Most accidents on mining conveyors are caused by the stored energy in
the belt. If not properly protected, a loss of power at a mine can allow
loaded inclined conveyors to reverse direction, causing damage to expensive
equipment. With the resulting loss of productivity, it is no surprise that safe
conveyor operation is a major concern for mine owners and conveyor
system OEMs around the world.
Reverse rotation of conveyor belts can be prevented by installing a standard
backstop or a torque-limiting backstop. However, to allow the crew a safe
maintenance routine, a loaded conveyor belt needs to be slowly rotated
backwards to clear the belt.
RESPONSIVE INNOVATION
To address the problem, Stieber Clutch introduced a new series of torque
limiting/load sharing backstops with release functionality. The release
function allows the tension of a jammed belt to be carefully released using a
simple hydraulic pump to actuate the internal hydraulic cylinder.
The components, which offer the possibility to rotate backwards under load,
are fully bearing supported. The new torque limiting/load sharing backstops
are capable of performing as many reverse rotations as may be required
(within the limits of energy dissipation) to completely unload the conveyor
prior to maintenance work being carried out. This feature can significantly
reduce downtime and ensure that any loss of productivity is kept to a
minimum. When the oil pressure is released, the backstop is automatically
re-set to the original slipping torque.
UNIQUE ENGINEERED BACKSTOP SOLUTION
Stieber RDBR-E roller ramp type low-speed backstops
are externally mounted, self-contained on a shaft
extension with a torque arm. With an internal torque
limiter, the RDBR-E is designed for use on large inclined
conveyors, where a release function or load sharing is
required. The RDBR-E also protects the conveyor belt
system by cutting peak loads.
The Stieber Clutch RDBK high-speed
releasable backstop with integrated
torque limiter for load-sharing.
The Stieber RDBK is a centrifugal lift-off sprag type
backstop with an internal torque limiter which is designed
for use on the high-speed or intermediate shaft of the
driving unit in multi-drive systems, such as on large
inclined conveyors, where two or more backstops share
the reverse load. These innovative backstops provide
up to 3.5 times more torque capacity within the same
volume and up to 15 times more energy dissipation
than other conventional designs.
STIEBER RDBR-E LOW SPEED BACKSTOPS ARE
HARD AT WORK IN AUSTRALIA
Dual RDBR 300 models with 70 kNm torque per unit are
installed on the 3,050 m (1.9 mile) long drift conveyor at the
Moolarben Coal Complex in Australia. The inclined conveyor
transports coal from the longwall system underground to
the surface and features an 80 m (262 ft.) lift and has a
capacity of 4,500 tph.
A load-sharing, releasable backstop solution was
needed for use on new conveyors at the Moolarben
Coal Complex in Australia. When fully operational, the
massive facility will produce approximately 17 million
tons of coal per year. The backstops are installed on
the mine’s 1800 mm (5.9 ft.) wide, 3,050 m (1.9 mile)
long drift conveyor that transports coal from the longwall
system underground to the surface. Additional releasable
backstops were also required for the mine’s surface ramp
conveyor.
Twin RDBR 360 models with 120 kNm torque per unit
are utilized on the ramp conveyor at the Moolarben
coal mine
The Stieber backstops were chosen to meet the tough
conveyor application requirements due to their superior
release functionality.
* Source: Mining Planning and Equipment Selection