ZF Gearbox Gear 4644 353 020 — OEM Transmission Component for 4WG200 / 6WG200 Powershift Gearboxes

This gear (part number 4644 353 020) is an OEM ZF transmission component for the 4WG200 and 6WG200 series powershift gearboxes used in wheel loaders, motor graders, and other heavy construction equipment. The ZF 4WG200/6WG200 is a fully powershifted, countershaft-type transmission with 4 or 6 forward speeds and 3 reverse speeds, capable of handling input torques up to 1,200 N·m — making it the transmission of choice for machines like the LiuGong 856H wheel loader and XCMG GR series graders. This gear is manufactured from case-hardened 18CrNiMo7-6 alloy steel (ZF specification ZF-21) with a surface hardness of HRC 60-62 and a case depth of 1.0-1.4mm after carburizing and quenching, meeting ZF’s proprietary tooth profile standard that differs from DIN 3960 by incorporating an asymmetric tip relief of 15-20 microns — this reduces gear mesh impact noise by approximately 5 dB during clutch-to-clutch powershifts at full load.

Gear replacement in a ZF 4WG200/6WG200 transmission requires specialized tooling for the transmission disassembly, including a hydraulic press with a minimum 20-ton capacity for gear removal from the intermediate shaft. Before pressing off the old gear, the shaft must be heated uniformly to 150-180°C using an induction heater — cold-pressing a gear off a ZF shaft will gall the shaft journal and render the shaft unserviceable. The new gear must be heated to 150°C and pressed onto the shaft in one continuous motion; stopping mid-press will cause the gear to seize due to thermal transfer cooling the shaft. After installation, the gear-to-mating-gear backlash must be checked with a dial indicator on the pitch circle — ZF specification is 0.10-0.18mm for the 4WG200 and 0.12-0.20mm for the 6WG200. Common failure symptoms: a rhythmic “thumping” noise in 2nd gear that changes frequency with transmission output speed (single-tooth spalling on the gear), metal particles in the transmission oil filter with a bright, flake-like appearance (case-hardened surface fatigue), and transmission dropping out of gear under load with a loud bang (gear tooth fracture from overload).

This gear fits ZF 4WG200 and 6WG200 powershift transmissions. Verify part number 4644 353 020 on your ZF transmission parts catalog before ordering. For related ZF transmission components, contact our sales team with your part numbers.

Technical Specifications

• Part Number: 4644 353 020
• Transmission: ZF 4WG200 / 6WG200 Powershift
• Material: 18CrNiMo7-6 (ZF-21 Spec), Case-Hardened
• Surface Hardness: HRC 60-62
• Case Depth: 1.0-1.4mm (Carburized & Quenched)
• Application: Wheel Loaders, Motor Graders

Compatible Machines

Each gear is inspected for tooth profile accuracy and case depth, packed in rust-preventive packaging, and ships within 1-2 business days. 12-month warranty. Browse our Forklift Hydraulic Transmission catalog.