VETTING THE SECOND-HAND VEHICLE.
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Hints to Prospective Buyers of Vehicles which Have Seen Service. What to Examine and How to Examine It.
BEFORE PURCHASING a second-hand commercial vehicle, there are many important points which should receive full consideration, and unless this be done there is a likely prospect of the purchaser obtaining a "pig in a poke." No sane man would think of buying a horse without knowing something (or getting advice from someone who knows) about horse flesh and without examining its teeth, but as regards motor vehicles, many, otherwise well-balanced, persons appear to be altogether too prone to accept the statements of the vendor, not realizing, perhaps, that it is not difficult to vet. the chassis.
Technical Knowledge Necessary When Making a Choice. .
The first important point, then, is to take several grains of salt with everything said about a, machine by interested persons', even if the statements seem to ring true. Again, what is left unsaid may cover a multitude of sins, and it is up to the buyer to find out the worst of these sins for himself, if he has not some friend with technical knowledge to assist him in his choice. .
When he has decided to purchase a vehicle, the prospective buyer should make absolutely certain as to what he requires before setting out. . Business acquaintances or friends may recommend the purchase of a certain vehicle because it is in good condition, but it is useless for him to buy a five-tormer when what he wants in his business is a two-tonner, and the reverse holds good. • it must. be remembered that a vehicle, which is constantly running only partially laden, is a constant drain upon the pocket, whilst one running constantly with more than the load for which it was designed is very liable to serious breakdowns. He must, therefore, be quite certain in his oi.vn mind as regards the weight-carrying capacity required.
The type of body is also an important consideration, as the fitting of a new one may add considerably to the total expenditure. .
Age of Chassis and Reputation of Maker Should Be Considered.
When the type of vehicle to purchase has been finally decided, the next thing to do is to find one which meets the requirements as nearly as possible. A satisfactory way to do this is to get into touch with some reliable dealer in second-hand vehicles— not so much the man who does this as a side line, but a reliable concern which has a reputation to maintainSome Of -these overhaul the machines and issue them under a guarantee, but, naturally, such services are reflected in the prices, and these may be beyond the pocket of our purchaser.
A second, and often. very, satisfactory, method is to scan the small advertisements 'in this and other joarnals, from which news-of many bargains can be obtained. Remember that, to a great extent, the value of a vehicle depends upon its age and the reputation of its manufacturer. Apparent bargains may prove costly at the finish, if spare parts are not readily obtainable and have to be specially manufac
tured. As a matter of fact, a large proportion of the correspondence in our enquiry bureau concerns spares for vehicles—chiefly of foreign origin—whose manufacturers or agents cannot be traced without difficulty, and often not at all ; even when traced, it is sometimes difficult to obtain the spare parts required.
Unless a vehicle is in a particularly good state of repair it is usually inadvisable to purchase one which is more than five years old. It must be remembered that, theoretically, a lorry is Worth nothing after it has run a distance -of. 125,000 miles, so it is as well to find out, if possible, its approximate total mileage.
Having found what, to all appearances, seems a. likely machine, the buyer must now prove whether its beauty is only skin deep or otherwise. Appearances are often deceptive. A. coat of paint and a little varnish may turn a palpable " dud,' into quite a showy, though hardly more valuable, article.
Parts to Examine and Methods to Employ in the Examination.
It is advisable before inspecting the machine to have the body removed, if that is possible without causing too much trouble, so that those parts which matter can be inspected more minutely. Then, start at one end of the chassis, and work towards the other. It is usually better to commence with the power unit as, if that is worn out, the inspection can be brought to a timely end and no more trouble need be taken. If possible, have the cylinders lifted so that attention can be paid to such important details as scores or signs of uneven wear in the cylinder hares, cracked pistons, and play in the small and big ends. The cover of the timing gear case should also be removed where possible, the timing gears exa,mined for "wear or broken teeth, and the smaller bearings tested forundue wear. The crankshaft bearings can also he tested by endeavouring to rock the cranlvhaft up and down at each end. NA• hile • this is beingdone the clutch should be withdrawn as, otherwise, end play Will not be apparent. If time and circumstances do not permit of the removal of the cylinders, the machine should be taken out and the engine run at various speeds to detect knocks or .piston slap. The compression of the various cylinders should be tested after the engine has been running for a short time. if hissing noises are produced and the compression is weak, it is important to find where the loss of compression occurs. If at the valves, unless one or more of the valve seats be cracked, it is not very important, but if th-e loss is occurring past the pistons it may be due to scores in the cylinders. Small engine knocks can be located 'conveniently by using an ordinary walking stick as a stethoscope, the ferrule of the stick being placed against the various parts a the cylinders and the other end against the ear. Careful examination should be made for cracked crankcase arms and also for cracks-in the water jackets, and it should be noted whether the pump is working satisfactorily, or otherwise.
