{"id":1816,"date":"2026-03-17T03:49:25","date_gmt":"2026-03-17T03:49:25","guid":{"rendered":"https:\/\/limitertorque.com\/product\/pto-shaft-overrunning-clutch-ra1-series-with-yoke\/"},"modified":"2026-03-17T03:49:26","modified_gmt":"2026-03-17T03:49:26","slug":"pto-shaft-overrunning-clutch-ra1-series-with-yoke","status":"publish","type":"product","link":"https:\/\/limitertorque.com\/it\/product\/pto-shaft-overrunning-clutch-ra1-series-with-yoke\/","title":{"rendered":"PTO Shaft Overrunning Clutch \u2013 RA1 Series (with Yoke)"},"content":{"rendered":"
\n

<\/p>\n

PTO Shaft Overrunning Clutch \u2013 RA1 Series (with Yoke)<\/h1>\n
\n
\n\"Overrunning\n<\/div>\n
\n

The PTO Shaft Overrunning Clutch \u2013 RA1 Series (with Yoke)<\/strong> is a premium-quality overrunning clutch<\/strong> specifically engineered for PTO (Power Take-Off) drive shaft systems used across agricultural, industrial, and forestry machinery. Also known as a PTO slip clutch<\/em>, PTO safety clutch<\/em>, or tractor PTO overload protector<\/em>, this device safeguards your expensive equipment from damage caused by sudden torque overloads, obstructions, and operational jamming.<\/p>\n

Available Models:<\/strong> 1RA1, 2RA1, 3RA1, 4RA1, 5RA1, 6RA1, 7RA1, 7NRA1, 8RA1<\/p>\n

Torque Range:<\/strong> Torque<\/span>: 2400 Nm (max)<\/span><\/span><\/p>\n

Spline Options:<\/strong> 1 3\/8″ Z6<\/p>\n

Key Components:<\/strong> Circlip, Retaining washer, Push pin kit, Hub, Prong kit (Qty.=3), Housing with yoke, Grease nipple<\/p>\n

Request a Quote →<\/a><\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Technical Specifications & Dimensions<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n
Series<\/th>\nMax Torque (Nm)<\/th>\nSpline<\/th>\nA (mm)<\/th>\nB (mm)<\/th>\n<\/tr>\n
1RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n138<\/td>\n21<\/td>\n<\/tr>\n
2RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n138<\/td>\n21<\/td>\n<\/tr>\n
3RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n149<\/td>\n21<\/td>\n<\/tr>\n
4RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n150<\/td>\n21<\/td>\n<\/tr>\n
5RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n154<\/td>\n21<\/td>\n<\/tr>\n
6RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n160<\/td>\n21<\/td>\n<\/tr>\n
7RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n171<\/td>\n21<\/td>\n<\/tr>\n
7NRA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n157<\/td>\n21<\/td>\n<\/tr>\n
8RA1<\/td>\n2400<\/td>\n1 3\/8″Z6<\/td>\n171<\/td>\n21<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

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

\"PTO<\/p>\n

<\/p>\n

Key Features & Advantages<\/h2>\n
\n
\n

🏭<\/p>\n

Industrial-Grade Materials<\/p>\n

Precision-machined from hardened alloy steel with heat-treated critical surfaces for maximum durability and service life.<\/p>\n<\/div>\n

\n

🛠<\/p>\n

Universal PTO Compatibility<\/p>\n

Standard 1 3\/8″ Z6 spline interface fits all major tractor and implement PTO shafts without adapters or modification.<\/p>\n<\/div>\n

\n

⛳<\/p>\n

Sealed & Protected Design<\/p>\n

Grease-lubricated internals with dust seals protect against contamination in harsh agricultural environments.<\/p>\n<\/div>\n

\n

📈<\/p>\n

Wide Torque Selection Range<\/p>\n

Available in multiple torque ratings (2400 Nm (max)) to match virtually any PTO-driven implement requirement.<\/p>\n<\/div>\n

\n

⚖<\/p>\n

Safety Certified<\/p>\n

Manufactured under ISO 9001:2015 quality management with CE marking for European and international compliance.<\/p>\n<\/div>\n

\n

📦<\/p>\n

Compact & Lightweight<\/p>\n

Engineered for minimal additional length and weight on the PTO shaft, preserving driveline balance and clearance.<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

