Part of the New Holland Repair Manuals.
That gearbox is the deepest job in this 12-page New Holland 438 service manual PDF, and the teardown takes your disc mower's drive from cover removal through the pinion gear, Woodruff key, and bevel gear to reassembly with the adjustment nuts set right. The cutter bar takes up the rest of the book: removing it from the base frame, splitting the halves open, servicing the disc gear bearings and hubs, then bolting it back on with the drive belts and sheaves lined up. Exploded views back up the procedures, so spacers and roll pins go back in the right order. Press the idler gear bearing snap ring free at 20 tons, and torque the cutter bar pivot support bolts to 120 ft. lbs. on reinstall. Every dry afternoon this mower sits in pieces is hay left standing. Bookmarked and text-searchable, the PDF goes to whatever barn or shed the 438 sits in, keeping your specs with the machine.
What's Inside This New Holland 438 Manual
| System | Pages | Key Topics |
|---|---|---|
| Removing the Cutter Bar From the Base Frame | 2 | Cover and Guard Assembly, Swath Board Assembly, Belt Shield, Drive Belts, Pivot Support, Hinge Pin |
| Opening the Cutter Bar | 3-4 | Crop Divider End Cap, Discs, Outer Skid Shoe, Cutter Bar Halves, Inner Shoes, Disc Shoes |
| Disc Gear Bearings and Hub | 5-6 | Disc Gear Shaft, Bearings, Roll Pin, Disc Hub, Spacer, Housing |
| Cutter Bar Assembly | 7 | Upper Trough, Idler Gears, Tapered Washers, Allen Head Stud Bolts, Skid Shoes, Disc Hubs |
| Gear Box Disassembly and Assembly | 8-9 | Gear Box Cover, Output Shaft, Pinion Gear, Woodruff Key, Bevel Gear, Input Shaft |
| Attaching the Cutter Bar to the Base Frame | 10-12 | Cutter Bar, Bolts, Drive Belts, Sheaves, Pivot Points |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Allen head stud bolts torque | 60 ft. lbs. | p. 8 |
| Adjustment nuts on shafts torque | 50 ft. lbs. | p. 9 |
| Idler gear bearing snap ring removal pressure | 20 tons | p. 6 |
| Gear box bearing pre-load | 12 in. lbs. | p. 9 |
| Bearing support nut torque | 60 ft. lbs. | p. 9 |
| Cutter bar attachment bolt torque | 120 ft. lbs. | p. 10 |
| Drive belt deflection force | 25 lbs. | p. 10 |
