×
Description
4243 640 0509 STIHL Gear Housing (0°, 500 mm) – Genuine OEM Gear Head Part
The STIHL Gear Housing (0°, 500 mm) (4243 640 0509) is a genuine OEM gearbox casing component designed for select STIHL long-reach hedge trimmers and KombiSystem hedge trimmer attachments. This gear housing forms the protective outer body of the 0° gear head assembly, supporting internal gears, bearings, and lubrication required for smooth blade drive operation.
Over time, gear housings can become damaged due to impact, excessive vibration, wear, or contamination from debris and grease leaks. A cracked or worn housing may lead to misalignment, lubricant loss, overheating, or premature gearbox failure. Replacing it with the correct OEM part restores proper gear head integrity without replacing the entire attachment system.
Manufactured to STIHL factory specifications, this genuine gear housing ensures precise fitment, secure sealing, and long-term durability under demanding professional trimming conditions.
Product Details
OEM Part Number: 4243 640 0509
Brand: STIHL (Genuine OEM)
Part Type: Gear Housing / Gear Head Casing
Configuration: 0° Gear Head, 500 mm
Application: Blade drive gearbox assembly
Condition: New Genuine OEM Part
Function
This STIHL gear housing is designed to:
-
Enclose and protect internal gear head components
-
Maintain proper alignment of gears and bearings
-
Retain gearbox lubrication for smooth blade drive operation
-
Replace cracked, damaged, or worn gear housings
-
Restore long-term gearbox durability and performance
⚠️ A damaged gear housing can cause grease leakage, gear misalignment, or gearbox failure.
Verify Fitment (Recommended)
Before ordering, confirm:
-
OEM part number 4243 640 0509
-
Gear head configuration (0°, 500 mm)
-
Your unit model matches those listed below
-
Application matches your STIHL illustrated parts diagram
⚠️ Gear head housings are model-specific — always verify by OEM part number and attachment configuration.
Compatibility
This OEM gear housing fits select STIHL hedge trimmer attachments equipped with 0° gear head assemblies (500 mm), including:
Kombi / Long-Reach Hedge Trimmer Attachments
HL-KM (Gear head 0° 500 mm)
HL-KM 0° (Gear head 0° 500 mm)
HL 0° (Gear head 0° 500 mm)
HL 56 K (Gear head 0° 500 mm)
(Exact fitment depends on production version — always verify using OEM parts diagram.)
Installation Notes
-
Disconnect spark plug before servicing
-
Remove cutter bar and access gear head assembly
-
Drain and clean gearbox area if grease leakage is present
-
Disassemble gear head carefully on a clean surface
-
Transfer internal gears, bearings, and seals as required
-
Install new gear housing and reassemble to STIHL specifications
-
Repack gearbox with STIHL-approved grease
-
Test blade drive for smooth operation
⚠️ Gearbox rebuilding should be performed by a qualified technician to ensure correct alignment and lubrication.
Maintenance Tips
-
Inspect gear head housing regularly for cracks or grease leaks
-
Maintain proper gearbox lubrication intervals
-
Avoid impact with hard objects during trimming
-
Replace worn seals promptly to prevent contamination
-
Always use genuine STIHL OEM gear head components for correct fit and durability


