The Sprocket is a metal cogwheel that consist of a metal inner ring with bolt holes or a compression hub and a gear ring in one unit. Usually, a sprocket rim is placed at the back part of the running device of an excavator.
The function of an excavator front idler is to guide the track links into running smoothly and to prevent dislocation. Idler also carry some weight of the excavator and therefore increasing the track links and decreasing ground pressure.
The track shoes are components of the undercarriage whose function is the transmission of the load to the ground. Usually, there are four connection holes on a track shoe and another two cleaning holes in the center to clean earth off the track shoe.