Current market conditions in the coal mining sector have put increased pressure
on mine operators worldwide. Now, more than ever, mines need to operate at very
high levels of productivity to achieve even modest profit targets.
With operating costs around $30,000 per hour, draglines are one of the most
expensive pieces of equipment found at any open pit coal mine operation.
Draglines provide the most efficient way to remove overburden (top layer of soil that
can be 150 ft. thick or more) to expose buried coal seam deposits.
The cost of a new dragline, depending on size, is in excess of $100 million. At that
price very few new machines are built as mine owners increase the demand on
existing machines to remain fully operational for many years.
These massive machines can weigh upwards of 8,000 tons, with a bucket capacity
of 150 cu.yds. or more. The dragline’s bucket is lowered over the desired area,
dragged along the surface, then lifted and swung to a dumping area.
A series of up to 30 different electric motors, each with multiple brakes, drive the
hoist rope, drag rope, and propel and swing movements. Under tough mine pit
operating conditions, dragline brakes typically last between 4-5 years before they
need to be rebuilt or replaced.
ADVANCED ALTRA BRAKING TECHNOLOGIES ARE DESIGNED FOR
USE ON DRAGLINE BRAKING APPLICATIONS
Industrial Clutch heavy-duty brakes and Twiflex caliper brakes are used for
controlled engagement and emergency stopping on rope hoists, bucket drag
winches and swing, propel, and crowd motion applications.
TWIFLEX GMR-SD BRAKES SUPPORT ALL TYPES AND
SIZES OF DRAGLINES
Twiflex Model GMR-SD
caliper brakes shown
operating on a drag motor
For more than 40 years, Twiflex has been providing
dragline caliper disc brakes for new builds and as
replacements for old shoe (drum) brakes. Back in the
1970’s Twiflex worked with Ransomes and Rapier
(1000/2000 Series machines) and more recently with
Caterpillar (formally Bucyrus) on the following draglines:
- Models 1370, 8050 and 8200 (drag and hoist)
- Model 8250 (drag, swing and propel)
- Model 8750 (swing and propel)
- Model 2750 (hoist drag)
GMR-SD Brakes offer many advantages:
- Modularity/Flexibility - Fit multiple units and size of
thrusters can be varied to suit installation
- Adjustable Torque - Torque can be adjusted
according to operating conditions
- Low Maintenance - Easy-to-replace brake pads, low
- Air Released - Spring applied, air released – both safe
Extensive dragline application experience allows Twiflex
to supply complete brake packages including:
- Brake calipers
- Mounting frames
- Mounting bolts
- Discs, hubs and taper-lock bushings
- Air pressure regulators
- Local piping
INDUSTRIAL CLUTCH LKB DISC BRAKES PROVIDE
SUPERIOR PERFORMANCE VERSUS DRUM STYLE BRAKES
One of the problems with drum brakes is that they are
difficult to maintain and require frequent adjustment. If the
adjustments are not made in a timely manner the brake’s
torque capacity falls off severely.
In contrast, Industrial Clutch LKB disc brakes are
designed with rotating discs that are splined to a hub
which is keyed or splined to the rotating motor shaft.
These discs, or plates, slide axially when engaged and
carry the friction lining. The braking surfaces are radial
and the friction surface is defined by its outside and
inside diameter. Springs move the plates axially and
engage stationary plates against the rotating discs
thereby affecting the braking action.
Heavy-duty LKB brakes feature high-energy metallic
linings with large swept areas to ensure excellent heat
dissipation, uniform stopping distances and long lining
life. Units also feature high-strength alloy steel drive
studs, actuation springs sized for maximum life, and
long-life piston seals. Long spline lengths on the brake
discs maximize load-carrying capacity.
Industrial Clutch has been supplying Model LKB brakes
for draglines and shovels to OEMs and the aftermarket
ALTRA BRANDS PROVIDE OPTIMUM DRAGLINE
Both Twiflex GMR-SD brakes and Industrial Clutch
LKB disc brakes are the preferred solutions for dragline
hoist, drag, swing and propel motions, providing many
advantages over shoe (drum) brake technology.