Lawn Mower Trimmer Gear Box Head Cutter Strimmer Grass Replacement for Stihl FS36 FS40 FS44 FS55 FS72 FS74 FS75 FS76 Weed Eater
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Free Shipping
Free shipping to the US for a limited time
Free Returns
30 days worry-free return.
Secure Payment
One year warranty
Key Features
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High-Grade Aluminum Alloy Construction: The gearbox housing is manufactured from premium aluminum alloy, offering excellent thermal dissipation, corrosion resistance, and lightweight durability for reduced operator fatigue.
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Smooth Power Transfer: Features precision-engineered internal gears designed to deliver high torque and consistent RPM transfer from the drive shaft to the cutting head under heavy landscaping loads.
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Complete Replacement Combo: Includes both the heavy-duty gear case and a matching trimmer head, allowing you to completely refresh your equipment’s lower drive system in one go.
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Precision Factory Tolerance: Designed to meet or exceed original equipment standards for a secure fit, minimizing shaft vibration and maximizing tool operating life.
Crucial Fitment & Drive Shaft Notice
Please Read Before Purchasing: To ensure proper installation and prevent component damage, you must verify your equipment's drive shaft shape.
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Drive Shaft Requirement: This gearbox is engineered exclusively for Round Drive Shafts. It WILL NOT FIT square drive shafts. Please inspect your trimmer's flex or solid shaft tip before ordering.
Official Application Matrix
| Make | Compatible Trim & Brushcutter Series | Included Drive Configurations |
| Stihl | FS36, FS40, FS44, FS65, FS72, FS74, FS75, FS76, FS80, FS80R, FS85 | Round Shaft Models Only |
| Stihl | FR130, FR220, FR350, FR450, FR480 | Round Shaft Models Only |
| Stihl | FS-KM (KombiSystem Attachments) | Round Shaft Models Only |
Product Specifications
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Part Type: Trimmer Working Gear Head / Gearbox Assembly
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Housing Material: Die-Cast Aluminum Alloy
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Shaft Spline Receiver: Round Configuration
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Condition: 100% Brand New
Interchange Reference Part Number:
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Factory OE Number: 4137 640 0100
Package Includes
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1 × Premium Gearbox Head Assembly
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1 × Matching Line Trimmer Head
Important Mechanical & Installation Notes
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Isolate Power Before Servicing: Ensure the engine is completely turned off and the spark plug wire is disconnected before removing the old gear head or installing the replacement.
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Check Factory Lubrication: While pre-greased during manufacturing, it is highly recommended to verify internal grease levels using a high-quality lithium-based gear grease prior to its initial high-RPM operation.
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Secure Clamp Bolts Evenly: When sliding the new gearbox onto the outer shaft housing, tighten the clamping bolts evenly in an alternating sequence to prevent cracking the aluminum collar or stripping the threads.
To ensure a faster and secure delivery, we choose FedEx, USPS, UPS, DHL Ground/Air shipping service. Available shipping methods are vary from different type of products and delivery destination. The majority in stock products and orders are going to be shipped the same day or within 1 business day. After which its delivery details can be tracked with the tracking number we email you. For custom or made to order products’ shipping time varies as they may have to be manufactured, painted, embroidered or assembled.
For more information, please check the following tips:
- Oversized products must ship by truck freight or LTL which is different from other ground shipping methods. Please noted that oversized products are required inspections and a signature service. Freight Shipping Information
- We offer free shipping service for 47 sates in domestics. HI, PR, AK, Guam, Virgin Islands, APOs are excluded from free shipping areas. You will be charged extra shipping fee for orders’ destinations that are not 47 free shipping states.
- "Free Shipping" applies only to orders shipped within the continental United States.
DISCLAIMER
In order to provide all our valued customers with the most up to date and accurate compatibility information, LABWORKAUTO is continuously implementing real-time updates to our line store. Due to the immediate nature of these updates, the correction of any errors or omissions might happen at any time without prior notice. This information may include but not limited to pricing, availability, suggested use, fitment, compatibility and warranties. LABWORKAUTO is not responsible for any additional labor cost, charge, loss or damage incurred as a result of correct or incorrect information, reference or products purchase from LABWORKAUTO. While we are working to avoid any errors or omissions that may appear on LABWORKAUTO website, we reserve the rights to cancel any undeliverable orders based on inaccurate information.
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RETURN
If you are not completely satisfied with your purchase, we will be happy to accept a return for a refund or exchange on products in new/unused condition within 30 days of delivery. All authorized returns must be unused and in their original condition, including all items and components that were included in the original package. Items being returned must not have been disassembled, mounted, modified, or damaged due to incorrect installation or user error. LABWORKAUTO.com will not be held responsible for installation or labor expenses, towing expenses, additional repair expenses, or rental car expenses caused by the use of wrong or defective parts during installation.We provide a limited warranty of 90 days for defective products from the date the product is received by the original purchaser or installer, unless otherwise specified at the time of purchase.
For each of our product warranties offered above, the following provisions apply:
The warranty is limited only to the original purchaser and is non-transferable.
Under NO circumstances will our liability exceed the amount of the original sale.
Each warranty does not cover any labor costs or incidental, indirect, special or consequential damages such as, but not limited to, physical injuries or property damage, loss of time, loss of use of the vehicle, inconvenience, air freight charges, rental vehicle charges, towing charges or accommodations resulting from a defect in or failure of the part.
A prepaid shipping label will be issued for all returns due to warranty claim.
The warranty does not cover lost or stolen packages. Because the customer is the shipper, he/she is the only one who can file any lost claim with the shipping company. Therefore, the claim must be coordinated and processed through the shipping company by the customer.