Slip Clutch PTO Shaft for Hesston & Case IH 1340 Disc Mower
Slip clutch PTO shaft for Hesston 1340, 1345 & Case IH 8312 disc mowers. 55N CV joint, 1000 rpm, friction-disc overload protection. OEM Weasler replacement.
Slip Clutch PTO Driveline for Hesston & Case IH Discbine 1340
This agricultural PTO driveline is a direct-fit replacement for the OEM 55N Weasler driveshaft used on Hesston 1340, 1345, Case IH 8312, 8315, Massey Ferguson PTD 12, and New Idea 5512 disc mower conditioners. The assembly pairs an 80-degree constant-velocity (CV) joint on the tractor side with a 50-degree CV on the discbine side, delivering uniform rotational speed across the full operating angle range.
What sets this PTO shaft apart from standard drivelines is the integrated friction-disc slip clutch. When the disc mower encounters a rock, fence post, or tangled crop, the clutch disengages the drive at a preset torque threshold, then automatically re-engages once the obstruction clears. This prevents torque spikes from reaching the tractor PTO output or the mower gearbox, avoiding costly repairs that can exceed $1,500 per incident on a single damaged driveline or gearbox.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Driveline Series | 55N (Weasler-equivalent) |
| Part Number | 14656849 |
| OEM Reference | Replaces AGCO # 700712572 |
| CV Joint Configuration | 80-degree CV (tractor) + 50-degree CV (implement) — Double CV |
| Tractor End Spline | 1-3/8" x 21 spline (slide-lock connection) |
| Implement End | 1.50" round clamp yoke |
| Operating Speed | 1000 rpm (rated to 2000 rpm max) |
| Clutch Type | Friction-disc slip clutch, preset torque threshold |
| Clutch Disc Diameter | 178 mm (7.00 in.) medium duty |
| Shaft Material | Alloy steel, anti-corrosion coated telescoping tubes |
| Guard Rating | 360-degree friction-welded guard bell, impact rated to -35 °C |
| Assembly Weight | Approx. 21 kg (46 lb) |
Engineered for Maximum Machine Protection
The friction-disc slip clutch is the core safety mechanism in this PTO shaft assembly. Unlike shear-bolt clutches that require a manual bolt replacement after every overload event, the friction-disc design absorbs the torque spike, allows controlled slipping, and then automatically re-engages drive once the resistance returns to normal. This eliminates downtime in the field and reduces replacement part costs.
Overload Torque Release
When the implement hits a fixed obstacle, the friction discs slip at the factory-preset torque threshold. The driving force disconnects within milliseconds, preventing torque spikes from reaching the gearbox, PTO output shaft, or tractor transmission.
Automatic Re-engagement
Once the obstruction clears, spring-loaded pressure plates bring the friction discs back into full contact. The drive resumes without the operator needing to stop, exit the cab, or replace any consumable parts.
Continuous Reduced-Power Transmission
During a partial overload such as heavy crop ingestion, the friction clutch continues to transmit power at a reduced level. This keeps the cutterbar running and aids in clearing plugged material rather than stalling the entire driveline.
Heat Dissipation Design
The clutch friction surfaces are engineered against cast-iron mating plates, which absorb and radiate heat rapidly. Corrosion-resistant friction discs maintain a stable friction coefficient across temperature swings, extending clutch pack service life.
Compatibility Guide: Hesston & Case IH Discbine Models
This replacement slip clutch PTO shaft for Hesston 1340 disc mower conditioner also fits several related platform models. All models listed below were originally equipped with the 55N Weasler driveline and share the same spline interface, CV joint geometry, and input shaft diameter.
| Brand | Model(s) | Machine Type |
|---|---|---|
| Hesston | 1340, 1345, 1360, 1365 | Disc Mower Conditioner |
| Case IH | 8312, 8315 | Disc Mower Conditioner |
| Massey Ferguson | PTD 12 | Pull-Type Disc Mower |
| New Idea | 5512 | Disc Mower Conditioner |
Note: All models above share the AGCO platform with 1.50" round implement input shafts and 1-3/8" x 21 spline tractor PTO connections. Verify your tractor PTO spline count and diameter before ordering.
Installation and Maintenance Best Practices
Installation Procedure
1
Secure the equipment. Park the disc mower on a flat, level surface. Engage the parking brake and shut off the tractor engine. Lower the mower header to ground level.
2
Measure the collapsed and working length. With the mower at its normal hitch position, measure the distance from the tractor PTO stub to the mower input shaft center. Adjust the telescoping tube so the PTO shaft operates within the middle 60% of its travel range. Running too close to either extreme causes binding or separation.
3
Connect the tractor end first. Slide the 1-3/8" x 21 spline yoke onto the tractor PTO stub until the slide-lock collar clicks. Pull back gently to verify the lock is seated.
4
Connect the implement end. Fit the 1.50" round clamp yoke over the mower input shaft. Tighten the clamp bolt evenly to the torque specified in your mower manual (typically 45–55 Nm).
5
Install the safety guard. Slide the guard shell over the shaft and lock both ends using the guard retention clips. The guard must spin freely without contacting the shaft at any point in the range of motion.
