Description
S Series PTO Drive Shaft – Star-Profile Engineering for Maximum Torque Capacity
When agricultural operations push beyond the limits of standard PTO shafts, the S Series star-profile PTO drive shaft delivers. Featuring a distinctive six-pointed star tube cross-section, the S Series is purpose-built for high-torque, high-horsepower applications where shaft integrity is non-negotiable. Twelve models — from S6 through S50 — span an operating torque range of 1,450 Nm to 3,700 Nm, covering the most demanding implements in modern farming.
Target sectors: Broadacre cropping, silage contracting, large-scale livestock operations, biomass harvesting, and heavy municipal maintenance.
Defining features: Star-profile torsional lock · Forged 42CrMo4 yokes · Oversized cross kits (up to 50×118 mm) · Full CE safety shield package · Rated for continuous 540 and 1,000 RPM service.
S Series Specifications – Complete Torque & Dimensional Data
| Model | Cross (mm) | 540 RPM Kw | 540 RPM Pk | 540 RPM Nm | 1000 RPM Kw | 1000 RPM Pk | 1000 RPM Nm | MP (NM) |
|---|---|---|---|---|---|---|---|---|
| S6 | 30.2×92 | 47 | 64 | 830 | 74 | 100 | 710 | 1450 |
| S7 | 30.2×106.5 | 55 | 75 | 970 | 87 | 118 | 830 | 1800 |
| S8 | 35×106.5 | 70 | 95 | 1240 | 110 | 150 | 1050 | 2250 |
| S38 | 38×105.6 | 78 | 105 | 1380 | 123 | 166 | 1175 | 2500 |
| S32 | 32×76 | 39 | 53 | 695 | 61 | 83 | 580 | 1200 |
| S36 | 36×89 | 66 | 90 | 1175 | 102 | 139 | 975 | 2000 |
| S9 | 41×108 | 88 | 120 | 1560 | 140 | 190 | 1340 | 2800 |
| S10 | 41×118 | 106 | 145 | 1905 | 170 | 230 | 1650 | 3500 |
| S42 | 42×104.5 | 79 | 107 | 1400 | 122 | 166 | 1175 | 2500 |
| S48 | 48×127 | 133 | 180 | 2390 | 205 | 277 | 1958 | 4200 |
| S50 | 50×118 | 119 | 162 | 2095 | 182 | 248 | 1740 | 3700 |
The Science Behind Star-Profile PTO Tubes
The S Series star-profile tube features six symmetrically spaced lobes that interlock with matching recesses on the mating tube. This geometry creates a mechanical lock in the rotational plane, preventing any relative angular slippage between inner and outer tubes even under extreme shock loads. Compared to triangular or lemon profiles, the star cross-section provides:
- Greater moment of inertia — resisting torsional deformation under peak loads during bale wrapping or forage chopping.
- Six-point contact distribution — spreading surface pressure across six lobes rather than two or three, dramatically reducing localized wear.
- Inherent anti-backlash behavior — the multi-lobe geometry eliminates rotational play, ensuring instant torque response when the PTO engages.
Main components: Forged tractor-end yoke · Star-profile outer tube assembly · Star-profile inner tube assembly · Implement-end yoke (push pin, quick release, or splined bore options) · Heavy-duty cross kits · Dual safety shield cones and tubes · Safety chains.
Five Reasons Contractors Choose the S Series
Unmatched Torque Density
Star tubes pack more torque capacity per millimeter of outer diameter than any competing profile, enabling a physically smaller shaft to handle the same load.
Shock-Load Resistant
Oversized cross kits and thick-wall tube sections absorb the transient torque spikes generated by balers, choppers, and stump grinders.
Field-Serviceable Design
Cross kits, yokes, and tubes are individually replaceable. Repair the shaft in the paddock instead of replacing the entire assembly.
Global Parts Network
Standard dimensions ensure spare parts availability across 60+ countries. No waiting weeks for an obscure OEM component.
Wholesale-Ready Pricing
Volume discounts for contractors running fleets of 5+ machines. Bundle shaft + cross kit + safety shield for best landed cost.
Material Specification & Build Quality
S Series tubes are cold-drawn from AISI 1050 high-carbon steel through proprietary six-lobe star dies, then stress-relieved at 580 °C to eliminate residual forming stresses. Wall thickness ranges from 3.0 mm on the S6 to 5.0 mm on the S50, far exceeding the minimum required for rated torque. Yokes are closed-die forged in 42CrMo4 alloy steel, CNC-machined, and selectively induction-hardened on bearing bores and spline teeth to HRC 58–62. Cross kits employ GCr15 bearing steel needles with polyurethane lip seals that maintain lubrication integrity for over 500 operating hours. All fasteners are Grade 10.9. Final assemblies pass a dynamic balancing check at 1,200 RPM before packaging.
