ON CULTIVATING THE USE of the GEAR BOX.
ON CULTIVATING THE USE of the GEAR BOX.
By MAJOR C. M. HARVEY.
OF all subjects beloved by motor scribes that of Gear Changing is, perhaps, the most popular, and therefore, from the reader's point of view, the most hackneyed. But, with all that has been written, there is still much to be said about the gentle art of manipulating the gear lever, most people being too much inclined to begin and finish their comments with the gear box itself and with the driver ; who, by the way, is generally assumed to be a novice and unacquainted with the niceties of double-clutching, and so forth.
The 5 to 50 m.p.h. on Top Gear Car.
To my mind, nothing is more calculated to encourage a lazy and inefficient style of driving than the oftrepeated statement that such-and-such a car can be driven from "five to fifty miles an hour on top gear." The intention of the advertisers is to convey the impression of the wonderful flexibility of their engines, but is too often taken by the novice as advice on how the car should be driven.
One can drive many modern cars almost continuously on top gear, and many drivers do, but the result can be discovered later, on examining the details of their repair bills. The virtue of top gear driving at all times can be vastly over-estimated, and in the following notes I propose to point out why the use of the gears should be cultivated, and also to enumerate some of the benefits accruing from a proper appreciation of the muchmaligned gear box.
Quick v. Fast Driving.
There are very few motorists who are not agreed as to the fascination of speed, regulated, of course, by a due consideration for the safety of other road users ; but whereas fast driving can only be indulged in at comparatively rare intervals, quick driving is a joy more easily obtained. Fast driving means that one hangs on to the maximum m.p.h. as long as possible on wide, open roads. It may take a mile, or even more, to get a really fast car into its best stride, whereas the pleasures of "
quick" driving are to be found when making very short journeys, such as the morning run up to the office, or the evening refresher.
If one pays due attention to the matter of engine tuning, an enormous amount of real driving pleasure can be got out of the r-h.p. type of car, preferably fitted with a four-speed gear box. One notices, on driving such a car, that it is possible to travel at much higher average speeds than those attained by the "all on top" gear class of driver, even though he be at the wheel of a much higher-powered car.
But, for " quick" driving, one must understand how to make the best use of the gears, and become adept in the art of rapid gear changing. Furthermore, the proper use of the gears is a great factor in economy of maintenance, for one can do far more harm to an engine by the perpetual labouring on top gear than when driving on the gears so as to minimise the stresses in taking up the drive.
Lessons from Competition Drivers.
Those who have watched the remarkable acceleration —or getaways—of competition drivers in various events, cannot but notice the ease with which the gears are manipulated. Hill climbs and short speed trials resolve almost entirely into a question of gear changing at the right instant, and one can learn a great deal by studying the gear changing of first-class competition drivers.
Novices are rather inclined to consider the difficulties of gear changing as being a matter of their own inexperience and the internal mechanism of the gear box, entirely overlooking the fact that other things are of equal importance. For instance, it is impossible to change gear properly on a car with a badly-adjusted carburettor, the presence of the much-discussed "flatspot "being quite enough to upset what otherwise might have been a perfect change. Quick acceleration is an absolute essential in changing from a high gear to a lower, and, unless the engine will respond immediately to the slightest touch of the accelerator, one may strive in vain to effect a quick and silent change on a steep hill, or even on level ground.
It is all very well to advise drivers to pay attention to getting the engine speed right before attempting the change, but few instructors make any reference to the influence of a well-tuned carburettor in this respect.
Then, again, for changing from a low gear to a higher, the engine must be capable of dropping quickly to a low number of revolutions per minute. This, again, calls for a sensitive carburettor, which will permit the engine to tick over steadily on the pilot jet, without the risk of an unpremeditated stop. Thus an air leak on the induction pipe, or worn valve guides, are quite sufficient to prevent good gear changing, by hindering the slow running of the engine, though the connection between an air leak or worn valve guides and gear changing may not be very obvious at first.
Other Factors Influencing Gear Changing.
