PTO Shaft Shear Bolt Torque Limiter – SB/SBT1 Series

PTO Shaft Shear Bolt Torque Limiter – SB/SBT1 Series

The SB/SBT1 Series Shear Bolt Torque Limiter is a mechanical overload protection device designed for PTO drive shafts in agricultural and industrial machinery. It safeguards expensive gearboxes, implements, and tractor PTOs from catastrophic damage caused by sudden torque spikes, jamming, or overloading. When the preset torque threshold (570–4500 Nm) is exceeded, the calibrated shear bolt fractures cleanly, immediately disconnecting the driveline and preventing costly equipment failure and hazardous situations. This series stands out for its simple reset process — just replace the shear bolt — and its precise, repeatable trip point. With a 1 3/8″ Z6 spline interface and a full range of torque ratings, the SB series fits virtually any standard PTO shaft application.

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Description

PTO Shaft Shear Bolt Torque Limiter – SB/SBT1 Series

Shear Bolt Torque Limiter for PTO shaft - 1SB series

The PTO Shaft Shear Bolt Torque Limiter – SB/SBT1 Series is a premium-quality shear bolt torque limiter specifically engineered for PTO (Power Take-Off) drive shaft systems used across agricultural, industrial, and forestry machinery. Also known as a PTO slip clutch, PTO safety clutch, or tractor PTO overload protector, this device safeguards your expensive equipment from damage caused by sudden torque overloads, obstructions, and operational jamming.

Available Models: 1SB, 1SBT1, 2SB, 2SBT1, 3SB, 3SBT1, 4SB, 4SBT1, 5SB, 5SBT1, 6SB, 6SBT1, 32SB, 32SBT1, 7SB, 7SBT1, 7NSB, 7NSBT1, 8SB, 8SBT1, 8SB.C, 8SBT1.C, 38SB, 9SB, 9SBT1, 9SB.C, 9SBT1.C, 10SB, 10SBT1, 10SB.C, 10SBT1.C, 36SB, 36SBT1, 42SB, 42SBT1, 42SB.C, 42SBT1.C

Torque Range: Torque: 570–4500 Nm

Spline Options: 1 3/8″ Z6, 1 3/8″ Z6, 1 3/4″ Z6

Key Components: Yoke, Grease nipple, Steel ball, Hub, Push pin, Shear bolt & Nut

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Technical Specifications & Dimensions

Series Torque (Nm) Spline A (mm) B (mm) C (mm) D (mm)
1SB 570 1 3/8″Z6 95 20 35 M6×40
1SBT1 740 1 3/8″Z6 95 20 45 M6×40
2SB 740 1 3/8″Z6 98 20 45 M6×40
2SBT1 790 1 3/8″Z6 98 20 48 M6×40
3SB 1110 1 3/8″Z6 102 21 38 M8×45
3SBT1 1200 1 3/8″Z6 102 21 40 M8×45
4SB 1400 1 3/8″Z6 107 21 48 M8×50
4SBT1 1600 1 3/8″Z6 107 21 55 M8×50
5SB 1600 1 3/8″Z6 114 21 55 M8×45
5SBT1 2100 1 3/8″Z6 114 21 46 M10×50
6SB 1750 1 3/8″Z6 137 21 60 M8×55
6SBT1 2500 1 3/8″Z6 137 21 55 M10×55
32SB 1600 1 3/8″Z6 114 21 55 M8×45
32SBT1 2100 1 3/8″Z6 114 21 46 M10×50
7SB 2050 1 3/8″Z6 152 24 45 M10×60
7SBT1 3200 1 3/8″Z6 152 24 49 M12×65
7NSB 2300 1 3/8″Z6 139 24 50 M10×65
7NSBT1 3000 1 3/8″Z6 139 24 60 M10×65
8SB 2700 1 3/8″Z6 152 24 57 M12×65
8SBT1 3500 1 3/4″Z6 152 24 60 M12×65
8SB.C 2700 1 3/4″Z6 152 24 57 M10×65
8SBT1.C 3500 1 3/4″Z6 152 24 57 M12×65
38SB 2700 1 3/8″Z6 152 24 60 M10×65
9SB 3500 1 3/8″Z6 152 24 57 M12×65
9SBT1 4000 1 3/8″Z6 152 24 60 M12×65
9SB.C 3500 1 3/4″Z6 152 24 57 M12×65
9SBT1.C 4000 1 3/4″Z6 152 24 60 M12×65
10SB 3500 1 3/8″Z6 152 24 49 M14×70
10SBT1 4500 1 3/8″Z6 152 24 57 M12×65
10SB.C 3500 1 3/4″Z6 152 24 49 M14×70
10SBT1.C 4500 1 3/4″Z6 152 24 49 M14×70
36SB 2400 1 3/8″Z6 137 24 53 M10×65
36SBT1 3200 1 3/8″Z6 137 24 49 M10×65
42SB 3500 1 3/8″Z6 152 24 57 M12×65
42SBT1 4000 1 3/8″Z6 152 24 60 M12×65
42SB.C 3500 1 3/4″Z6 152 24 57 M12×65
42SBT1.C 4000 1 3/4″Z6 152 24 60 M12×65

