DETAILED DESCRIPTION OF THE INVENTION FIG.
1 schematically shows an agricultural tractor having an operator's cab.
The drive train is formed by an engine 1 with a succeeding continuously variable transmission 2 and a differential gear 3 distributing the drive torque to the left and right rear wheels 4, 5.
The engine 1 and the continuously variable transmission 2 are controlled by a control device 6.
This may, for instance, be a control device performing the control method set out in the European Patent Application 98890183.
1.
A forward/backward selection lever 8 is disposed near the steering wheel 7 which is only schematically shown, preferably such that this lever may be actuated by the hand actuating the steering wheel 7.
Within the reach of the other hand of the operator, the actuating device 9, according the invention, is disposed.
The two semi-pedals 10,11 are provided for braking, one (10) for actuating the brake of the left rear wheel 12 and the other one (11) for actuating the brake of the right rear wheel 13.
In normal operation, semi-pedals 10, 11 are coupled with one another.
To act as a steering brake, there they are individually actuable such that the respective in-turn rear wheel is braked.
The control commands from the forward/backward selection lever 8 and the actuating device 9 are transmitted via cables 14, 15 to the control device 6.
The control device is a microcomputer that repetitively performs a control program that may, among other things, also perform a cruise control function.
FIG.
2 shows the system according to the invention in a preferred embodiment.
Somewhere within reach of the second operating hand of the operator (the first one is at the steering wheel), for instance at the instrument board or preferably in prolongation of the arm rest, a preferably stationary hand lever 19 is provided, which is embraced by the hand of the operator.
At the top end of the hand lever and within reach of the thumb (not shown), there is a control surface 20.
On the control surface 20 there is provided an actuating element 21 for adjusting the real speed, said actuating element preferably consisting of two momentary push button switches 22, 23, the first one being clearly marked with a minus sign, and the second marked with a plus sign
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