Hydraulic technologies play an increasingly important role in our lives. Ranked per capita, Sweden is one of the leading users of such technology for industrial applications.
For most people, the excavator or backhoe is the epitome of hydraulic technology that transforms diesel power into propulsion and excavation muscle. Modern hydraulics are also used in forestry machinery, trucks, brake systems, aircraft, farm machinery, cranes, machines for plastic injection molding, machine tools, paper machines, wheel loaders, industrial presses and many other applications.
Globally, Swedish industry is advanced in hydraulics usage in excavators, forestry machines and drilling. There are also a variety of companies that manufacture hydraulic components or tools where the hydraulic system is a key technology.
Revolutionary hydraulic system
The potential for energy efficiency in hydraulic systems is large. Research in the field of “Innovative Green Hydraulics” is growing in Sweden. There are many examples where hydraulics offer environmental benefits and RunWise®, used in garbage trucks, is one such technology.
“With RunWise®, hydraulic and mechanical drive elements interact in a revolutionary new way. The result is reduced fuel consumption, lower emissions of carbon dioxide, less wear and tear on the brakes, smoother operation and lower operating costs,” says Bengt Andersson,
Product Sales Manager Hydraulics, at Parker Hannifin.
“An ordinary garbage truck consumes more than 30,000 liters of fuel in a year. RunWise® reduces fuel consumption by an order of 35-50 percent, depending on the route and operating conditions, averaging about 43 percent. RunWise® also reduces carbon emissions by up to 48 tons per unit per year.”
What is RunWise®?
“RunWise® is an advanced hydraulic hybrid drive system for trucks that replaces a conventional vehicle’s drive train. The system consists of a hydrostatic drive used in an urban environment for the collection of waste and a separate mechanical drive that provides efficient driving at higher speeds. By combining hydraulic components and advanced control processes with technologies for braking energy recovery, more than 70 percent of the vehicle’s braking energy can be recovered. This is energy that would otherwise be lost,” says Andersson.
“No other alternative fuel technology for trucks gives similar performance, fuel savings and reduced environmental impact. In an urban environment, the system provides reduced noise, which is also advantageous. For the vehicle owner, braking energy recovery reduces brake pad replacement intervals saving both money and the environment. The hydrostatic drive provides smooth and faster speeds –allowing the driver to save on driving time.”
“The hydraulic pumps/motors are produced at Parker’s factory in Trollhättan. The electronic control system IQAN is developed at Parker in Mölnlycke. Other components are manufactured at Parker’s facilities in the US and Europe,” concludes Andersson.
How it works. RunWise® on a garbage truck
The drive has three gears and two modes of operation – hydraulic and mechanical. Mechanical operation is intended for highway driving. Hydraulic operation meanwhile pumps fluid through a secondary pump/motor to achieve high speeds of 35-65 km/h, and low speeds 0-35 km/h. The switch is also provided with a coupling for direct drive. This provides better efficiency at speeds up to about 100 km/h.
When the driver presses the brake, a signal is sent based on the pedal pressure to the pump/motor and pneumatic brake. The action maximizes the recovery of braking energy. The two secondary pumps/motors receive a signal to operate as a pump to help slow the vehicle and pump hydraulic fluid back to the accumulators.
Collecting garbage requires driving many short distances during a shift. The cycle between running and braking can therefore be repeated a few thousand times in a single day. However, this is not a disadvantage since many starts and stops provide efficient use of the RunWise® system. For vehicle owners, this translates into less fuel consumption and brake wear.
This article was published in April 2015