Global demand for copper is high as it is a key resource in the manufacture of electrical goods. To ensure productivity, copper mines need highly reliable equipment, which includes the large service hoists used to transport apparatus and miners down to the face.
On a hoist, two braking systems are usually present. High-speed service brakes are installed on the high-speed side of the hoist’s drive motor. These brakes hold the hoist in place when the motor isn’t generating torque, offering parking functionality. A low-speed braking system delivers stopping power in all conditions, including power loss.
Achieving a gradual stop is very important. Sudden braking can cause disturbance to the equipment or personnel loaded on the hoist, which must be avoided. Therefore, integrated controls are required to ensure a ‘soft stop’ during braking.
In terms of the low-speed braking system, Svendborg Brakes supplied pedestal-mounted Model BSFH 512 spring-applied, hydraulically released, dual-spring calliper brakes, each with 96,000 N braking force. The brakes act on two 12 ft. diameter discs installed on the 10.5 ft. diameter rope drum.
For the high-speed side of the motor, pedestal-mounted Model BSFI 3100 spring-applied, hydraulically released, mono-spring calliper brakes were chosen. Offering of 80,000 N braking force, the brakes are applied on a 47.5 in. disc.
To deliver the soft stop needed for the application, Svendborg Brakes provided customised SOBO iQ hydraulic power units. These and the braking systems are operated by a single SOBO iQ control.
The SOBO iQ braking controller is flexible and durable, ideal for mine hoists and conveyors. Using a state-of-the-art dual-loop proportional integral control system to measure hydraulic pressure and speed, pressure control is applied with reference to speed and hoist deceleration. Braking torque is controlled by comparing actual hoist speed feedback against a pre-determined speed ramp. Consequently, braking is smoothened throughout operation.
Selecting a provider that can deliver complete braking systems with associated controls is an advantage for a hoist OEM. First of all, the interoperability of the systems means increased performance and reliability in application, essential for equipment that will often carry personnel.
Maintenance is also simplified and expedited. Spares and service support are available from a single source, which ensures a faster response and reduced downtime. All braking systems on the hoist can be maintained by a single knowledgeable team, so high quality repairs and instant familiarity with the system can be expected.