WAYS AND MEANS.
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Useful Contributions from Our Driver and Mechanic Readers.
An Unusual Breakdown.
IN THE issue of The Commercial Motor dated January 11th we published a letter from " W.O.K.," of Ilford, describing what might rightly be called an unusual breakdown, viz., bath floating axles breaking at once. A oorrespondent, " D.J.F.," of Edinburgh, says that in his 20 years' experience he has only known of one instance of a motor lorry or bus having both axles break at the same time. The instance he mentions was one in which a lorry was working under war conditions in a very hilly country, and his careful investigation of the ease revealed what he thinks was the cause of this seemingly impossible occurrence, as one would naturally think that when one axle had broken all strain would be relieved from , the remaining axle, so that no breakage could occur.
He encloses a sketch of the differential, which was of the parallel type, both wheels being splined and butting against each other. The first breakage was of an angular kind, and it is evident that half the broken part acted as a cam to force the other half inwards so that it engaged the splines of the other section of the differential, so locking the two and driving the vehicle through a single wheel, all the strain coming on one axle shaft. This prevented the differential from acting, as well as preventing the driver from knowing thatone axle had broken. The continued strain eventually became more than one axle alone could bear, GO it broke.
We think this is a very likely solution of what otherwise might have remained a mystery.
A Simple Lap for Enlarging Holes.
A CORRESPONDENT, " A.A.," of
Harborne, sends us a description of a simple but very useful device which he has used for years, but he tells us that, so far as he knows, it has never been described in any journal or book. The tool is useful for lapping out bushes of all kinds, and of any metal, and he tells us that he has even used it for lapping cylinders as large as 41 ins. din.
The device consists of a piece of hard wood turned to about in. smaller than the hole to be operated upon ; a saw cut is then made through the centre for a distance rather more than the length of the hole to be treated. A piece of goodquality emery cloth is inserted in this saw cut and wrapped round the wood. The wooden lap is gripped in a chuck in a lathe, the bush pushed over and by screwing up the poppet centre the lap can be expanded to any required degree without stopping the lathe.
Where expanding reamers are not available, this method is useful, and in the case of holes in articles that are hardened it is especially good. Our correspondent suggests that it can be used for big-end bearings, but our experience of lapping with emery cloth in white metal leads us to believe that the emery will embed itself in the soft metal and cause damage so we should not recommend it in such cases. Even when lap.
ping bronze, care should be taken to ' wash out every trace of emery, and it is a good plan to turn the emery "Cloth so that the emery is on the inside, and give the bearing a good run with oil only, so n's to be sure that 110 grains of emery are left in the metal. Getting Home with a Disabled Magneto.
SOME drivers seem to find a way of getting home no matter how impossible matters may seem. This was the case when " W.A.G.," of Colchester, found himself stranded with a Morris van fitted with an old type Lams magneto. On testing the magneto be came to the conclusion that the armature had given out, and being very late he could not get another magneto, yet he had to get home somehow.
He managed to procure a Ford coil, to which he soldered three wires as shown in the sketch. He then drilled a hole in the distributor to take the pickup, and proceeded to wire up as shown in sketch. He then also took out the screw in the front end that controls the amount of advance and retard, and brought the earn round until the points closed to correspond with the distributor opposite the contact on the cover. After removing the rear end cover and timing the engine (with points about to close) he started up and ran home a distance of 30 miles without any trouble.
Trouble with a Vernier Magneto Drive.
WHEN 34 miles away from home, a correspondent, " T.M.," of Huddersfield, found that his engine was getting very hot and running heavily. He suspected trouble with the timing of the magneto, so he investigated the timing, and when taking the magneto down he found that the vernier drive had become worn to such an extent that the pins which engage the rubber had worn almost through the rubber between the pin holes, and thus allowed the timing to become retarded.
The wear appears to have been so great that he was not able to ensure the timing remaining in the proper relation, so he begged a few short nails from a house near by and pushed them through the rubber as shown in the sketch. By this means he made a fairly good drive for the metal pins. The nails being pushed in from the inside, they could not work out.
Slack Ball Bearings.
WHEN reassembling ball bearings it is often found that they are slack in their housings, often to such a slight degree that even the thinnest foil cannot be inserted to make them a tight fit again. A correspondent, " D.D.I.," of Cleckkeaton, describes a method which he has found very satisfactory for dealing with this common trouble.
He procures a stick a Chatterton's compound, which somewhat resembles vulcanite, only with the difference that it can be melted. By slightly beating the ball bearing and smearing it with the compound over all but the first eighth of an inch, he is able to force the bearing into its housing, leaving a thin film of compound to fill up the gap due to wear. The object of leaving the first part of the bearing uncovered with the compound is to enable the bearing to be more accurately entered in its housing.