For efficient repairs, begin by locating the main drive belt pulley assembly at the rear left side–this component often requires replacement after 1,200–1,500 operational hours. Use a torque wrench set to 45–50 Nm when reinstalling to prevent slippage or premature wear. If experiencing belt misalignment, inspect the tensioner arm spring for fatigue; a compromised spring reduces pressure by up to 30%, leading to uneven bale formation.
Check the knotter mechanism every 500 bales: worn twine disks can cause twine breakage at a rate of 1 in 7 cycles. Clean the needle path with compressed air weekly–debris accumulation increases jam risk by 40%. When replacing needles, verify alignment with the billhook cutter; a 0.5 mm misalignment reduces knot strength by 60%.
For hydraulic issues, prioritize the ram cylinder seals: leaks typically originate from the rear gland nut, which should be tightened to 75 Nm. If the bale chamber fails to open, examine the latch pivot pins–bent pins cause incomplete door release in 80% of cases. Use high-pressure grease (NLGI Grade 2) on moving joints every 100 hours to extend component life by 25%.
When sourcing components, match original part numbers exactly–aftermarket equivalents for the pickup tine shaft may lack heat treatment, reducing durability by 50%. Store spare belts in a cool, dark environment; UV exposure degrade rubber compounds within 6 months, even unused.
Preventive Maintenance Using Your Equipment’s Schematic
Start by cross-referencing the pickup tine series number–look for the stamp beneath the feeder frame near the pivot shaft (typically “BT-43” or “HT-57”). Replace any bent or worn tines in pairs, even if only one appears damaged; uneven wear disrupts crop flow and accelerates belt slippage. Keep a narrowed 10mm wrench in your toolkit–this size tightens the retaining bolts without stripping, unlike standard 3/8-inch sockets that can round the hex heads. Grease zerks every 50 operational hours using NLGI #2 lithium complex; avoid cheaper calcium sulfonate blends that separate under centrifugal force, leaving dry residues that clog plunger mechanisms.
Critical Wear Components and Replacement Intervals
| Component | OEM Part Code | Service Life (Hours) | Inspection Frequency | Failure Symptom |
|---|---|---|---|---|
| Bale chamber belts | 3P0138 | 200-300 | Every 40 hrs | Uneven bale density, visible fraying |
| Needle roller | HT-118 | 150-250 | Every 30 hrs | Misaligned knotter, twine breakage |
| Density control spring | BS-49 | Replace annually | Pre-season | Soft bales, inconsistent core formation |
| Slip clutch disc | MT-102 | 100-180 | Every 25 hrs | Excessive noise, uncut crop wrapping shaft |
Store the schematic sheet laminated under the operator’s seat; scribble measurements directly on it with a grease pencil–note belt stretch at specific marking points (e.g., 3/8 inch from original seam after 100 hours). Replace the hydraulic pump strainer (code RP-22) biannually, even if it appears clean; microscopic metal shavings accelerate piston wear, leading to expensive rebuilds. Always torque the flywheel bolts to 75 lb-ft using a calibrated click wrench; over-tightening cracks cast mounting ears, while under-tightening allows harmonic vibrations that loosen bearings.
Critical Assemblies in the 135-Model Hay Compactor and Where to Find Them
Start by checking the pickup tines assemble at the front intake. These rotating forks, positioned just above the windguard, lift crop into the feed chamber with adjustable spring-loaded teeth spaced 50mm apart. If windrows jam, inspect the slip clutch located behind the main drive shaft–torque settings should never exceed 25 Nm. Misalignment here causes premature wear on the knotter bills, which are mounted on the right-side binding arm and must engage twine within 120° of rotation.
The feeding rotor, a 480mm diameter drum with six helical blades, sits centrally beneath the bale chamber. Its bearings require lubrication every 50 operating hours–failure leads to uneven compression. Directly above, the bale density control hydraulic cylinder extends from the rear frame cross-member to regulate core tightness; check for 150 bar pressure on the gauge before adjusting the relief valve. Side panels on the left must remain free of debris to avoid overheating the variable-speed belt drive pulley coupling.
For binding reliability, examine the twine disc assembly inside the upper chamber door. The disc’s needle mechanism must retract fully before the plunger activates–sticking indicates a worn eccentric roller requiring replacement. Below, the floor conveyor chain spans the length of the chamber, supported by hardened steel slats every 12 inches. Replace slats exhibiting more than 3mm wear to prevent misalignment with the top compression belt, which runs on a 4-ply polyester carcass with 1,500 kg breaking strength.
- Rear gate hinge pins: Two 40mm diameter pivot points secured by cotter keys; grease every 20 hours to prevent seizure under 2,500 kg load.
- Bale kicker arm: Hydraulically actuated lever on the rear left; ensure the microswitch at the 70° position triggers ejection before gate opens.
- Electrical solenoid: Located near the binding arm motor–replace if coil resistance drops below 12 Ω.
