SWITCH AS 8W4857 - Caterpillar

Introduction
This instruction describes flange wear patterns and the proper measurement of flange thickness of Duo-Cone Seals with Formed Steel Seal Rings. Also included are estimates of expected seal life.Flange Wear Patterns
Cross section comparison of formed steel rings and cast iron rings.Formed steel rings are more flexible than cast iron rings. Because of this characteristic, the seal contact face will be wider during machine operation, with more surface contact area.As the rings wear during machine operation, the contact surface becomes wider, until it extends completely across the ring flange. This amount of wear is the normal maximum service life for the cast iron rings, but not for the new steel rings.The total thickness of the flange is usable wear material on the steel rings and good seal performance can generally be expected until the flange is completely worn away.Measurement of Flange Thickness
Measurement of flange thickness on hardened steel rings.With formed steel rings, the measurement used to check the remainder seal service life is the flange thickness at the outer edge. The measurement must be made carefully because of the shoulder, which is only 1.52 mm (.060") from the edge of the flange.
Location of wear lip on seal ring.Before the flange is measured, it must be inspected for a wear lip around the outer edge as shown. The development of a wear lip at the outer edge is a normal condition any time the edges of the two ring flanges are not exactly even when the seal is installed.A wear lip in this location does not damage the seal ring and has no effect on seal performance, but it must be carefully ground off before the flange thickness is measured and/or before the seal is installed again.If any type of wear lip is found around the inner edge of the seal face or if the seal face has any scratches or other damage, a new seal must be installed. The seal face must be flat and smooth.Estimates of Expected Seal Life
Estimates of expected seal life are difficult because of the many differences in machine applications, job conditions, maintenance and other factors which have an effect on seal service life.The chart above can be used as a guide to make an estimate of the remainder of seal service life, according to flange thickness.Protection from rust and corrosion, especially on the machined seal face, is very important. The seals need protection from moisture and/or mechanical damage (scratches, bend stresses, etc.). Damage can also be caused by hand contact because of moisture and salt from the person's body.Be sure seal rings are thoroughly cleaned and have an application of heavy oil on the seal face before storage. This needs to be done for storage intervals as short as one or two days during service work on the machine.