Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Impeller-turbine type fluid circuit and mechanical path in...
Patent
1989-03-13
1990-10-09
Diehl, Dwight
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Impeller-turbine type fluid circuit and mechanical path in...
F16H 4706
Patent
active
049617214
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a vehicle transmission particular to drive lines for use in industrial and agricultural tractors.
Tractors used in the construction industry have conventionally tended to use a relatively small number of ratios, four ratios is common, which are required to cope with the drive requirements of the tractor on the construction site and also provide a higher drive ratio for use in driving the tractor to the site on the road. As a result, it is not uncommon to find such tractors with a relatively low top road speed.
Also, such tractors often employ a torque converter to provide the drive connection between the prime mover and the multi-ratio transmission. Although the use of a torque converter provides advantages in the smooth take-up of drive, torque multiplication and slip during loader work, etc., it leads to inefficiency when the tractor, for example, encounters a steep incline when being driven to the construction site, since internal slip within the converter can lead to significant loss of road speed.
It is an object of the present invention to provide a vehicle which at least partially alleviates the above problems.
Thus, according to the present invention, there is provided a vehicle having a prime mover which drives a drive shaft via a torque converter and a multi-ratio transmission, the vehicle also including a drive line "transmission connected to the drive shaft" independent of the torque converter and multi-ratio transmission from the prime mover to the drive shaft, the independent drive line providing an overdrive or underdrive function to extend the drive ratio range provided by the multi-ratio transmission and including clutch means for the engagement of the additional ratio or ratios, and an interlock arrangement connected to the multi-ratio transmission to prevent the simultaneous connection of drive to the drive shaft via the multi-ratio transmission and the independent drive line.
By making the independent drive line fully mechanical, i.e. not involving the torque converter, the additional ratio or ratios can be selected to provide a higher road speed capability (say over 20 mph) without the possibility of torque converter slip. This also has the added advantage that the ratios provided by the multi-ratio transmission do not need to be comprised to the same degree by the consideration of providing an adequate road speed capability so that a better spread of ratios for site use is also obtained.
The interlock arrangement which prevents simultaneous engagement of drive to the drive shaft via the multi-ratio transmission and the independent drive line may also be arranged to prevent initiation of engagement of drive via the independent drive line unless the vehicle is operating in a predetermined transmission ratio when engagement is selected. For example, if the independent drive line is operating to provide a higher road speed ratio, (i.e. an overdrive capability) the interlock may be arranged to prevent initiation of engagement of drive via the independent drive line unless the transmission is operating in its highest ratio when engagement of overdrive is selected. Such an arrangement reduces the load on the clutch means in the independent drive line.
A further aspect of the present invention is the appreciation that a vehicle arrangement of the form described above can be achieved by converting a well-known vehicle drive configuration (hereinafter referred to as a vehicle of the type specified) in which a prime mover drives: and
Thus, according to this further aspect of the present invention, there is provided a method of converting a vehicle of the type specified to provide an additional drive ratio comprising the steps of: and give the required additional drive ratio at the drive shaft; and the drive train to the drive shaft to enable engagement and disengagement of the additional drive ratio; and transmission to prevent simultaneous connection of drive to the drive shaft via the multi-ratio transmission and the PTO drive line.
When a vehicle design is con
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patent: 4474079 (1984-10-01), Crockett
patent: 4483212 (1984-11-01), Ohtsuka
patent: 4724720 (1988-02-01), Ohkubo
Pawson Kenneth
Sword John D.
Diehl Dwight
Massey-Ferguson Services N.V.
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