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Light Up Your Lamps At
9.0 on Thursday ; 9.1 on Friday ; 9.2 on Saturday ; 0.4 on Monday ; 9.5 on Tuesday ; 9.6 on Wednesday.
A Jig for Grinding-in Gears.
[1505] " R.T." (Bedfoxd Hill) writes :—" Some time ago, while I was engaged in assembling a number of chassis built up from components purchased abroad, I found that one consignment of gears gave a great deal of trouble on account of the noise they made while running, the cutters used in making them having apparently worn slightly, thus leaving the teeth over Size " As it was important that no time should be lost, several means were tried for overcoming the difficulty, all of them proving more or less unsatisfactory. Finally, I made a jig to provide a means for running each pair of wheels together in a bath of emery and " The necessity for a special arrangement arose through the objection to grinding-in the gears within the actual gearbox casting, as the emery, of course, would then come in contact with the ball races and most likely injure them. Also, it is very difficult thoroughly to :dean out the emery from the box, and there is always a likelihood of the grinding process -continuing while the car is doing its normal work.
" The method of constructing the jig will be seen from the sketch [We have had this redraen.—En.] which T enclose. The ball races are carried by four brackets mounted on a base, which forms part of an oil-tight case. This case contains the oil and emery in which the Fars are to be run, and it will be noted that the bearings are quite external to it. "In order to prevent any leak occurring between the shafts and the case through which they run, thick felt washers are provided at each end, these being squeezed between the brackets and the case. One of the shafts is fitted with a belt pulley, in order to allow for driving the gears. The casing is provided with slides for each of the shafts, so that these can be removed when necessary for fitting the gears. "To use the device, the gears are placed on the shafts and the box filled with a mixture of oil and emery. After running the gears for some time until E2 they are quietened down, the grinding mixture is drained off through a plug in the bottom of the casing, the latter being sluiced down with paraffin. "If it be found necessary, the gears may now be run in pure paraffin, in order to remove any particles of emery which may have become slightly embedded in the teeth, after which they may be run dry for a short time, to give them a polish. "While running-in, it may be found necessary to fit distance pieces at each side of the sliding pinions in order to keep these properly in mesh. With some shafts and gears the slides in the casing are not necessary, as it is quite a simple matter to slide the gears off and on by slightly withdrawing the shafts."
Truing Bent Crankshafts.
[l506] ' H.M." (West Bromwich) writes :—" The commercial motor which I drive recently had ties misfortune to burst one of its lubricator pipes, thus throwing the forced lubrication system entirely out of action. The result was that the crank pins ran hot, and one of them seized, breaking off the connecting rod and smashing a hole in the top half of the crankcase, and, worst of all, bending the crankshaft. "The bend was rather a. bad one, being in two directions. The force of the impact, caused by the broken connecting rod fouling the top of the crankcase, had the effect of bending one of the end webs beck in the opposite direction to its rotation. The web was also bent in towards the next one, and the whole crankshaft put out of truth about in.
" The actual bend was in the crank pin itself, and I endeavoured to straighten it by raising it to a blue heat with a blow-pipe, and then by the aid of a strong croevbar I was able to spring it true sideways—that is to say, at right angles to the web, giving two or three sharp taps on the side and end of the defective web at the same time. This greatly improved matters, but the end journal was still about in. out in one direction, and it was evident that the web must be bent out to correct this. "To do this. I emplcyed a in. bolt and nut. By fitting this tightly between the two end webs, and unscrewing the nut by the aid of two spanners, great pressure was brought to bear an the bent crank pin,
and by reheating the latter, the shaft was set sufficiently to bring it almost true. "After trying once or twice more and testing the shaft between centres, barely any defect could be discovered, and on refitting to the engine with a new oonneeting rod and repaired crankcase, the result proved quite satisfactory.
'Truing a crankshaft is usually a very difficult job, and great care should be taken, as, while trying to reduce one bend, you are very liable to make another, and a crankshaft is not a part which can be roughly handled."
Another Valve-removing Tool.
