Mr. Pietie Conradie, well known for his farm solutions in the town of Richmond in South Africa, designed an oil purifying ‘rocket’ – practical, cheap, simple and easy to assemble.

The goal of Pietie’s oil purifying system was to keep the oil in his tractors’ hydraulic system clean. The oil in these systems are usually exposed to lower temperatures as the oil in engines, allowing it to stay cleaner for longer and retain it’s lubrication better.

In some tractor models, however, the brakes, the power steering and the power lift use the same oil as the hydraulic system, causing the filter to become blocked as a result of impurities from the brakes landing in the oil. This type of blockage affects the functioning of the brakes, the steering wheel and the lifting system .

“My son-in-law’s tractor works in this manner and he is always changing filters,” he says. This brought Pietie to decide to rather filter the oil from time to time – before the expensive tractor filter, which costs about ZMW 500, needs replacing.

This is how it works

His filtration system consists of the following:

• A steel pipe shaft with a diameter of 150 mm that is about 600 mm long. It holds about 20 l. the hydraulic system of his son-in-law’s tractor takes about 40 l of oil.

• The oil filter of a large truck. Pietie managed to get hold of four of these disposable Hino filters. The cost is only about a third of that of the recommended tractor filter. While the filter is still clean, the oil runs fairly fast through the system into the container.

• A wooden lid which he made on the turning table.

Picture 1 indicates the pipe shaft that the oil gets poured through, the shaft of the filter at the bottom of it and the exit pipe that runs into the catchment container. Pietie is holding the disposable Hino filter in his right hand and in the left, a lid for the system.

A disc is welded onto the base of the filtering pipe. Eight holes are then drilled into the disc around the outside of the filter (Picture 2). The old oil runs through it to the bottom pipe shaft, through to the inside of the oil filter and then through a pipe into the bottom oil container. The impurities are caught between the outside rim between the filter and the back shaft.

The diameter of the filter’s shaft is big enough so it fits easily. A gasket and eight bolts ensure the oil doesn’t leak out. The filter is kept in place by a long bolt that runs through the middle.

Picture 3 shows the bottom lid of the filter that is fastened with the eight bolts, as well as the bottom of the pipe with four holes through which the filtered oil runs into the catchment container. Note the bolt and the nut at the bottom which keeps the filter in place.

Pietie’s oil purifying ‘rocket’ stands on three legs made of angle iron.