Description
Overview:
This gear housing is a genuine Stihl replacement part for the drive head of the HSA 66 and HSA 86 cordless hedge trimmers. It is a robust metal alloy casing that encloses and supports the internal gearing and bearings, keeping the mechanism aligned, protected, and correctly sealed. Replacing a damaged or worn housing restores the trimmer's smooth blade drive, reduces vibration, and helps retain grease where it should be. Designed to Stihl's original specifications, it provides a precise fit on the specified models and maintains the correct mounting geometry for reliable operation. Use it to bring your hedge trimmer back to dependable service after impacts, cracked casings, or stripped threads that compromise performance or sealing.
Key Features:
- Genuine Stihl part for assured compatibility and performance (part ref: 4851 640 0501)
- Durable metal alloy construction for strength and long service life
- Accurate mounting faces help maintain gear alignment and blade timing
- Protects internal gearing from dust and moisture to preserve lubrication
- Direct-fit for HSA 66 and HSA 86 with OEM dimensions and fastener positions
- Ideal when the original housing is cracked, distorted, or has damaged threads
- Supports smooth, low-vibration cutter bar drive and consistent cutting results
- Install with basic hand tools; follow Stihl service guidance and torque settings
Typical Applications:
Used during repairs of Stihl cordless hedge trimmers when the gear head casing is cracked from impact, threads are stripped, or sealing faces are worn. Suitable for restoring correct gearbox alignment, reducing noise or heat from misalignment, and preventing grease loss for reliable day-to-day trimming.
Also known as:
Gear case, gearbox housing, gear cover, drive head housing, transmission case, cutter head casing, trimmer gear casing, gearhead cover.
Fits Models:
HSA 66, HSA 86
Alternate Part Numbers:
4851-640-0501, 48516400501
