一種圓柱體,其中心有一個孔,用於安裝銷釘或軸,以便將其連接到推桿導軌、軛桿、搖臂、轉盤或導軌上。此零件與引擎、燃油噴射幫浦、門鎖、轉盤、需要滾輪支撐的平行軸承面等上的氣門桿表面或凸輪環或凸輪軸的凸角形成滾動接觸。不包括:圓柱滾子軸承;電氣開關滾子;以及摩擦軸承。另請參閱凸輪從動件、滾針軸承。
0.374 inches minimum and 0.375 inches maximum bore inside diameter, not casehardened casehardening indicator, 0.999 inches minimum and 1.000 inches maximum outside diameter, 0.020 in. min,0.030 in. max chamfer chamfer/radius of outside corner, 0.620 inches minimum and 0.625 inches maximum face width