Twiflex VMS3/SPS Spring-Applied, Hydraulically Released Brakes For Mine Hoists
An industry leading designer and manufacturer of mine hoists has specified Twiflex Ltd. VMS3/SPS brakes for use at a gold mine in northern Canada. The mine is projected to process 7,000 tons throughput per day, producing 600,000 ounces of gold per year over a 15 year lifecycle.
The order consisted of VMS3/SPS calipers for installation on a 20 ft. diameter double-drum, single-clutch mine hoist which has two brake discs: one disc is positioned on the fixed drum and one disc on the clutched drum. The fixed drum utilizes VMS3/SPS’s and the clutched drum has VMS3/SPS’s. Each brake produces 240 kN braking force at a 2.5 mm air gap with > 2 million cycles fatigue life available at this rating.
The mine-ready, robust design of the VMS3/SPS features a strengthened housing which integrates additional springs for improved braking force. Totally sealed to give excellent corrosion and dust protection, the brake design offers set-up and maintenance advantages including tamper-proof pad/air-gap adjustment, external pad retraction, on-site torque adjustment and a “Park-Off” feature which allows for fast seal changes without special tools. Seals can be changed from the rear without having to remove the brake from its mounting.
The VMS3/SPS design also integrates small size pistons for quicker reaction times, coupled with an improved drainage system and a reduced retraction pressure of 137 bar at this rating. Braking force can be simply changed (up to 275 kN at 3mm air gap) by adding or removing shims located behind the rear cover. In addition, sensors can be supplied which work in conjunction with the customers’ PLC to signal brake on/off and pad wear.