The Clutch and Gearbox Should Receive
Following along the chassis, the next component to be examined is the clutch, and the way tautest this for signs of slipping is to hold the clutch out, put the gear into topspeed, keep both brakes hard on,
and let the clutch in slowly with the engine running at a fair speed ; the clutch must, of course, not be let right in, otherwisesomething may have to go, but as to whether the clutch friction is sufficient or otherwise can easily he determined by this method.
Some clutch shafts are provided with two universal joints, others with one ; but, in any case, these should be examined for wear.
The cover of the gearbox should be lifted and the condition of the teeth of the gearwheels and ball races ascertained. A little wear on the sides of the teeth, where these slide into engagement, is not of great consequence ; but if the teeth themselves are pitted and ridged they 'will not last much longer. Where dog clutches are embodied, the condition of the dogs is very important as, if worn badly, they are very liable to ilide out of engagement while the vehicle is running. Any play in the ball bearings may have serious consequences, as the balls are very likely to break and, in any ease, the painions are not meshing at their correct pitch circles. The gears should also be examined in their various engaged positions, as wear on the connections and on the change-speed forks may prevent them from meshing over the full width of their.faces.
Cardan joints are often a. source of considerable trouble and noise and, if slack, the drive is taken up with a jerk, which puts considerable stresses on the final drive gears. Where thojoints are of the ordinary star type, signs of wear can easily be detected ; but where leather or fabric joints are employed, these should be examined carefully for sip's of cracking and disintegration of the plies. If either of these two faults is present, there islittle likelihood of the joints standing up to their work for any length of time.
Points to Look For When Examining Rear Axle.
Now we come to bne of the most important units of the chassis, that is to say the rear axle. Wherever inspection plates or covers are provided, these should be removed and the condition of the gears minutely examined. One rear wheel should be jacked lip and the top gear put into mesh by rocking the wheel from side to side, slackness in the transmission can easily be ascertained by the amount of play in the wheel. By jacking up both wheels and keeping the footbrake hard on, if this operates through the final drive, and again rocking one or other of the rear wheels, any play in the differential gearing can be detected. A certain amount Of play must naturally always be present, but this should not be excessive. ' If this is so, it is better to have the axle right down rather than risk failure in the.nearyfuture.
Whilst the rear wheels are jacked up is an opportune time ifor testing them for slackness on their bearings and for end plaY. At the same time, the hub caps should beremoved and the wheel retaining nuts and the threaded ends of the axle examined. In certain makes, the threads on the axle ends and in the nuts wear badly, and then there is a danger of the wheels coming off whilst the vehicle is in operation. The .brake drums are apt to wear thin after considerable use, and there is a possibility of these being worn right through in a short time.
After Inspection of Important Components, Details Require Attention.
The inspection has now been made from end to end of the chassis, but there are still a few points which require examination. Each front wheel should he jacked up and its bearings tested for wear, which is shown by side wobble, and whilst at this point a very thorough examination should be made of the steering connettions to •see that these are all shipshape. Play of the steering Wheelis of great importance and should never exceed three or four inches.
Finally, the frame should be examined for cracks. These may quite easily be hidden by dirt and oil ; therefore points where weaknesses are likely to occur should be scraped clean. In some vehicles cracks occur where the dumb-irons enter the channel section sidemembers in others they occur at the underside of the channels at about the neighbourhood of the gearbox, and where holes are drilled through the side'members particular attention should be paid, as cracks often extend from one hole to the other. Fortunately frame cracks do not occur to any great extent in this country because the roads are comparatively good, but there was a great prevalence of them in France, and returned war vehicles should be examined for this fault more particularly. Another fault which occurs in frames is the loosening of the rivets employed for fastening the cross-members and at other points. It is a costly and somewhat difficult task to tighten these effectively; that iswhy so many makers are now using bolts throughout the chassis instead of rivets.
Although these hints are naturally brief, as the scope is such a large one we trust that they will be of some use to intending buyers. Many other points could be dealt with, but we-have confined our advice to the details which should receive primary consideration.