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Changing the enormous tires on massive earthmoving vehicles is no easy trick. Tires on rims may weigh as much as 33,000 lb., which requires heavy lifting capacity combined with precise control. Servicing one machine with conventional tire-handling equipment can take up three maintenance bays, owing to its bulk.

Hedweld Engineering, based in Australia, set out to design a new tire handler with a narrow profile to reduce the space required for maintenance. The company also wanted it to have a low center of gravity to improve handling of the large, heavy tires. To achieve these goals, Hedweld engineers aimed to centralize hydraulics on the machine as much as they could to improve efficiency, simplify maintenance, and reduce overall complexity.

Fig. 1Previous models had many small manifolds located around the machine, requiring lots of interconnecting hose assemblies. The machines also required multiple controllers housed in waterproof enclosures mounted some distance away from the valves they controlled. This necessitated additional wiring running throughout the equipment.

Tackling the Task

In their pursuit of a better design and a more efficient, compact machine, Hedweld worked with its local Sun Hydraulics distributor, Custom Fluidpower, and its team of mechatronics engineers to specify, design, build, and provide the entire manipulator control system. Keeping the remote-controlled mobile hydraulics system light, compact, and easy to service while maintaining precise control required coordinating the design of mechanical, hydraulic, and electrical systems. A more efficient design and more highly integrated hydraulic system that fully leveraged Sun’s cartridge and electrohydraulics technology would be required to meet its goals.

Fig. 2In the new design, a large central manifold (shown) is mounted low in the machine to keep the center of gravity low. The integrated hydraulic circuit controls forward and reverse motion, steering, and leveling. Mounting the electronic controls directly to the hydraulic manifolds is key to minimizing the amount of hoses and wiring required.

The other three integrated packages on the tire handler manage the motion of the machine’s manipulator arms and safety locks. In all, the four packages incorporate 36 Sun proportional valves and multiple check valves.  Separate counterbalance valves are used with in-line manifolds mounted directly on the cylinders and wheel-hub motors for extra safety. Furthermore, aluminum manifold blocks, rated to 3000 psi, are used to reduce vehicle weight. They are stamped for easy part identification and anodized for corrosion protection.

The machine is controlled entirely by six High-Country Tek HCT DVC 710 controller modules that network to each other using the SAE J1939 digital standard to minimize wiring and ensure reliability.

For more information on cartridge valves, manifolds, electronics, and other products and services from Sun Hydraulics, Sarasota, Fla., call (941) 362-1200.

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This file type includes high resolution graphics and schematics when applicable.