DOUBLE DECLUTCHING.

Evening Post, Volume CVI, Issue 126, 24 November 1923, Page 23

DOUBLE DECLUTCHING.

It should be mentioned, in reference to the description published in this column on 12th November on the proper method of changing down by the process of double declutching—commonly known as '' double-clutching " —that the car in question was one with four forward gears.

Owners of American three-geared cars were, no doubt, a little puzzled by the allusion to coming down into third gear. In their case it should be coming down into second, of course, and from second to first in further changing. The reason for double declutching, with,its intermediate stage of gear in neutral, clutch in, is simply ti accelerate the lay shaft in the gear-box so that, when the final stage of getting into the lower gear comes, the speed of spur wheels through •which the gear operates will be the. sajnq,-- so that-the teeth will slide, in toYther -with as little jioise and fdctinn aa

possible. Ifc stands to reason that the lower the gear the greater the revolution of the engines. per minute to maintain the same road speed on the wheels. As double declutching is used to get into low gear before the engine speed drops in climbing a hill, it is obvious that on the flat, say, running at 20 m.p.h. the engine must be accelerated to drive the lay shaft carrying the lower gears at a greater rate, in order to effect a silent change. Of course, as in all matters dealing with mechanism, a pound of diagram would equal a ton of description, and an ounce of practice beat the whole lot' The owner-driver wh 0 still waits on hills to make his change and runs the nsk of missing his gears altogether ought to try double declutching at once according to the methods first described in this column.