un beau son vraie truck

Valiant 65 a écrit:


surement fin des annee 40 ou debut 50

firebuick a écrit:

Valiant 65 a écrit:


surement fin des annee 40 ou debut 50

ces un GMC 1950

T/A Fanatic a écrit:Coudon le starter es tu as air?
Sa fais un drole de bruit quand y vire la clef?

Vinces a écrit:Ca fonctionne comment les deux leviers de vitesse ?

One stick is for the main transmission and the other one is for the auxiliary gearbox. The main box usually has 4 or 5 speeds but because a diesel engine has such a narrow powerband, 4 or 5 gears is not enough to keep the engine in a comfortable operating range where it will produce good torque and horsepower.

To accomplish this, They add the auxiliary box which, in simple terms, divides the gears in the main by thirds.... I know.. it's confusing, but here is how it works....

First some terminology... Main box gears are labeled 1 through 5 and auxiliary is labeled Deep or double under (1st), Under (2nd), Direct (3rd), and Over or Overdrive (4th).

Normally in a 5 and 4.... (5 speed main and 4 speed auxiliary) you would start out in 2nd Under from a dead stop. You would accelerate and shift the aux to Direct, acelerate and shift to Over. Then the fun begins.... Leaving the aux in over, you grab the main stick and shift it to 3rd... once it's in, then you grab the aux and shift it back into the Under position and continue on with the shifting until you get to the legal speed limit or 5th Over... whichever comes first.

Why, you ask, is there a deep under (or double under) in the aux box??? If you are climbing a hill and you have downshifted to the point that you are in (example) 4th under and you need one more gear to get over the top. If you have to shift the aux to overdrive and then grab the main and downshift it to 3rd gear, you will be stopped before you get it all accomplished due to the grade of the hill. So... you can just shift the aux into deep or double under and you will basically have the same gear ratio as 3rd over with out all the shifting.

I hope this helps.... I have driven just about every combination of transmission you can think of in a truck at one time or another during the past 30 years.

En passant, sur les transmissions modernes, le deuxième bâton a été remplacé par une switch sur le bras de vitesse pour faire les changements sur l'auxiliaire: