ENGINEERING APPRENTICE DAYS 2




Time in the workshop was spent in learning machining components in lathes and gear and chain sprocket cutting in the milling machine. Also did my share of striking for the blacksmith at the forge and anvil. He was a master at heating and manipulating the work with tongs and form tools while I with mighty hammer obeyed his commands, "when I nod my head, you hit it".

A timber mill and box factory in the town powered its large steam engine with a pair of horizontal multitubular boilers fired by Dutch ovens burning wood slabs, sawdust and shavings. One of the boilers had reached its economic life. Some of the lower tubes were taken out and another apprentice and I were sent to chip scale from inside the bottom surface. This confirmed the state of the boiler and it was condemned. The factory staff dismantled and removed the boiler and loaded it onto an old horse drawn lorry adapted for towing by motor truck. The procession was headed for the city dump, but as it passed our works the manager just happened to meet it and pointed out advantages in terminating a relatively long journey by dumping the load in our works yard. The driver saw the logic and no sooner said than done! The late owners were a little miffed that their throw-away had suddenly come to represent some value. A few weeks later I was to learn to appreciate the economics to be gained from a bit of canny recycling.

Along with its two steam rollers the city council owned an internal combustion engined road roller. I think that it bore the name "Barford" but not sure. However it had the typical front roll and large rear rolls but on a smaller scale than its steam stable mates. The quite large horizontal single cylinder sniff and bang engine lay where one would see the boiler in a steamer. The speed was governed by a hit and miss device that broke the regular action of the mixture inlet valve, hence a mighty firing stroke followed by several revolutions of the massive flywheel then another bang. Everything that could work loose was indeed loose. The canopy structure and the engine cooling radiator convulsed with each power cycle of the engine. The front roller consisted of two castings whose surfaces had worn through thus creating holes. It became our job to reface them and this was done by rolling up two steel cylinders from metal cut from the above mentioned dumped boiler. The blacksmith with oxy-acetylene torch cut the plates from the boiler shell, rolled them to size and finely trimmed them for heat expansion and cooling shrinkage to measurements made with his time proven measuring wheel. The meeting edges were then electric welded ready for the final operation that took place out in the works yard. The roll halves were placed on their ends on steel packing strips and the new rings stacked end to end on top of each-other and packed up from the ground on fire bricks. Wood fires were stoked inside and around the outsides. When red hot the rings were lifted one at a time by workers with tongs and dropped over the rolls to rest on the packing strips to cool and shrink on for ever. A skilful job well done!

A job came up to recommission an Aveling tandem steam roller that had lain stored in a trucking company yard in the city. The works foreman and I worked about a week preparing it for steam-up and drive it to the railway yards for transport to new owners at Auckland. We opened up the vertical boiler for inspection and renewed hand hole door packings, water gauge glasses and test cock gland packings. The engine mounted beside the boiler was a compact unit with chain drive to the leading roll. The machine was guided by the rear steering roll. The valve operating mechanism on the engine was my first encounter with the Marshall linkage. I was so intrigued with its configuration and action that I reproduced it many years later in the power unit of a small two passenger steam car to be described in future postings.