The Drivers' Page.
Page 16
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Hints to Drivers of Petrol Vehicles : by "A.S.B."
Never start out on a car without seeing that the brakes are properly adjusted. Mechanically propelled vehicles have the reputation of being able to pull up in a remarkably short space, and it is well to live up to this reputation. Oil leak ing out of the gear box or differential casing is the chief cause of brakes failing to act. This, however, can generally be removed by squirting petrol between the brake band and drum, taking care to first remove as much of the oil as possible with a cloth. This trouble may generally be pre vented by fitting a fibre or leather washer on to the counter shaft, so that it presses tightly on the end of the bearing, thus minimising the possibility of the oil coming through the bearing and finding its way on to the surface of the brake drum. Side brakes, of the internal expansion type, are sometimes apt to become so fierce as to entirely lock the wheels, no matter how gently they may be applied. This will usually be found due to water getting into the brake drums and forming rust, also to grit from the road getting in. Each wheel should be jacked up in turn, and the wheel removed, then the whole of the brake mechanism thoroughly cleaned with plenty of paraffin, not forgetting the drums themselves. The pins should then be carefully oiled with the lubricating oil, after which the wheels may then be replaced.
Should the carburetter flood, grind in the needle valve with just a trace of fine emery ; this will effect a cure in most cases. The flooding, however, may be due to the float being punctured, petrol entering the float and upsetting the balance. If this should happen to be the case remove the float and ascertain if this is the cause by shaking the float, when the petrol may be heard inside. Considerable difficulty is sometimes experienced in locating the puncture, and the following is the easiest way to accomplish this. Hold the float, by means of the needle valve, about an inch above the flame of a candle, turning it round and round and not allowing it to get too hot, as this would melt the solder used in the making of the float. The heat from the flame will convert the petrol into a gas, which will expand and be forced out of the puncture, becoming ignited and burning in a small jet. Mark the position of the hole, and continue warming the float until all the petrol has been vapouris,ed, then carefully clean round the hole and solder it up by
dropping a dab of solder on the place, and flatten it as much as possible with a fine file. For .g-rinding in valves use flour
emery, and any thin lubricating oil, mixing them to a paste.
When the surface appears fairly even, wash out all traces of emery with petrol and finish grinding in with oil alone ; in this way a remarkably fine seating can be obtained. Use a small screw4lriver and not much pressure, giving sharp, quick turns backwards and forwards and lifting the valve off its seat from time to time and turning it round a quarter of a turn to bring it into a fresh place. Always be sure that the valve stem is not touching the tappet before starting to grind in the valve. Avoid grinding automatic inlet valves, especially when of the flat-faced type, as these will make a better seating if left to themselves, through their continual hammering. Of course, in the event of their being found to be badly fitted, grinding in must be resorted to. The clearance which it is best to leave between the ends of the valve stem and the tappet should vary with the length of the stem. In some cases, when the valves are extra long, over 1-32nd of an inch must be left; with short valves 1-64th will generally he found ample. The trembler blades on the coil should be frequently examined. An engine was recently overhauled which was constantly misfiring; this was due to excessive sparking at the platinum points on the trembler coil, which necessitated constant trimming up of the platinum points. On making a careful examination, the sparking proved to be due to the platinum points on the roil not being centrally placed one above the other, being as much as half their breadth out of truth. The trembler blade was removed and the hole at the fixed end slotted, after doing which the points were adjusted centrally one above the other and the mis firing ceased. Efficient lubrication is a most important point over which one cannot be too careful. Always see that the lubricators have plenty of oil in them, and give a turn to all grease caps before starting out on a run. Where one has to deal with all sorts of strange cars at short notice, it is difficult to tell whether there is sufficient oil in the crank
chamber, and the following is perhaps the best method to adopt to guard against a shortage of oil :—Start up the engine and note whether smoke issues from the exhaust on accelerating the engine ; should this not be the case pump a charge of oil into the crank chamber, and accelerate the engine, looking for smoke at the exhaust again. Repeat the operation, giving only half a charge at a time until smoke appears at the end of the exhaust pipe on accelerating the engine. The crank chamber will now have its proper amount of lubrication oil. The clutch fork and rollers are parts that receive very scant attention, taking into consideration the amount of work they have to perform; in many cases no means is provided for lubricating them at all. It will always be found worth while to fit a drip lubricator if such is the case, taking care to fix the lubricating pipe firmly in position by means of a wire. Do not forget to oil the sliding sleeve actuated by the governor; unless this is attended to the control of the engine may be seriously interfered with. By not properly lubricating the sleeve it becomes stiff, and will not slide along the shaft until the engine races. The governor then cuts out quite suddenly, and the sleeve will then stick in this position till the engine has almost stopped. it will be found a good plan to go over the car carefully „at intervals with an oil can, oiling every moving part possible, and not forgetting the shackle joints of the springs. Unless the pins in the universal joints are efficiently lubricated they will wear out and require renewing in a very short space of time, besides producing an annoying rattle. These joints should be well soaked in lubricating oil and then encased in leather filled with solid grease. Steering gear and the pivots of the front axle should also receive attention, as well a.s the pins of the front axle tie bar, which should be fitted with leather caps filled with plenty of solid. The foregoing may save somebody trouble.
J. Morris (Leicester) writes :—" I think the following will be interesting, as it shows what a lot of trouble will arise from some small want of adjustment. A few days ago, whilst driving my delivery van, I noticed that for some unaccountable reason the engine would not pull as it should du when running normally. I therefore tested the sparking of each plug separately by holding down the trembler blades in rotation, and found that one was not sparking at all. I at first thought that the particular plug was at fault, so I took it out and fitted a new one in its place; then I tried again, but with no better result. So I then disconnected the high-tension wire of the same plug at the coil, and had the engine turned round, at the same time placing the end of the wire and the terminal close to one another, hoping to get a spark, but the result was disappointing. Then the low-tension was disconnected at the contact breaker, and experimented with in the same manner, but all to no purpose. I then took the cover of the contact breaker off and had a look inside : there I found my trouble at once. The fibre of the ring had become swollen, apparently by absorbing some of the oil in the casing of the contact breakers. This caused a high place on the inner side of the ring, with the result that the wipe, when revolving, did not touch the brass contact piece, so, of course, no spark was made. After I had carefully trimmed down the excrescence level with the contact piece, I started up the engine, and all the cylinders worked splendidly again. This is the first time that this has ever happened to me during my experience a; a driver. I wonder if many have had the experience?"