Experimental Evaluation of Tappet/Bore and Cam/Tappet Friction for a Direct Acting Bucket Tappet Valvetrain 902086
Tappet/bore friction and torque at the camshaft were measured for a direct acting bucket tappet using a cam/tappet friction apparatus. Tappet/bore and cam/tappet friction torque and friction coefficient as a function of cam angle were derived from those measurements. The results showed that, for the particular geometry tested, tappet/bore friction torque accounted for about 13% of the total cam/tappet/bore friction torque at 250 cam rpm. This fraction decreased with increasing speed. Tappet bore friction was greatest at about ± 40 degrees of cam angle, where side loads on the tappet bore were highest. In contrast, earlier results for a center pivot rocker arm design showed tappet bore friction to be negligible.
Citation: Pieprzak, J., Willermet, P., and Dailey, D., "Experimental Evaluation of Tappet/Bore and Cam/Tappet Friction for a Direct Acting Bucket Tappet Valvetrain," SAE Technical Paper 902086, 1990, https://doi.org/10.4271/902086. Download Citation
J. M. Pieprzak, P. A. Willermet, D. P. Dailey
Ford Motor Co.
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