Mine conveyors pose several hazards to
the safety of equipment, particularly on
long inclined and declined conveyors,
where the operation is mostly unmanned
due to its distance, terrain and profile.
With an increase in tonnages on declined
conveyors with several hundred meters
of drop, it is imperative to install an
intelligent soft-braking system to address
the starting and stopping requirements
under various load conditions.
In order to improve efficiencies and handle larger loads, mining
conveyors and their belts have grown in size. As the larger capacity
of inclined and declined conveyors with higher torques became
more common, it became critical to engage the conveyor brakes in a
gentler, controlled manner. Also, mine operators wanted the ability to
stop conveyors at a specific time, regardless of the load, to improve
optimization throughout the mine. A more sophisticated braking
control was required.
Very high levels of tension are applied to the conveyor structure
and the belt when trying to stop a high-speed, high-load conveyor.
These conveyors need to be stopped in a gradual, controlled way since
conveyor structures are not designed to support the kind of tension
caused by simply slamming on the brakes.
Competitive forces constantly challenge conveyor OEMs to
reduce costs. All conveyor system components including structure,
belts and rollers are scrutinized for maximum efficiency and
performance. It is important that braking systems are selected to meet
the specifications of each conveyor. This will ensure that the most
cost-effective brakes and controls are optimized to precisely match the
In response to industry needs, Svendborg Brakes introduced
the first generation of the popular SOBO
® (Soft Braking Option) controller in 1998. The revolutionary control provided smooth,
controlled braking on mining conveyors around the world. Over
the years, PWM (Pulse Width Modulation), PFM (Pulse Frequency
Modulation), and a combination of both methods, of the SOBO
controller were introduced. These models provided improved control
for low-torque/low-volume hydraulic brakes and reduced oil flow, an
important feature to achieve long controlled braking in case of power
The Next Generation
Today, mining conveyor OEMs are building even larger, more
complex conveyors that combine greater strength and capacity for
increased productivity. Mine operators are demanding braking systems
that are more intelligent, quicker and more user-friendly.
While some competitors are still offering controls based on older
technology, Svendborg Brakes recently introduced the new SOBO iQ
at the SME show in February 2015 to meet the latest market demands.
The innovative SOBO iQ system represents the latest technology
in braking, which includes brakes, hydraulics and the SOBO iQ
“The first version of SOBO was basically a black box that the
customer didn’t have to think about,” said Soren Holm, Svendborg
Area Sales Manager (Chile & Peru). “But today, mine operators need
and want to know what’s going on in every area of their facility.
The unique SOBO iQ soft-braking controller
provides a range of safety and durability
benefits in mining conveyor applications
The SOBO iQ empowers mine operators as it provides all conveyor
braking data online for easy access.”
The unique SOBO iQ soft-braking controller provides a range
of safety and durability benefits in mining conveyor applications.
Start up, deceleration, and the stopping of heavy conveyor loads is
critical, and controlled start up and braking is essential for a significant
reduction of torque peaks, preventing damage to the belt and
SOBO controls braking torque based on preset speed ramps and
actual speed and system pressure feedback. Different braking profiles
are provided for different scenarios. Advanced functions including
independent overspeed monitoring, rollback and gear monitoring are
integrated into the control box.
The SOBO soft-braking controller benefits and features include:
- Controlled braking independent of load and load position
- Braking on time or distance
- Adjustable brake ramp/curves
- Compensating for variable friction factors
- Controlled start-up
- Real-time monitoring of brake sequence time
- BUS communication with customer PLC
SOBO iQ Braking System Functions the Same as a VFD in Drives
SOBO iQ features a revolutionary dual-loop PI control (pressure/
speed) and an internal pressure control loop. Pressure control is not
only based on speed but also on deceleration. The control provides
only the torque needed for a safe, controlled stop. Units have three-
state digital modulation – never used in a braking system before.
Each controller can accommodate up to 4 HPUs with defined torque
sharing. Other features include full BUS-based communication with
the master control system. Remote access and touchscreen for setup
and monitoring are also available.
“The SOBO iQ controller offers customers enhanced functional
flexibility,” according to Robin Schmidt, Svendborg Application
Specialist (North America). “It can be used as a backstop, a dynamic
brake and a parking brake all incorporated in the same system.
Users can get signal feedback for all the braking system functions.”
The control utilizes different communication ties plus different
communication protocols. Users can easily access and change the
parameters inside the control, such as defining a parking sequence or
pre-setting a stop time.
Jan Mikyska, a Svendborg engineer who helped develop the
SOBO iQ explained, “Control flexibility also means we can stop the
conveyor – no matter if it’s fully loaded or empty – in the same time
or distance, depending on what the customer needs. We simply add ‘S’
curves with specific desired braking profiles.”
“For example,” he said. “When you want to stop your car,
you apply hard pressure to the brake pedal. When the car is almost
stopped, you begin lifting your foot. We can apply the same kind of
curve to the SOBO system.”
SOBO iQ units have three-state digital
modulation – never used in a braking
system before. Each controller can
accommodate up to 4 HPUs with defined
torque sharing. Other features include full
BUS-based communication with the master
So when the conveyor is almost stopped, less braking force is utilized.