As the matter of gear box design is one over which the owner has little control, we will not discuss the technical points connected therewith at present, though in passing it may be remarked that one should be careful when purchasing a new car, to select one with gear ratios suitable for the particular part of the country in which one resides. For example, in some parts of the country the hills are too steep to be tackled by small cars unless the bottom gear has a ratio of not less than 16 to 1. Cars built for Continental roads and imported for use in this country are sometimes provided with excessively high gearing, and a few weeks ago I was driving a very high-powered French car with a three-speed gear box, the top gear ratio being 3 to 1, which had to be driven very hard to keep in front of a small 4-h.p. English car (four-speed) along a tortuous route. This goes to show the importance of selecting the correct gear ratios, if one desires to make the best use of the gear box. To secure a quick change, the clutch must not only engage accurately, but must also be capable of rapid
disengagement with the minimum amount of effort, and in this respect those of the single disc variety have a great advantage. Another very important point is that of absolute freedom of the clutch on its spigot, for, unless this bearing is kept well lubricated, some time elapses between the time when the clutch pedal is depressed and the full release of the drive from the engine to the gear box.
Anything that tends to interfere with the free running of the chassis, such as a binding brake, or a stiff wheel bearing, is inclined to upset one's calculations when endeavouring to make accurate gear changes, these minor points being frequently overlooked. A comfortable and convenient driving position is a very great asset in good gear changing, for if the arms or hands are unduly cramped, it is impossible to get a good control over the gear lever. At the same time, the position of the clutch and accelerator in relation to one another is most important, and these must be located so as to avoid undue driving fatigue. I remember having considerable difficulty in making good changes on one well-known make of car, owing to the cramped position of the gear lever, but on altering the position of the adjustable steering column, and thus raising the
wheel slightly, there was sufficient room to get at the gear lever comfortably, which made all the difference in the world.
Changing without the Clutch.
One of the best tests for proficiency in the art of gear changing is to make all the changes (except from neutral to first) without using the clutch at all. On the first attempt, one should only change from a low to a higher gear, and then, when these changes can be made without noise or jerk on the transmission, the more difficult changes from high to low may be attempted. A little practice in this way will impress upon the driver the necessity for getting the engine and car speeds right before the change is made, and when once proficiency is reached, the need for using the clutch will be very rare, except, of course, in traffic driving.
Practical Hints on Effective Changes.
When a car has a third gear of a reasonably high ratio, it is important to take full advantage of this on cross-country runs by changing down early on long slopes and main road hills, thus obtaining rapid acceleration and high average speeds up hills.
Many people defer the change downto the last moment, and, as a result, never properly appreciate the capabilities of their cars. Some even defer changing down so long that when the next intermediate gear to top gear has been engaged the road speed is so low that another change into a still lower gear becomes necessary.
One should always change down before a corner ; not on the corner or after it. This applies to ordinary driving as well as to racing work, because if one has a low gear engaged before taking a corner, in the event of an emergency presenting itself just round or after the corner, it is useful to have rapid acceleration at one's disposal in order to quickly extricate the car from any difficulty, and it is equally useful to have rapid deceleration, by using the engine as a brake. On certain cars on which the " change up" is rather slow, it is possible to make what one would call a "slip" change. This can be done by slightly releasing or
slipping the clutch and pulling the gear lever over quickly into the next higher gear, at the same time keeping the foot down on the accelerator pedal, instead of releasing the accelerator pedal as one does when normally changing down.
This is very useful in all forms of driving, but, on the other hand, the writer does not recommend it to be applied unless one has been previously shown the exact method by somebody who can do the " slip " change, as, in the event of the slightest error, a terrific crash of the gears is bound to result, and, as a consequence, perhaps, broken or bent selector mechanism.
Many people think that to change down early and to make use of the gears on a car means greater petrol consumption owing to the higher number of "revs." at which the engine has to turn over in the lower gear.
But there is a certain engine speed at which any particular engine will run most efficiently and, therefore, most economically.