Twiflex has launched a larger, enhanced version of its highly successful VMS2-SP safety brake, aimed specifically at the demanding Mine Hoist market. In common with the VMS-2, the VMS-3 is a spring applied, hydraulic released safety brake, but offers faster operation and superior performance, delivering a maximum static braking force of 300kN*, and 230kN** of dynamic braking force, with the added benefit of infinite fatigue life.
The mine-ready, robust design of the VMS-3 is characterised by a strengthened, longer housing which integrates additional springs for improved braking force. Totally sealed to give excellent, corrosion and dust protection, the new design offers users the set-up and maintenance advantages of tamper proof pad/air-gap adjustment, the facility for external pad retraction, on-site torque adjustment and a “Park-Off” facility for achieving fast seal changes without the requirement for special tools.
The VMS-3 design also integrates small size pistons for quicker reaction times, coupled with an improved drainage system and a reduced retraction pressure of between 120 - 160bar (depending on rating). In addition, the status of the VMS-3 braking system can be linked to a PLC, providing warnings for such factors as low pad pressure and alarms for high oil temperature, low oil level and clogging of pressure filters.
Also optimising the operation of the VMS-3 safety brakes is Twiflex's "MP" (Modular Range) of Electro Hydraulic Power Units. These provide an advanced and flexible means of brake control in the most arduous of operating conditions; typically, mining steelmaking and container handling. The "MP" unit is essentially an assembly consisting of a base unit, a hydraulic circuit and various auxiliary options. There is a selection from three common base units; the selection is determined by the brake to be controlled and the circuit opted for. There are four standard control circuits ranging from a basic on/off control to full closed loop utilising a PLC.
The base units can be tailored with various auxiliary options to ensure all specifications are met. The modular system is particularly useful when the installation requires the operation and control of two or more independent brake circuits, or there is a special requirement for meeting a particular industrial specification.
*Static Braking: 300kN (with 1mm air gap).
**Dynamic Braking: 230kN (with 3mm air gap).