Overview
This OEM genuine ZF 4644.014.005 component is a critical hydraulic control element designed specifically for the WG 158 series transmission. Positioned within the valve body assembly, it regulates oil flow to the clutch packs and shift actuators, ensuring precise gear engagement under load. The SKU 4644.014.005 interfaces directly with the TRANSMISSION HOUSING and the SHIFT SYSTEM to maintain consistent hydraulic pressure during torque converter lockup and gear changes. As a genuine ZF part, it meets factory tolerances for durability in heavy-duty industrial applications.
Symptoms of Failure
- Erratic gear engagement or delayed shifts — When the 4644.014.005 wears, hydraulic pressure drops, causing hesitation when shifting from neutral to drive or between forward gears.
- Transmission fluid leaks near the valve body — A degraded seal or cracked bore in this part allows ATF to escape, often pooling under the bell housing area.
- Slipping under load or uphill — Insufficient clutch pack pressure due to a failing 4644.014.005 results in RPM flare without corresponding vehicle acceleration.
- Harsh or clunking shifts — Worn internal spools cause pressure spikes, leading to abrupt engagement that stresses the GEAR SHIFT HOUSING and driveline components.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4644.014.005 |
| Material | Hardened steel with nitrile sealing surfaces |
| Weight | 0.85 kg (1.87 lbs) |
| Length | 142 mm |
| Bore Diameter | 18.5 mm |
| Operating Pressure | 12–18 bar |
| Temperature Range | -30°C to +120°C |
| OEM Reference | ZF 4644.014.005 (WG158 series) |
Compatibility
This part is engineered for the ZF WG 158 transmission series, commonly found in municipal trucks, fire apparatus, and heavy construction vehicles. It also fits select variants of the WG 180 and WG 200 series when used with the appropriate SCREW-IN SLEEVE adapter. Always verify your transmission model suffix (e.g., WG158-5, WG158-6) before ordering. The 4644.014.005 is not backward-compatible with older WG 120 or WG 150 series without housing modifications.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101190 | TRANSMISSION HOUSING | Encloses gear train and valve body assembly |
| 4644159347 | SHIFT SYSTEM | Controls hydraulic flow to clutch packs |
| 4475280036 | SCREW-IN SLEEVE | Secures hydraulic line connections |
| 4644306511 | GEAR SHIFT HOUSING | Houses shift fork and selector mechanism |
| 4644306440 | PISTON | Applies pressure to clutch packs |
| 0635470104 | ROLLER | Reduces friction in shift linkage |
| 0730006344 | RING | Seals piston bore (size A) |
| 0730006345 | RING | Seals piston bore (size B) |
| 0730006346 | RING | Seals piston bore (size C) |
| 0730006347 | RING | Seals piston bore (size D) |
Frequently Asked Questions
Q: Can the 4644.014.005 be replaced without removing the transmission?
A: Yes, in most WG158 installations, the valve body cover can be accessed from the side of the transmission. However, you must first remove the GEAR SHIFT HOUSING to reach the retaining bolts. Always drain the fluid and replace the RING seals during reassembly.
Q: How do I confirm this part fits my WG158 transmission?
A: Check the stamped serial number on the TRANSMISSION HOUSING. If the suffix is WG158-4 or newer, the 4644.014.005 is a direct fit. For older units, you may need the SCREW-IN SLEEVE adapter kit.
Q: What causes premature failure of this valve component?
A: Contaminated transmission fluid with metal debris from worn clutch plates is the primary cause. Always inspect the SHIFT SYSTEM and replace the PISTON if scoring is visible.
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Phone: +86 158 2286 3467 |
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