MOTORS AND DRIVES_proof 26/10/2016 09:43 Page 4
MOTORS AND DRIVES
time monitoring, and its modular design
simplifies installation and
maintenance. The innovative
system offers fast response
and precise control to reduce
conveyor chain wear and
The Cat HTD4100 High Torque Drive System will
start field trials in 2017
Hydraulic travel drives
failures, and the high-torque motors deliver
maximum torque independent of speed to
optimise production while minimising wear."
The new drive system consists of two main
components—a variable frequency converter 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, which Cat states is the most advanced
AC-drive control technology available.The
converter-controlled torque motor operates at low
speeds, between 0 and 300 rpm versus 1,500 rpm
for induction motors. Lower speed reduces inertia
acting on the output shaft by a factor of eight and
enables the system to react quickly, which
translates 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 1,250 kW (1,900 hp @ 60 Hz) with
maximum torque of 650,000 Nm (480,000 lb-ft).
“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% 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
soft start and stop, the HTD4100 delivers very
fast acceleration. The variable conveyor chain
speed can be efficiently adapted to the
production conditions - resulting in less wear on
the conveyor. The system also is about 5% more
efficient than conventional drives. The improved
system efficiency means lower energy
consumption and reduced cooling requirements.
Caterpillar also says it 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 1,600 kW
(400 hp to 2,100 hp). “Systems for additional
applications, such as longwall plough systems
and beam stage loaders, will follow.”
56 International Mining | NOVEMBER 2016
In the past year, Liebherr has extended its
components portfolio with electric travel drives
(FAT 325). The first drives have now been
successfully put into operation for a customer in
Austria and the solution was presented to the US
market at MINExpo 2016 in Las Vegas.
With the launch of the new FAT 325 in 2015,
Liebherr added an electric version to its hitherto
hydraulically operated travel drives. “On the one
hand, this development takes into account the
increasing demand for electrically powered
crawler-tracked vehicles. On the other hand, it
meets the demand for environm