For Komatsu PC200-6 PC210-6 Excavator Final Drive Sun Shaft 20Y-27-21161

20Y-27-21161 Final Drive Sun Shaft

The 20Y-27-21161 sun shaft is an integrated shaft-and-gear component used in an excavator travel reduction gearbox. Its long shaft section transfers rotational input into the final drive, while the geared end engages with the planetary reduction system.

This one-piece design differs from a separate short sun gear. Shaft straightness, spline condition and gear alignment all influence how smoothly torque is transmitted through the travel drive.

Because the shaft connects input rotation with the reduction gear set, damage at either the spline end or gear end can affect the operation of the complete final drive.

A Shaft and Gear Working as One Component

The geared end of the sun shaft transmits force into the planetary reduction stage, while the shaft section maintains the rotational connection between the drive input and the gearbox.

This means the component must maintain both correct gear engagement and stable shaft alignment. A gear section that appears usable may still cause problems if the shaft is bent, the splines are worn or the bearing contact areas are damaged.

For this reason, inspection should cover the full length of the component rather than only the visible gear teeth.

Areas to Inspect on the Original Sun Shaft

During travel gearbox repair, check the original shaft for conditions such as:

• Chipped, pitted or unevenly worn gear teeth

• Worn or rounded drive splines

• Scoring on shaft or bearing contact surfaces

• Visible bending or abnormal runout

• Heat discoloration around the gear or shaft area

• Metal contamination inside the final drive oil

Wear concentrated on only one side of the gear teeth can also indicate alignment problems elsewhere in the travel reduction system.

Why Visual Similarity Is Not Enough

Many excavator travel shafts have a similar long-shaft appearance, but differences in spline profile, shaft length, gear dimensions and gearbox configuration can prevent interchangeability.

For older Dash-6 machines, the installed final drive may also have been replaced during previous repairs, so the machine model alone should not be treated as the only fitment reference.

Comparing the original shaft and travel gearbox information before shipment is the safest way to confirm the correct replacement.

Useful Information for Fitment Verification

If you need help checking the correct sun shaft, send the following information with your inquiry:

• Excavator model and machine serial number

• Final drive or travel gearbox information

• Clear photos of both ends of the original shaft

• Overall shaft length

• Spline dimensions and spline count

• Gear diameter, width and tooth information when available

These details are especially useful when several visually similar travel shafts are used across related excavator models.

Final Drive Parts Support from Topvelsun

Topvelsun supplies replacement final drive shafts, gears and travel reduction components for excavator repair and parts distribution.

Send us part number 20Y-27-21161 together with your machine and original shaft information, and we can help verify the application before quotation.