[1)07] J.M." (Manchester) writes :—" Having oeeilsion to take out a set of valves, I found the springs exceptionally strong, and it was very difficult to remove. the valves with an ordinary pair of valve spring lifters. To improve matters I procured a forked lever which had been discarded owing to wear in the hole.
" As the fork had been ease-hardened. I softened this and flattened out the round stem about 1 in.
from the fork, as shown in the sketch [We have had this redrawn. Era]. In the flatteited portion I drilled a. 5-1 ti in. hole. 1 next cut away the fork in such a way that two hook-like projections were left, and these I rounded off with a smooth file.
" The fulcrum was made from a piece of 5HI in. round mild steel, bent into a hook at lhe top and sharpened to a point at the base. The lever itself was finished oil with an old file handle, which was screwed on to it.
" This little device has proved to be one of my limidie,st tools. It leaves more room for taking out
and replacing cotters than the usual type of lifter, and it is easily adjustable by using fulcrums of different lengths."
How to Remove Carben Deposit.
[10S] " (Norwood) writes :—" Dirty cylin ders offer a source or trouble which is sornee hat difficult to cure without removal of the cylinders, and any easier method of getting rid of the carbon deposit when this occurs should be welcomed by drivers and mechanics. I have found that a. small quantity ci denatured alcohol, squirted into the cylinders while they are hot, and the engine then run fairly fast for a few minutes until the alcohol is all burnt eel., will clean out the carbon in a mosit effective manner. In fact, it would be as well to do this every now and again simply to keep the cylinders in their best condition."
How to Bed-in Bearings.
[Iii091" G.D.J." (Hastings) writes :—" I should like to draw the attention of my fellow driver-mechanics to the danger or throwing connecting rods out of truth when scraping in a set of big-end bearings. I have found this danger can be practically eliminated by doing nearly all the work on the caps or lower halves of the bearing, touching the top halves only if it be found absolutely necessary, and then being very careful to work equally on each' side of the centre towards the sides.
"If desired the process may be reversed, and all the work done on the upper halves, but whichever method is used, all the rods should be treated in the same manner. The same principle should be adopted with any other parts running in bearings and requiring to be in perfect alignment."
An Exciting Towing Experience.
The sender of the followtng communication has been awarded tit* 2.)rize this week,
L1510" W.E." (Hants.) writes : —" I have sometimes seen steam wagons towing petrol vehicles, but it is not often that a petrol lorry has to tow a steamer, as, of course, there are not so many steamers on. the road. A few months ago one of the steam lorries belonging to my employers broke down when it was carrying a full load. As it was only a .4!ew miles away from the depot, I was sent out with a three-ton petrol lorry to tow it home, first of ail tra.ushipping the load and delivering it where it was required.
" On getting back, I hooked on to the steamer and endeavoured to tow it along, suceeednig in breaking the chain twice helm-e I managed to get it out irom the side road, where it had broken down, on to the main road. Luckily there were no steep hills to go up, but there were two ralhur severe (mos to cie:icend. The engine of the steamer !airing broken down, the driver was, of Course, not able to use it as a brake, and the hand brake was hardly to be depended upon.
" At the top of the first hill I unhooked from the front of the steamer and .hastened the chain on to its rear portion, holding back with my brakes until the bottom was reached, where. I reversed the poeition again and proceeded to the next hill. At the top of this the driver of the steamer thought he could hold it back with the hand brake, and, taking his advice, I did not proceed in the same manner as I had on the previous hill but kept towing in front.
" When a little way down, I heard a shout from behind, and on looking round, saw that the steamer was gaining rapidly, the brakes having failed. Before
could increase my speed, it ran into the rear of the lorry I was driving. I accelerated to get out of the way, and went the full length of the chain, which checked my vehicle so much that, the steamer rail into the back again. This time I accelerated still more and succeeded in breaking the towing chain, after which I ran away from my unruly charge and stopped in a safer position sonic way from the bottom of the hill.
" Luckily, although the hand brake of the steam wagon was not very effective, it was strong enough to prevent the vehicle from going at a very dangerous speed, and the driver was able to pull up at the bottom of the hill. Looking round for damage, all we could find were a few dents in the smoke box, and no damage whatever to my vehicle."