Skill Still Needed When Changing Gears

Gisborne Herald, Volume LXVI, Issue 20032, 2 September 1939, Page 11

Skill Still Needed When Changing Gears

piVE or six years ago, because of the mechanical design of cars, a motorist had to pxercise some skill in his driving to make silent changes, o.f gear. The attainment of this necessary skill automatically safeguarded 1 the gearbox and other transmission parts from the thoughtlessly brutal treatment which is often their portion to-day. The introduction of a synchronising mechanism, in the gearbox, to enable clean and silent gear-changes to be made without any expert knowledge, has proved a tremendous boon. But, by performing a work which formerly was left to the driver, these devices undoubtedly have placed in many instances a far more onerous strain on the various transmission parts. This is because the motorist who has learned to drive within the past few years is often quite ignorant ot the forces at work. Before synchromesh was introduced we knew that in changing gear downward from top to second we had to mesh a fastmoving gear with a slow-moving one --quite an impossibility. Therefore, we were /taught the now almost obsolete method of changing gear bv what was known as double declutching.

In this a nice judgment whs re■quired. While the gear lever was in neutral in the process of changing, it was necessary to .speed up the engine with the clutch engaged, so that the slow-moving gear would be brought to the speed of the fast pne and the gears could be meshed without a .sound when the clutch was once more pushed out. How Damage Occurs When properly carried out (and most people became quite expert in the art) the lower gear could be engaged without a sound. That meant no wea r on the gear teeth and no nastv jar through tile line of transmission, which occurs on engaging the clutch when the engine speed rs vastly different from the road speed. Yet that sudden bump in. the transmission is often felt by Jhe modern driver. The synchronising cones automatically bring the gears inside the box to the required speed, but, they do not also bring the engine speed into line with the road .speed,! and when‘the clutch is let in after a change to a lower ration the slowmoving engine will act as a brake. This puts a sudden check on the road speed, causing that jar in the, transmission. The jar means a sudden strain on the clutch, on the teeth, of the gears < in the gear-box. and on the teeth of the gears in the differential housing. Too much of this is responsible i for most of the transmission trouble i which aifliejs many cars of to-day. ,' Although there is no longer any] need to accelerate the engine while « the gears arc in neutral with the i clutch it is necessary to ; accelerate the engine to approximately the right, .speed before the clutch is engaged on completion of the actual change. It this is done with reasonable judgment there will ■ be no sudden checking of the car’s . SDoed. and the transmission parts < should mst the life of the car with little if any attention. j' “Riding' The Clutch." Another bad fault which observajion has shown is indulged in by

some of the newer owners is the old one of “riding the clutch.” By this Is meant keeping the foot on the dutch pedal while driving the car. This also is responsible for early expense by causing unnecessary wear. The old trick of slipping the clutch while temporarily halted on a hill generates heat and wear in the fabric clutch facings. The ear should always be held with the hand-brake, or if* that is inaccessible, as so often is the case, with th e .fc.ot-brake, and the car started by using the handthrottle until the right foot can be transferred to the accelerator. Consideration for the various pads of the transmission is vastly important, because bills for gearbox, back axle, and clutch repairs can bo very heavy.