HOISTING TECHNOLOGY
mitigation on-site, is the “Parked Off ” design
which is included on all Twiflex modular brakes.
Unlike conventional mechanical lock-out systems
where a nut and centre bolt arrangement is used
to hold the spring force and prevent the brake
from closing during maintenance, the “Parked
Off ” feature actively removes the spring force,
meaning when hydraulic pressure is removed
there is no force acting on the pad and therefore
no possibility of an unexpected closure.
Powell concludes: “The overall performance of
the VCSD-VR lends itself to the application at
Elko gold mine and we were able to engineer a
solution which met all of the requirements while
also delivering additional performance
advantages such as faster installation and
reduced maintenance costs.” IM
Twiflex late last year provided a parking and
emergency brake for use on hoists at a gold
mine in Elko County, Nevada
Se
ce
r vi
g
in
C om mi s si o ni
S ta r tu p ng
pad) version of the popular Twiflex VCSD (15,700
mm 2 each pad); both brakes producing a braking
force between 11 kN and 60 kN. Due to its
increased braking path, the large pad version
enables higher rubbing speeds and greater
thermal capacity (the ability to absorb and
dissipate heat) to be achieved. In addition to
testing the braking torque at the start of each
shift, hoist operators carry out visual checks of
the calipers and condition of the disc surface. To
assist with maintenance, Twiflex brakes
incorporate a monitoring system to signal brake-
pad wear and loss of braking force.
Twiflex says it is continually investigating new
materials to meet the demands of the mining
market and has invested in modern test equipment
at its UK plant in Bedford. The company can
provide full testing capability including a climatic
chamber (-75°C to +180°C), a fatigue room for
brake cycling and a fully automated 40 kW
stop/start inertia rig for dynamic stopping.
“All Twiflex modular brakes are subject to a
cycling test and pressure test before leaving the
factory,” explains Powell. “For mine hoists, all
critical brake components undergo non-
destructive testing. The main limitation for brake
manufacturers is the friction material and the
brake pad swept area, which needs to be
carefully selected for the operating cycle.”
A unique Twiflex feature, which helps to
reduce maintenance costs and contributes to risk
cale
ll-s
Fu sting
Te
dissipation during the stop are high.
“Our selection is based on providing enough
braking torque to deal with the static out-of-
balance load, in addition to considering the
dynamic stopping duty,” explains Powell.
“Modern control systems offer lower hoisting
cycle times and high production levels, all of
which affect the brake selection.”
The VCSD-VR is a large pad (28,990 mm 2 each
From concept to
installation & beyond,
your success is our priority
At GIW, our focus is on supporting you through the entire life cycle of your slurry systems.
This includes working together to optimize your up time to increase productivity. How do
we do this? We offer an entire business model under one roof. From research and design
to aftermarket services we are your one stop shop for slurry pumps, cyclones and parts.
This includes dedicated foundries for casting, machining and assembly and an on-site test
facility to ensure optimal product performance.
As the OEM, we offer services that others try to provide but can only copy. Whether you
need mill discharge or cyclone feed pumps, new materials for your wear parts, or to upgrade
your current slurry equipment to match your ever changing processing requirements, we
have the answer.
GIW Industries, Inc. (A KSB Company) · www.giwindustries.com
AUGUST 2017 | International Mining 33