Overview
The ZF 4108.006.028 PK 5300 is a genuine OEM hydraulic control valve assembly engineered specifically for heavy-duty powershift transmissions in construction machinery. This critical component regulates the flow and pressure of transmission fluid to engage and disengage individual clutch packs, enabling precise gear selection under high torque loads. Positioned within the valve body housing of the transmission, the PK 5300 variant is distinguished by its calibrated spool geometry and hardened steel sleeves, which ensure consistent shift quality even under extreme thermal stress. The SKU 4108.006.028 corresponds to a factory-sealed unit, guaranteeing exact OEM tolerances for direct bolt-on replacement without adaptation.
Symptoms of Failure
When the ZF 4108.006.028 PK 5300 begins to degrade, operators will notice distinct operational anomalies. Below are four specific failure indicators that signal imminent replacement is necessary:
- Erratic or delayed gear engagement: A worn spool or contaminated internal passages cause sluggish clutch application, resulting in a noticeable pause between selecting a gear and the machine moving. This is often reported as “transmission hesitation under load.”
- Internal hydraulic oil leakage past the valve: Deteriorated O-rings or micro-fractures in the valve body allow pressurized fluid to bypass, leading to a gradual drop in sump oil level without external drips. This manifests as “transmission slipping in forward gears.”
- Harsh or jarring shift shocks: If the pressure regulation spring loses temper or the spool sticks, clutch pack engagement becomes abrupt. Operators describe this as “hard upshifts when cold” or “bang shifting in reverse.”
- Intermittent loss of drive in specific ranges: A failing PK 5300 may cause one clutch pack to remain partially open, resulting in “no drive in second gear” or “transmission overheating during grading operations.”
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4108.006.028 |
| Product Designation | PK 5300 Hydraulic Control Valve |
| Overall Length | 215 mm (8.46 in) |
| Overall Width | 95 mm (3.74 in) |
| Overall Height | 110 mm (4.33 in) |
| Weight | 2.85 kg (6.28 lbs) |
| Body Material | High-tensile cast iron (GGG-40) |
| Spool Material | Case-hardened 20MnCr5 steel |
| Seal Material | Nitrile rubber (NBR) with PTFE backup rings |
| Maximum Operating Pressure | 25 bar (362 psi) |
| OEM Reference | ZF PK 5300 Series |
Compatibility
This genuine ZF 4108.006.028 PK 5300 valve is designed for use in the following ZF transmission families commonly found in wheel loaders, dozers, and excavators:
- ZF WG 180 (4-speed powershift, used in compact construction loaders)
- ZF WG 200 (5-speed heavy-duty, prevalent in mid-size articulated dump trucks)
- ZF WG 211 (6-speed with integrated torque converter, for large graders)
- ZF 4WG-200 (4-speed variant with modulated clutch control)
Always verify the transmission serial number against ZF’s official parts catalog before installation. The PK 5300 designation indicates a specific flow rate calibration that must match the original valve’s stamping.
