Oilers/Plant Tenders (HHC) Civil Service Practice Exam

Low-viscosity lubricants are best suited for which type of machines?

1. High-speed machines

2. Heavy-duty machines

3. Medium-speed machines

4. Low-speed machines

The correct answer is: High-speed machines

Low-viscosity lubricants are specifically designed to reduce friction in machines operating at high speeds. The lower viscosity allows these lubricants to flow more easily and quickly through the narrow spaces within the machinery, ensuring that moving parts are adequately lubricated without creating excessive drag or resistance. This is particularly important in high-speed applications, where the heat generated by rapid motion can lead to increased wear and wear-related failures. In high-speed machines, the rapid movement necessitates a lubricant that can maintain its lubricating properties under the stress of increased shear rates and temperature. Low-viscosity lubricants achieve this by undergoing less structural change due to mechanical action, ensuring efficient and effective lubrication. On the other hand, heavy-duty, medium-speed, and low-speed machines generally require lubricants with higher viscosity levels, which can provide the film thickness needed to support the loads often encountered. These machines operate under different conditions where thicker oils provide better protection against wear and help absorb shock loads.