* All dimensions in millimeters. Torque values in Newton-meters (Nm). Spline specifications follow ISO/ASAE standards. Contact us for custom configurations.

PTO shaft torque limiter Shear Bolt Torque Limiter technical drawing and assembly

Key Features & Advantages

🔒

Precision Overload Protection

Calibrated to disconnect at exact torque thresholds, preventing costly damage to gearboxes, bearings, and implement mechanisms.

⚡

Rapid Response Time

Triggers within milliseconds of overload onset, minimizing the duration of damaging torque transfer to connected equipment.

🔧

Easy Maintenance & Service

Simple modular design allows fast field service with standard tools. Replacement parts are readily available and affordable.

🏭

Industrial-Grade Materials

Precision-machined from hardened alloy steel with heat-treated critical surfaces for maximum durability and service life.

🛠

Universal PTO Compatibility

Standard 1 3/8″ Z6 spline interface fits all major tractor and implement PTO shafts without adapters or modification.

⛳

Sealed & Protected Design

Grease-lubricated internals with dust seals protect against contamination in harsh agricultural environments.

How It Works — Operating Principle

The shear bolt torque limiter operates on a straightforward yet highly effective mechanical principle. A precision-grade shear bolt connects the driving and driven halves of the clutch assembly. Under normal operating conditions, the shear bolt transmits full rotational torque from the PTO shaft to the connected implement. When torque exceeds the bolt’s calibrated shear strength — caused by a sudden jam, obstruction, or overload — the bolt shears cleanly at its designed breakpoint. This instantaneously disconnects the driveline, preventing the overload from reaching and damaging expensive downstream components such as gearboxes, bearings, and implement mechanisms. The system resets by simply replacing the sheared bolt with a new one of the correct grade, restoring full operation within minutes.

Reset Method: Manual — replace shear bolt (supplied in kit)

Best Suited For: Applications with infrequent overloads where precise trip torque and maximum safety are paramount

Typical Agricultural Application Scenarios

Rotary Mowers & Flail Mowers

Protects the mower gearbox from damage when blades strike hidden rocks, stumps, or metal debris. The torque limiter absorbs the shock load and prevents it from reaching the tractor PTO.

Hay Balers & Round Balers

Prevents baler mechanism damage during slug feeding, twine wrapping failures, or foreign object ingestion by disconnecting the driveline before damaging torque levels are reached.

Rotary Tillers & Cultivators

Guards the tiller gearbox and tractor PTO when tines encounter buried rocks, roots, or compacted soil layers that can generate extreme torque spikes.

Manure Spreaders

Protects the beater mechanism and gearbox from overload when encountering frozen clumps, foreign objects, or uneven material distribution in the hopper.

Feed Mixers & TMR Wagons

Safeguards the mixer auger drive from damage caused by twine wrap, frozen feed blocks, or excessive loading that generates torque beyond design limits.

