Overview
The ZF 4108.303.307 SUN GEAR is a critical planetary component engineered for the WG100, WG130, and WG131 transmission series. As the central gear in the planetary gearset, it transfers torque directly from the input shaft to the planetary pinions, enabling smooth ratio changes under load. This OEM genuine part (SKU: 4108.303.307) is precision-machined to maintain exact tooth geometry and axial clearance. It sits within the main housing assembly, working in concert with the 4108101151: HOUSING to ensure concentric rotation. The sun gear also interfaces with the 0501211695: MOTOR drive shaft, making its integrity vital for consistent power delivery in heavy-duty industrial applications.
Symptoms of Failure
- Whining or growling noise during acceleration – Worn sun gear teeth create irregular contact patterns, producing a distinct high-pitched whine that intensifies under load.
- Erratic gear engagement or delayed shifting – A damaged sun gear causes planetary gearset binding, leading to hesitation when shifting between forward and reverse ranges.
- Metallic debris in transmission fluid – Flaking or pitting on the sun gear’s tooth flanks sheds fine metal particles, often visible during fluid drain inspections.
- Loss of torque in higher gears – When the sun gear’s splines strip, the transmission fails to hold ratio, resulting in a noticeable drop in pulling power during operation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4108.303.307 |
| Material | Case-hardened alloy steel (20MnCr5 equivalent) |
| Outer Diameter | 98.5 mm |
| Inner Spline Diameter | 42.0 mm |
| Tooth Count | 24 teeth (involute profile) |
| Weight | 1.85 kg |
| Surface Hardness | 58–62 HRC |
| OEM Reference | ZF 4108.303.307 |
Compatibility
This sun gear is specifically designed for ZF’s WG-series powershift transmissions. It is a direct fit for the WG100, WG130, and WG131 models commonly used in forklifts, telehandlers, and construction machinery. While it shares tooth geometry with the WG180 and WG200 series, those models require a different sun gear due to variations in shaft diameter. Always verify your transmission’s serial number before ordering. The gear must be installed with a new 0501314793: COVER and 0501314799: BUSH to maintain proper preload and lubrication channels.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101151 | HOUSING | Encloses planetary gearset and supports sun gear shaft |
| 0501211695 | MOTOR | Hydraulic drive unit that powers the sun gear input |
| 0501314793 | COVER | Seals the gear cavity and retains lubrication |
| 0501314799 | BUSH | Wear sleeve for sun gear pilot bearing surface |
| 0735370299 | TAPERED ROLLER BEARING | Supports axial and radial loads on the sun gear shaft |
| 0501317874 | HOUSING | Secondary housing for planetary carrier assembly |
| 0501317875 | ROLLER | Needle roller for planetary pinion rotation |
| 0501209497 | PISTON | Hydraulic clutch piston that engages the sun gear |
| 0501317876 | COMPRESSION SPRING | Returns piston after clutch disengagement |
| 0501314823 | BUSH | Guide bushing for sun gear thrust washer |
ZF 4108.303.307 SUN GEAR – Gear RFQ Support
ZF 4108.303.307 SUN GEAR is handled as a gear-train sourcing item for transmission repair teams. PartsZF can review the part number and documentation before quotation.
Part-Number Summary
Use ZF number 4108.303.307 when sending your RFQ. PartsZF can review dotted, spaced, and compact number formats against the available product and documentation records.
Application Context
- Illustration section: OUTPUT
Cross Reference Support
If you have an OEM number, old supplier number, or visible marking, include it with your RFQ so PartsZF can compare it with the available records.
Specification Snapshot
| ZF part number | 4108.303.307 |
|---|---|
| Normalized SKU | 4108303307 |
| Part name | SUN GEAR |
| Product category | gear |
| RFQ support | Part-number lookup and documentation review |
| Media support | Product photo or diagram review when available |
Image and Documentation Notes
Current product media status: fallback. Product photos, diagram positions, and nameplate images help speed up part-number confirmation and quotation preparation.
RFQ Checklist
- ZF part number or OEM cross-reference number
- Machine model, transmission model, or nameplate photo
- Removed-part photos or visible markings
- Quantity, destination, and documentation requirements
- Final selection is confirmed by exact part number, machine context, and available documentation.
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- ZF 4143.142.013 GEAR SHIFT SENSOR
- ZF 4143.142.022 GEAR SHIFT SENSOR
