Track roller wheels, also known as undercarriage rollers or carrier rollers, are used in the undercarriage of tracked vehicles like bulldozers, excavators, and tanks.

The most common materials used in the construction of track roller wheels are:

1. Steel: Steel is the most widely used material for track roller wheels. Steel rollers provide excellent durability, strength, and wear resistance.

2. Polyurethane: Some track roller wheels are made with a polyurethane outer surface. Polyurethane rollers offer good shock absorption, noise reduction, and resistance to abrasion compared to steel.

3. Rubber: Rubber-coated track roller wheels are sometimes used to provide a softer ride and reduced ground pressure on sensitive terrain.

4. Composite Materials: In some specialized applications, track roller wheels may be made from composite materials like fiberglass-reinforced polymer, which can offer a balance of light weight and high strength.

The choice of material depends on factors like the weight of the tracked vehicle, the terrain it will operate in, the required ride quality, and the desired service life of the rollers. Steel is the most common and cost-effective option, but polyurethane or rubber coatings may be used for specific performance requirements.