Quick checks before you begin
- Stop, isolate and prevent restart. Wait for all motion to stop; secure raised units with the specified mechanical supports.
- Record the unit, serial number, row and installed position before removing components.
- Keep parts, shims and observations separated by assembly. Use qualified personnel and the complete applicable service procedure.
First locate which drive is affected
A report of gear noise does not identify a replacement part. Record whether the problem concerns one spindle, one picker bar, the drum drive above the bars, the idler assembly or the row-unit gearcase. Include the row, front or rear drum and any recent repair or impact.
Do not run a suspected damaged drive just to obtain another recording. Photographs and observations should be gathered only under the applicable safe-access procedure.
| Reported area | Useful evidence | Next inspection |
|---|---|---|
| One spindle or one bar | Exact height and bar position; recent spindle or bar work | Spindle and picker-bar checks |
| Drum-top gears or shaft | Overall location and visible tooth, bearing or lubrication-line damage | Drum-drive and idler inspection |
| Row-unit gearcase | Box location, lubricant type and leakage or contamination | Gearcase inspection |
- Inspect a picker-bar assembly
Use the separate guide when findings are inside the bar rather than in the drum-top drive.
- Check idler gears and slip clutches
Inspect the related wear surfaces rather than tightening an unexplained slipping assembly.
- Check gearcase oil, leaks and identity
Identify the lubrication type and installed box before choosing service parts.
Front, rear and gear version belong in the order
The manual illustrates different tooth counts at different drive positions and distinguishes picking-unit configurations. A tooth count without its location and reference is not a parts specification. Do not select a replacement merely because its outside diameter or number of teeth looks similar.
It also distinguishes welded and machined gear constructions. The associated spacer instructions apply to a particular gear arrangement, not every spacer on the shaft. Keep the original stack identified and resolve the applicable service revision before substitution.
- Photograph both faces, the mounting interface and the installed location after safe access.
- Record the existing reference and any documented supersession separately from a visual guess.
- Keep front/rear journal retainers, screws and removed components separated; the manual warns against interchanging them.
- Do not reuse Style A/B labels from a sensor or gearbox section as if they described the same gear versions.
A speed indication and a mechanical fault are different findings
If a speed indication changed after top-cover work, record the sensor connector and bracket arrangement as well as the repair history. TM2109 illustrates two-wire and three-wire sensor arrangements and checks the installed relationship with the cover secured.
A previous tip-to-bracket measurement is only a starting reference in that procedure, not proof of the final installed gap. This guide does not diagnose wiring, prescribe a sensor setting or interpret fault codes. Ask qualified service to distinguish an indication problem from mechanical drive damage.
Send a parts request that preserves the location
YUCHENG HARVEST can review a legible reference, retained sample, interface photographs and required quantity for a replacement-parts inquiry. Keep the workshop diagnosis separate from the supply confirmation.
- Machine and picking-unit identity, serial number, row and front/rear drum.
- The exact assembly and the removed part reference, if legible.
- Both gear faces, mounting holes, shaft interface and the mating component.
- Measured dimensions with the measurement positions shown, plus the required supply contents.
- Identify gears and drive parts
Compare the installed reference, location and interfaces before requesting replacements.
- Drum and picker-bar parts
Use a category review when the exact reference remains unknown.
- Already identified KK27793?
View the existing 138-tooth reference record. It is not a replacement recommendation for every drum-drive position.
Technical basis for this article
The article paraphrases and organizes the sources below. It does not copy a service manual, and it does not replace the current documentation for the exact machine.
- TM2109 — PRO-12, PRO-12 VRS and PRO-16 Picking Unit Repair (20 July 2020), Sections 50, 60 and 100John Deere Des Moines Works | repair manual
Reviewed printed pages 50-05-1–19, 60-05-1–8 and 100-05-1–24, including illustrations. Bibliographic reference only. Configuration-specific service information remains controlling.
Questions buyers and technicians ask
Does a chipped gear mean every gear must be replaced?
Not automatically. Inspect the damaged part, mating teeth, shaft and bearing support under the applicable criteria. Preserve the findings so the workshop can define the repair scope.
Can I order from tooth count alone?
No. Location, tooth form, mounting, reference and installed configuration must agree. Similar counts do not prove interchangeability.
Should all spacers be removed with a newer gear?
No. A version-specific spacer instruction cannot be applied to the complete shaft stack. Confirm the exact arrangement and current service information.