For DRIVERS, MECHANICS & FOREMEN.
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A PBIZB 01' P.kN SIIILLINGS is awarded each week to the sender of the best letter which, we publish on this page ; all others are paid for at the rate of a penny a line, with an allowance for photographs. All notes are edited before being published. Mention your employer's name, in confidence, as evidence of good faith, Address, D., M. and " The Commercial Motor," 7-15 Rosebery Avenue, London, B.C. 1, Lamps Alight—
Light your lamps at 5.43 in London, 6.13 in Edinburgh, 5.43 in Newcastle, 5.51 in Liverpool, 5.48 in Birmingham, 5.53 in Bristol, and 6.36 in Dublin.
A Troublesome Bevel-pinion Shaft.
[1787] "HM" (West Bromwich) writes : —" We had some trouble lately with the bevel-pinion shaft of an electric motorbus. The shaft itself was quite a, short one, one end was tapered and key-wayed for the bevel, the other end—parallel—carried the brake drum. The first thing to go wrong was the key which held the pinion in place. This was of the Woodruff type, and it worked loose and wore the hole in the shaft. I remedied this by re-cutting a key-way the whole length of the taper part of the shaft and fitting a parallel key made of cast steel. "This trouble having been thus finally scotched, the other end of the shaft had a turn. Here again the key was a Woodruff, and it gave out in precisely the same way as the other. The difficulty was intensified in this case, however, owing to the fact that the shaft too had worn and was a loose fit in the hole in the drum. The bore of the drum also, as it turned out, was not quite round. I therefore commenced operations by reboring the drum, taking out as little as possible, but making the hole a true one. The shaft was then trued up by being turned down, and a steel sleeve was shrunk on to it. A good stout cast-steel key, twice as long as the old one, was then fitted, and the drum replaced.
" Both of these jobs were carried out some time ago, and although a new drum and shaft were purchased at the time as spares, I have not yet had the least occasion to disturb the old ones."
Forethought When Repairing.
[1788]" J.K.O."..(Scotstoun) writes :—" A little forethought will often save tirne even in the course of jobs which are quite trivial in themselves. I recently had to replace the timing wheel of a two-cylinder engine. The gear was a built-up one, that is to say, it had a steel rim to which was bolted a rim Of bronze. Several of the teeth on the wheel had been torn out by some accident or other, and it was decided,to fit a new rim, using the old steel centre. Before taking off the old wheel I examined it, to see if the teeth were marked to facilitate re-erection. They were not, and at first I was inclined not to trouble any further since the rim had to be replaced. However, it occurred to me that
if it were marked some time might be saved in. the reerection of the new wheel. I therefore marked the teeth to correspond with a marked tooth on the crankshaft pinion, and also scribed on the broken rim the centre line of the key on the boss.
"After bolting the new rim on to the boss, and before fitting the complete wheel on to the shaft, it was marked eofffrom the old rim. The wheel was then erected in place, and owing to its having been marked as described therehere was no need for any valvesetting, and the engine started up on the first turn of the starting-handle."
A Regulator-valve Fitting.
The sender of the following communication has been awarded the 10s. prize this week.
[1789] " W.A.B." (Hollinwood) writes :—" There are many occasions, when driving a wagon, on which it is possible, and even preferable, to keep the regular tor-valve handle stationary for .tv time as, for example, when ascending a fairly long -hill of the same gradient throughout. There is no reason why the driver should not, during a climb of this kind, fix the regulator valve, leaving his two hands free for other things. Scania effective means of fastening the handle, for the time, is, however, essential, as, left to itself without any such fastening, it is liable tO slip about. I have fitted a special quadrant for this purpose. "All the material required is a piece of steel plate 6 ins. by in. by in. This should be bent to the sme curvature as the starting-lever quadrant and a slot must then be cut in the centre, 4 ins, long by R. in. wide. A set-screw in the lever engages with this slot, and the lever may be secured in any position by means of the wing-nut which is shown on the sketch which I enclose. [We have had this redrawn and it is reproduced herewith—ED.]. "I often think that the regulating lever is regarded with too little seriousness by many drivers, especially those who are new to the business. Its position when starting, or, rather, the position of the engine cranks, when the valve is about to be opened, particularly on an over-type compound engine, is well worth noting. If the driver will be careful to see, before engaging his gears, that the h.p. crank is in such a position that, the h.p. cylinder will immediately receive steam, the engine will, as a rule, start at once. even under full.load, without necessitating the use of the_h.p. gear 'The, latter, if used more frequently than is absolutely necessary, is responsible for much of the depreciation of the steam wagon, causing as it does, additional strains on he mechanism Of the chassis."