Posted by Daniel Gleeson on Apr 22nd, 2020
Condra will manufacture a “technically complex crane” for the maintenance of a towline in a coal mine in Mpumalanga, South Africa, after winning an order from its authorized representative for the Witbank region, GTB Industrial Services.
The contract, which was won against stiff competition, is for a maintenance crane capable of working in the very narrow area of the towline house. This includes motors and gears that control the excavator boom and towline, as well as large hydraulic cylinders that control the pontoons, so that space is limited.
Condra said, “Condra has proven better than its competitors in being able to meet the complex criteria of the specification. Above all, this was the requirement that the hoist must be able to completely separate itself from the maintenance crane and move as independently operated roof girders along individual roof beams. “
The hoist must also be able to independently deliver loads for transportation outside the towline house in the event that the components cannot be repaired inside the house, the company added.
The requirement was met by designing the crane’s 12.5 t hoist as a beam changing machine and equipping the crane with a lock to prevent the hoist from leaving it unless, according to Condra, the crane is firmly attached to the selected beam connected. The hoist is powered by a cable drum and not by the crane’s cable loop system.
Managing Director Marc Kleiner said Condra could draw on previous experience with towline maintenance cranes and overcome the technical complexities to deliver a machine that could allow a single hoist to do what would normally be done by multiple units.
“Our design office came up with an innovative proposal that could also offer more work space than our competitors,” he said. “We can pull a rabbit out of our hat quite often when no one else can, but we believe this time our ability to make within a short lead time also helped win the contract (lead time for the contract is only 14 weeks). ”
A key component of Condra’s overall design for the crane is the manual beam lock, which includes a derailment breaker to prevent lifting movement until the beams are locked together, the company said.
This design not only prevents the hoist from moving near the end of the beam, it also provides the large tolerances required to accommodate movement of the beam as the tow line moves in position, according to the company. The towline is moved by “walking” on pontoons, which have been repositioned for each step, tilting the nacelle forwards and loading the structure and the crane itself.
A hoist from Condra’s K series was selected for the design due to its adaptability and its particularly robust construction, which are well suited for these loads.
K-Series hoists are manufactured in three main configurations: foot-mounted, underground monorail, and double-rail crabs. Fully covered series hoists have a load capacity of up to 32 t, while open drum units have a capacity greater than 250 t (Condra K series open and closed drum hoists are shown painted green in the photo).
Features of all models include electromagnetic DC disc brakes, frame-sized standard motors with parallel rotors, double-acting limit switches, solid bronze rope guides, and fully enclosed, spray-lubricated gears. The center lift is one of the lifting and lifting devices.
Condra says the dragline maintenance crane will be shipped later in the month following the relaxation of COVID-19 quarantine restrictions.