Part of the John Deere Repair Manuals.
TM4585 pulls the rotary harvesting units down to the last shim: the John Deere 686, 688 Technical Manual PDF runs 256 pages and treats the head as a set of serviceable gear cases. Power train work fills most of the book: removal, disassembly, assembly, and installation for the L-Gear Case, both drum transmission cases, the cross feed drum gear case, and the U-joint drive shaft. Exploded views show how each stack of gears, bearings, and shims goes back together, backlash procedures give you the target before you close a case, and troubleshooting charts at the back sort out feeding trouble. Fill the L-Gear Case with 1.80 L, the cross feed drum gear case with 0.85 L, and set the radial-pin clutch to trip at 1800 N·m, plus or minus ten percent. Backlash guesswork wrecks a gear case. Bookmarks jump you between cases, pages print clean, and the file stays yours for as long as you own the head.
What's Inside This John Deere 686, 688 Manual
| System | Pages | Key Topics |
|---|---|---|
| Safety | 5-16 | Safety Information |
| General | 17-40 | Description, Torques for Hardware, Specifications |
| L-Gear Case | 41-50 | Removing L-Gear Case, Disassembling L-Gear Case, Assembling L-Gear Case, Installing L-Gear Case |
| Main Drive Friction Clutches | 51-56 | Removing Friction Clutches, Disassembling Friction Clutches, Assembling Friction Clutches, Adjusting Torque |
| Gathering Drum Gear Case | 57-100 | Removing Gear Cases, Disassembling Gear Case, Assembling Gear Case, Adjusting Backlash, Mechanical Brake Device |
| Feed Drum Transmission Case | 101-143 | Removing Transmission Case, Disassembling Transmission Case, Assembling Transmission Case, Adjusting Backlash |
| Cross Feed Drum Gear Case | 144-186 | Removing Cross Feed Drum Gear Case, Disassembling Cross Feed Drum Gear Case, Assembling Cross Feed Drum Gear Case, Adjusting Backlash |
| U-Joint Drive Shaft | 187-190 | Removing U-Joint Drive Shaft, Disassembling U-Joint Drive Shaft, Assembling U-Joint Drive Shaft |
| Hydraulic System | 191-198 | Hydraulic Cylinders |
| Miscellaneous | 199-214 | Foldable Outer Units, Harvesting Unit Frame |
| Feeding System | 215-250 | Gathering Drums, Gathering Drum Radial-Pin Clutch, Cross Feed Drums, Feed Drums, Rotating Crop Divider, Troubleshooting |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Safety valve fixing fittings | 35 N·m (26 lb-ft) | p. 193 |
| L-Gear Case Oil Capacity | 1.80 L | p. 43 |
| Feed Drum Transmission Case Oil Capacity | 1.20 L | p. 133 |
| Cross Feed Drum Gear Case Oil Capacity | 0.85 L | p. 161 |
| Radial-pin Clutch Trip Torque | 1800 ±10% N·m | p. 227 |
| Cross Feed Drum Radial-pin Clutch Trip Torque | 570-630 N·m | p. 161 |
| Main Drive Friction Clutch Torque Setting (688 up to SN 51299) | 800 ±80 N·m | p. 51 |
| Main Drive Friction Clutch Torque Setting (686 and 688 from SN 51300) | 900 N·m | p. 51 |