Or, a two-stage mode can be inserted to put the same pressure onto
the stops. It depends on the situation, whether its a normal stop or an
emergency, but in all cases the conveyor can be stopped in a smooth,
The SOBO system is also capable of providing additional
dynamic braking functionality. For example, in a situation where the
motor VFD loses control of the conveyor due to material overload,
causing the conveyor to accelerate beyond its normal running speed,
the SOBO can be setup to send an overspeed alarm to the main PLC.
The main PLC then decides whether a full SOBO stopping ramp
should be initiated or if it is preferred to just bring the conveyor speed
back to normal running speed again (in this case, the brakes will be
programmed to automatically release when normal speed is reached
and let the conveyor continue to run).
SOBO Control vs. Proportional Control
Proportional controls utilize proportional valves which generally
work fine but are typically more expensive. The biggest disadvantage
of proportional valves, however, is they require quite a bit of oil
volume as the braking system needs constant motor and pump feeds
in an emergency situation. Or, very large accumulators are required
to keep feeding oil into the proportional valve during an emergency
braking event. A very large UPS system and battery back-up system is
required to power the pumps and the motors in order to maintain the
large oil flow.
In contrast, the more cost-effective SOBO controller requires
much less oil, eliminating the need for extra pumps and/or
accumulators. A very small power source (the size of a motorcycle
battery) is all that’s needed to support the stand-alone, maintenance-
free SOBO system. Minimal energy and oil requirements, combined
with extensive electronic features provide solid advantages to SOBO
Experience and Service Makes the Difference
Remote access and touchscreen for
setup and monitoring. The control utilizes
different communication ties plus different
communication protocols. Users can easily
access and change the parameters inside
the control, such as defining a parking
sequence or pre-setting a stop time
Svendborg has a very large number of SOBO systems installed
on mine conveyors around the world which provides a huge database
of how mining conveyors should work in different situations. All
this data is used when a new control system is installed. Similar
competitor control manufacturers don’t have the level of experience
and performance data to guide the design and setup of new conveyor
Svendborg’s technology leadership with control braking systems
plus their teams of on-staff dedicated service technicians located in all
the major mining centers are unmatched in the industry.
SOBO control and braking systems are installed on most of
the world’s largest incline and decline mining conveyors in Europe,
Chile, Peru, Mexico, North America, South Africa and Australia.
Svendborg’s SOBO brand is known for outstanding performance in the
field and is well recognized and trusted by all global mine conveyor
OEMs and consultants.
A full line of Svendborg hydraulic brakes are offered to meet
the specific motor size and torque requirements of all types of mine
conveyor applications. A series of smaller calipers is available for use
on the high-speed (low-torque) side of the conveyor drive shaft, while
a full selection of larger caliper models is available for mounting to the
All Svendborg power units are designed
and manufactured in-house to ensure
compatibility with other Svendborg braking
system components. Units are equipped to
monitor oil level and temperature, motor and
pump function, and system pressure.
Svendborg also offers a broad range of specialized hydraulic
power units, custom-engineered to meet any mining conveyor
requirement. Unlike many competitors, all Svendborg power units
are designed and manufactured in-house to ensure compatibility with
other Svendborg braking system components. In order to minimize
downtime, the units are equipped to monitor oil level and temperature,
motor and pump function, and system pressure to immediately identify
any failure and, thereby, prevent further damage.
Custom-designed Svendborg hydraulic power unit features
include fast braking and retraction time, brake on/off indicator,
redundant motor/pumps and valve blocks, accumulator monitoring,
and smooth operation in cold climatic conditions – as low as
Svendborg’s ability to design complete packaged braking
solutions including the state-of-the-art SOBO iQ controller, a wide
range of long-lasting brakes, custom hydraulic power units, and other
quality components makes them a leading expert in the mine conveyor
industry. Extensive support provided by an unmatched global network
of local service centers makes Svendborg a preferred choice for mine
Conveyor OEMs and consultants have grown to trust Svendborg
as a true engineering partner. When called in early on a project, the
Svendborg team can provide useful information and recommendations.
For example, instead of positioning a brake disc between the gearbox
and the pulley, which would require a coupling, it might be suggested
that the disc be installed on the other side of the pulley, using a hub
instead of a coupling, which would save two-thirds of the cost.
While initial system costs are scrutinized, end users continue to
focus on the total cost of ownership when considering their conveyor
braking systems. Svendborg systems might cost slightly more for
the initial installation. However, downtime will be eliminated or
significantly reduced because Svendborg technicians can typically be
on-site within five to ten hours, whereas a competitive vendor may
take three times as long and they may not speak the local language.
Svendborg application specialists utilize heat calculators when
reviewing a conveyor braking application. The economical aspect
of how much heat the discs and pads can handle is analyzed. For
example, if a customer has specified a single brake disc but the
calculator shows that too much heat will be generated, he will be
advised that two discs likely will be required.
