Preventive Maintenance a Necessity
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A UTHORITIES to-day are much
more interested, than in the past, in the condition of vehicles in use on the roads, and rightly so. Therefore, to avoid the receipt of those annoying little papers prohibiting the use of a vehicle until certain work has been done, periodic examination should be made, which will take only a few minutes if done systematically.
For this purpose I will itemize those points which an examiner will inspect once his attention has been drawn to a vehicle by one or other of the more obvious defects, so let us embark upon a tour of inspection of a vehicle, having in mind the safety of the general public.
Tyre Examination.
First and foremost come the lyre treads. Are these worn smooth? We must also inspect the walls, to see if springs or steering gear have caused any damage, whilst a glance between the rear twins -to ascertain if stones have been jammed there and have chafed the tyre inner walls, is advisable.
Now we turn to the steering joints, for obvious reasons, and the swivel pins and bushes. We also examine the hub races while the wheels are jacked up. This near-side front hub race is slack, and if the brake facings are somewhat thin, the lorry might be ditched by those races. You ask why? Well, with races slack like that, every time you apply the brakes you have first to lift the whole vehicle, until the drum is in correct alignment. This can easily tear off a thin facing which may lock the wheel and take the steering out of the driver's hands.
Spring Maintenance.
Next we investigate the spring shackles. If slack they are a common cause a wheel wobble. Now for the spring cambers. On some vehicles, where the steering arm passes over the top of the axle beam, a badly deflected spring will cause the steering to lock under certain conditions. Those loose U bolts must be tightened, too, or you will have a broken spring, and anyway, with rod or cable-operated brakes, your axle beam moves out of true alignment with the rear axle and braking efficiency is seriously impaired. Moreover, if the rear axle moves a smashed propeller shaft may result.
a30 These details more or less cover the running gear; now let us take a look at the body. What's this? Now what do you think would happen to a person hit by this split wing?
I see yotudepend on some pieces of wood to retain the body sides in pa. silion. These may give way and cause your load, to fall on someone's head; you must have proper tapered wedges and chains there please.
Your cab is in a bad state. Here, jot these down for immediate atten tion. (1) Driving-mirror silvering peeled off, (2) screen-glass laminations separated causing bad discoloration, (3) off-side-door striking plate worn, and door closing only on safety step, (4) bad-fitting seat cushion preventing full travel of hand brake, (5) speedometar cable broken.
Legal and Practical Lighting Requirements.
Lastly, the lights; these wing-lamp bulbs have not got their wattage marked on them; you have a' clear glass in one of your head lamps, and the off-side head lamp would direct its light straight into the eyes of oncoming drivers.
Well, there we are ; attend to these points, and you will have a roadworthy lorry, but you can quite understand why it must not go out till they're done, It is in the interest of everyone to see that such matters as these are promptly dealt with before discredit is brought upon the industry in general.
Reverting to the question of fronttyre wear, where vehicles are operating in narrow streets, particularly those adjacent to dock areas in which considerable shunting is done, I consider the small amount of time spent in accurately checking front-wheel alignment, at regular intervals of, say, once a month, or even twice, will be amply repaid by a substantial reduction in the tyre bill. Also, because kerb fouling and jumping submits the whole steering to such heavy shocks, it would be as well, at the same time, to check steering-arm, • and drop-arm bolts and nuts for tightness, likewise steering-box-support bolts.
One can hardly over-stress the importance of not only keeping accurate petrol and oil consumption figures, but of comparing them with previous figures and with those returned by other vehicles of similar type on the same class of work. In this connection I often encounter complaints of heavy petrol consumption which, in reality, should never be brought to me at all, because when I examine the operator's figures, and find that the m.p.g. for the vehicle in question have recently dropped, I know perfectly well it is not a question of changing jets or giving attention to any latent defect,
Checking Compression.
My first request, in such a case, after I have, checked over the petrol system for leaks, is for the starting handle, and, sure enough, in the majority of cases, I discover a loss of compression. So here again is a case for checking at regular intervals, because in these days of electric starters a driver seldom has any need to engage the handle, with the result that the state of compression is not known unless deliberately checked.
While on the subject of petrol consumption, I think, where a large fleet is concerned, there is much to commend a graph for this important figure, because so much information can be obtained from it, literally at a glance. To mention one factor a graph reveals, the influence of temperature on consumption is clearly shown, and this brings home the need for making such adjustments as are necessary to maintain as constant a figure as is possible.
Freeing Brake Linkage.
Another commonly neglected point is the effort required to operate a mechanical brake when the joints in the rod linkage are partially seized, especially, in a system employing compensator mechanism. The consequence is a loss in efficiency, although happily the more general use of hydraulic brakes is reducing the need for this attention. Even so, with many types of brake operation, the ordinary shoe fulcrum pins are used, and these, if partially seized, will considerably reduce efficiency, and possibly prevent the return
springs from functioning so that the brakes bind.
From drivers of vehicles carrying heavy loads, I often hear complaints of rear-axle trouble, which all show by examination of the parts to be due to overheating through loss of oil In this connection, I would emphasize the importance of checking axle-centre case bolts, where the banjo-type of casing is not used, because there is a strong tendency for the halves of the casing to pull apart, when heavily stressed, and stretch the bolts, allowing oil to escape from the underside of the joint.
I have encountered instances, of this sort, where bolts were pulled down to the ends of the threads and screws to the bottoms of their holes, but were not seating on the casing flange, having stretched to such an extent.
To sum up this question of pre
ventive maintenance, it is noticeable that, as a general rule, the small operator has not realized its importance, and although costs are just as important to him as tc . the big organization — probably more so — he seldom makes any effort to compile figures which will show him how his losses take place. To these gentlemen I would say that preventive me,intenance is no luxury, but a necessity. R.D.