Machine element or mechanism – Gearing – With fluid drive
Patent
1997-10-02
1999-07-06
Marmor, Charles A.
Machine element or mechanism
Gearing
With fluid drive
192 8713, 192 91A, 477 55, F16H 6126
Patent
active
059185090
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a powershift reversing transmission having a hydrodynamic torque converter, an input shaft, an output shaft, at least one countershaft and gearwheels which form a reversing set, and clutches with idler gearwheels which have actuating devices and can be optionally non-rotatably connected with the input shaft or countershaft for a shifting direction.
BACKGROUND OF THE INVENTION
A transmission of the kind described above is a reversing transmission as used especially in lift trucks, such as loaders. But it can also be the entry unit of a multi-speed reversing transmission as particularly used in constructions machines, such as wheel loaders, excavator loaders, etc.
Reversing transmissions of the kind mentioned have, in general, an input shaft and, as a rule, several countershafts. Clutches (so-called direction and gearshift clutches) having idler gearwheels which can optionally be non-rotatably connected with the shafts for shifting a gear and direction, are situated upon said countershafts. The power take-off is effected by a driven gear system. The number of fixed gearwheels depends on the number of gears of the transmission.
Powershift reversing transmissions of a countershaft design stand out by a series of advantages. Such transmissions are consequently used in several industrial vehicles. Said transmissions must be compact in construction and comfortable for gearshifts. For this purpose, the hydraulically actuatable clutches are mainly shifted by modulation of the actuating pressure in a manner such that a controlled load take-up results. In certain vehicles, for example, in lift trucks such as fork lift trucks or the like, other operating conditions are of special importance together with the reversing operation. To said conditions mainly belong starting off, inching and raking.
SUMMARY OF THE INVENTION
The problem, on which the invention is based, is to provide a reversing transmission which stands out by great comfort of operation and a simple design. This must not only apply to the reversing operation but also to the other operating conditions mentioned.
The problem, on which the invention is based, is solved by the fact that each clutch is actuatable by spring tension when engaging and hydraulically against spring tension when disengaging, and that a directional valve is provided for actuating the clutch which, in one shifting position, connects an annular chamber of the actuating device with a feed pipe and, in another shifting position, connects the annular chamber, via a return pipe, with a reservoir from which the pressure medium conveyed from the annular chamber to the reservoir flows out through an aperture. The clutches (reversing clutches) used for a shifting direction are negatively actuated, that is, engaged by spring tension and hydraulically disengaged. This is a requirement to make possible, in combination with a reservoir, a modulation of the clutches without an additional modulation valve being needed. Despite a very simple design, the load take-up can be controlled by pressure modulation by a respective clutch. Contrary to seat valves, no problems result in the case of different viscosities since the used aperture works relatively independently of viscosity. The control can be hydraulic or electrohydraulic, which reduces the needed expenditure. A simple start off is made possible by the hydrodynamic torque converter. The used reservoir is designed for reversing shifts. This means that it quickly absorbs, almost completely, the oil suddenly removed from the annular chamber of the actuating device when the clutch is actuated. The subsequent modulation operation obviously develops so that the driver is relieved from the pressure modulation. The time function for engaging a clutch can be adjusted by a simple variation of the aperture. When actuating the clutch, the starting point of the modulation is very quickly reached. This advantage cannot be attained with proportional valves since the positive actuation of a clutch naturally takes a certain amount of ti
REFERENCES:
patent: 3099166 (1963-07-01), Shou
patent: 3110196 (1963-11-01), Hilpert et al.
patent: 5234087 (1993-08-01), Jurgens et al.
patent: 5261517 (1993-11-01), Hering
patent: 5429005 (1995-07-01), Fukui et al.
patent: 5509860 (1996-04-01), Legner
Eymuller Helmut
Heilig Eduard
Legner Jurgen
Mann Egon
Estromsky Sherry Lynn
Marmor Charles A.
ZF Friedrichshafen AG
LandOfFree
Powershift reversing transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Powershift reversing transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Powershift reversing transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-891999