How It Works \u2014 Operating Principle<\/h2>\n

The overrunning clutch (also known as a freewheel clutch) allows the output shaft to rotate freely in one direction while transmitting full torque in the other. Inside the housing, spring-loaded prongs engage with a ratchet surface on the hub. When the input shaft drives the output shaft in the intended direction, the prongs lock into the ratchet teeth and transmit power. When the output shaft attempts to overdrive the input (such as when a tractor PTO is disengaged while a heavy flywheel implement is still spinning), the prongs disengage and the output freewheels. This prevents dangerous back-drive forces from traveling through the PTO shaft to the tractor transmission, protecting both equipment and the operator.<\/p>\n

Reset Method:<\/strong> Automatic \u2014 continuous engagement\/disengagement<\/p>\n

Best Suited For:<\/strong> Implements with high rotational inertia (mowers, balers, flail choppers) requiring back-drive protection<\/p>\n

<\/p>\n

Typical Agricultural Application Scenarios<\/h2>\n
\n
\n

Rotary Tillers & Cultivators<\/p>\n

Guards the tiller gearbox and tractor PTO when tines encounter buried rocks, roots, or compacted soil layers that can generate extreme torque spikes.<\/p>\n<\/div>\n

\n

Manure Spreaders<\/p>\n

Protects the beater mechanism and gearbox from overload when encountering frozen clumps, foreign objects, or uneven material distribution in the hopper.<\/p>\n<\/div>\n

\n

Feed Mixers & TMR Wagons<\/p>\n

Safeguards the mixer auger drive from damage caused by twine wrap, frozen feed blocks, or excessive loading that generates torque beyond design limits.<\/p>\n<\/div>\n

\n

Grain Augers & Conveyors<\/p>\n

Prevents auger tube distortion and gearbox failure when grain bridges, moisture-swollen grain, or foreign objects create sudden resistance in the conveying path.<\/p>\n<\/div>\n

\n

Post Hole Diggers<\/p>\n

Absorbs extreme torque shock when the auger bit strikes rock, buried concrete, or dense root masses, protecting both the auger drive and tractor PTO.<\/p>\n<\/div>\n<\/div>\n

\"PTO<\/p>\n

<\/p>\n

Torque Limiter Type Comparison<\/h2>\n
\n\n\n\n\n\n\n\n\n
Feature<\/th>\nBall Detent<\/th>\nFriction Disc<\/th>\nShear Pin\/Bolt<\/th>\nRatchet (Pawl)<\/th>\nAutomatic (Cam)<\/th>\n<\/tr>\n
Torque Range<\/strong><\/td>\nLow\u2013Medium<\/td>\nMedium\u2013High<\/td>\nLow\u2013Very High<\/td>\nLow\u2013High<\/td>\nMedium\u2013High<\/td>\n<\/tr>\n
Speed Range<\/strong><\/td>\n540\u20131000 RPM<\/td>\n540\u20131000 RPM<\/td>\n540\u20131000 RPM<\/td>\n540\u20131000 RPM<\/td>\n540\u20131000 RPM<\/td>\n<\/tr>\n
Reset Method<\/strong><\/td>\nAutomatic<\/td>\nAutomatic (slip)<\/td>\nManual (replace bolt)<\/td>\nAutomatic (ratchet)<\/td>\nAutomatic (cam)<\/td>\n<\/tr>\n
Best Application<\/strong><\/td>\nLight implements<\/td>\nFrequent moderate overloads<\/td>\nInfrequent severe overloads<\/td>\nFrequent transient overloads<\/td>\nHigh-utilization, no consumables<\/td>\n<\/tr>\n
Consumable Parts<\/strong><\/td>\nNone<\/td>\nFriction linings (long life)<\/td>\nShear bolts<\/td>\nNone<\/td>\nNone<\/td>\n<\/tr>\n
Torque Precision<\/strong><\/td>\nModerate<\/td>\nGood (adjustable)<\/td>\nExcellent (bolt-grade calibrated)<\/td>\nGood<\/td>\nVery Good (adjustable)<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

<\/p>\n

Installation & Usage Guide<\/h2>\n
\n

Installation Steps<\/h3>\n

Step 1:<\/strong> Verify that the PTO shaft spline size matches the torque limiter spline specification (1 3\/8″ Z6). Clean all spline surfaces thoroughly.<\/p>\n

Step 2:<\/strong> Slide the torque limiter onto the PTO shaft spline, ensuring full engagement. Secure with the provided push pin kit or retaining hardware.<\/p>\n

Step 3:<\/strong> 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.<\/p>\n

Step 4:<\/strong> Apply grease through the grease nipple to lubricate the spline interface and internal components. Use lithium-based EP grease (NLGI #2).<\/p>\n

