a) Magnetic Filter:
The magnetic filter in the lubricating oil system of a reduction gear serves the purpose of removing ferrous wear debris from the oil. Here’s how it works:
- Magnetic Attraction: The filter contains strong magnets that attract ferrous particles (made of iron or steel) suspended in the lubricating oil.
- Contamination Capture: As the oil flows through the filter, the ferrous wear debris is drawn towards the magnets and gets trapped on their surface.
- Cleaner Oil: By removing these ferrous particles, the magnetic filter helps to keep the lubricating oil cleaner and free from contaminants.
This cleaner oil offers several benefits:
- Reduced Wear: Abrasive wear caused by metal particles circulating in the oil is minimized.
- Improved Gear and Bearing Life: By reducing wear, the lifespan of gears and bearings is extended.
- Protection from Scoring: Large ferrous particles can cause scoring damage on gear teeth and bearing surfaces. The magnetic filter helps prevent this by removing these larger particles.
Magnetic filters are a simple and effective way to remove a specific type of contaminant (ferrous wear debris) from the lubricating oil in reduction gears. They are often used in conjunction with other filtration methods like full-flow filters that remove non-ferrous contaminants and other impurities.
(b) Importance of Gear Teeth Surface Finish:
The surface finish of gear teeth in reduction gearing is crucial for several reasons:
- Reduced Friction: A smooth surface finish minimizes friction between gear teeth as they mesh. This reduces power losses and improves overall efficiency.
- Improved Load Distribution: A smoother surface allows for more even load distribution across the tooth profile, reducing stress concentrations and minimizing wear.
- Reduced Noise: Rough surface finishes can lead to increased noise during gear operation. A smooth finish helps to minimize noise generation.
- Enhanced Lubrication: A smooth surface allows for better retention of lubricating oil film between gear teeth, improving lubrication effectiveness.
The specific surface finish requirements depend on factors like gear material, load rating, and operating speed. However, a well-honed or lapped surface finish is generally preferred for optimal performance and longevity of reduction gears.
(c) Preference for EP (Extreme Pressure) Lubricating Oil:
EP (Extreme Pressure) lubricating oils are preferred for reduction gearing due to the demanding operating conditions these components experience. Here’s why:
- High Pressure Contact: Gear teeth in reduction gearing undergo high contact pressures during operation. EP oils contain special additives that activate under these high pressures.
- Anti-Seizure Protection: The EP additives form a thin film on the gear teeth under high pressure, preventing metal-to-metal contact and seizure. This protects the gear teeth from severe wear and potential damage.
- Reduced Friction: EP additives can also help to reduce friction between gear teeth under extreme pressure conditions.
- Improved Load-Carrying Capacity: EP oils can enhance the load-carrying capacity of the lubricating oil film, enabling the gears to handle higher loads without failure.
While EP oils offer these benefits, it’s important to note that they can break down over time due to the activation of the EP additives under pressure. Therefore, regular oil changes are essential to maintain the effectiveness of EP lubrication and protect the reduction gearing.