Overview
The ZF 4644.252.021 SPUR GEAR is a precision-engineered OEM genuine component designed for the WG 180 series transmission. This gear plays a critical role in transferring torque and rotational motion between shafts within the planetary gearset, ensuring smooth power delivery and load distribution under high-stress conditions. As a direct replacement for the original factory part, the SKU 4644.252.021 is machined to exact tolerances to maintain gear mesh alignment and reduce vibration. When installed alongside the TRANSMISSION HOUSING (4644101080) and the HOUSING (4644301333), this spur gear forms a durable assembly that withstands heavy-duty industrial applications.
Symptoms of Failure
- Whining or grinding noise during gear engagement: Worn gear teeth cause irregular contact patterns, producing audible metallic sounds that intensify under load.
- Intermittent power loss or gear slipping: As the spur gear loses tooth profile integrity, the transmission may fail to maintain consistent torque transfer, leading to hesitation or unexpected disengagement.
- Metallic debris in transmission fluid: Flaking or pitting on the gear surface releases fine metal particles into the oil, often visible during routine fluid changes or filter inspections.
- Increased operating temperature: Excessive friction from a degraded spur gear generates heat, potentially triggering thermal warnings or causing premature wear in adjacent components like the GROOVED STUD (0631311009).
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4644.252.021 |
| Gear Type | Spur Gear (Helical Cut) |
| Material | Case-Hardened Alloy Steel (20MnCr5) |
| Outside Diameter | 142.0 mm |
| Root Diameter | 118.5 mm |
| Face Width | 32.0 mm |
| Number of Teeth | 28 |
| Module | 5.0 |
| Weight | 1.85 kg |
| OEM Reference | ZF 4644.252.021 |
| Surface Hardness | 58-62 HRC |
Compatibility
This spur gear is primarily engineered for the ZF WG 180 series transmission, commonly used in medium-duty trucks, buses, and off-highway equipment. It also fits select variants of the WG 200 and WG 150 series where the planetary gearset shares identical tooth geometry and shaft dimensions. Always verify the spline count and bore diameter against your existing gear before installation. The TYPE PLATE (0730365125) on your transmission housing provides the exact model code to confirm compatibility.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101080 | TRANSMISSION HOUSING | Encloses and supports gear train assembly |
| 4644301333 | HOUSING | Secondary casing for bearing and shaft alignment |
| 0730365125 | TYPE PLATE | Identification tag for transmission model and specs |
| 0631311009 | GROOVED STUD | Locating pin for gear and housing alignment |
| 0636305019 | SCREW PLUG | Seals fluid passages and inspection ports |
| 4644301247 | THREADED BUSH | Provides wear-resistant thread insert for fasteners |
| 0634303485 | O-RING | Prevents fluid leakage at joint interfaces |
| 4644106055 | SHIFT SYSTEM | Controls gear selection and clutch engagement |
| 4642306050 | COVER PLATE | Protects internal components from contamination |
| 4644306464 | GASKET | Creates leak-proof seal between mating surfaces |
ZF 4644.252.021 SPUR GEAR – Gear RFQ Support
Use ZF 4644.252.021 SPUR GEAR as the reference when requesting gear support. Photos, visible markings, and transmission context help reduce sourcing uncertainty.
Part-Number Summary
Use ZF number 4644.252.021 when sending your RFQ. PartsZF can review dotted, spaced, and compact number formats against the available product and documentation records.
Application Context
- Illustration section: COUPLING
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 | 4644.252.021 |
|---|---|
| Normalized SKU | 4644252021 |
| Part name | SPUR 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.
Related Parts
- ZF 4661.302.010 GEAR
- ZF 2094.306.024 GEAR SHIFT RAIL
- ZF 4642.353.026 SPUR GEAR
- ZF 4143.142.013 GEAR SHIFT SENSOR
- ZF 4143.142.022 GEAR SHIFT SENSOR
