HINTS ON MAINTENANCE.
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How to Get the Best Out of a Vehicle, to CONTRIBUTIONS are invited for this page from fleet managers, drivers, garage foremen and mechanics, works staff and draughtsmen, and will be paid for on a generous scale. Every system, make, and type of commercial motor vehicle will be dealt with, and the matter should be written with a view to the disclosure of workshop and garage practice in the maintenance of a vehicle—practices Secure Reliability and to Avoid Troubles.
which, whilst they may be quite normal, are peculiar to the particular vehicle and may not be generally known to those responsible for its running. Expedients and suggestions for overcoming roadside and other troubles are covered in the following page, headed " Roadside and Garage." Communications should be addressed to "The Editor, The Commercial Motor, 7-15, Rosebery Avenue, London, E.C. 1."
47.—Removing Napier Road Wheels. In the two ton Napier chassis one of the advantage's incorporated in the design is that, in order to remove the road wheels for re-tyring or for any other reason, it. is unnecessary to removejhe, hubs. The bolts securing the wheels to the hubs should be removed and the wheels can then be drawn off, leaving the hubs in situ. When replacing the wheels, see that the hubs are quite dean, and if a little oil is smeared over them, it will be found that the wheels can be replaced more easily, and the oil will ensure that the wheels can be removed quite freely the next time it is required to take them off.
48.—Reducing Petrol Consumption on an A.E.C. The carburetter is often the first thing to be blamed for heavy petrol consumption, when it should he the last. The elasS of work undertaken should always be taken into consideration ; traffic work and frequent stopping and starting all count against good consumption. If a vehicle gives a good mileage on test, say, with one gallon of petrol, but at the end of a week's running the consumption is found to be excessive, it is time that the driver looked for reasons outside the actual tuning up of the carburetter. Before attempting to tune up the carburetter, attend to the following points: Grind the valves ; adjust the tappets to .00e in. with the engine warm ; check the magneto timing ; adjust the make-andbreak points to a gauge supplied by the 'makers of the magneto ; clean the distributor and collector ring ; adjust the plug points ; ensure that the water pipes to and from the carburetter adapter (waterlacketed induction pipe) are quite clear. This is important, as a good circulation-of hot water through the jacket is essential. Tffey can be cleaned out by heating to a dull red and cooling off quickly in cold water. This not only loosens the deposit, but also anneals the pipes, so that there is less danger of breakage. In some of the earlier chassis the water pipes are made of steel, and these should be cooled slowly. Next see that there are no air leaks at the indues tion pipe joints; make certain that the silencer is not choked'•' see that the brake shoes are not rubbing on the brake drums; and check the level of petrol In the float chamber. .1334 If the vehicle is a second-hand one, it is advisable to fit a stanslardsjet, as in many cases the old jets have been opened out or closed up.
49.—The Care of Steam Glands. There are numerous glands to be looked after on the average steam wagon, and it is only by paying systematic attention to these that the engine efficiency can be maintained. It is quite possbile to cause serious damage by tightening them up or packing badly, and to replace a defective piston or slide valve gland it is usually, necessary to remove the piston red from the cross-head ; to fit a new stud it may be necessary to remove the whole cylinder before the broken stud can be drilled out. The glands should be tightened up before they start blowing. The packing should be cut in lengths and, when inserting it, the joints should be crossed. In some eases the ends are cut at an angle of 45 degrees, but if the joints are arranged to 'be opposite each other there cannot be any blowing. The packing should be of the exact size, ass hammering it is a bad practice, the strands being disarranged, also it is much harder to tighten up. After each ring of pack ing is inserted the gland should screwed up in order to bed it in properly. If this be done, after the packing is completed. the glands nuts need not be mach more than finger-tight ; in any case, only a short spanner should be employed._ To keep the glands steam tight, priming should be avoided, also starting with the cylinder cocks shut after a lengthy stop. Pulling up against steam and by means of the reverse is also bad practice. If trouble is still experienced it will be found beneficial to soak the packing in svarrn tallow before fitting.
During the overhaul of motor vehicles, and especially of steam wagons, it is often necessary to test the amount of play in the brasses, particularly of the crankshaft. As the weight of the flywheel is considerable it is not always easy to de this, and the end of the crankshaft must he levered up in some manner. A pinch bar and a block of• wood are often employed, but a useful permanent device can easily be made. Its construction will be seen in h the sketch
A simple tool for testing bearings.
which we reproduce. It consists Of an upright made from two pieces of stout wood separated by distance pieces at top and
bottom ; through these distance pieces are passed bolts holding the uprights and distance pieces firmly together. The lever can be made either of 'wood or metal, but a stout piece of wood is usually quite satisfactory. This is placed between the two uprights and fularumed on a phi Which is pushed through holes in the latter and in the lever. The width of the latter gives the length oi the distance pieces for the uprights. By drilling a, number of holes in the uprights and in the lever the whole device is made adjustable to suit the varying requirements of users of different types Of vehicles.