Orders for unusually large overhead cranes destined for mines in Zambia, Namibia and South Africa, have been received by crane manufacturer Condra leading to the company increasing manufacturing capacity at its Johannesburg factory by introducing additional shifts.

The cranes include three with box‑girders of over 30 m in length, two 50 t cranes with spans of 34 m, and a third, high-lift, 5 t crane with a 35 m span. Condra is simultaneously completing the manufacture of a further four 50 t cranes with spans of about 20 m, as well as three single-girder overhead cranes, two portal cranes and a jib crane.

The company explains that cranes with spans of 34 m and 35 m present specific manufacturing challenges, as box girder dimensions include spans measuring 2 m in height and just under 1 m in width.

“Girders this long are delicate to manoeuvre on the shop floor. They require resource and workflow planning and tie up use of our factory cranes. Manufacture involves intricate welding and very careful jigging to incorporate the correct camber to counter girders’ natural tendency to sag under load,” a Condra spokesperson said.

“End-carriage design has been important to ensure crane longevity, because the wheels must accommodate continuously changing stresses imposed by the girders as they flex under different loads,” the spokesperson added.

The orders are being filled for an engineering and project management consultancy with a global presence and a long association with Condra. The company has also ordered 18 electric hoists of between 2- and 25-ton capacity, and four chain blocks.

In addition, Condra is currently commissioning two cranes at Gamsberg Phase Two in the Northern Cape, where the same consultancy contributed to metallurgy and process plant design. The cranes are a 40/5 t machine with a 22 m span and an 80/20 t machine with an 18 m span.

The company says it has completed delivery of two additional cranes to Gamsberg Phase Two, for installation as the structural steelwork progresses and that it anticipates further orders from Southern and East Africa, notably from Tanzania and Mozambique.