where M, R, F, [alpha], and b in equations (1) and (2) are friction moments, the radius of the counterpart wear ring, the applied load, the contact angle, and the width of abrasion marks
Beginning at a testing temperature of 600[degrees]C, the wear behaviour changes and abrasion marks
and highly deformed areas can be detected.
This could cause a knocking sound and in rare instances, abrasion marks
could possibly occur on the fuel line itself.
The lack of abrasion marks
(also noted in Marsh & West 1981, but not mentioned by Knusel & Carr), excellent condition and complete facial regions form a striking contrast to the assertions of Knusel & Carr.