The Caterpillar Cat 3S-1223 O-ring is a Buna‑N (NBR) elastomer seal sized 5.33 mm cross‑section by 145.42 mm inside diameter, with a hardness rating of 75A. As Cat OEM part 3S‑1223, it serves as a general‑purpose O‑ring seal for Caterpillar equipment where Buna‑N material and this size are specified. The Buna‑N (NBR) composition provides resistance to petroleum oils and fuels typically encountered in Cat machines, helping maintain a reliable seal under normal operating conditions. Verify fitment against your Caterpillar model’s service part specifications and use with compatible Cat housings and gaskets to ensure proper sealing performance.
