12-speed gear box with a 2×3×2 construction

Details 12-speed gear box with a 2×3×2 construction 12-speed gear box with a 2×3×2 construction

2000-05-15

2001-11-20

Marmor, Charles A (Department: 3681)

Machine element or mechanism

Gearing

In series plural interchangeably locked nonplanetary units

C074S335000

Reexamination Certificate

active

06318211

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a 12-speed transmission for utility vehicles in 2×3×2 construction.
Such 12-speed transmissions consist of a front-mounted or split section, a 3-gear main section and a rear-mounted or range section wherein each section has pneumatically or manually actuated shifting devices. The front-mounted and rear-mounted sections are usually pneumatically actuated while the main section is manually shifted. For the manual shift, shifting devices are used which are based on those of 16-speed transmissions. However, the shift diagram that results has a blank, i.e. the shift diagram does not allow any uninterrupted complete shifting of the gears with movements alternating in direction. From the third to the fourth gear, the selector lever, after disengaging the third gear, has to be shifted in the same direction again as in the engagement of the third gear. Thereafter the fifth gear is switched by a direct opposite movement. As a result of this, a shift blank is formed between the second and fifth gear. Such a shift diagram is illogical as to the movement sequence and makes the control of the shifting device difficult or, at least, is unusual.
The problem to be solved by the invention is to modify a 12-speed transmission in 2×3×2 construction so as to obtain a conventional logical shift diagram without shift blanks.
SUMMARY OF THE INVENTION
Pursuant to the invention accordingly,” with and contrary to the prior art, the 3-gear main section is not manually shifted and the split or front-mounted and the range or rear-mounted section are automatically shifted pneumatically and it is only the front-mounted section which is manually shifted. The pneumatic shifting devices for the main section and the rear-mounted sections are manually activated when changing from one gear to the next.
For the front-mounted section is preferably provided with a manually actuated shifting device having gates for six forward gears and at least one reverse gear in which, during continuously increasing and decreasing speed sequences, alternatively accesses the two gears of the front-mounted group. For the main section and the rear-mounted section, pneumatic shifting devices are provided which, during selection of the manual shifting device, are correspondingly activated in the gate of the desired gear. The shift diagram thus obtained corresponds to that of a customary 6-speed transmission with addition of one or two reverse gears. To shift the forward gears, the selector lever of the shifting device alternatively actuates the two gear steps of the front-mounted section wherein, upon each change of a gear step, a synchronization block of the main section is pneumatically activated. It is important that for each two opposite gears, e.g. the first and second, the third and fourth and the fifth and sixth gears, the same gear step of the main section is pneumatically activated. The other pneumatic shift from the respective slow to the fast step of the individual gears then takes place via the rear-mounted section.


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Looman, Johannes: Zahnradgetriebe: “Grundlagen, Konstruktionen, Anwendungen in Fahrzeugen”. Heidelberg, Germany: Springer-Verlag Berlin, 1996, pp. 257-267.

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