Step 5:<\/strong> Perform a low-speed test run to verify correct engagement and smooth operation before full-power operation.<\/p>\n

Safety & Maintenance Tips<\/h3>\n

⚠ Always disengage the tractor PTO before inspecting or servicing the torque limiter.<\/p>\n

⚠ Use only genuine replacement parts specified for your series to maintain the correct torque rating.<\/p>\n

⚠ Re-grease spline connections every 8 operating hours or as specified in your equipment manual.<\/p>\n

⚠ Inspect for wear, cracks, or damage before each season. Replace worn components immediately.<\/p>\n

⚠ Never operate with damaged or missing PTO shaft safety shields.<\/p>\n<\/div>\n

<\/p>\n

Selection Guide \u2014 Choosing the Right Model<\/h2>\n
\n

Selecting the correct torque limiter requires confirming the following parameters:<\/p>\n

✓ Required Torque Rating (Nm):<\/strong> Match the implement’s maximum operating torque plus a 20\u201330% safety margin.<\/p>\n

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

✓ PTO Speed:<\/strong> Standard 540 RPM or economy 1000 RPM \u2014 confirm your implement’s requirement.<\/p>\n

✓ Connection Type:<\/strong> Yoke output for standard shaft tubes, splined shaft for inline assemblies, or flanged output for direct gearbox mounting.<\/p>\n

✓ Overload Frequency:<\/strong> Frequent overloads favor auto-reset types (ratchet, friction, automatic). Infrequent but severe overloads suit shear bolt types.<\/p>\n

✓ Environmental Conditions:<\/strong> Consider dust, moisture, temperature extremes. Sealed automatic and friction types offer superior protection in harsh environments.<\/p>\n

Need help choosing? Contact our engineering team<\/a> for personalized selection assistance.<\/p>\n<\/div>\n

<\/p>\n

Quality Certification & Service Commitment<\/h2>\n
\n
\n

✅<\/p>\n

ISO 9001:2015<\/p>\n

Certified quality management system ensuring consistent product excellence<\/p>\n<\/div>\n

\n

✅<\/p>\n

CE Marked<\/p>\n

Compliant with European safety, health, and environmental protection standards<\/p>\n<\/div>\n

\n

💪<\/p>\n

12-Month Warranty<\/p>\n

Full warranty against manufacturing defects under normal operating conditions<\/p>\n<\/div>\n

\n

🚚<\/p>\n

Global Shipping<\/p>\n

Fast worldwide delivery with professional export packaging and documentation<\/p>\n<\/div>\n<\/div>\n

\"PTO<\/p>\n

<\/p>\n

Frequently Asked Questions (FAQ)<\/h2>\n
\n
\n
\nWhat torque rating do I need for my implement?<\/summary>\n
\n

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.<\/p>\n<\/div>\n<\/details>\n<\/div>\n

\n
\nHow do I know when the torque limiter has activated?<\/summary>\n
\n

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.<\/p>\n<\/div>\n<\/details>\n<\/div>\n

\n
\nCan I adjust the torque setting?<\/summary>\n
\n

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 \u2014 different torque ratings require different bolt specifications. Ratchet types have a fixed setting determined by the number and spring rate of the pawls.<\/p>\n<\/div>\n<\/details>\n<\/div>\n

\n
\nWhat maintenance does the torque limiter require?<\/summary>\n
\n

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.<\/p>\n<\/div>\n<\/details>\n<\/div>\n

\n
\nIs this torque limiter compatible with my PTO shaft?<\/summary>\n
\n

This product uses standard 1 3\/8″ 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.<\/p>\n<\/div>\n<\/details>\n<\/div>\n

\n
\nWhat is the difference between 540 RPM and 1000 RPM PTO?<\/summary>\n
\n

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.<\/p>\n<\/div>\n<\/details>\n<\/div>\n

\n
\nDo you offer OEM and private-label manufacturing?<\/summary>\n
\n

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.<\/p>\n<\/div>\n<\/details>\n<\/div>\n<\/div>\n

<\/p>\n

What Our Customers Say<\/h2>\n
\n
\n

🇧🇷<\/span> Carlos S.<\/strong> \u2014 Sugarcane equipment dealer, São Paulo, Brazil<\/em><\/p>\n

“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.”<\/p>\n

★★★★★<\/p>\n<\/div>\n

\n

🇨🇦<\/span> Robert T.<\/strong> \u2014 Hay producer, Alberta, Canada<\/em><\/p>\n

“Running on our round balers through three seasons now without a single issue. The auto-reset feature is a huge advantage during busy harvest \u2014 no stopping to replace shear bolts when you hit a gopher mound.”<\/p>\n

