Hitachi Construction Machinery has expanded its Zaxis-7 wheeled excavator range with the addition of the ZX220W-7, the largest wheeled model in the series, aimed at utility trenching, road rehabilitation, and infrastructure maintenance applications that demand both tracked-machine productivity and road-legal mobility. Wheeled excavators have historically traded digging performance for mobility-their on-road travel speed comes at the cost of reduced traction on soft or uneven ground, limiting their usefulness on rough terrain where tracked machines dominate.
The ZX220W-7 addresses this tradeoff with the new "Wheel-Grip" intelligent traction system. The engineering breakthrough is the "Per-Axle Hydraulic Torque Vectoring." Instead of a single drive line to both axles, the machine features independent hydraulic circuits feeding each axle's drive motor, with a hydraulic limited-slip differential at each axle. When one wheel begins to lose traction (detected via rapid wheel-speed increase without corresponding ground speed), the ECU instantly reduces hydraulic flow to the slipping wheel's motor and redirects that flow to the traction-equipped wheels on the opposing axle. This torque vectoring effectively delivers tracked-machine traction on soft or uneven terrain while preserving the wheeled machine's superior on-road mobility.
The system integrates with the machine's "Intelligent Axle-Differential Lock" that engages the inter-axle differential lock automatically when the ECU detects extended slippage, allowing the machine to "lock all four wheels" for maximum traction when climbing out of soft soil. Furthermore, the ZX220W-7 features a "Suspension-Compensated Digging System" that hydraulically locks out the wheeled suspension during digging to prevent chassis rocking that would degrade digging accuracy, then automatically releases the suspension for travel mode. This intelligent suspension management, combined with the new Hitachi ZX220W-7's 22-ton operating weight and 5.9-meter dig depth, allows the machine to deliver true tracked-class productivity while maintaining road-legal mobility for utility contractors working across dispersed job sites.
