SEAL 1905743 - Caterpillar

Illustration 1. Contact between the idler and link is in the center of the link.The track rollers have a similar effect on the ends of the links, which are narrowed to permit them to overlap where they are connected together. Because this overlap isn't 100 percent, the greatest amount of wear is near the ends of the links, and the size of the worn area has a radius similar to that of the track rollers. (See Illustration 2.)
As a result of this wear, a scallop pattern is formed on the surface of each track link. (See Illustration 3.)
This type of link wear can be accelerated by three factors--abrasiveness and moisture content of the soil, machine weight and travel speed and underfoot conditions.
A wet, abrasive soil can accelerate the wear of the links.
The higher the operating weight of a given machine due to attached equipment, the faster the links will wear.
Higher travel speeds result in more frequent contact and, therefore, more wear on the links per hour of operation.
Illustration 2. Areas of links worn by contact with track rollers.
Illustration 3. Scallops from the rollers and idler.Rough underfoot conditions can place higher loads at a given point on a link. It is possible on rocky or rough terrain to have a higher load on a link on one side of the machine than on the other side.
Although rough terrain can accelerate wear, it is some times possible that track-excited vibration will go unnoticed on rough terrain, yet be apparent when the machine is working on a smooth surface.
To understand this, we must study the effect of the worn links on the machine.
Visualize the tracks laying on the ground. They provide a track similar to a railroad track over which the machine travels. (See Illustration 4.)
Observe the scallop pattern along the entire length of the track, and how the spacing relates to the spacing of the track rollers.
Along with the depth of scallop, this scallop-roller spacing relationship is what determines how smoothly the machine will travel on the links.
Illustration 4. Rollers on high and low points on the links.If the spacing of the track rollers and scallops are uneven, so that some of the rollers are on the high points of the links while others are over the low points, the machine will move across the scallops smoothly. However, if the spacing is the same, the rollers will rise and fall in unison with each scallop as they pass over the links, thus creating vibration.
If the machine were operating in rough terrain, the vibration might not be noticed because it could be masked by the bouncing of the machine. On a smooth surface, though, the vibration could be very apparent. This is especially true on a smooth surface which allows full grouser penetration so the shoe plate area is fully supported.
Two factors, machine speed and the depth of the scallops, affect the amount of vibration. The speed of the machine determines the frequency of the vibration while the depth of the