LIGHTING AND IGNITION DETAILS.
Page 27
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Our Driver and Mechanic Readers Offer Some Useful Advice.
TN TIRING recent years many im provements have been effected in the design and construction of ignition and lighting devices, but, in spite of this, an analysis of the roadside troubles !experienced by drivers will show that , the majority of these fall under one or other of the two headings. Many of the faults can easily be rectified -with but little delay, although in some cases they may cause the complete stranding of they vehicle.
! This week we have a variety of letters dealing chiefly with magneto couplings, 'sparking plugs and improving lamps for i 'driving n fog, and the prize of 15s. is awarded to `R.H.," of Trowbrid.ge, who has sent a description and sketches showing the construction of a simple r but effective magneto coupling, and also of an easily made sprocket.
ts For the coupling two steel or brass !discs are required. These should be about %! ins, diameter and provided I with bosses, which must be bored to fit the magneto armature shaft and engine shaft respectively. A stud is screwed into one disc near the circumference, , whilst on the other is cut a slot from g in. to in. -wide. A fibre block is then cut to fit the slot and drilled to suit the stud. This drive has the advantage of being silent and almost instantly detachable; also the parts can easily be
, replaced when worn, for the fibre isIeld , in position merely by a split pin in the end of the stud, which must, of course, be drilled for the purpose. . 'st For the magneto sprocket a disc of suitable size has a number of holes drilled on a circle, the circumference of which is equal to the product of the pitch multiplied by the number of teeth. ! For instance, if it be required to make a sprocket of 10 teeth of & in. pitch, the :circle will have to be 10 x = 5 ins. circumference. The diameter will be the circumference divided by is (approxi mately 3 1-7). , After dividing the circumference into the requisite number of spaces, centre' punch each and drill the ten 5-16-in. holes. It is advisable to give a lead to ' these with a small hand drill. When the holes have been drilled, the surplus , metal can he turned off in the lathe, _leaving the disc with the holes partly broken into and of a diameter equal to that of the finished sprocket. The tooth ends can now easily be shaped off by means of a file, each tooth being fitted in turn into a piece of the cOrrect chain. The teeth should also be filed to give clearance in the thickness, and if mild steel:lie employed there will be no necessity for hardening.
THE desire to control the ignition from the driver's seat was the reason for " W.D.," of Stockton,!! altering the spark control on the 31-ton Fiat lorry which he'drives.VThe original method for adjusting this spark was by altering
the position of a knob carried under the radiator, and once the engine was running the spark had to remain in the advanced, position. By making the alteration shown in our sketches the flexibility of the vehicle was increased, and the engine could be made to run very slowly when required, thus saving on fuel consumption. ses
THE letter sent by "LW.," of Heck
mondwike, contains information which will assist those drivers who are called upon to operate their vehicles at night in foggy weather. He states that he always carries with him a small tin of powdered yellow ochre, and if it be foggy at night time a little of this powder should be mixed with water and smeared on to the glasses of the lamps. It will then be found that the yellow light which results appears to penetrate the fog in a much better manner and does not merely form a blur of white ligh‘ against the curtain of fog.
He also finds it advisable to shade the lamps so that the light is directed downwards. This can be done by means of two pieces of stiff wagon sheeting cut into half-circles and tied over the lamps so that they form cowls, projecting about 4 ins. over the glass.
A SOMEWHAT drastic method for
cleaning old sparking plugs, particularly those of the non-detachable-centre type, is recommended by " A.W.R.," of Gillingham. His method is to heat the whole plug bright red, and then to plunge it into cold water for not more than three or four minutes, withdrawing the plug and allowing it to cool slowly. When the plug enters the water it will be noticed that a small shower of carbon particles shoots out from inside, and almost invariably it will be found that the inside and electrodes are perfectly clean.
" A.W.R." states that he has performed this operation on dozens of plugs with most successful results.
THE contribution from " H.E.," of Manchester, also deals with a magneto coupling, but in this case the device is of an emergency nature, and was originated through the loss of a standard type cross-piece when the vehicle was running down a hill, apparently through the magneto becoming loose on its base. The emergency cross-piece was made from a fin, square nut. This was cut across on each side, as shown in the illustration, the cuts being at rightangles to each other. The vehicle on which this coupling was used was a Dennis subsidy model, and the only alteration which had to be carried out wee to the ignition rod, which was led to the other side of the timing lever, for the magneto was found to be a little further forward as the emergency cross-piece was thicker. This replacement was Used for some 800 miles before a new part was substituted, and it is still kept as a useful spare.