Condra’s authorised agent for the Witbank area, GTB Industrial Services, has secured a contract for a technically complex crane to service a Mpumalanga-based colliery’s dragline excavator.

Condra will manufacture a maintenance crane capable of working within a very constricted area of the dragline house, which contains motors and gearboxes controlling the excavating boom and dragline, and large hydraulic cylinders to control the pontoons.

The lead time for the contract is 14 weeks.

The complex criteria of the specification requires the capability of the hoist to separate completely from the maintenance crane, and move away along individual roof beams as an independently operated underslung hoist.

The hoist, powered through a cable drum, as opposed to the crane’s cable loop system, is also able to independently deliver loads to transport vehicles waiting outside the dragline house, should components repair within the house not be possible.

Condra designed the crane’s 12.5 t hoist as a beam-changing machine, with a manual beam interlock, which incorporates an antiderailment limit switch to prevent hoist movement until the beams are locked together.

“Condra was able to draw upon previous experience of dragline maintenance cranes, overcoming engineering complexities to deliver a machine that allows a single hoist to carry out work that would more usually be undertaken by multiple units,” says Condra MD Marc Kleiner.

“Besides rendering impossible any movement of the hoist close to the end of the beam, this design also delivers the large tolerances needed to cope with beam movement when the dragline moves position,” he continues.

A hoist from Condra’s K-Series was chosen for the design because of its adaptability and robust construction.

Condra will deliver the dragline maintenance crane during the month following the easing of Covid-19 lockdown restrictions.