The sun shaft and the drive motor shaft, which is a harmonious set

The drive motor shaft is an element of the excavator driving hydromotor drive system. Transmits the drive directly from the engine piston pump to the final drive where it connects with the final drive shaft. These two gear shafts are a great duo!

Driving motor shaft

The motor shaft has two multi-key teeth along its length. The first (wider) is mounted to the drive engine block, the second (smaller) is the place of transferring the drive to the reduction axle shaft. The main symptom of driving shaft damage is the lack of power transmission. In other words, the final drive does not turn – despite the movement of the drive lever and audible operation of the drive engine. Another sign of damage to the drive engine is also the grinding inside the transmission.

What is the follower shaft and what is it for?

The follower shaft is a mechanical transmission element in planetary gears driving or turning tracked machinery. It has a longitudinal structure. On the upper part there is a gear wheel that drives the upper row of satellites and at the same time puts the entire transmission in motion. At the bottom, we find a multi-wedge, which is the place where the tiller shaft joins the motor shaft.

The gear shaft is the most important element of the planetary gear, because without it it would not be possible to start the gear at all. Importantly, due to the double-sided drive of the travel or rotation hydromotors, the reducer shaft is the gear element most vulnerable to damage. Jerking the machine forward or backward or side to side significantly reduces its service life.

Gear shafts: failures – can they be avoided?

Basically it can’t be avoided. Sooner or later the shaft will wear out and you will need to repair the drive train. However, attention should be paid to the most smooth operation of these components.

If a damage to the driving motor shaft is diagnosed, replace the damaged shaft together with the reduction axle shaft. In 99% of cases, both transmission components are damaged. If we replace only one element, then of course the machine will start working as before. However, in half a year – maybe a year, we have to disassemble the engine again to replace the second element. After replacing both rollers, the backlash will be minimized when changing the direction of travel of the excavator (front, back). Thus, the device will withstand much, much longer and save time associated with dismantling the hydromotor and the purchase and replacement of parts.

How do you search for gear shafts?

If you are looking for a roller follower you should prepare some information. Namely, the number of rack teeth, the number of multi-wedges and the total length of the shaft. This information will help you find the right roller for the final drive. The same is true for the drive motor shaft – you will need the length and the number of splines. If you have a problem finding or replacing them, please contact our specialists