★★★★★<\/p>\n<\/div>\n

\n

🇮🇳<\/span> Vikram P.<\/strong> \u2014 Farm equipment distributor, Punjab, India<\/em><\/p>\n

“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.”<\/p>\n

★★★★★<\/p>\n<\/div>\n

\n

🇫🇷<\/span> Pierre L.<\/strong> \u2014 Vineyard operator, Bordeaux, France<\/em><\/p>\n

“Perfect for our vineyard mowers operating in tight rows. The compact design doesn’t add excessive length to the PTO shaft, and the protection is reliable when vines or stakes get caught.”<\/p>\n

★★★★★<\/p>\n<\/div>\n

\n

🇦🇷<\/span> Miguel R.<\/strong> \u2014 Ranch manager, Buenos Aires Province, Argentina<\/em><\/p>\n

“Outstanding durability in our dusty Pampas conditions. We’ve been using these for two years on grain augers and feed mixers with zero failures. The sealed design keeps the dust out.”<\/p>\n

★★★★★<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Related PTO Shaft Products & Accessories<\/h2>\n
\n
\n\"PTO<\/p>\n

PTO Shaft Components<\/p>\n

Complete range of PTO shaft yokes, cross bearings, tubes, shields, and adapters for all standard sizes.<\/p>\n

View PTO Shafts →<\/a><\/p>\n<\/div>\n

\n\"PTO<\/p>\n

Agricultural Gearboxes<\/p>\n

Matched gearboxes designed to work seamlessly with our PTO shafts and torque limiters.<\/p>\n

Explore Products →<\/a><\/p>\n<\/div>\n

\n

Available PTO Accessories:<\/p>\n

• PTO shaft yokes (plain bore, splined, quick-release)<\/p>\n

• Safety shields and guard tubes (EN 12965 compliant)<\/p>\n

• Spline adapters (1 3\/8″ to 1 3\/4″ conversion)<\/p>\n

• Cross bearing kits and U-joint repair kits<\/p>\n

• Telescoping PTO shaft tubes (triangular and lemon profile)<\/p>\n

• Push pin kits and retaining hardware<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

\n

Ready to Protect Your Equipment?<\/h2>\n

Whether you need a single replacement unit or bulk OEM supply, our team is ready to help you select the perfect torque limiter for your application. We offer competitive B2B pricing, technical consultation, and fast global delivery.<\/p>\n

Get a Free Quote →<\/a>
\nBrowse All Products<\/a><\/p>\n

OEM & distributor partnerships welcome · MOQ as low as 10 units · Custom specifications available<\/p>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

The RA1 Series Overrunning Clutch<\/strong> is a one-directional freewheel mechanism engineered for PTO-driven agricultural implements. It prevents dangerous reverse rotation (back-drive) from heavy implements such as mowers, balers, and feed mixers when the tractor PTO is disengaged, protecting both equipment and operators. Rated at 2400 Nm (max)<\/strong>, this clutch uses a robust prong-and-ratchet engagement system on a 1 3\/8″ Z6 spline hub. The yoke-type housing allows direct connection to standard PTO shaft tubes. Key advantages include maintenance-free operation<\/em>, instant engagement in the driven direction<\/em>, and smooth freewheel release<\/em> \u2014 all critical for keeping flywheel-inertia implements safe during shutdown sequences.<\/p>","protected":false},"featured_media":1777,"comment_status":"closed","ping_status":"open","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":""},"product_brand":[],"product_cat":[5063],"product_tag":[5068,5072,5069,5065,5073,5064,5067,5071,5070,5066],"class_list":{"0":"post-1816","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-overrunning-clutch","7":"product_tag-agricultural-freewheel-coupling","8":"product_tag-implement-overrunning-safety-clutch","9":"product_tag-pto-back-drive-protection-clutch","10":"product_tag-pto-freewheel-clutch","11":"product_tag-pto-one-direction-clutch-assembly","12":"product_tag-pto-overrunning-clutch","13":"product_tag-pto-shaft-anti-reverse-clutch","14":"product_tag-pto-shaft-overrun-protector","15":"product_tag-ratchet-freewheel-pto-clutch","16":"product_tag-tractor-pto-one-way-clutch","18":"first","19":"instock","20":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/product\/1816","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/comments?post=1816"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/media\/1777"}],"wp:attachment":[{"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/media?parent=1816"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/product_brand?post=1816"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/product_cat?post=1816"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/limitertorque.com\/it\/wp-json\/wp\/v2\/product_tag?post=1816"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}