H345 Onepiece Passive Disc Transmission Wheel for Gasoline and Electric Chain Saws (Size H345A, Model 678) This replacement passive disc transmission wheel is designed for H345 series chain saw drivetrains and sized to H345A specifications. It restores reliable power transfer between the engine and the chain, making it a practical maintenance part for professional users and homeowners who depend on their saws. Key benefits Restores drive performance: Replaces worn or damaged transmission wheels to reestablish smooth rotation and consistent chain movement. Precise fit: Manufactured to H345A dimensions for correct alignment with compatible clutch drums and chains, reducing vibration and uneven wear. Easy swapin replacement: Onepiece design simplifies installation and reduces service time compared to multipart assemblies. Reliable engagement: Engineered to work with both gasoline and electric chain saws that accept H345A passive disc components, maintaining proper sprocket engagement. Low maintenance: Durable construction and accurate machining reduce the need for frequent adjustments. What it does Transfers torque from the engine or motor to the chain sprocket. Serves as a direct replacement for worn or damaged passive disc transmission wheels sized H345A. Supports consistent chain speed and engagement under normal cutting loads. Compatibility and sizing Size: H345A (matches saws and assemblies that require H345A passive disc transmission wheels) Model identifier: 678 (use as reference when matching parts) Suitable for gasoline and electric chain saws that specify H345 passive disc transmission wheels. Verify your saws specifications and existing part number before ordering. Practical use scenarios Field : a stripped or worn transmission wheel during a job to get the saw back into service quickly. Scheduled maintenance: Swap in a H345A wheel during routine service to prevent slippage and uneven wear before it affects cutting performance. Spare parts kit: Keep a ready replacement on hand for rental fleets, landscaping crews, or property maintenance teams to minimize downtime. Installation notes Confirm the saw requires an H345A passive disc wheel and match the model identifier 678. Inspect the clutch drum, bearings, and chain for wear when replacing the wheel to ensure performance. Follow the saw manufacturer recommended torque and installation procedure. This H345A passive disc transmission wheel is a functional replacement part intended to restore drivetrain operation for compatible chain saws.