RUNNING, UPKEEP AND OVERHAUL
Page 71
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Interesting Contributions from Maintenance Engineers, Drivers and Mechanics
A Practical Solution of Fourwheel-brake Adjustment. THE suggestion sent us by of Peckham, would appear to be the most practical means for adjusting brakes in four wheels that we have seen. As compensation has been abandoned on most makes of commercial vehicle, we should recommend the manufacturers to consider the advisability of fitting as standard the simple device here suggested.
When one brake rod is appreciably shorter than the remaining three, the result is that the oue wheel is locked %-tdien the brake is applied, whilst its
rod • prevents the full pressure being applied between the shoes and drums of the other three wheels. This happens frequently if the adjustment of the operating rods be carried out in a haphazard manner, or by guesswork. Accuracy in adjustment is assured if a small gauge be made from a piece.ef I-in, by mild steel, and calibraie6 along its length. This strip should be drilled for fixing to a stud at the top of the servo motor, or to any other convenient point, in such a manner that it crosses the operating lever on the brake cross-shaft. The lever should then be marked on its length in the plane of the gauge ; this enables the operator to read off, by means of the calibrations on the gauge, the position of the lever.
The four brake rods should he adjusted individually go that the lever on the cross-shaft coincides with the same mark on the gauge on each-occasion, when the brake is applied by means of the servo motor, i.e., by depressing the brake pedal while the engine is running at slow speed. The engine speed must be kept constant for the independent trial of all four brakes in order to prevent any variation in the power given out by the servo motor, and consequent variation in pressure.
Should it be desired to adjust the brakes in such a. manner that the front ones operate in advance of the rear ones, the difference in the gauge readings for front and rear rods can be ascertained by experiment on the vehicle concerned. This will vary, among other circumstances, with the condition of the surfaces of brake linings and drums.
ONE of our readers, " I..P.N.," of Warrington, tells of a plan, which he has found te be a great advantage ; A Good Tip for Driving in Fog.
he has adopted it for driving in foggy weather. His buses are of Chevrolet make, and he has found that the brackets which support the headlamps oan be fixed in any position: On a foggy night he arranges the lamps so that their beatrig cross each other, and by slightly inclining them downwards the light falls on the sides of the road, illuminating the kerbs or hedges, and at the same time slightly illuminating the centre of the road.
As we are now in the period of the year when fogs are most frequent, this tip should be of neat •value.' Those who have to drive vehicles on which the lamp brackets are fixed might rig up some experimental arrangement, and, if found satisfactory, they could have some permanent device fitted so that in foggy weather the beams can be crossed.
Our correspondent thinks so much of the idea that he requests us to draw the attention of lamp makers and the manufacturers of commercial vehicles to the suggestion. We shall he particularly interested to hear the opinions of any of our readers who may try the plan.
An Easily Made Magneto. testing Drive.
A CORRESPONDENT, " F.S.," of
. Orpington, sends us the followiug description: of a bench for testing magnetos, which he has found very useful. It is easily made up in the following manner :—
Procure a plummer block with a good bearing, three diameters long if possible—there is a certain make of block in cast-iron (no bushes) which is very substantial—and fit • a shaft to it with a pulley about 3 ins. or 4 ins. in .diameter (this will vary, of course, with the diameter of the driving pulley). At the other end of the shaft fit a spider for a fabric universal joint, make a shaft about 6 ins, by in., and fit. two spiders to this. Keep the diameter of the spiders and shaft small or they may vibrate badly if out of balance ; two or three spiders will be required to fit various makes of dynamo and magneto ; two fibre or leather discs will also be required. Sometimes the whole outfit can be obhained from a lorry which is being broken up. A block of hardwood with a V-shaped notch and a fiat (as shown), two long f-in. bolts with fly nuts, and another V block complete the fitting. Keep this fitting low to allow for packing roughly to centre height when required: If the end of a long lathe bed—which is not often required for long work—be available, it is a most convenient place to Ex the outfit, and there will usually be a shaft running over the top on which to fit a suitable driving pulley. If the magneto spiders have fixed studs which just slide into the holes in the leather discs; it makes for easier handling should the dynamo or magneto have to be removed several times during the progress of any one test.