Heavy-Duty Application Scenarios
| Implement | Recommended Model | Why the S Series? |
|---|---|---|
| Large Round Baler (>150 HP) | S8 – S10 | Peak torque during bale chamber compression exceeds 2,000 Nm; S8–S10 handle spikes without fatigue. |
| Self-Loading Forage Wagon | S7 – S9 | Continuous chopping and loading generates sustained high torque; star profile eliminates tube slippage. |
| Rotary Cutter / Bush Hog (>2 m) | S6 – S8 | Impact from cutting dense brush creates extreme shock loads that the S Series cross kits absorb. |
| TMR Feed Mixer (>20 m³) | S38 – S42 | Heavy wet rations demand constant high torque; oversized S38–S42 prevents premature yoke failure. |
| Grain Cart Auger | S6 – S7 | Elevated unloading angles increase torsional demand; star tubes maintain alignment under load. |
| Biomass Chipper / Mulcher | S9 – S50 | Chipping hardwood generates extreme cyclic loads; the S50 provides the highest available margin. |
Sizing Your S Series PTO Shaft – Step by Step
- Determine peak torque requirement: Consult the implement’s technical manual for maximum input torque (Nm). For implements with high inertia (balers, choppers), add a 25–30% safety margin.
- Select RPM rating: Choose between 540 and 1,000 RPM columns in the spec table. Higher RPM reduces torque for the same power, potentially allowing a smaller shaft.
- Measure closed & open lengths: Ensure the shaft telescopes enough to cover the full range of motion between tractor and implement, maintaining ≥ one-third overlap at maximum extension.
- Specify yoke type: Tractor side: push-pin or quick-release. Implement side: splined bore, plain bore, or flange — confirm bore diameter, keyway, and spline count.
- Evaluate duty cycle: Continuous operation (e.g., forage harvesting 10+ hours/day) warrants selecting one size up from the minimum torque match.
- Optional torque limiter: For implements sensitive to overload (e.g., gearboxes, augers), pair the S Series shaft with a shear-bolt or friction torque limiter.
Our team can validate your selection — submit your application details here.
OEM Cross-Reference & Brand Compatibility
The S Series star-profile PTO shaft serves as a precision aftermarket substitute for star-tube drivelines supplied with equipment from these manufacturers:
- Walterscheid – W series star-profile driveshafts
- Bondioli & Pavesi – Star-tube PTO assemblies
- Comer Industries – Heavy-duty star drivelines
- Weasler Engineering – Star series shafts
- Elbe Gelenkwellen – Star-profile cardan shafts
All brand names referenced are the property of their respective owners and are cited solely to indicate dimensional and functional compatibility. No endorsement or sponsorship is implied.
Browse replacement cross kits, yokes, and star tubes individually in our online parts store.
Certifications & Warranty
ISO 9001:2015
End-to-end quality management from raw material procurement through final assembly and testing.
CE Compliant
Full shield assemblies tested to EU safety directives. Declaration of Conformity included with every shipment.
18-Month Warranty
Extended warranty on S Series reflecting confidence in heavy-duty component longevity. Free replacement on verified defects.
S Series FAQ
Why choose star profile over triangular for heavy implements?
Star profiles offer six load-bearing contact points versus three on a triangular tube, delivering roughly 40% more torsional rigidity at the same outer diameter. This makes them the preferred choice when peak torques exceed 1,200 Nm.
Can the S Series be paired with a torque limiter?
Absolutely. Shear-bolt, ratchet, friction, and automatic torque limiters are all available as integrated options or bolt-on additions. Specify the desired trip torque when ordering.
How does the S Series handle high operating angles?
Standard cardan joints operate reliably at angles up to 25° at 540 RPM. For applications requiring greater articulation — such as front-mounted implements — consider adding a constant-velocity (CV) joint at the tractor end.
What is the expected service life of an S Series shaft?
With proper lubrication (every 8 hours) and operation within rated parameters, cross kits typically last 800–1,200 hours and tubes well over 2,000 hours. Harsh conditions (dust, mud, overloading) will shorten intervals.
Do you offer custom tube lengths?
Yes. We manufacture custom-length star tubes to your exact specification with a typical lead time of 10–15 business days.
Contractor & Fleet Operator Case Studies
“Our silage contracting fleet runs eight S9 shafts through 14-hour days during harvest. After three seasons, not one has needed a cross kit replacement — that’s a first for us.” — Fleet maintenance manager
“We fitted S38 driveshafts to our large TMR mixers. The star profile eliminated the tube wear we were seeing every 600 hours with triangular shafts.” — Dairy nutritionist & equipment coordinator
“S10 on our 200 HP rotary cutter. It chews through eight-foot-tall CRP grass and volunteer trees without breaking a sweat. The hefty cross kits are worth every cent.” — Custom hay operator
“We import S Series shafts for our dealer network. Consistent quality across shipments and competitive pricing make them our best-selling aftermarket PTO line.” — Import distributor
“Running S7 and S8 on large square balers. The star profile handles the hammering torque of the plunger cycle far better than any triangular shaft we’ve tried.” — Agricultural contractor
Scale Your Operation With the Right Driveline Partner
Contractors, OEMs, and agricultural dealers worldwide rely on the S Series to keep their most productive machines running without interruption. We offer: factory-direct pricing for bulk purchases · custom yoke and tube length options · private labeling for dealer networks · dedicated export packaging for ocean freight.
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