The Engine as a Brake.
Page 13
Page 14
If you've noticed an error in this article please click here to report it so we can fix it.
AKNOWLEDGE of the •braking power afforded by the engine comes to every driVer in time— and all the quicker to the man who possesses mechanical instincts, and who, therefore, .is not hidebound in his driving methods. But, curiously enough, the art of using the engine as a brake never forms part of any course of instruction. Learning of the art must commence with the instruction " Keep your foot off the clutch pedal," whereas tuition. invariably commences with the opposite instruction. The habit of resting the feet on the. pedals must be unlearned, and until it has ceased to be a habit driving on the brake is an art that can never be acquired.
The engine should always be used as a brake, for it is the kindest brake of all, as well as the most powerful—although, of course, it will never entirely arrest the motion of the vehicle. For that the drumgripping brake is necessary. Judging from a remark let fall by the.manager of a small fleet of trade cars recently, we gathered that few drivers of commercial vehicles habitually use the engine as a brake. With the heavy weight of a commercial vehicle and its load, the question of ample brake power becomes important, and as brakes, however powerful, may quite possibly fail through, perhaps, the breaking of a con nection, or for some other cause, it is important that the driver should know and appreciate the' checking power afforded by the engine. When descending steep hills, especially where there are known turns ' in the middle of them, where the bottom ends in a town or village, or where the conditions before him are unknown, the driver should in all cases change into bottom gear before commencing the descent of the hill, and then he can adopt either of two courses. He can do down on the brakes with the clutch out, keeping the pace down to about the speed of the car on the, level when running on the low gear, and at the slightest :indication of the brake having insufficient power to hold the car down to that-speed letting the clutch in, and bringing the engine resistance into operation as a supplement to the brakes. Or, with the low speed engaged at the top of the hill, the throttle may be closed and the car taken down on the engine, using the brakes as supplementary retarding agents to secure full and complete control during the descent of the gradient. The latter method is the one we recommend, as it is not really good practice to hold a. clutch out of engagement when the clutch shaft and male-member are rotating at a high speed. Many h clutch boss has burst through the clutch being held out on a declivity..
What, India Wants.
Peculiarities of the Market for Heavy Duty Vehicles.
Now That the naGtor manufacturing industry of these islands is reduced to a state of flux, and designers, so far as -national exigencies will permit, are threshing out post-bellum ideas, some hints enumerated by an expert-on-the-spot, as expressed to one of our Indian contemporaries, may prove of distinct assistance. It is refreshing to learn that the British-built heavyduty vehicle, despite the embargo on exports, and a clear field beirg left to competitors in trade, still retains pre-eminence. Light 11-ton lorries are distinctly in favour, and have apparently created popular interest from their relatively extensive adoption by the local authorities for ambulance work. In the heavy class, the 4and 5-totners are in greatest demand. According to this authority there should be no departure from standard practice, but the manufacturer should be conservative in advancing the capacity claims of his vehicle. The Indian 'user likes to have ample reserve : he does not like to be bound down to any hard and fast limit. Apparently he is somewhat American in his ideas of loading—a vehicle is not fully laden until it is abso 1 i utely mpossible to carry another ounce. For this reason it is advisable to carry an overload factor of at least 25 per cent. Live axle drive is a sine qua non : the chain is anathema.
In designing heavy-duty vehicles for the Indian market too muth stress cannot be placed upon ample cooling arrangements, The tendency to overload, coupled with the extreme heat which is encountered, renders it essential to provide, inter alia, ample tank and radiator capacity; a powerful pump, wide diameter water pipes without kinks and angles, well-cooled valve chests, and an efficient radiator. So far as the wheels are concerned there is a pronounced reversion to the. wooden wheel. While steel wheels ifre appreciated, their employment at present is attended by a grave disability. In the event of breakdown or injury, repairs are difficult, if not impossible, even in such centres as Bombay and Calcutta. But the native wheelwright is ubiquitous, and is a master of craft. He will build a wheel readily and cheaply Go long as the hub is obtainable. We learn it is essential for all heavy-duty vehicle-s to have a governed engine, and with a governor which may be set to the maximum speed allowed by the police authorities in the districtwhere the lorry is to go on ditty.
