Construction + Civil Engineering

Heavy machinery used for construction has a built-in flaw, despite the best efforts of the manufacturers. Relying on pivoted joints that allow elements of the equipment to move on their axis, it consists of a steel rod and a lug in which it rotates. A small difference in size between the diameter of the pivot pin and the lugs is unavoidable due to the need for assembly.

This gap is ‘wear waiting to happen’ simply because the moving parts are subjected to extreme forces as the operator is getting the job done. In time this will lead to a carved ovoid in the lug where the forces are exerted from side to side or vertically over a period of hours.

Operators of heavy machines such as excavators, cranes, or dumper trucks rely on a smooth pivot of steel rods inside lugs as they position drills, move objects across a site, or empty the dump bed. With time, however, they are likely to find that their job becomes harder and harder.

“At one point or another, the operator will notice that things start to feel loose as the lug begins to wear out. Sometimes they won’t even be able to use the equipment exactly as they want to,” says Jens Carlsson, area manager for construction at Expander System.

This can inevitably result in extra time to do the job, inaccuracy, and even accidents.

A traditional solution for pivot wear is not only costly but also a time-consuming process with significant downtime. The worn out part will normally be taken to a workshop where a hole slightly larger than that made when manufactured is drilled into the lugs. Then, a replacement bushing is welded into the lug. This is in fact a temporary solution and the need for line-boring and welding can occur several times over machinery’s lifetime.

This is where the Expander System comes into the picture. The Expander pivot pin – which includes a tapered axle, expansion sleeves, washers and fasteners – can be slotted straight into the lugs. Then the fasteners are tightened and the expansion sleeves are pushed up the tapered axle, gradually expanding, until they fit into and even out the pattern of wear.

Even if the hole has been worn oval, the Expander System fills out the shape and gives a secure solution without any preparatory machining, creating a perfect fit into the lug and locking the pin both radially and axially, eliminating the need for welding. The backlash-free joint prevents further wear. The result is a stable and secure joint, and the machine operator can continue with his or her job as planned without having to down tools.

Expander believes its System is a proven solution minimizing production shortfalls and lowering the life cycle cost of the machinery and equipment. During field tests of the Expander System over 50,000 hours usage extended the life of the equipment by at least three times and even up to 10 times the original longevity. Carlsson adds that some owners refuse to believe that such a simple system could affordably replace line-boring and he encourages those sceptics to ask for a trial of the system.