Machine element or mechanism – Gearing – Interchangeably locked
Patent
1995-05-08
1997-01-14
Ta, Khoi Q.
Machine element or mechanism
Gearing
Interchangeably locked
74331, 192 7011, 192112, F16H 3093, F16H 6100
Patent
active
055928536
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a power-shiftable multiple gear reversing transmission. It is a transmission such as specially used in construction machines like wheel loaders, excavator loaders, etc. or in lift trucks.
BACKGROUND OF THE INVENTION
A reversing transmission of the kind in question has an input shaft and several countershafts. Wheels forming a changing set are provided. Upon the countershafts are situated clutches (so-called directional clutches and gear-selector clutches) with idler gears, which can optionally be non-rotatably connected with one countershaft for shifting speed and direction. The power take off results from an output gear set. The number of fixed gears depends upon the number of speeds of the transmission.
Power-shiftable reversing transmissions with a countershaft design are distinguished by a series of advantages. For this reason such transmissions are used in many commercial vehicles. The multiplicity of working machines demands a constantly increasing degree of adaptability of the transmission in order to utilize the power and torque of the engine. It is disadvantageous that the installation space is sometimes considerably large, to which to the fact that said transmissions have considerable axial length and/or considerable width in the cross section of the vehicle also contributes. Another problem is that the known transmissions tend to vibrate and generate noise. It has been shown that noise generation that was accepted years ago in construction machines is no longer accepted today.
SUMMARY OF THE INVENTION
This invention is based on the problem of providing a power-shiftable multiple gear reversing transmission in a countershaft design, which in particular, has a great number of equal parts, is flexible in the number of speeds to be provided and is also especially distinguished by a small emission of noise.
The problem on which the invention is based is solved by the fact that a single clutch is situated on each countershaft and a single idler gear is associated with each clutch, in a manner such that the idler gears of each countershaft are constantly meshed with each other. The idler gears of each countershaft thus form a drive gear chain. For each speed to be shifted, one fixed gear of one countershaft is in permanent engagement with one fixed gear of the output shaft. A valuable advantage of the solution according to the invention is the small axial length of the countershafts, since each one has to house only three structural parts (clutch, idler gear and fixed gear). Gearings with large angles of slope can preferably be used without the countershaft being thereby burdened with high bending loads. The proposed design ensures a high number of equal parts. The transmission is flexible with regard to the number of speeds to be provided and is especially distinguished by a very smooth running. It is to be borne in mind here that the transmission is preferably installed separate from the axle to be driven. It is advantageous to arrange the clutches and the idler gears in a common vertical plane so that the installation space can be kept relatively small in the axial direction.
Since each countershaft has to accommodate only a limited number of parts, there results the added advantage that each countershaft can be supported on both ends by two roller bearings within one housing. It is of further advantage here to arrange the plurality of roller bearings in equal vertical planes.
In a housing formed of at least two parts, a particularly simple design results when the partition is used for the supply of oil. The valves can here be placed in a housing part. It is then further advantageous to provide ducts in a common vertical plane, which produce a connection of the valves to the clutches for oil supply. The ducts are preferably integrally cast. An oil supply is thereby made possible without a cutting process.
In a specially advantageous structural configuration, the fixed gears of the reversing and output gear set abut directly on a housing wall. The strong tooth forces can
REFERENCES:
patent: 2867126 (1959-01-01), Bolster
patent: 3102432 (1963-09-01), Gerst
patent: 3913411 (1975-10-01), Jameson
patent: 4570503 (1986-02-01), Theobald
patent: 4771647 (1988-09-01), Stevens
patent: 4864881 (1989-09-01), Beeson et al.
Design Practices Passenger Car Automatic Transmission, 3rd Edition, by SAE Transmission/Axle/Driveline Forum Committee, p. 194, Aug. 1994.
Leber Fritz
Rebholz Wolfgang
Ta Khoi Q.
ZF Friedrichshafen AG
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