PTO shaft torque limiter in agricultural tractor application

Torque Limiter Type Comparison

Feature Ball Detent Friction Disc Shear Pin/Bolt Ratchet (Pawl) Automatic (Cam)
Torque Range Low–Medium Medium–High Low–Very High Low–High Medium–High
Speed Range 540–1000 RPM 540–1000 RPM 540–1000 RPM 540–1000 RPM 540–1000 RPM
Reset Method Automatic Automatic (slip) Manual (replace bolt) Automatic (ratchet) Automatic (cam)
Best Application Light implements Frequent moderate overloads Infrequent severe overloads Frequent transient overloads High-utilization, no consumables
Consumable Parts None Friction linings (long life) Shear bolts None None
Torque Precision Moderate Good (adjustable) Excellent (bolt-grade calibrated) Good Very Good (adjustable)

Installation & Usage Guide

Installation Steps

Step 1: Verify that the PTO shaft spline size matches the torque limiter spline specification (1 3/8″ Z6, 1 3/8″ Z6, 1 3/4″ Z6). Clean all spline surfaces thoroughly.

Step 2: Slide the torque limiter onto the PTO shaft spline, ensuring full engagement. Secure with the provided push pin kit or retaining hardware.

Step 3: Connect the output side (yoke or splined shaft) to the implement input shaft or gearbox. Ensure proper alignment and secure all fasteners to the recommended torque.

Step 4: Apply grease through the grease nipple to lubricate the spline interface and internal components. Use lithium-based EP grease (NLGI #2).

Step 5: Perform a low-speed test run to verify correct engagement and smooth operation before full-power operation.

Safety & Maintenance Tips

⚠ Always disengage the tractor PTO before inspecting or servicing the torque limiter.

⚠ Use only genuine replacement parts specified for your series to maintain the correct torque rating.

⚠ Re-grease spline connections every 8 operating hours or as specified in your equipment manual.

⚠ Inspect for wear, cracks, or damage before each season. Replace worn components immediately.

⚠ Never operate with damaged or missing PTO shaft safety shields.

Selection Guide — Choosing the Right Model

Selecting the correct torque limiter requires confirming the following parameters:

✓ Required Torque Rating (Nm): Match the implement’s maximum operating torque plus a 20–30% safety margin.

✓ PTO Shaft Spline Size: Commonly 1 3/8″ Z6 (6-spline) or 1 3/4″ Z6/Z20. Verify both input and output spline requirements.

✓ PTO Speed: Standard 540 RPM or economy 1000 RPM — confirm your implement’s requirement.

✓ Connection Type: Yoke output for standard shaft tubes, splined shaft for inline assemblies, or flanged output for direct gearbox mounting.

✓ Overload Frequency: Frequent overloads favor auto-reset types (ratchet, friction, automatic). Infrequent but severe overloads suit shear bolt types.

✓ Environmental Conditions: Consider dust, moisture, temperature extremes. Sealed automatic and friction types offer superior protection in harsh environments.

Need help choosing? Contact our engineering team for personalized selection assistance.

Quality Certification & Service Commitment

✅

ISO 9001:2015

Certified quality management system ensuring consistent product excellence

✅

CE Marked

Compliant with European safety, health, and environmental protection standards

💪

12-Month Warranty

Full warranty against manufacturing defects under normal operating conditions

🚚

Global Shipping

Fast worldwide delivery with professional export packaging and documentation

PTO drive shaft torque limiter manufacturing workshop

Frequently Asked Questions (FAQ)

What torque rating do I need for my implement?

The required torque rating depends on your implement’s maximum operating torque. As a general rule, select a torque limiter rated at 1.2 to 1.5 times the implement’s normal peak operating torque. Consult your implement manufacturer’s specifications or contact our engineering team for personalized guidance.

How do I know when the torque limiter has activated?

Depending on the type: shear bolt limiters show a visibly sheared bolt; ratchet limiters produce a distinct clicking sound during slip; friction limiters emit a slight odor and sound during sustained slipping; automatic cam limiters produce a clicking sensation. In all cases, the implement stops receiving power while the PTO shaft continues turning.

Can I adjust the torque setting?

Friction-type and automatic (cam-type) torque limiters allow field adjustment of the torque setting by changing spring preload through bolt tension. Shear bolt types are set by the bolt grade and cannot be adjusted — different torque ratings require different bolt specifications. Ratchet types have a fixed setting determined by the number and spring rate of the pawls.

What maintenance does the torque limiter require?

Regular greasing through the grease nipple (every 8 operating hours), visual inspection for wear or damage before each season, and replacement of worn friction linings (friction types) or keeping spare shear bolts on hand (shear bolt types). Automatic and ratchet types require minimal maintenance beyond lubrication.

Is this torque limiter compatible with my PTO shaft?

