MOTORING NOTES

Te Awamutu Courier, Volume 25, Issue 3766, 8 June 1936, Page 7

MOTORING NOTES

WHAT TO LOOK FOR, AND W HERE.

WHEN YOUR VEHICLE GIVES * OUT -

(Reprinted from The World’s Carrier, London,)

It matters not how careful the owner of a fleet of road, goods-carry-ing vehicles may be—no matter how much thought he may expend daily in the endeavour to avoid trouble—breakdowns and stoppages on the road, from some cause or other, are bound to occur. These little things are (shall we say) sent to try even the most painstaking and longsighted in the carrying business, and one can only anticipate what is likely to happen and prepare accordingly. THE HUMAN ELEMENT. Man is man’s biggest enemy in any mechanical venture. The machine performs most perfectly without man’s presence, or when man’s attention is devoted to the simplest routine. Because a machine is man made it Breaks down and fails us nine times out of ten, as a result of the human element necessary in its maintenance and manufacture.

From what follows it will be seen that the most frequent breakdown is due to back axle trouble. If Driver “ X ” treats his vehicle in the manner the designers intended it to be treated, the back axle will perform its function perfectly for years—provided that Fitter “Y” attends to it as the designers intended. Driver “X” is supposed to notice all peculiarities and report them for immediate attention to Fitter “Y,” who will be checked by Foreman “ Z,” who gets his maintenance directions from Messrs “ ? ”

Yes! The human element has many opportunities for creeping in. Driver “ X ” at the end of a long day may be tired, careless and indifferent He may let the clutch in with a bang that will almost demand an echoing snap from an exhausted back axle.

All this points to a combination of fallibility in man and maintenance—two things impossible to compete against indefinitely—-and they are the Human Element Remember this when trouble is experienced. Cheek up on your Jonahs, and from your personal knowledge of them whether the collection of breakdowns which they gather are due to more human element being allowed to creep into the work than is profitable for you. But to particularise and to suggest what to do in an emergency:—

There are two kinds of stoppages: those which a driver can himself rectify on the road and those for the overcoming of which a driver has to ask for assistance., Therefore, before phoning for assistance, the driver should know as accurately as possible what has gone wrong, so that essential parts and tackle may be brought to him. While waiting for assistance he should start dismantling his machine. TRANSMISSION. Failure in most cases is not repairable on the road. BACK AXLE SHAFT FRACTURE. Ensure that the transmission is continuous to back axles by inspection.

Jack up each wheel in turn and start up the engine, engage gear and gently ease in the clutch. If the jacked-up wheel does not turn, then it is apparent that the shaft is at fault, provided that the transmission is in order as far as the shaft. COLLAPSED BALL RACES. Their failure will be fairly evident from the rock or wobble of the wheel and possible noise. In practically all instances this failure is attended by excessive localised heat. STRIPPED CROWN WHEEL AND PINION AND DIFFERENTIAL TROUBLE. Both wheels will remain stationary or behave abnormally when tested as for back axle shaft fracture. There will also be a local noise. Before towing, both shafts should be removed. Local heat is again a symptom of failure, and if this is noticed at an early stage the cost of a new crown wheel and pinion may be saved. Differential Trouble.—When this is suspected one or more of the shafts should be removed before the vehicle is towed to its home depot. SLIPPING CLUTCH AND CLUTCH WITHDRAWAL GEAR. A slipping clutch may be due to the need for adjustment, in which case a roadside repair may be effected, but if there is oil on the plates (dry plate type) then a temporary “ repair ” can be made by sluicing out with petrol and dressing with resin or fuller’s earth. BROKEN SPRINGS. Although not part of the transmission these may be properly included under this heading, and in haulage work they rank with pride of place with transmission failures. Inspection will determine whether the vehicle is in a safe state to continue to the nearest repair depot. An effective temporary repair can bften be made by placing a block between spring mounting and chassis and roping round forward end of spring to ensure that spring and axle will not be swept back. >. , PETROL FAILURE. This is notoriously bad after overhaul of the petrol system, due to scale from pipes and tanks getting loose into the system. In these days of clean petrol and improved carburetters, jets do not often have to be dismantled for cleaning, but they do sometimes give trouble after the tank has been allowed to run dry. The last few revolutions of the engine draw up residue that normally exists harmlessly on the bottom of the tank. A few spanners and patience will put right trouble experienced on this score. AUTOVACS. A great deal of inconvenience and delay can be caused by these, especially as the trouble is often difficult to locate. One of the most common causes is due to the valve sticking in the suction elbow. The symptom of this is the carburetter running dry. A temporary measure, and one that will get the vehicle to the nearest repair depot, is to remove the top of the Autovac and fill the body with petrol. It may he necessary to do this a number of times before assistance can be obtained and the elbow changed. A sticking or broken clack valve will cause similar

symptoms. Other failures may be due to broken Autovac top joint, punctured float, broken float, spring or faulty air valve. The remedy is self evident. The thing to do here is check all filters in the system and clean where necessary. IGNITION FAILURE. To the experienced mechanic, and to the average driver, the location of faults in any ignition system does not present much difficulty. Failure can be localised by a. systematic check, and a quick diagnosis of the fault by the driver, which may be made at the roadside, will save time. MISFIRING. May be caused by a faulty plug, broken wire, loose terminal, water on the plug insulator or cracked distributor. A few minutes only should be required to discover the actual cause. COMPLETE FAILURE. (a) In the case of magneto ignition this may be caused by a faulty earth lead, which defect may be quickly checked by removing the lead or earth cap from the magneto and seeing if the engine will then start. (b) Contact points sticking open, generally due to the contact breaker arm Sticking on its pivot. Cleaning and easing will cure this. (c) A further failure may be due to a broken contact breaker spring. The quickest method of checking magneto defects, if it is suspected that the magneto itself is defective, is to remove it, taking care to note, by means of a scratch across the coupling, the magneto’s position for replacing. A spark should easily be obtained, by spinning it by hand, and if none is obtained and as far as can be seen everything is in order, then it is obvious that the magneto must be replaced. Before finally deciding that the magneto is no use it would be as well to check the brushes and contact breaker spring. The failure may be due to a broken timing chain or coupling, cracked slip ring, faulty armature or condenser. Beware of the magneto that produces a spark in the open air but will fail under the pressure in the cylinder head. A faulty condenser is to blame in this case.

The main object is for the driver to locate the failure, and if he is unable to effect a repair, to be able to give useful information when phoning for assistance.

For coil ignition the coil must be suspected, and, if it is not working, no spark will be produced when the points are opened with current switched on. ENGINE FAILURES. As a rule mechanical failure cannot be made good on the road, though a cylinder head gasket might be changed if a. spare was easily procurable and the driver had sufficient technical knowledge.

The following is a list of failures in order of frequency:—Blown cylinder head gasket, big end failure, stripped magneto vernier coupling, broken pistons, broken valves on overhead valve engines, and broken timing chains.

Failures are due in the majority of instances to lack of maintenance, and to abuse, as much as to structural weakness, and the same can be said of most other failures. In conclusion it may be said that a driver who abuses his vehicle, who disregards the oil pressure gauge, peculiarities and changes in vibration and noise, who takes no heed of oil and water levels, and who puts stresses on his vehicle for which it was not designed, is not the best type of man to have in one’s employ.