Machine element or mechanism – Gearing – In series plural interchangeably locked nonplanetary units
Patent
1983-10-28
1988-12-13
Staab, Lawrence
Machine element or mechanism
Gearing
In series plural interchangeably locked nonplanetary units
74791, F16H 3704
Patent
active
047902132
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL DISCLOSURE
This invention relates to planetary gear assemblies particularly, though not exclusively, for use in agricultural or industrial tractors.
Such assemblies are well known for use in the input or output stages of a tractor or similar vehicle to provide an overdrive or underdrive function. Examples of such assemblies are shown in UK Pat. No. 1430 962 and UK Patent Application No. 2046 853.
Previously if a vehicle manufacturer wished to offer an overdrive and underdrive option it has been necessary to provide overdrive and underdrive units which, whilst possibly containing a number of common parts, did require the provision of parts specifically for the overdrive unit and other parts specifically for the underdrive unit. This increases manufacturing costs and leads to a larger parts inventory.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide an improved form of planetary gear assembly which, dependent on the manner in which the parts are assembled, can function as either an overdrive or underdrive unit.
According to the present invention there is provided a planetary gear assembly comprising co-axial input and output shafts having the same diameter and spline formations of the same cross-sectional form on their adjacent end portions, first and second sun gears splined one onto each shaft end portion, a carrier rotatable about the axis of the input and output shafts, planet gear means carried by the carrier and meshing with the first and second sun gears respectively, a stationery housing, brake means operable to hold the carrier stationery so that the assembly operates in its planetary ratio and clutch means operable to clutch one of the shafts to the carrier via a torque path not involving either sun gear in order to lock-up the assembly and provide a direct drive ratio, the arrangement allowing either sun gear to be splined onto either the input or ouptut shaft end portion and the meshing planet gear means to be located accordingly so that a given gear asssembly can be assembled to give either an overdrive or underdrive planetary ratio.
A planetary gear assembly in accordance with the present invention offers significant economies for the manufacturer since a single set of parts, by appropriate assembly, can form either a planetary overdrive or underdrive unit thus reducing the number of parts which must be produced and stocked.
In a preferred arrangement the torque path includes a torque transmitting member which is splined onto the input shaft end portion. This arrangement reduces the torque loading on the clutch means.
Preferably the brake and clutch means are of the liquidcooled type and are disposed generally radially one within the other so that the same radially outwardly flowing coolant can cool both the clutch and brake means.
As indicated above, the planetary gear assembly of the present invention will normally form part of a series arrangement of transmission elements which form a total vehicle transmission. The vehicle manufacturer may wish to offer the transmission without the planetary gear assembly of the present invention but still retaining the housing of the planetary gear assembly since this may, for example, support other components (e.g. other parts of the transmission) which are required in the vehicle although the customer does not require an overdrive or underdrive unit.
In such circumstances it is possible for the manufacturer to connect the splined input and output shaft end portions of the assembly of the present invention using a simple internally splined sleeve and to omit or remove the sun gears, carrier, planet gear means, brake means and clutch means and to simply and cheaply provide a transmission alternative without a planetary gear assembly.
The present invention thus also provides a vehicle transmission of the form described in the two preceding paragraphs in which the input and output shaft end portions are connected by an internally splined sleeve and also a method of converting a planetary gear assembly in accordanc
REFERENCES:
patent: 1712956 (1929-05-01), Gustafson
patent: 1954200 (1934-04-01), Fromm
patent: 2228617 (1941-01-01), Ware
patent: 2575522 (1951-11-01), McFarland
patent: 2959987 (1960-11-01), Miller
patent: 3148556 (1964-09-01), Gibbs et al.
patent: 3352166 (1967-11-01), Marquart et al.
patent: 3703031 (1972-11-01), Fodrea
patent: 3774474 (1973-11-01), Recker et al.
patent: 3774475 (1973-11-01), Meysenburg et al.
Diehl Dwight G.
Staab Lawrence
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