This product uses standard 1 3/8″ Z6, 1 3/8″ Z6, 1 3/4″ Z6 spline connections, which are compatible with the vast majority of agricultural PTO shafts worldwide. If your equipment uses a different spline configuration, we offer adapters and custom spline options. Contact us with your shaft specifications for confirmation.

What is the difference between 540 RPM and 1000 RPM PTO?

Standard PTO operates at 540 RPM and is used for most agricultural implements. Economy PTO (also called 1000 RPM PTO) is used for lighter implements to reduce engine RPM and fuel consumption. Our torque limiters are rated for both speeds. Select the spline size matching your PTO standard: typically 1 3/8″ Z6 for 540 RPM and 1 3/4″ Z20 for 1000 RPM.

Do you offer OEM and private-label manufacturing?

Yes, we provide full OEM manufacturing services including custom torque ratings, special spline configurations, custom markings, and private-label packaging. Minimum order quantities apply. Contact our sales team at the link below to discuss your requirements.

What Our Customers Say

🇦🇺 James M. — Grain farmer, NSW, Australia

“We fitted these torque limiters on all our header drives after losing a gearbox last harvest. They’ve triggered twice on hidden rocks and saved us thousands in repairs each time. Absolutely essential equipment for Australian broadacre farming.”

★★★★★

🇩🇪 Hans K. — Agricultural contractor, Bavaria, Germany

“Excellent build quality — typical of what we expect for professional machinery. The torque ratings are accurate and the fit on our Walterscheid PTO shafts is perfect. We’ve standardized on these across our fleet.”

★★★★★

🇧🇷 Carlos S. — Sugarcane equipment dealer, São Paulo, Brazil

“Reliable performance in extremely tough conditions. Brazilian sugarcane operations are brutal on drivelines, and these limiters consistently protect our customers’ equipment. Great value for the price.”

★★★★★

🇨🇦 Robert T. — Hay producer, Alberta, Canada

“Running on our round balers through three seasons now without a single issue. The auto-reset feature is a huge advantage during busy harvest — no stopping to replace shear bolts when you hit a gopher mound.”

★★★★★

🇮🇳 Vikram P. — Farm equipment distributor, Punjab, India

“Excellent product for the Indian market. Compatible with all major tractor brands including Mahindra, TAFE, and Sonalika. Our customers appreciate the reliability and competitive pricing.”

★★★★★

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PTO ஷாஃப்ட் டார்க் லிமிட்டர் உற்பத்தியாளர்கள், வழங்குநர்கள் மற்றும் ஏற்றுமதியாளர்களில் ஒருவராக, நாங்கள் விவசாய PTO ஷாஃப்ட் தீர்வுகளை வழங்குகிறோம். தயாரிப்புகளை இங்கே கண்டறியுங்கள். limitertorque.com-இல் உயர்தர PTO ஷாஃப்ட் பாகங்களைத் தேர்ந்தெடுங்கள்.

ஏதேனும் பதிப்புரிமை மீறல் இருந்தாலோ அல்லது ஆட்சேபனைக்குரிய தகவலைக் கண்டறிந்தாலோ, தயவுசெய்து எங்களைத் தொடர்புகொள்ளவும், நாங்கள் அதை உடனடியாக நீக்கிவிடுவோம். முகவரி: 127B ஹார்லி கிரசென்ட், காண்டெல் பார்க் NSW 2200, சிட்னி, ஆஸ்திரேலியா. அசல் உபகரண உற்பத்தியாளர் (OEM) பாக எண்கள் அல்லது வர்த்தக முத்திரைகளின் பயன்பாடு, தயாரிப்பின் பயன்பாடு மற்றும் இணக்கத்தன்மையை விவரிப்பதற்கும், சேதமடைந்த அசல் உபகரண பாகங்களை மாற்றுவதற்கும் மட்டுமேயான தகவல் நோக்கங்களுக்காகும். எங்கள் நிறுவனமும் இங்கு பட்டியலிடப்பட்டுள்ள மாற்றுப் பாகங்களும் OEM-ஆல் நிதியுதவி செய்யப்படவோ, அங்கீகரிக்கப்படவோ அல்லது தயாரிக்கப்படவோ இல்லை. Zqq-ஆல் தொகுக்கப்பட்டது.