What is a coupling?
A coupling is a mechanical device used to connect two shafts together at their ends to transmit power.
Couplings accommodate slight misalignments, absorb shock loads, and reduce wear on connected equipment
Why are couplings essential in machinery?
They prevent damage due to thermal expansion, vibration, or alignment issues.
Couplings help in the smooth operation of machinery components.
What is the purpose of a gearbox in a propulsion system?
To adjust the speed and torque from the prime mover to the desired level required by the propeller.
Gearboxes ensure efficient propulsion and optimal performance.
How does a gearbox affect engine and propeller efficiency?
It reduces speed while increasing torque, allowing engines to run efficiently at high speeds and propellers to work at lower speeds with higher torque.
Describe the difference between a pump and a compressor.
A pump moves liquids, while a compressor moves gases, increasing their pressure and reducing volume.
Pumps handle incompressible fluids; compressors handle compressible gases.
Why is alignment critical when fitting propulsion shafts?
To prevent excessive wear, vibration, and potential failure of machinery.
Correct alignment ensures smooth power transmission and prolongs equipment life.
What can misalignment of propulsion shafts cause?
It can cause bearings, seals, and couplings to fail prematurely, leading to costly downtime and repairs.
Name a few types of bearings and their uses.
Types of bearings include:
* Ball Bearings – Handle radial and axial loads; used in pumps, motors, and fans.
* Roller Bearings – Support heavy radial loads; used in gearboxes and large rotating machinery.
* Thrust Bearings – Designed for axial loads; found in propeller shafts and vertical pumps.
* Sleeve/Journal Bearings – Support shafts with sliding motion; used in engines and turbines.
How do pneumatic systems differ from hydraulic systems?
Pneumatic systems use compressed air or gas, while hydraulic systems use pressurized liquids.
Pneumatics are cleaner and faster; hydraulics provide higher force and precision.
What is a key difference between air and hydraulic fluids?
Air is compressible, whereas hydraulic fluids are not, making hydraulics more precise.
How would you use an engineering drawing on a job?
By reading the drawing to understand specifications, dimensions, tolerances, and materials, and using it as a reference throughout the job.
What critical information does an engineering drawing provide?
It provides part numbers, assembly sequences, and alignment points.
Can you explain what a coupling is and why it’s used in machinery?
A coupling connects two shafts so power can be transferred, even if the shafts aren’t perfectly aligned.
For example, when installing a propulsion shaft on a ship, we use flexible couplings to connect the gearbox to the shaft. This accounts for any slight movement or misalignment as the ship flexes while moving through rough seas, preventing damage to the gearbox.
What is the purpose of a gearbox in a propulsion system?
The gearbox reduces the high speed of the engine to the lower speed required by the propeller while increasing torque.
On large vessels, the diesel engine might operate at 1,500 RPM, but the propeller turns efficiently at around 150 RPM. The gearbox allows that adjustment, ensuring the propeller generates enough thrust to move the ship efficiently through water.
Describe the difference between a pump and a compressor.
A pump moves liquids like seawater, fuel, or lubricating oil, while a compressor deals with gases like air.
For example, onboard a ship, we might install a bilge pump to remove water from the bilge areas, while an air compressor supplies compressed air to start a diesel engine or operate pneumatic tools. The pump maintains flow, while the compressor stores air at high pressure for controlled release.
Why is alignment critical when fitting propulsion shafts?
Alignment is essential to prevent vibration and premature wear.
For instance, when installing a propulsion shaft, laser alignment tools are used to ensure the shaft is perfectly aligned with the engine and gearbox. If not aligned, bearings might wear out faster, or the shaft could vibrate excessively, leading to expensive repairs or even failure at sea.
Can you name a few types of bearings and their uses?
• Ball Bearings are used in electric motors onboard to handle both axial and radial loads.
• Roller Bearings are fitted in the gearbox to support the heavy rotating gears.
• Thrust Bearings are installed at the propeller shaft to handle the forward push (thrust) when the ship moves.
• Sleeve Bearings might be used in a pump motor where the shaft slides inside the bearing during rotation.
How do pneumatic systems differ from hydraulic systems?
Pneumatics use compressed air, while hydraulics use oil.
Onboard, air tools like impact wrenches or grinders run off the ship’s compressed air supply. These tools are light and fast but don’t generate as much force. In contrast, hydraulic systems operate the steering gear or winches because they need the strength to move heavy loads like rudders or anchor chains.
Explain how you would use an engineering drawing on a job.
If I were tasked with installing a pump system onboard, I’d study the engineering drawing to check the exact position of the pump, bolt hole locations, and pipe connections.
I’d measure and mark the foundation, drill holes as per the drawing, and verify alignment with other systems like the piping routes. The drawing ensures everything fits together and meets design specifications, avoiding costly rework.
