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Bringing a new level of control to hydraulic systems

With over 20 years in the industry, Norrhydro has seen its hydraulic cylinders incorporated into everything from ships and harbour installations to forest, mining, and industrial equipment. Recent R&D work has opened up the potential for a major step forward in the world’s most widely used form of power transmission in mobile industrial machinery and ships.

Norrhydro manufacturers tens of thousands of cylinders a year, ranging in size from 25 mm to 450 mm across, with strokes up to 6,000 mm, and capable of operating at pressures up to 500 bar. In addition to standard products, Norrhydro supplies customised designs when an off-the-shelf product will not do.

Many leading manufacturers of heavy-duty machinery rely on the strength and durability of Norrhydro’s hydraulic cylinders for forest machinery, container and material handling equipment, rammers, mobile crushers, mining drills, and agricultural machinery. The ability to withstand the corrosive conditions of life at sea has seen the company’s products carve out a strong market for themselves in products such as ship cranes, steering gear, hatches, and propulsion systems. While back on dry land, large numbers of paper machines, sawmill equipment, and mining systems also depend on Norrhydro products.

Going to the next level

Following a change of ownership a couple of years ago, Norrhydro embarked on a programme of intense R&D. Working with the University of Tampere’s Institute of Hydraulics and Automation, one of Europe’s leading centres of research in the field, the company concentrated on looking at what digital know-how had to offer hydraulic system control.

This work has borne fruit in a raft of patent applications and a breakthrough innovation that brings the engineer’s dream of a hydraulic cylinder with an adjustable piston area to life. Norrdigi – as the technology for secondary-controlled multi-chamber actuators is known – makes it possible to control the movement of hydraulic actuators by changing their effective force area ‘on the fly’ and looks set to bring a new level of energy efficiency and fault tolerance to the hydraulic systems used in power transmission.

While Norrdigi still requires valves, these are of the simple on/off type and are not compromised by energy losses. Thanks to the use of constant pressure systems and throttleless digital force control, Norrdigi can achieve 70-80% lower losses compared to systems currently in use. It also offers enhanced controllability and fault tolerance, a simpler and more cost-efficient design, and a lower total power requirement.

In theory, replacing all the hydraulic systems in current machinery with NorrDigi technology would save the equivalent of the output of 500 medium-sized power stations. As just one heavyduty earth-moving machine uses as much fuel as 40–50 cars, it is easy to see how CO2 emissions would benefit as well.

Norrhydro’s breakthrough in discretely variable piston area and multi-chamber cylinder design opens up the potential for practically zero throttling loss, significantly lower energy losses compared to conventional proportional valves, and excellent controllability.
> Yrjö Trög
(Published in HighTech Finland 2010)