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 |
John Deere 686, 688 Common Problems This Manual Covers
John Deere 686, 688 cutting rotors not rotating smoothly
The general difficulties chart on page 249 points to leaves or dirt packed under the cutting rotors and around the drums, or to defective cleaners. Clean the cutting rotor area daily, or as often as needed in continuous operation, and install new cleaners where they are damaged.
Manual Section: Troubleshooting p. 249Harvesting unit vibrates in the field
Page 249 lists unequal blades, a broken cleaner and dirt inside the cutting rotor as the causes. Replace mating blades in pairs, replace both cleaners when one has broken, and clean out the cutting rotor. Excessive vertical play of the cutting rotor calls for straightening the blades or fitting new ones.
Manual Section: Troubleshooting p. 249Drives overheating
Too much oil in the drives is the cause the chart gives. Check the level against the specifications: 1.80 L (0.48 U.S. gal) for the L-gear case on page 43, 1.20 L (0.31 U.S. gal) for the feed drum transmission case on page 133 and 0.85 L (0.22 U.S. gal) for the cross feed drum gear case on page 161.
Manual Section: Troubleshooting p. 249Gathering or feed drums stop rotating while the cutting rotor still turns
Crop built up in the feeding area is the first suspect on page 250: reverse the feed unit for a short moment and repeat if necessary. If the drums still stay put, the chart sends you to the relevant gear case in Section 50. The gathering drum radial-pin clutch trips at 1800 N·m ±10% (page 227).
Manual Section: Troubleshooting p. 250Entire left-hand or right-hand side of the unit stops rotating
Page 250 traces this to a defective friction clutch on that side. The main drive friction clutch torque setting on page 51 is 900 N·m (657 lb-ft) on 686 units and on 688 units from SN 51300, and 800 ±80 N·m (584 ±58 lb-ft) on 688 units up to SN 51299.
Manual Section: Main Drive Friction Clutches p. 250Outer folding section moves slowly or will not fold
The chart names a foreign body, such as a grain of sand, obstructing the restrictor in the hydraulic system. Work through the hydraulic cylinder procedures in Section 70, Group 05, relieving pressure before you open any connection. The safety valve fixing fittings torque to 35 N·m (26 lb-ft) on page 193.
Manual Section: Hydraulic System p. 250Frequently Asked Questions
What is the torque spec for the safety valve fixing fittings on a John Deere 686, 688 rotary harvesting unit?
Tighten the safety valve fixing fittings to 35 N·m (26 lb-ft). The value sits in the Hydraulic Cylinders specifications. p. 193
What is the gear case oil capacity for the gathering drum gear case on a John Deere 686, 688?
The gathering drum gear case holds 4.80 L (1.27 U.S. gal) of gear case oil. p. 57
What is the maximum allowable hydraulic pressure on a John Deere 686, 688 harvesting unit hydraulic system?
19000 kPa (190 bar; 2713 psi) is the limit. The manual tells you to make sure the tractor used will not exceed this pressure. p. 30
What is the torque spec for the cross feed drum fixing screws on a John Deere 686, 688?
Torque the cross feed drum fixing screws to 77 N·m (57 lb-ft). p. 233
What is the trip torque for the radial-pin clutch on the gathering drum of a John Deere 686, 688?
It is set to trip at 1800 N·m ±10% (1332 lb-ft ±10%). p. 227
Is this John Deere 686 Technical Manual a digital download?
One non-searchable PDF covering 256 pages, delivered instantly. No disc, no shipping, no waiting on the post.
Is this John Deere 686 Technical Manual printable?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Reviews
There are no reviews yet.