Danfoss Digital Displacement® Excavator: Test Results and Analysis

There is a long trend in off-highway vehicles toward higher energy efficiency and electro-hydraulic control. Digital pumps and motors are poised to become a significant enabling technology in this trend. This paper analyzes a 20-tonne tracked excavator that was equipped with digital displacement pumps and evaluated for efficiency and productivity. Previous research by Artemis Intelligent Power demonstrated improvements compared to a conventional, negative flow control excavator hydraulic system. With support from Artemis, the Danfoss Digital Displacement Excavator (DDE) is a step forward in terms of technology and commercial readiness. DDE is based on a CAT 320 next-generation excavator with completely electronic controls and advanced sensor and operator-assistance features. In before/after testing, DDE showed 15% higher productivity (in meters of trench per hour) and 13% higher efficiency (in meters per liter of fuel) for a trench digging cycle. Static pump efficiency is only part of the story; dynamic response and controllability contributed to the measured performance gains. Potential causes for variation in measurement were analyzed including operator variation, flow variation, and machine response.