One other money-saving recommendation that may be
considered is brake type standardization. While it might cost
slightly more initially to specify the same brake models on two
different conveyors within a facility, there may be significant savings
achieved through standardization of parts and by making it easier for
maintenance teams to become familiar with only one brake type.
Braking Systems with SOBO® Controllers Installed on Copper Mine Conveyors in Chile
Svendborg was recently selected by a major mine conveyor
OEM to supply complete braking systems for use on a series of
three downhill in-line conveyors at a large copper mine in Chile.
Two of the conveyors are 1600 m (1 mile) long and another is
700 m (.4 mile) long.
While this particular conveyor application may be
considered challenging by competitors, providing a custom
packaged solution to meet the unique requirements was fairly
routine for the Svendborg team.
The copper mine conveyors can transport 5,000 tonnes/
hour with a belt speed of 5.5 m/s (12.3 mph). The braking
systems provide emergency stopping and parking functions.
Each conveyor braking system consists of two model BSFH 520
caliper disc brakes, a SOBO controller, a hydraulic power unit
The spring-applied, hydraulically-released BSFH 520
brakes act on a 1.6 m (5.2 ft.) diameter disc mounted on the low-
speed side of the drive shaft. The brake system provides up to
134,354 ft.lbs. (182,160 Nm) nominal braking torque to stop the
conveyor in a controlled manner over a 50-second time period.
Svendborg’s unique SOBO soft-braking controllers
provide a range of safety and durability benefits in mine
conveyor applications. Deceleration and the stopping of heavy
conveyor loads is critical, and controlled braking is essential for
a significant reduction of torque peaks, preventing damage to
the belt and mechanical components. Manufactured in-house,
Svendborg’s custom hydraulic power units are engineered to
meet any mining requirement. In order to minimize downtime,
the braking systems are equipped to monitor oil level and
temperature, motor and pump function, and operational pressure.
The three SOBO controllers allow the customer to give a
brake command to each conveyor brake system at the same time,
or they can program a delay if desired. In this case, they give the
same brake command at the same time for the three conveyors.
The brake control can be set up with three to four different
stopping ramp programs.
In many bigger mines the energy generated by a large
downhill conveyor (easily 2,000 kilowatts per hour) can power
the entire mine with electricity. Most mines are in remote
locations, and they require electricity to run the conveyor VFDs.
If power is cut at the mine, the VFD stops running and the
braking system has to stop the conveyor. So, in the event of a
power loss, brake Ramp 1 will automatically be applied. Brake
Ramp 1 is always defined as an emergency, worst case scenario.
A power loss stopping Ramp 1 might be set for 40 seconds.
Brake Ramp 2 is for normal braking and might be
programmed for 60 seconds. Typically, the motor VFD can
slow the conveyer to a couple RPMs. At that point, the braking
sequence will be applied at approximately 5% to take over the
final stop, and then the parking brakes will be applied to hold the
conveyor in the locked, secured position when the conveyor is
A large copper mine in Chile utilizes a series
of three downhill in-line conveyors. Two of the
conveyors are 1600 m (1 mile) long and the
third is 700 m (.4 mile) long. The conveyors
can transport 5,000 tonnes/hour with a belt
speed of 5.5 m/s (12.3 mph).
Spring-applied, hydraulically-released BSFH
520 brakes act on a 1.6 m (5.2 ft.) diameter
disc mounted on the low-speed side of the
drive shaft. The brake system provides up to
134,354 ft.lbs. (182,160 Nm) nominal braking
torque to stop the conveyor in a controlled
manner over a 50-second time period.
Each conveyor braking system consists
of two model BSFH 520 caliper disc brakes,
a SOBO controller, a hydraulic power unit
Braking Systems with SOBO® iQ Controllers Installed on Coal Mine Conveyor in Czech Republic
Svendborg supplied a complete braking system for use on
an overland conveyor at a large coal mine in Tusimice, Czech
Republic. The 1800 mm (71 in.) belt conveyor is 900 m
(.55 mile) long and powered by three 500kW drives.
The opencast coal mine conveyor transports overburden
at a rate of 3,000 tonnes/hour with a belt speed of 4.5 m/s. The
braking system, consisting of eight model BSFI 320 caliper
disc brakes, a SOBO iQ controller and two hydraulic power
units, provides emergency stopping and parking functions.
The spring-applied, hydraulically-released BSFI 320
brakes act on a 0.8 m (2.6 ft.) diameter disc mounted on the
high-speed side of the drive. The brake system can provide
60 kNm of torque max. and allow for controlled braking up to
50-seconds in case of a power failure.
The braking system, consisting of eight model BSFI
320 caliper disc brakes, a SOBO iQ controller and two
hydraulic power units.
A 900 m (.55 mile) long overland conveyor,
powered by three 500kW drives, installed at a
large coal mine in Tusimice, Czech Republic.
Spring-applied, hydraulically-released BSFI
320 brakes act on a 0.8 m (2.6 ft.) diameter
disc mounted between the electric drive
motor and the gearbox on the high-speed
side of the drive. The brake system can
provide 60 kNm of torque max. and allow for
controlled braking up to 50-seconds in case
of a power failure.