Quick checks before you begin
- Make the unit safe before access; use the specified support and isolation procedure.
- Record the picking unit, drum and front/rear doffer position.
- Keep height, tilt and disc-spacing observations separate.
- Stop adjustment attempts if there is binding, nut contact, unusual heat or noise.
Height, tilt and disc spacing answer different questions
These checks are related but are not interchangeable. If one height cleans well while another does not, changing the entire column height can increase contact at the less-worn positions without correcting the uneven stack.
| Check | What it concerns | What it cannot fix |
|---|---|---|
| Column height | The vertical relationship between pads and spindles at the prescribed checking position | Unequal spacing through a worn or incorrectly assembled stack |
| Column tilt | Column alignment relative to the spindle path, checked with the applicable gauges | A damaged disc, distorted shaft or an unidentified contact source |
| Disc spacing | The relationship between successive working pads through the complete column | A mounting or installed picker-bar height problem |
Identify the structure before comparing settings
TM2109 separates Style A and Style B adjusters and column connections. Record the top adjuster, connection and installed identification while safely accessible; a whole-machine model or the apparent age of a part is not enough to choose the procedure.
Also record the picking-unit designation, serial number, drum bar count and front/rear location. PRO-16 does not by itself establish a 16-bar drum: the tilt-gauge instructions distinguish a 12-bar arrangement as well. Drum bar count and doffer disc count describe different components.
- Do not equate Style A/B with a supplier's small-bore/large-bore labels.
- Do not infer solid-shaft or hollow-core compatibility from the adjuster style alone.
- If identification is incomplete, send the configuration record to the repair shop before selecting a setting or replacement assembly.
Contact location helps decide the next check
The manual describes a relationship that changes along the spindle path: light working contact on entry, clearance on exit and the correct pad orientation when the spindles are fully beneath the pads. It is not a requirement to clamp the spindles against the pads throughout the path.
| Observation | Next inspection | Avoid |
|---|---|---|
| Cotton remains on several spindle levels | Disc condition, deposits, moistening and the documented height relationship | Lowering the column before checking the wider system |
| Pads contact spindle nuts or collars | Qualified column-alignment and tilt assessment | Treating nut contact as normal working contact |
| Only a top or bottom band works poorly | Wear distribution, disc spacing and crop-height history | Assuming a general drag feel proves every pad is working correctly |
| Binding, heat, noise or rapid new marks | Stop and investigate support, mounting and contact under the service procedure | Using further adjustment to force the unit free |
The checking position matters. Use the complete applicable service procedure and qualified personnel; this explanation is not permission to rotate or operate a unit while someone is inspecting it.
- Cotton not fully doffed: start with the symptom
Check disc condition, spindles and moistening before attributing the problem to height.
Gauge thickness is not running clearance
The tilt procedure uses radius and leaf gauges selected for the picking unit and drum arrangement. The upper and lower checking positions have different roles, and the lower leaf-gauge specification differs between PRO-12 and PRO-16.
Do not turn a gauge thickness into a universal doffer-to-spindle gap. Likewise, measurements of loose-pad runout, assembled-column runout, flange-face runout and stub-shaft runout describe different objects and setups; they cannot share one pass/fail limit.
A useful workshop result includes the component, assembled state, measuring location, fixture, units and applicable manual criterion. An unexplained number cannot establish that the assembly is ready for service.
When another height adjustment is not the answer
TM2109 makes equal pad spacing a prerequisite for effective height adjustment. Unequal wear can leave the less-worn pads producing a drag sensation while other positions still do not doff properly. Grinding or rebuilding, where the applicable assessment calls for it, is a workshop task with dedicated equipment.
Tall and short crops can load different parts of the column. Do not copy an extra-turn instruction from another adjuster or apply an extreme-condition procedure as a routine setting. Investigate the wear distribution and avoid binding.
- Read the top-to-bottom wear pattern
Compare crop exposure, disc condition and contact location before deciding on repair.
- Decide what needs wear assessment
Separate a damaged disc from a column that needs spacing or runout checks.
Send the repair shop a record it can use
Separate diagnosis from ordering. Once the required repair and installed part identity are confirmed, YUCHENG HARVEST can review the replacement reference, sample measurements, supply form and quantity. If the reference is uncertain, start with the category instead of choosing a part from the symptom.
- Picking-unit identity, serial number, drum bar count and front/rear doffer position.
- Adjuster/connection photographs and all legible installed references, taken after safe isolation.
- A top/middle/bottom wear map and the corresponding spindle positions.
- Contact marks, binding, heat or noise, plus the point when the problem first appeared.
- Recent disc, spacer, bearing or assembly changes; keep removed parts and their positions labeled.
- Measured spacing and runout only with the setup, units and applicable service criterion recorded.
- Browse doffer parts for identification
If the installed reference is unknown, compare the category and send photos and unit details; do not choose a model from the symptom alone.
- Prepare doffer identification and bore measurements
Distinguish an individual disc from a complete assembly before requesting a replacement.
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), Section 70, Group 05John Deere Des Moines Works | repair manual
Doffer-column repair and adjustment reviewed at printed pages 70-05-1–28. This is a bibliographic reference, not a download. Confirm the applicable structure and current service documentation before work.
Questions buyers and technicians ask
Will lowering the doffer fix uneven disc spacing?
No. Height moves the column's working relationship as a whole; it does not restore equal pad spacing. Have uneven spacing assessed under the correct service procedure.
Are Style A and Style B the same as small-bore and large-bore doffers?
No. The manual's adjuster structures and a supplier's bore options are different classifications. Confirm the installed interface and measured part separately.
Should pads touch the spindle nuts?
Nut or collar gouging is not the intended working relationship. Stop and have column alignment and the contact source checked rather than continuing to lower the column.
Does a PRO-16 unit always use the same tilt gauge?
No. The manual distinguishes drum arrangements within PRO-16. Confirm the unit and drum configuration before selecting gauges or applying the procedure.
Can this page confirm which assembly to buy?
It helps record the condition and configuration. Exact replacement selection still needs the installed reference, unit and serial context, interface and required supply form.