M.K. Abdul Hamid

Effects of hard particles on friction coefficients and particle embedment in brake system during hard braking

The effects of hard particles on the friction coefficients and particle embedment during hard braking were investigated. Silica sands grit of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient, the fluctuation of frictional oscillation amplitude, and the percentage of particle embedment. Different sliding speeds were applied to investigate the relationship between particle embedment with friction coefficient and friction oscillation amplitude. Presence of hard particles of different grit size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficient and standard deviation values of friction oscillation amplitude increase with particle embedment due to the rapid changes of the effective contact area and the abrasion mode operating in the gap interface. Also, particle embedment tends to increase the disc surface roughness and influence the stopping time of the disc.

Maximizing the Life of Lubricating Oils for Resources and Environmental Sustainability through Quality Monitoring in Service

Objective: To establish that in-service quality monitoring of lubricants as opposed to oil change intervals recommended by the oil/equipment manufacturers is more economical and can preserve the environment and resources. Methods/ Statistical Analysis: A pilot study conducted in capital cities of eight states in Nigeria to estimate the volume/annum of crankcase oils being drained from Nigeria used vehicles without confirming the true states of the oils. Used oil sample drained from a CAT3616-generator running on 1700 liters, at the replacement cycle (1000 hours) recommended by the oil/equipment manufacturer was tested in the laboratory and compared with data of a new oil sample from the same supplier. Findings: In this study, the economic, environmental, and resource conservation benefits of in-service lubricant testing are seen to be outstanding compared to the standardized maintenance schedules recommended by the oil/ equipment manufacturers. The pilot study conducted in capital cities of eight states in Nigeria revealed that huge volume of crankcase oil, which may still be very serviceable, are being drained from Nigerian used vehicles, available in densely populated cities. Used oil, drained at a predicted replacement cycle of 1000 hours, from a CAT 3616 generator running on around 1700 liters, was discovered still serviceable, when tested and compared with data of a new oil sample from the same supplier, tested for benchmarking. Applications/Improvements: Through In-service monitoring of lubricating oils, the OEM regulation can be effectively moderated without causing damage to the equipment, and it can result in economic savings, and environmental/resources sustainability.