"Service." ervice."
A Few Words of Advice to the Horse-sick.
"Service" means requirements, actual conditions and after results. When all these three are reduced to figures, there is a straight problem to tackle, and a merchant, if he acts in co-operation with a sane motor-vehicle salesman, will make motor vehicles a paying proposition. To put it into "tabular" form, the advice to the horse-sick man is:— (a) Put the whole of your transportation department down on paper. Put down what is actually being done, and arrange it so that the work of ea,ch vehicle, each horse or each motor, and each man can be read off successively as a unit. Arrange it RO that the tabulation shows at a glance how routing's arranged, how service is detailed to each vehicle, how each vehicle is detailed to each driver. and how all work is in a, continuous circular way. From this you can find out, what sort of .vehicle you require. That is to say, you won't know what make of carburetter to use or wh it make of van you need, but you know exactly wl at work your vans will have to do. (b) These data, obtained, it is necessary to see the salesman. Go to many, and talk to them all. There are some that know more than others, and they are always ready to give you what they know. And better than the salesmen are the actual users of motor vehicles. Some of these latter data can be obtained from the makers who follow the history of vehicles sold-by them, and so have actual working figures to hand. But if they cannot provide you with figures, you can obtain them by personal inquiry, and by application to THE COMMERCIAL MOTOR. By comparison of all you get in, you can come to a pretty good estimate of existing conditions so far as motor vehicles affect your own particular line of busineas. This is what forms a real study of actual conditions, and it can be supplemented largely by personal observation. Keep your eyes open in the streets, and you will see how many vehicles are used, and often how absurdly great numbers of them are under-worked and overworked. Just translate " under-work " and " overwork " into shillings and pence, and you will understand what not to do when yours is in hand for duty. (c) After the selection of the vehicle, and the purchase and installation of it, if you want that machine to pay, you will have to keep an eye on it, not by literally following-it everywhera, but by getting into your books,with your pen and paper all it costs, does and earns.
How the Electric Scores.
Noteworthy Points Regarding House to House Delivery.
So far as the item of wear and tear is concerned, the electric vehicle scores overwhelmingly. Whereas the petrol-driven car has hundreds of moving parts—eccentric, oscillating, and rotary—the modern electric lorry has very few. Indeed, one of the most popular models has barely 40 moving parts, and all of these are rotary.. In point of acceleration, it is easy to demonstrate the superiority of the electric vehicle. If a five-ton petrol -lorry and a five-ton electric car are started simultaneously in a street, the latter will be first away and on. top 'speed, by which time it will have left its rival well behind. in stepping up from zero to maximum through the controller there is no interference with the persistent forward momentum of the propelling effort. With the petrol ear there are two distinct breaks. After the first speed has been clipped in, the changes from first to second, and second to top, successively demand that the clutch shall be lifted twice to bring the respective gears" into operation. No matter how slickly changing speed may be effected, at each change the transmission of the power from the engine to the driving wheels is interrupted, and there is a fall in the speed, which has to be recovered before the additional impetus can be attained. Consider house-to-house delivery, which probably comprises 75 per cent. of inter-urban commercial traffic. A dozen stops Amy have to be made within 100 yards. To attempt such work with a petrol-driven car is tantamount to utilizing the most expensive transportation system available: The actual deliveries, that is, movement of the man from car to door and back, may not represent more than 3 mins. in the aggregate, but there are the delays inseparable from the door to be taken into consideration, which, as dead time, may aggregate 10 mins., so that 7 mine, work of the motor in that street is wasted. While the electric vehicle is likewise subjected to equivalent stopping and restarting efforts, such exercise no ill-effects upon the mechanism, are more easily and promptly achieved, while the value of 7 mins, fuel as well as motor wear and tear are saved. Even if the car be subjected to a definite run between two points, such as between a warehouse and a railway terminus, the electric vehicle scores.