KR design cam followers
KR design cam followers are fitted with a needle roller and cage assembly. They are also available with a full complement needle roller set (fig. 1), which is identified by the letter V at the end of the basic designation. The outer ring is axially guided by the pressed-on flange ring and the head of the stud, which also serves as an integral flange.
KR design cam followers without a designation suffix or with the designation suffix B (fig. 2) have a narrow gap between the outer ring and the two flanges that serves as a gap-type seal.
KR design cam followers are also available with an axial sliding ring made of PA66 on both sides, identified by the designation suffix PPA (fig. 3, fig. 4 and fig. 5), PPSKA (fig. 6) or PPXA. In the radial direction, the sliding ring forms a narrow labyrinth seal with the outer ring to protect against coarse contaminants. In the axial direction, the sliding ring serves as a contact seal to reliably retain grease in the bearing. This improves the lubrication conditions in the bearing, keeps friction and frictional heat low, and extends grease life.
Cam followers with axial sliding rings can accommodate somewhat heavier axial loads than those without axial sliding rings. Axial loads are induced when operating in an inclined or tilted position.
KR design cam followers, sizes 16 and 19, either without a designation suffix or with the designation suffix PPA have one slot in the head of the stud that enables the stud to be held in place by a screwdriver during mounting. In the centre of that slot is a relubrication hole for a press-in grease fitting or a plug if relubrication is not required (→ Accessories). SKF also supplies these two sizes with a hexagonal recess in the head of the stud. They are fitted with an axial sliding ring on both sides and are identified by the designation suffix PPSKA (fig. 6).
KR design cam followers with the designation suffix B, sizes 22 and larger, have a hexagonal recess at each end of the stud (fig. 2), enabling the cam follower to be held in place by a hexagonal key (Allen wrench) during mounting. In the centre of each hexagon is a relubrication hole for a press-in grease fitting, if needed. Sizes 35 and larger can accommodate adapters from a central lubrication system (→ Accessories).