Two-step roller finger follower

摘要

A two-step roller finger follower (100,300,400,500,600) having a high-lift follower portion (110,310,510,610) that rotates relative to a low-lift follower portion (114) about a pivot shaft (116), including a lost-motion compression spring (138,338,538) disposed in a linear bore (134,434,534,634) formed in the high-lift portion to exert force against an curved pad (136,536) on the back side of the valve pallet (126) of the low-lift portion. The spring is retained and guided in its bore by a spring retainer (140,340,640) having a planar bottom (147,642) for engaging the curved pad. Preferably the retainer is a cup (140,640) positioned in the spring bore such that the stroke of the cup is limited, to prevent leak-down of the associated hydraulic lash adjuster. Driving the spring by a linear-acting retainer in a linear bore causes the spring to be compressed linearly, resulting in a highly stable and predictable spring rate.