Hard rock is no obstacle

Electrical switching & drive systems & components

2nd Quarter 2011 Electrical switching & drive systems & components

Astec Underground’s Trencor 1760, one of the world’s largest and most powerful trenchers, was fitted out with an intelligent Sauer-Danfoss system.

Whether digging a trench for a new gas or oil pipeline, or cutting through a limestone shelf or permafrost north of the Arctic Circle, it takes a machine of colossal power to do the job – a machine like the new Trencor 1760 chain trencher from Astec Underground. At 950 HP, the giant Trencor 1760 is built to dig trenches 2 metres wide and 8 metres deep, and dwarfs all other trenchers on the market. With a Sauer-Danfoss hydraulic and control system, it gives a performance to match its size.

In-house programming

The Trencor 1760 was the first of Astec Underground’s mechanical drive chain trenchers to have a Sauer-Danfoss PLUS+1 control system. Because PLUS+1 was already featured on a number of other machines in the company range, Astec Underground had its own trained PLUS+1 programmers to develop

customised controls using the software programming environment, PLUS+1 GUIDE. “Nothing comes close to PLUS+1,” said Claudio Verzilli, director of Engineering at Astec Underground. “Compared to other control systems, where you have to go back and forth to the supplier during programming, the ability to train our own engineers and do our own customised programming is a key feature. Our intention is to take the same control system down the line to our smaller machines.”

The PLUS+1 hardware used on the Trencor 1760 consisted of two MC50 microcontrollers, two DP600 graphic displays and three JS6000 joysticks. Like the displays and joysticks, the microcontrollers are located in the cab, securing them maximum protection from the rugged outdoors. Control signals to the machine functions were transmitted via CAN bus. Of the three joysticks, one was allocated to each of the two Caterpillar track drives. The third controlled the speed of the conveyor that carried rock and dirt out of the trench. Customised joystick buttons included left/right shift controls and a lockout switch that prevented involuntary conveyor movement.

Taking the load

Cutting through hard rock places big demands on the transmission system. Here, two Sauer-Danfoss Series 90 100ccm closed circuit axial piston variable pumps took the load, driven by one of the Trencor 1760’s two transmission power take off (PTO) shafts.

The other PTO drove the Series 90 100ccm pump that supplied flow to the large, robust OMT motor at each end of the conveyor. This PTO also distributed power to the auxiliary system, which elevated the boom and cab and powered the crumber and burn scrapers that kept the trench and trench sides clean. In addition, the Trencor 1760 had a Sauer-Danfoss Series 45 E-Frame 147ccm open circuit pump in the auxiliary system.

Impressive resilience

Verzilli described the sheer resilience of the Sauer-Danfoss components as impressive. “The biggest challenge to the hydraulic system is the high pressures on the track drives. Sometimes we push the pumps up to a pressure of 345 bar,” he said. “We expect components to perform under the most rigorous trenching conditions where it may be hot or cold, wet or dusty. So they have to be robust. Because the machines typically operate far from cities and service centres, they must also perform flawlessly.”

The self-diagnostic program integrated in the control system supported the consistently high functionality, reporting performance information to service technicians via the graphic displays.

Altogether the system reconfirmed all the reasons why Astec Underground has come to rely on Sauer-Danfoss as one of its main suppliers. “We chose a Sauer-Danfoss solution because of the quality, technical support and availability,” said Verzilli. “That commitment to us is behind our commitment to using Sauer-Danfoss products.”

For more information contact Ron Sheehan, Sauer-Danfoss Hydraulics, +27 (0)11 803 8390, [email protected], www.sauer-danfoss.com

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Electrical switching & drive systems & components

Hard rock is no obstacle

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