The oil-cooled torque limiter on the left sidewall protects the main gearbox from shock loads–clean the heat exchanger fins weekly to maintain performance. Inside the gearbox, the planetary reduction set reduces input speed from 540 RPM to 85 RPM at the feeding rotor. Regularly drain and replace 8 liters of ISO 46 hydraulic fluid, ensuring no contaminants exceed 16/14/12 ISO cleanliness code. The bale chamber latch, a spring-loaded hook on the right frame, must engage smoothly with the gate lock bar–misalignment indicates bent frame rails needing straightening.
After 1,000 bales, inspect the side compression belts for fraying at splice points–replace if cord exposure exceeds 2 inches. The right-side idler roller, positioned 30° from vertical, should rotate freely with less than 0.1mm radial play. On the opposite side, the left knife assembly cuts crop against the feeder fork with a serrated edge; sharpen or replace blades displaying nicks wider than 1mm to prevent uneven windrow intake.
Locating Authentic Components for the Hesston Model Using Schematic Guides
Purchase directly from authorized dealers listed in the AGCO PartsFinder database–filter by machine serial number and reference the exploded-view schematics for exact matches. Dealers like Northland Power Equipment in Minnesota or Sloan Implement across Illinois stock OEM knotting needles (pn: 65900), bale chamber rollers (pn: 42311), and pickup tine assemblies (pn: 50040), each cross-referenced via the numbered callouts on the official service blueprint.
Farm supply chains such as Farm Equipment Solutions in Nebraska or Mid-South Ag in Mississippi retain backordered drive belts (pn: 70013) and main gearbox seals (pn: 30055); verify compatibility against the assembly breakdown’s indexed segments before ordering.
Step-by-Step Disassembly Guide Using the Schematic
Locate the torsion spring assembly on the left side of the wrapping mechanism by referencing position B-12 in the exploded view. Secure the tension rod with a 19mm socket before releasing the spring–failure to do so risks sudden rotation, which can damage the housing or cause injury. Keep the retaining clips (marked C-4) in a labeled container; their small size makes them easy to misplace. For the knotter assembly, disassemble components in this order: billhook (D-7), twine disc (D-3), and gear cluster (D-9), using a 5mm hex key for set screws.
When removing the pickup teeth (A-5), note their staggered arrangement–document with photographs if reinstalling out of sequence compromises alignment. The roller bearings at positions F-2 and F-8 require a bearing puller with a 3-ton capacity; attempting manual removal risks warping the shaft. Clean all disassembled pieces with pressurized air and a parts cleaning solvent before inspection–residue buildup accelerates wear. Store hydraulic fittings (E-6) in sealed bags to prevent contamination, and mark identical bolts from different sections with colored tape to avoid mix-ups during reassembly.
Key Replaceable Components in the Large Square Bale Former and Visual Troubleshooting
Begin by locating the knotter assembly in the schematic–this section includes the billhook, twine disc, and needle components. These elements show wear fastest due to constant friction during binding cycles. Inspect the billhook for chipped edges or deep grooves; a worn unit misfeeds twine, causing loose bales. Replace if the cutting edge exceeds 0.5 mm depth loss or visibly loses its sharp contour. The twine disc, often made of nylon, should have unbroken teeth–if edges appear rounded or missing, expect inconsistent knot formation. Needles bend under stress; verify alignment by running a finger along their path–any resistance indicates deformation requiring immediate change.
- Roller chains: Check sprocket engagement gaps; slack over 1.5 cm between links signals elongation. Replace chains if more than 3% beyond original length, measured over 10 links.
- Pickup tines: Look for bent or missing fingers–replace any tine exceeding 15° deflection to prevent uneven crop feeding.
- Bale density control springs: If coils appear compressed beyond 5% of their free length, tension loss reduces bale firmness.
Examine the plunger blades–nicks or uneven wear patterns above 0.8 mm indicate misalignment with shear bars. Sharpen or replace blades when cutting efficiency drops, typically after 200–300 hours. Shear bars should show uniform wear; grooves deeper than 0.3 mm or irregular edges demand resurfacing. Bearings in the flywheel and plunger crankshaft often fail silently–listen for grinding or squeaking. Replace if radial play exceeds 0.1 mm or grease leakage occurs.
Identify the plunger knife holder on the diagram–wear plates here protect the housing from metal-to-metal contact. If wear exceeds 2 mm thickness loss, the plunger will knock, risking catastrophic failure. Check the slip clutch discs; glazed or cracked surfaces reduce torque transfer. Replace if friction material wears below 1 mm or grooves appear deeper than 0.2 mm. The twine tension arm spring adjusts automatically–replace if it fails to maintain 3–5 kg tension, verified by a spring scale.
- Drive belts: Replace when cracks appear on the underside or if stretch exceeds 1% of original length–check for glazing indicating slippage.
- Rolled bale chamber belts: Inspect for fraying or delamination; replace if surface thickness drops below 70% of original.
- Hydraulic cylinders: Leaking seals or scored rods reduce pressure–replace if rod pitting exceeds 0.05 mm depth or seals show visible cuts.