Sprocket And Sprocket Segement For Excavator/Bulldozer

What’s Excavator Sprocket?

Sprocket, the power transmission operator of construction machinery excavator and bulldozer. In the excavator, because the whole is casting processing, so called “sprocket”. In the bulldozer, because it is separated from several pieces of by casting or forging, so called “sprocket segement” . Sprocket for excavator is generally directly connected with the driving motor, directly power to the tracks to drive the entire chassis forward.

The excavator sprocket material is mainly cast, but the bulldozer sprocket segement of the high-power bulldozer is mainly forge, so that the product will withstand greater driving force, so as to ensure the quality of the product. No matter what kind of material, the product must go through blank casting (forging) mechanical processing, tooth quenching and other processes, and finally give the customer to use.

Sprocket Design:

The excavator sprocket can install on the back or the front of the crawler chassis. In general,the crawler chassis is rear, which can reduce the length of drive section, reduce the power loss. But with the speed increase, as the crawler vibrate band jumps and loses more energy, the power loss of the rear sprocket is become more.So it’s generally thought that, the drive speed is less than 15-20km/h, it’s benefit for rear sprocket. Crawler loader adopts the method of driving wheel rear positioning.

According to the shape of the tooth surface, the sprocket tooth shape can be divided into three types: convex, linear and concave.The latter two types are mostly used in the crawler construction machinery. Therefore, concave tooth profile is the best choice. The sprocket for excavator is used to drive the track, which is generally made of medium carbon steel, and the gear surface is not machined after static heat treatment. Another kind of drive sprocket for excavator is consists of hub and gear ring, and connected by bolts. This design not only does not waste materials, but also is convenient for processing.

Requirement for sprocket tooth shape:

(1) Make the track pin smoothly enter and exit the engagement, and reduce the impact force on the contact surface.
(2) Tooth surface contact stress to reduce friction.
(3) When the track pitch increases due to abrasion, the track pin and sprocket teeth can still work without out of chain.

Sprocket Abrasion:
The wear of the excavator sprocket teeth often occurs at the root, front and rear sides, left and right sides and top of the gear teeth. When the bulldozer moves forward and the gear teeth lift the track pin sleeve, the wear occurs on the front side of the gear teeth; On the contrary, When the bulldozer moves backward, wear occurs on the rear side of the gear teeth. When the track is too loose, the track deflects ,and the gear teeth impact on the side of the chain rail link will cause wear on the side of the drive wheel teeth.
Another form of wear of the drive wheel teeth is top wear. Top wear occurs on the track and drive wheel teeth. When the meshing relationship between the driving wheel tooth and the track pin sleeve is changed due to the viscous material. When the bulldozer moves forward, marks will be made on the top of the tooth back on the drive side of the drive wheel and on the side of the pin sleeve.