Product Description
Shimano 10HBH Idle Gear (RD15368)
The Shimano 10HBH Idle Gear (RD15368) is a critical internal component of the oscillation system in Shimano spinning reels. It acts as the "transmission" link between the Pinion Gear and the Oscillating Gear.
While the pinion gear turns the rotor, the 10HBH Idle Gear transfers a portion of that rotation to the oscillation gear, which then moves the spool up and down. This gear is essential for achieving the perfect line lay that Shimano is known for. Because it is usually made of high-strength polymer to ensure quiet operation and "sacrificial" protection of the metal gears, it can eventually wear down or strip if the reel is subjected to extreme loads or if the spool becomes jammed.
Product Specifications
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Part Name: Idle Gear / Intermediate Gear
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Part Number: 10HBH
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Shimano Code: RD15368
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Material: High-Impact Engineering Polymer
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Function: Transfers rotational force from the drive/pinion assembly to the oscillation system.
Compatibility & Fitment
The 10HBH (RD15368) is a common part found in several generations of Shimano's mid-range and popular spinning reels. It is a direct factory fit for the following series:
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Shimano Sedona: SE-2500FI, SE-C3000FI, SE-4000FI, SE-C5000XGFI
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Shimano Sahara: SH-2500FI, SH-C3000FI, SH-4000FI, SH-C5000XGFI
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Shimano Nexave: Fits various modern "FE" and "FI" variants.
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Shimano Catana: Fits select modern models (e.g., CAT-2500HGFI).
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Shimano Sienna: Fits select modern "FG" series models.
Key Features
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Low Friction Design: The polymer material is self-lubricating to a degree, ensuring the reel feels smooth and effortless during the retrieve.
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Noise Reduction: Unlike metal-on-metal gears, the 10HBH dampens mechanical vibration, making the reel operate more quietly.
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Precision Timing: The tooth count and pitch are precisely calculated to sync the spool's vertical speed with the rotor's rotation, preventing line "humps" or gaps.
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Corrosion Proof: Being non-metallic, this part cannot rust or seize, even if the reel is submerged in saltwater.
Maintenance & Troubleshooting
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Symptom of Failure: If the rotor spins but the spool does not move up and down, this gear is often the first thing to check. If the teeth are stripped, the mechanical connection to the spool is broken.
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The "Hitch": If you feel a "tick" or "bump" in the handle every few rotations, check the teeth of the 10HBH for a piece of debris or a single damaged tooth.
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Lubrication: When servicing, apply a light coat of Shimano DG06 (Ship Grease). Avoid using heavy, "tacky" greases that can increase resistance on these small, lightweight gears.
Pro Tip: During installation, ensure the Idle Gear Bushing (if your model uses one) is properly seated. If the gear sits at an angle, it will strip its teeth within a few minutes of use. You can view the full gear-train assembly in the PDF schematics at www.reelschematic.com.
