Caterpillar 4J-3420 Wear Ring

Caterpillar 4J-3420 Wear Ring is a 127 mm bore piston guide designed for Cat hydraulic cylinders in the AD-series machines, including AD40, AD45, AD45B, AD55, AD55B, and AD60. This genuine Cat wear ring provides a precise bearing surface that supports the piston as it travels within the cylinder, helping maintain concentric alignment and reduce side loads that can cause wear on cylinder walls and seals. Specifically chosen for replacement in Cat cylinder assemblies, the 4J-3420 is compatible with Cat AD-series hydraulic systems and is intended to deliver consistent performance under the high-load conditions typical of these machines. Proper installation seats the wear ring in the piston guide groove to establish a stable, low-friction interface between piston and bore, contributing to longer service intervals and smoother operation. Cataloged as Caterpillar part 4J-3420, this wear ring serves as a direct replacement component when worn rings or piston guides are required on compatible AD-series equipment.