Copyright 2017 - The Friends of Mostert's Mill is a Non-Profit Organisation. NPO# 120-838
Today the commonest windmill in South Africa is the familiar steel wind-pump. These are particularly prevalent in the arid highveld region, where rainfall is limited to torrential thunderstorms but where water can often be reached by shallow boreholes. Throughout this semi-desert region these slender wind-engines pump up water to fill the concrete or corrugated iron tanks storing water for the sheep, or to irrigate a tiny green oasis near the farmstead.
 
They are usually lightly-built pylons of lattice steel, surmounted by a head which carries an annular sail, or wind-wheel, aptly described by Reynolds as ‘a circle of curved metal vanes, arranged like the petals of a flower’. In the wind-engine the sails are arranged in a circle instead of radiating from the stock as in the normal windmill.
 
The head is turned into the wind by a broad metal vane, on which the name of the maker is usually prominently displayed. One had the message: ‘Wherever you go you see them, wherever you see them they go’.
 
A cranked shaft transmits a reciprocating motion to a long rod, which passes down the centre of the pylon to the pump at the top of the borehole.
 
Such wind-engines permitted settlement in many areas which had previously relied on unpredictable springs or streams. The extent to which they were used is well illustrated by the 1914 War Office map of the Reddersburg district in the Free State, when they averaged one wind-engine per 40 square km.
 
The first steel wind-engines were imported from America, Australia and England in about 1895. Stewart and Lloyds were appointed agents for Thomas and Son of Worcester, England. The early wind-engines had heads which required lubrication, and as this was often neglected, Stewarts and Lloyds suggested the introduction of the oil bath type, which is still in use today. During the Second World War it was not possible to import wind-engines and from 1942 many local firms manufactured various makes under license and since then have made hundreds of thousands.