6
Test at low rpm. Start the tractor and engage the PTO at idle speed. Listen for unusual vibration or noise. Gradually increase to the working 1000 rpm. Check shaft runout visually — excessive wobble (more than 3 mm at the midpoint) indicates a yoke or U-joint issue.
Routine Maintenance Schedule
| Interval | Task |
|---|---|
| Every 8 operating hours | Grease all U-joint cross bearings and the telescoping tube slip joint via the zerk fittings. Use NLGI #2 lithium-based grease. |
| Every 50 operating hours | Inspect the slip clutch friction discs for wear indicator tab depth. If the tabs are flush with the disc surface, the clutch pack requires replacement. |
| Every 100 operating hours | Remove the safety guard and inspect the CV joint boots for cracks, tears, or grease leakage. Replace damaged boots immediately to prevent bearing contamination. |
| Start of each season | Check all yoke clamp bolts and guard retention clips for tightness. Verify the telescoping tube slides freely without scoring. Replace any cross kits that show bearing play exceeding 0.5 mm. |
Frequently Asked Questions
What is a slip clutch PTO shaft, and why is it needed on a disc mower?
A slip clutch PTO shaft includes a friction-disc mechanism between the tractor output and the implement input. When the disc mower hits a rock or dense obstruction, the clutch allows the shaft to slip at a controlled torque level rather than transmitting the full shock load to the gearbox. This prevents gear tooth fracture, bearing seizure, and PTO stub shaft damage. On machines like the Hesston 1340 that operate at 1000 rpm, the kinetic energy stored in the rotating driveline is substantial, making slip clutch protection particularly important.
Can I use this replacement slip clutch PTO shaft for Hesston 1340 on a Case IH 8312?
Yes. The Hesston 1340 and Case IH 8312 share the same AGCO driveline platform. Both use the 55N Weasler 80/50 Double CV configuration, a 1-3/8" x 21 spline tractor connection, and a 1.50" round implement input shaft. The same part number (14656849) fits both machines without modification.
How do I adjust the slip clutch torque setting?
The friction-disc clutch pack is factory preset for the torque range appropriate to Hesston and Case IH disc mower conditioners. In most cases, no field adjustment is needed. If the clutch slips too easily in heavy crop (a sign of worn discs or insufficient spring pressure), tighten the pressure plate bolts evenly in small increments and test. If slipping persists after adjustment, the friction disc pack should be replaced. Avoid over-tightening: a clutch that never slips provides no overload protection and defeats its purpose.
What is the difference between a slip clutch and a shear bolt clutch on a PTO shaft?
A shear bolt clutch uses a sacrificial pin that snaps at a specific torque, fully disconnecting the drive. The operator must then stop, exit the cab, and replace the bolt before resuming work. A friction-disc slip clutch absorbs the overload through controlled slipping and re-engages automatically. For disc mowers that encounter frequent minor obstructions in pasture or roadside conditions, the slip clutch provides continuous protection without the recurring downtime of bolt replacement.
How do I know when the slip clutch friction discs need replacement?
The clutch pack includes wear indicator tabs on the friction disc surfaces. When these tabs wear flush with the disc face, the clutch pack has reached the end of its service life and should be replaced. Other signs include the clutch slipping under normal load even after pressure plate adjustment, or a burning smell during heavy cutting operations.
Can I convert my existing 55N standard PTO shaft to a slip clutch version?
In many cases, yes. The friction clutch pack bolts directly to a compatible 55N yoke hub. However, ordering a complete slip clutch PTO shaft assembly ensures correct CV joint alignment, balanced tube length, and factory-calibrated torque settings. A mismatched retrofit can introduce vibration issues at 1000 rpm.
Related Agricultural Driveline Products
A complete agricultural PTO driveline system includes several precision components beyond the shaft assembly. The following products are commonly paired with this slip clutch PTO shaft:
Universal Joints & Cross Kits
55N cross kits with sealed or greaseable bearing caps. Field-replaceable without removing the full driveline.
Right-angle and inline gearboxes for disc mowers, rotary cutters, and hay rakes. Matched to 540 and 1000 rpm applications.
CV Joint Assemblies
35N, 55N, and H8 constant-velocity heads for upgrading or replacing worn CV joints on existing drivelines.
Safety Guards & Shields
Cone and bell-type PTO guards rated to -35 °C for cold-climate operations. Meets ASABE S493 operator protection standards.
Yokes & Spline Hubs
Clamp, quick-disconnect, and push-pin yokes in 6-spline, 20-spline, 21-spline, and round-bore configurations.
Get the Right Slip Clutch PTO Shaft for Your Disc Mower
Send us your machine model, tractor PTO spline size, and collapsed/working length measurements. We will match the correct part number and provide a delivered price within 24 hours.
Explore Our Full Agricultural Driveline Range
We manufacture PTO shaft assemblies and driveline components for a wide range of agricultural implements beyond disc mowers:
- PTO Shaft for Square Balers — Series 4/5/6 drivelines with shear-pin or slip clutch protection for Hesston, New Holland, and Krone square balers.
- PTO Shaft for Round Balers — Heavy-duty Series 6/8 assemblies with double CV joints rated to 150 HP for large-frame round balers.
- PTO Shaft for New Holland Discbines — 55N CV drivelines for Discbine 1431, 1432, H7220–H7560, and Case IH DC 132 models
