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Cat develops new high torque longwall drive systems

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Caterpillar has unveiled new longwall armoured face conveyor high-torque drive systems at MINExpo.

The Cat HTD4100 enables a higher level of automation for enhanced speed and torque control and real-time monitoring, while its modular design simplifies installation and maintenance,” claims the manufacturer.

It offers fast response and accurate control to cut conveyor chain wear or failures.

The drive system consists of two main parts – a variable frequency convertor and the motor-gearbox combination.

“In the new Cat system, a medium voltage converter-controlled torque motor replaces the AC induction motor, the control principle of the drive is Direct Torque Control—the most advanced AC-drive control technology available,” Cat said.

The converter-controlled torque motor operates at low speeds of between 0 and 300 rpm versus 1500 rpm for induction motors.

This lower speed reduces inertia acting on the output shaft by eight times, enabling the system to react quickly, translating to little or no damage to the gearbox and chain in the event of a conveyor blockage. The installed motor power of the modular drive system is 1250 kW) with maximum torque of 650000 Nm.

The torque motor design reduces the need for as many gear stages, which enables the entire system to be simplified. This in turns allows smaller dimensions while retaining the same torque capabilities as systems that are as much as 20 per cent larger.

The smaller size allows flexibility in laying out longwall entries.

The system also has a reduced number of parts, which enhances reliability, and the components are standardised to simplify support of the system.

In addition to its soft start and stop, the drive system provides fast acceleration, and is reportedly five per cent more efficient than conventional drives, which translates into lower energy consumption and reduced cooling requirements.

Caterpillar will be able to configure the High Torque Drive System for retrofitting to existing longwall face conveyors. Plans call for supplying a range of High Torque Drive Systems to handle voltages of 3.3 kV or 4.16 kV in a mechanical power range of 300 kW to 1600 kW.

Systems for additional applications, such as longwall plow systems and beam stage loaders, will follow.

The system will begin field trials next year.

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