LOCATING FAULTS

Press, Volume LXXI, Issue 21411, 1 March 1935, Page 8

LOCATING FAULTS

CARE OF ELECTRICAL EQUIPMENT J . I i ADVICE TO THE INEXPERT i Because the average motorist is not Of an electrical turn of mind, he seems to have more trouble treating and remedying faults in the electrical system of his car than with any other part of its mechanism. Most electrical matters appear Chinese puzzles to him, and the mere thought of groping amongst the mysterious wires and instruments that the bonnet and dash conceal is enough to cause him to seek the repair man at once, even though in reality some very simple fault may be causing the trouble. Like any other feature of the car, the more the owner knows concerning its electrical system the better off he is, for he can diagnose the troubles that are inevitable sooner or later, and can better guard against difficulties through intelligent care. The first thing to do is to get clearly in mind just what the function of each unit is. understand how it operates and what it controls, and figure out the wiring through careful study of the diagram going with the car. Having clearly in mind what each unit is for, the owner will be surprised how readily he will determine when anything is wrong, and why any particular part of the electrical system does not function as it should.

Process of Elimination Locating troubles in electric starting, lighting, and ignition systems largely is a matterjof eliminating one possibility after fanother, and then reasoning out which unit is not functioning properly in the part located as being defective. The most common causes of open circuits are loose connexions, faulty lamp sockets and connexions, switches, and fuses. If all lamps fail to light, the 1 rouble obviously is in wiring common to all, as all lamps hardly would burn out at the same time. Usually the trouble will be found in a loo.se connexion or broken wire between the switch and battery or in the contacts of the switch. If only one lamp or the lamps on one circuit fail to light, the trouble is in the wiring belonging to that circuit only. Exchanging bulbs with another circuit which lights properly will indicate whether the fault is in burnt-out bulbs. In the same way an exchange of fuses at the switch box will tell whether the fuse has burned out. All switch and generator connexions should be checked up to see if they are tight. The dashboard ammeter will indicate discharge, when all switches are open, if there is a short circuit between it and the lamps. It will not indicate, however, if the "short" is between itself and the battery. If the ignition fails absolutely, and the engine refuses to start the trouble must be in those parts of the system which assist in the production of the sparks for all cylinders. It is not impossible for all of the sparking plugs to be faulty, of course, but such a condition is extremely unlikely. In detection of sparking plug faults, the method of substitution is useful. A new plug, known to be in good condition, is substituted for one suspected, and if this makes no change there is nothing wrong with the original plug.

OIL ECONOMY CHASSIS LUBKICATION ATTENTIONS Except with those cars that have a centralised system of chassis lubrication—where a stroke or two of an oil-pump plunger, projecting usually through the front floor, serves to supply lubricant to all the bearings of the springs, brake gear, steering, etc. —a bugbear of the conscientious owner-driver is the need for periodically using an oil-gun or a grease-gun on any number from halt a dozen to 20 nipples. It is a tiresome job; and one that becomes more tiresome the longer it is deferred, for the reason that in course of time—no longer than a month in some cases or less than that on a car used every day—the lubricant in the bearing passages tends to solidify and to refuse to move on when the gun is next used. Time, energy, and oil (or grease) are economised, therefore, if attention to chassis lubrication is given frequently. A good plan is to keep a gun charged ready for immediate use, in an accessible position in the garage, and to use it* once a week sparingly, at the following points: Front and rear spring shackle pins, steering swivel nipples, steering-rod joints, and brake camshaft bearings. Only five minutes is occupied, and the lubricant enters each nipple without heavy pressure on the gun. Once a month other nipples are attended to. They are under the bonnet (fan shaft, steering box, etc.), where the old lubricant keeps fluid owing to the warmth of the engine. On the same occasion an oil-can is applied to all joints of brake rods, throttle, ignition, and other details with the object not only of keeping them lubricated, but also of preventing rattle due to wear.

The following points are worthy of note, in replenishing gear-box and rear axle lubrication. In both gearbox and axle it is highly desirable that a good brand of gear oil should be used; an inferior quality is uneconomical in the long run, no matter how cheap it may be to buy. The gear-box and rear axle should always have their oil level tested just after the car has returned from a run, so that the oil shall be in a fluid state, due to its temperature having risen with use. Testing the level of a thick gear oil when it is cold is prone to result in a "false reading," and the same applies to replenishment. A car should never be run for longer than 12 months with the same oil, plus replenishments. Oil deteriorates in lubricating qualities, and becomes contaminated with minute but harmful particles of metal. In special transmission, such as the self-charging gear-box and the fluid flywheel, no oil other than those recommended by the car makers should ever be used.

I A very comfortable air mattress for camping can be made out of six old inner tubes, providing that they are in sufficiently good repair to remain inflated. An old mattress cover is opened along one end and stitched into three sections from end to end. The inner tubes are doubled and pushed into the mattress cover with two in each section. Care should be taken that the valves are at the open ends. Pieces of tape can be sewn to the ends of the cover so that it can be closed, and when the mattress is required for use it is only necessary to inflate the tubes to a moderately low pressure. For a vehicle safely to overtake and pass another travelling at 40 miles an hour on a road where speeds of 50 miles an hour may be expected, the driver overtaking must have at least 900 feet of clear road ahead. In overtaking a slower vehicle, travelling at 20 miles an hour, there must be 650 feet of clear road ahead, made up to 200 feet for the overtaking vehicle, plus 450 feet for a vehicle approaching at 50 miles an hour. Commenting on these facts, disclosed in tests made in the United States under the control of the National Bureau of Standards, the Commissioner for Road Transport (Mr S. A. Maddocks) says that motorists would do well to bear them in mind. Statistics indicate that 20 persons were killed and 315 injured during the year ended June 30, 1934, in accidents caused through overtaking without sufficient clearance. In ihe three months ended September 30 six persons were killed and 82 injured through the same causa. _ A u^.Uut^M.u