Electrohydraulic Disruption: Part Two

Hydraulics Hold a Trump Card

Even as electric power transmission is proving to be cleaner and more efficient, and as electronic controls integrate with existing technologies, hydraulics remains unsurpassed when it comes to power density, pointed out Mitch Eichler, a business development manager at Parker Hannifin’s Motion Systems Group. “It’s hard to beat the power ratio of hydraulics,” he said. “High-force, high-demand applications still are largely done by hydraulic valves.”

The good characteristics need to be weighed against the bad in each application, Eichler said.

“In some applications, components are going more electromechanical for its motion control capabilities. But with all the energy that it consumes, it would be size- and cost-burdensome to drive everything this way.”

Electrohydraulic upgrades. Consider Caterpillar’s self-propelled Cat 651 Wheel Tractor Scraper (WTS). This new single engine was big news at CES earlier this year, and has re-entered the market with upgrades to the powertrain, controls, hydraulics and overall design.

Its single engine design features the Cat C18 engine powering the tractor with 469 kW (629 hp) and meets EU Stage V/U.S. EPA Tier 4 Final emission standards. Advanced Productivity Electronic Control System (APECS) fully integrates the transmission and engine drivetrain to provide smooth and responsive shifts. The scraper can load 104,000 lb of material in 30 sec. (In the U.S., the 651 scraper is usually tandem pushed by a D10-sized tractor for optimum payload and cycle times.)

Caterpillar noted that improvements to the hydraulics include an electrohydraulic implement system for improved multifunction capability and a short throw for the T-handle implement control. And, with a high-pressure steering system that requires significantly less steering effort—therefore reducing fatigue—efficiencies to the work cycle and operator experience have been enhanced.

Reference: Rehana Begg, Power&Motion. powermotiontech.com

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