Machine element or mechanism – Gearing – Interchangeably locked
Patent
1998-05-22
2000-10-17
Marmor, Charles A
Machine element or mechanism
Gearing
Interchangeably locked
192 8718, 13762564, 91461, F16H 6100
Patent
active
061314757
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a gear control system for a synchro-shuttle gear or a powershift gear.
BACKGROUND OF THE INVENTION
In construction machinery, such as excavator loaders, group transmissions are used in the practice which need at least two actuated switching elements per gear. These group transmissions are either synchromesh gears (also known as synchro-shuttle gears) having hydraulically actuatable switching elements for travel direction only, or powershift or full-throttle powershift gears, the design of which has, in addition to switching elements for selection of travel direction, switching elements with which other reduction ratios can be adjusted, for example, in forward drive.
The control blocks used for controlling said gear designs differ mainly in that the synchromesh gears need a special idling valve, for reasons of safety, by means of which, depending on certain limiting conditions in the vehicle or in the transmission, but independently of the momentary state thereof, an idling speed can be adjusted. To control powershift gears, on the contrary, the gear control system needs its own shifting valve, by means of which it is possible to switch between several gear steps for traveling under load.
Different control blocks with different shift valves and switching elements are thus disadvantageously required for said gear design.
Due to the non-uniform constructional design of the gear control systems high manufacturing costs for the individual shift valves and switching elements, result because of the quantity of parts.
SUMMARY OF THE INVENTION
Therefore, the problem addressed by this invention is to provide a simplified gear control system with universally utilizable control and switching elements which are suited to both synchro-shuttle gears and to powershift gear.
According to the invention, this problem is solved by having a control valve situated between the switching elements for a forward drive or a reverse drive and the shift valve for selection of the travel direction, which is actuatable by the switching devices. The control valve can be actuated by another switching device, and is optionally utilizable as a neutral-position valve or idling valve in a synchro-shuttle gear, or as a shift valve for switching elements for a forward drive in a powershift gear.
With the constructionally simplified gear control system according to the invention, a common control block can be advantageously used unchanged both in a synchro-shuttle gear and in a powershift gear.
Another advantage is that no additional parts are needed in the gear control system according to the invention. Moreover, only the necessary and already existing parts are used in both gear versions, whereby the production cost can be clearly reduced.
The use of uniform parts in both gear designs permits a reduction in the total number of parts by which the design and manufacture of the individual parts can be carried out at specially reasonable cost.
In addition, because of the uniform design of gear parts the supply and stockage of the parts is considerably simplified and less expensive.
Other advantages and advantageous designs of the invention result from the sub-claims and from the embodiment described below in principle with reference to the drawing.
BRIEF DESCRIPTION OF THE DRAWING(S)
In the drawings
FIG. 1 is a fundamental representation of a synchro-shuttle gear for construction machines; and
FIG. 2 is a fundamental representation of a powershift gear for construction machinery.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
FIG. 1 and FIG. 2 show a gear control system for construction machinery, especially excavator loaders, having switching elements SEV1, SEV2 (FIG. 2 only) for forward drive and one switching element SER for reverse drive. FIG. 1 diagrammatically shows the gear control system for a synchromesh gear or synchro-shuttle gear 1, and FIG. 2 a gear control system of the same kind for a full-throttle gear 2.
In both gear designs, the switching elements SEV1, SEV2, SER are hydraulically loaded with pressu
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Marmor Charles A
Parekh Ankur
ZF Friedrichshafen AG
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