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MINExpo 2016: Caterpillar develops operator assist system to electric rope shovels

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World Coal,

For mine operators, keeping an electric rope shovel in the bank is essential for optimum productivity and profitability. To assist operators with this, Caterpillar has developed the Operator Assist—Enhanced Motion Control system, which is standard on new 7495 Series shovels and available for certain Cat 7495 and Bucyrus 495 shovels in service.

The new software is designed to simplify machine operation, allowing the shovel to be operated in a manner that both promotes high production and protects the machine from inadvertent misuse. The new system can enhance production by reducing the occurrence of operating faults, such as crowd over-speeds and boom jacks.

Depending on the specific digging practices followed in the mine, the system can yield a number of benefits, including more reliable crowd rope replacement schedules, full design life for hoist ropes, reduced wear on crowd brakes and longer life for hoist gear case components. By controlling machine motions under certain conditions, the system reduces downtime for maintenance and repair. This translates to added production and lower cost per tonne – with a return on investment typically less than six months.

When developing the Operator Assist—Enhanced Motion Control system, Caterpillar engineers reviewed the operating habits of numerous operators of all skill levels. Based on this practical information, the new system addresses specific operating situations that could potentially jeopardise both the machine and the production schedule.

Hoist stall prevention: over-crowding the dipper and excessive loading can stall the dipper and place detrimental forces on hoist gear-case components. The Operator Assist—Enhanced Motion Control system monitors force and optimises crowd/retract commands in relation to hoist speed. Optimising the loading cycle reduces stress and wear on hoist system components.

Boom jack prevention: current in-service machines can crowd against the bank floor and lift the boom with the dipper handle. This triggers faults that adversely affect cycle times. The Operator Assist—Enhanced Motion Control system aims to prevent boom jacking by automatically adjusting hoist and crowd to maintain proper rope tension. With the new system, the operator will experience fewer digging interruptions.

Crowd impact prevention: a crowd impact occurs when the dipper hits the bank with high inertia, resulting in high crowd rope stresses. If the crowd motor continues to apply force in this situation, the crowd ropes are subjected to shock loading. The Operator Assist—Enhanced Motion Control system measures force on the crowd rope and automatically adjusts motor output to avoid shock loading, keeping the dipper in the bank with just the right amount of force. The net result is extended life for crowd ropes.

Crowd over-speed prevention: a crowd over-speed occurs when the commanded speed is exceeded and the brake automatically applies. This action interrupts the digging cycle and causes unnecessary wear on the crowd brake. The Operator Assist—Enhanced Motion Control system provides more braking power to prevent over-speed situations. This feature eliminates the need to de-rate crowd speed in near-vertical handle positions, unburdens the operator and improves crowd brake life.

In-bank swing prevention: when the operator attempts to swing the dipper through the bank, side-loading forces on the dipper can damage shovel components. The Operator Assist—Enhanced Motion Control system can determine dipper engagement and limit swing forces to avoid damage.

The Operator Assist—Enhanced Motion Control system is available for three 7495 machine classes: 7495 (ER601143 & up); 7495 HF (ER801136 & up); 7495 HD (ER701167 & up). The control system software update typically requires two hours.

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