An overhead camshaft bench rig has been used to reproduce scuffing failures and these were compared with those obtained from fired engines. A base oil and a fully formulated oil were used under different experimental conditions to produce non scuffing and scuffing characteristics Surfaces of the cam were periodically examined and replicated by stopping the test for a short period of time, these replicas were used to obtain a record of the changing topopgraphy of the wear surface. Spectroscopy, ferrography and thin layer activation (t.l.a.) were all used to monitor wear continuously. Spectroscopy and t.l.a. were both satisfactory in following running-in and scuffing wear. Ferrography was not satisfactory when the system was run with a standard motor engine oil filter but performed well when the filter was bypassed. Wear debris under all conditions was plate-like and under normal wear condition was of the order of 5 microms in size. Under scuffing conditions much larger plates were obtained, some exceeding 50 microms. The appearance of the wear damage on the replicas and on actual worn cams examined at the end of the test correlated very well with appearance of the wear debris produced.
Wear monitoring of CAM and tappet systems
Verschleissueberwachung von Nocken- und Stoesselsystemen
1987
12 Seiten, 9 Bilder, 1 Quelle
Conference paper
English
I. C. Engine Cam and Tappet Wear Experience
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