Reducing the environmental impact of hydraulic systems

  • 06-Dec-2012 02:28 EST

Caterpillar remanufactures 67% of hydraulic system components such as hydraulic cylinders, pumps, motors, coolers, drive groups, and actuators, saving raw materials.

Hydraulic systems may contain large reservoirs of hydraulic fluids and oils. Their numerous hoses and connections can be prone to leaks that can result in environmental impact in work areas. Environmentally focused OEMs and vendors are developing new hydraulic systems, fluids, and components to save materials and energy and to reduce the environmental impact of off-highway equipment.

One of those companies is Texas Hydraulics Inc., an ISO 14001-certified custom hydraulic cylinder, swivel, and system manufacturer that developed a hydraulic actuator system that eliminates the need for hydraulic hoses and reduces the number of leak points and the potential for fluid leaks.

The EcoCyl integrates a cylinder, a valve manifold with speed, pressure, and directional controls, reservoir, and a pump motor power pack unit into a single device. Its efficient, self-contained design provides actuation with low pressure drops, making it suitable for use in operations that raise and lower loads remotely, in auxiliary circuits that raise or lower, lift, and steer a unit’s front wheels, provide leveling, and many other applications.

Some applications power the hydraulic pump motor with a small dc battery, ac power in stationary applications, and some run off of the equipment’s alternator, depending on whether it is a prime mover and what power is available.

“Applications that require hydraulics or actuation at the end of a boom or a ladder, or that have a long hydraulic hose run find this type of system most advantageous,” explained Brent Brown, Texas Hydraulics’ EcoCyl Product Development and Account Manager. Rather than have a separate hydraulic unit or add auxiliary circuits for a second hydraulic function, OEMs integrate the EcoCyl into their vehicles.

“The main advantage is that it is self-contained and plug-and-play. OEMs appreciate that this device reduces or eliminates the need for hoses, fittings, and other devices for moving fluids during assembly. Manufacturers simply pin the cylinder in place and power the control signals,” Brown said.

It is compatible with natural and synthetic biofluids as well as standard hydraulic fluids, and it offers OEMs a custom compact design that is efficient. “We fully customize the EcoCyl, stroke, bore, pumps, motor size, and hydraulic circuits. There are many advantages to the environment, efficiency, better battery life, and it is simpler with fewer parts. It is also easier to maintain, unpin, and unplug.”

It reduced 24 leak points down to zero on a cardboard baling application, and it reduced the number of leak points on a scissor-lift application by dozens more.

Texas Hydraulics has supplied mining, material handling, military, aerial work platform, and other off-highway industry OEMs since 1968, and it has provided this product for use in other industry applications for several years.

Brown says that Texas Hydraulics recently rolled it out to off-highway vehicle markets. “We see lots of potential for entering this space, since OEMs want fully customized systems in a kit form that are easier to assemble—bolt together, test, and ship.”

Consuming less energy with auto-adjusting valves

When hydraulic power is used to raise loads such as earth or building materials, counterbalance valves hydraulically lock the loads safely in place while they are suspended. After loads are deposited, the counterbalance valves need to be hydraulically powered open to bring implements back to ground level for the next load. The lighter the load coming down, the more hydraulic power is required as the motion is not weight-assisted. Powering the counterbalance valves and implements during the return down wastes energy.

Sun Hydraulics, a high-performance component manufacturer, recently released an energy-saving LoadMatch counterbalance valve that senses the load pressure and automatically adjusts the valve’s setting. These valves require less power to actuate and open than standard counterbalance valves.

LoadMatch counterbalance valves are simple hydromechanical systems that contain a grounding spring whose preload changes when the load pressure changes. This means less energy is needed during low-load conditions. Using these valves helps extend the runtime of battery-powered machinery and can reduce fuel consumption in equipment powered by internal-combustion engines.

According to David Herbert, Chief Engineer at Sun Hydraulics, this new, patented valve design is a unique approach to saving power during repetitive lift/lower operations. “Our approach addresses the new focus on energy savings by using the potential energy that is already stored in the system as a result of raising the load. No one else is promoting this type of solution.”

Herbert estimates that this valve saves around 25-55% of the base amount of horsepower used to drive the load down, but he says savings may vary. “Applications that raise a load from ground level and come down empty would benefit greatly, with the potential to save 40% of the energy consumed in that function.”

Several OEMs are using these valves in production and others are testing them for future applications. Their designs are targeted for use in off-highway vehicles such as telehandlers, cranes, excavators, winches, and other machines that raise heavy loads and lower light loads. High duty cycle applications will benefit the most from the LoadMatch valve’s energy-saving characteristics.

Developing better fluids

Caterpillar believes that targeted development of hydraulic fluids can reduce the environmental impact of a machine. Its approach is to develop and recommend fluids that increase the overall value and life of the machine while supporting Cat sustainability initiatives.

Cat’s fluids development activities continue on the path of its prior high-performance fluids and focus on properties that contribute to reducing the environmental impact from a life-cycle analysis basis: high performing, long drain intervals, and biodegradeable.

High-performance fluids, such as Cat’s HYDO Advanced fluids, offer enhanced anti-wear protection, enhanced protection against rust and corrosion, and improved filtration properties. These characteristics result in cleaner and longer-life hydraulic system components, which enable less raw material usage over a system’s lifetime.

Long drain-interval fluids, such as Cat’s HYDO Advanced SAE 10W and SAE 30 and Cat Bio HYDO Advanced, ranging from 3000 to 6000 h, decrease the total oil volume used throughout a machine’s life.

Cat’s Bio HYDO Advanced hydraulic fluid has a renewable content exceeding 90%. It complies with the European Eco label and is listed in the USDA BioPreferred Program. Its Bio HYDO Advanced oil can be used in any application, including any worksite that requires biodegradable products, such as work conducted near bodies of water and forestry.

Saving raw materials via remanufacturing

Another important industry practice worth mentioning is remanufacturing. It reduces waste and minimizes the need for raw materials to produce new parts.

Caterpillar formed a Remanufacturing and Components Division in 2005, demonstrating its commitment to sustainable development and growth. It is a world leader, annually remanufacturing 2 million components and recycling 148 million lb (67 million kg) of end-of-life components.

It remanufactures engines, fuel systems, machine systems, and components, including 67% of hydraulic system components such as hydraulic cylinders, pumps, motors, coolers, drive groups, and actuators.

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