Products Description
FS120 Brush Cutter Drive Shaft 4T | Inner Flexible Transmission Shaft for 4-Stroke Straight-Shaft Brush Cutters & Grass Trimmers
Precision-Ground Polished Steel Drive Shaft with Press-Fitted End Ferrule - Direct Replacement for FS120 & Compatible 4-Stroke Brush Cutter Transmission Assemblies
FS120 Brush cutter drive shaft 4T
This inner drive shaft is the power transmission core of the FS120 straight-shaft brush cutter - the component that transfers engine rotation from the clutch at the top of the shaft tube down to the gearhead and cutting attachment at the bottom. The "4T" designation is critical: 4-stroke brush cutters operate at lower peak RPM (typically 6,500–7,500 RPM) than 2-stroke units (8,000–10,000+ RPM), but deliver higher torque per revolution. The drive shaft must be dimensioned for the torque character of a 4-stroke engine - a shaft designed for the higher-RPM, lower-torque pulse of a 2-stroke engine will fatigue and fail prematurely in 4-stroke service. This shaft is manufactured from precision-ground polished steel with a press-fitted hardened steel end ferrule that engages the clutch drum at the top and the gearhead input at the bottom. When the shaft's splines wear, the shaft bends from impact, or the ferrule loosens - the brush cutter transmits no power to the cutting head. Replacement restores full torque transfer and eliminates the vibration that a worn or bent shaft generates at operating RPM.
Technical Profiles & Materials
4-Stroke-Specific Torque Rating - Built for Lower RPM, Higher Torque：
4-stroke brush cutter engines produce peak torque at lower RPM than equivalent-displacement 2-stroke engines - typically 4,500–5,500 RPM for peak torque on a 4-stroke versus 6,500–7,500 RPM on a 2-stroke. This changes the fatigue profile of the drive shaft: a 4-stroke shaft experiences higher peak torsional stress per revolution but fewer total stress cycles per operating hour. The shaft diameter, steel grade, and heat treatment are selected for this specific torque-RPM combination.
Direct Replacement for FS120 & Compatible Models：
The FS120 is a widely cloned brush cutter platform. This shaft is dimensionally matched to the FS120 outer tube length, ferrule engagement profile, and overall shaft diameter. For repair shops and equipment dealers servicing multiple brush cutter brands that share the FS120-type straight-shaft architecture, one drive shaft SKU services multiple machine models - restoring full power transmission without sourcing an entire shaft-and-tube assembly.
Technical Specifications
| ITEM | DETAILS |
| Type | Inner Flexible Drive Shaft - 4-Stroke Brush Cutter Transmission |
| Application | FS120 & compatible 4-stroke straight-shaft brush cutters, grass trimmers & clearing saws with inner-shaft transmission |
| Code | 0204012 |
| Material | High-carbon polished steel shaft, hardened steel press-fitted end ferrule |
| Details explanation | Precision centerless-ground polished steel shaft. Press-fitted hardened ferrule. Engineered for 4-stroke torque (lower RPM, higher torque per revolution). Direct replacement for FS120 4T models. |
| Brand Name | SeaSummer |
| Operating Temp | −20 ~ +100 °C (shaft operating temperature) |
| Delivery Time | 30 Days |
| Packaging | Cardboard packaging |
Products Application
Shaft Failure Repair - Avoiding Full Assembly Replacement
When an inner drive shaft fails, the original equipment approach is often to sell the complete shaft-and-outer-tube assembly - a significantly more expensive part than the inner shaft alone. For cost-conscious operators and independent repair shops, replacing only the failed inner shaft while reusing the existing outer tube, bushings, and end fittings is the economical repair path. The rigid cardboard tube packaging protects the precision-ground shaft surface during shipping and storage, ensuring the replacement shaft arrives straight and undamaged - a bent shaft in a flexible polybag is useless regardless of material quality.
4-Stroke Straight-Shaft Trimmer Platforms
Beyond the FS120 specifically, this shaft fits a range of Chinese and Southeast Asian manufactured 4-stroke straight-shaft brush cutters and grass trimmers sharing the FS120-type transmission architecture. These machines are the dominant brush cutter format in rice-growing regions, palm oil plantations, and tropical landscaping markets where 4-stroke engines are preferred for their fuel efficiency, lower noise, and compatibility with straight gasoline (no oil mixing required). For dealers and parts distributors in these markets, stocking one 4T-rated drive shaft SKU covers the most common straight-shaft trimmer transmission replacement need.
FS120 4-Stroke Brush Cutters & Grass Trimmers
The primary fitment. The FS120 is one of the most widely produced straight-shaft brush cutter platforms globally - used with nylon trimmer heads for grass and steel blades for brush, saplings, and light clearing work. The inner drive shaft is a wear component: over hundreds of operating hours, the ferrule engagement surfaces wear, the shaft develops micro-bends from blade impact, and the surface finish degrades from contact with the support bushings. Symptoms of a worn shaft include progressively worsening vibration, reduced cutting power (the shaft winds up torsionally instead of transmitting torque), and an audible rattling or grinding from the shaft tube.
Quality and Craftsmanship Details
Products Package
About Us
As a premier garden machinery parts supplier, Jiaxing Norsun Trading Co., Ltd. bridges global distributors with over 100 vetted China manufacturers. We streamline your B2B supply chain through strict quality control, flexible production, and factory-direct wholesale pricing. Partner with us for reliable, high-volume sourcing of precision-engineered outdoor power equipment components.
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FAQ
Q: Are you an impartial industrial components dealer or a direct China water pump factors factory?
A:We are a direct, ISO9001-certified engineering water pump components manufacturing facility and precision fluid-control factor manufacture exporter primarily based in China. We function our personal cleanroom injection molding bays, computerized ultrasonic welding arrays, computerized hydraulic stress check stations, and clean-room packaging lines, passing direct-factory wholesale price financial savings straight to your element procurement margins.
Q: Can your manufacturing unit furnish full certification forms for food-contact or consuming water compliance?
A: Yes, absolutely. For food, beverage, or scientific applications, our manufacturing unit makes use of one hundred percent virgin, un-recycled polypropylene resins accompanied by means of fabric traceability certificates. We mechanically furnish B2B purchasers with complete FDA compliance documentation, NSF-grade compound declarations, and RoHS/REACH chemical protection screening sheets to make certain clean clearance thru worldwide customs.
Q: Do you provide customization picks for distinctly corrosive fluids like sturdy acids or ozone?
A: Yes, we are a thoroughly succesful OEM/ODM supplier. For aggressive chemical or ozone environments, we can improve the 12x26.5mm valve configuration in our factory: substituting the general PP housing with top class PVDF (Fluoropolymer) and changing any steel springs with Hastelloy or whole springless gravity-ball architecture, making sure final chemical resistance.
Q: How do we impervious a pattern batch to execute computerized lifecycle and burst-pressure testing?
A: We relatively inspire complete laboratory contrast earlier than logging mass grant agreements. We can ship a pattern lot of 5-10 gadgets of our inventory 12x26.5mm take a look at valves for assessment (setup costs and DHL/FedEx air freight apply). Once the factors pass by your inner lifecycle verification and a formal wholesale quantity manufacturing contract or container run is locked in, the sampling charges are a hundred percent credited returned to your industrial balance.
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