Part of the New Holland Repair Manuals.
New Holland covers five Round Baler models (638, 648, 658, 678, 688) in this 464-page repair manual (OEM #87012151), and if you're hunting a New Holland 648 repair manual pdf with real factory depth, this is it. Inside you get complete wiring diagrams for the electrical system, hydraulic schematics covering the tailgate lift and density cylinders, and a full troubleshooting section walking density pressure drops back to their root cause. You also get torque tables, fluid capacity charts, and step-by-step procedures spanning driveline, feeding, pressing, and tying systems. Set net counter roll sensor clearance to 1.5 mm and the 638's tailgate lift orifice to 2.08 mm; other models run 2.6 mm. No more guessing which orifice size fits your baler. This PDF carries bookmarks for every section, so you jump straight to hydraulics or electrical without hunting through 464 pages by hand.
What's Inside This New Holland 638–688 Repair Manual
| System | Pages | Key Topics |
|---|---|---|
| General Information | 15-50 | Foreword, Introduction, Precautionary Statements, Fluid Safety (Handle Fluids Safely, Avoid Heating Near Pressurized Fluid Lines, Use Care Around High-Pressure Fluid Lines) |
| Implement Driveline | 51-108 | PTO, Slide Collar Quick-Disconnect, Drive Shaft and Clutch, Gearbox, Slip Clutches, Special Tools |
| Hydraulic System | 109-142 | Tailgate Lift System, Lockout Valve, Belt Tension System, Density Cylinder(s), Relief Valve Operation, Pickup Lift System |
| Electrical Systems | 143-214 | Components, Adjustments, Electric Components Replacement, Electrical Diagrams, Diagnostic Tests, Connector Repair |
| Product Feeding | 215-238 | Finger Replacement, Cam Bearing Replacement, Slip Clutch Repair, Pickup Removal, Cam Track Replacement, Auger Repair |
| Pressing | 239-360 | Floor Roll, Starter Roll, Apron Rolls, Apron Belts, Sledge Rolls, Take-Up Arm Assembly |
| Tying | 361-464 | Twine Wrapper, Twine Tubes, Twine Knives and Supports, Clutch and Brake Assembly, Cam and Worm Gears, Net Wrapper |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| 648, 658, 678, 688 | ||
| Net Counter Roll Sensor clearance to magnet | 1.5 mm (1/16″) | p. 149 |
| Tailgate lift system orifice size (648, 658, 678, 688) | 2.6 mm (0.104″) | p. 112 |
| Troubleshooting: Density pressure drop - Possible Causes | Internal leakage., Air in the system., Dirt in the relief valve. | p. 140 |
| Troubleshooting: Density pressure drop - Correction | See internal leakage., Bleed the system., Clean valve. | p. 140 |
| Floor Roll Drive Clutch Slip Torque | 915 - 1125 N∙m (675 - 830 ft lbs) | p. 101 |
| Sledge Roll Drive Clutch Slip Torque | 677 - 767 N∙m (500 - 573 ft lbs) | p. 104 |
| 638 | ||
| Tailgate lift system orifice size, 638 | 2.08 mm (0.082″) | p. 111 |
| 638, 648, 658, 678 | ||
| PTO Speed (638, 648, 658, 678) | 540 RPM | p. 46 |
| 688 | ||
| PTO Speed, 688 | 540/1000 RPM | p. 48 |
| All Models | ||
| Hydraulic System Minimum Pressure | 11,032 kPa (1800 PSI) | p. 46 |
| Pickup Slip Clutch Torque | 316 N∙m (2800 in. lbs) | p. 46 |
| 648 (silage special), 658, 678, 688 | ||
| Main Drive Slip Clutch Torque (540 RPM) | 1085 - 1627 N∙m (800 - 1200 ft lbs) | p. 98 |
