A gearshift control device for a transmission, comprising:
- a gearshift including a first pressure medium chamber and a second pressure medium chamber which are separated from each other by a piston movable in a direction of a longitudinal axis thereof;
- a first controllable valve device via which the first pressure medium chamber is selectively connectable to a pressure medium source or to a pressure medium sink, the first controllable valve device including a pressure medium input, a first pressure medium outlet connected to the first pressure medium chamber and a second pressure medium outlet;
- a second controllable valve device via which the second pressure medium chamber is selectively connectable to the pressure medium source or to the pressure medium sink, the second controllable valve device including a pressure medium input, a first pressure medium outlet connected to the second pressure medium chamber, and a second pressure medium outlet;
- an electrical control system for actuating the first and second controllable valve devices;
- a third controllable valve device controllable by operation of the electrical control system, said third valve device being connected to the first controllable valve device and to the second controllable valve device, as well as to the pressure medium source, in such manner that the pressure medium input of the first controllable valve device and the pressure medium input of the second controllable valve device can be selectively connected to the pressure medium source or can be closed off against said pressure medium source;
- wherein the first, second and third controllable valve devices are configured to enable each of the first and second pressure medium chambers to be closed off separately and simultaneously against the pressure medium source and against the pressure medium sink;
- a pressure sensing device for measuring a first pressure in the first pressure medium chamber and a second pressure in the second pressure medium chamber, the pressure sensing device being connected electrically to the electrical control system, and the pressure sensing device measuring each of the first and second pressures independently from each other;
- the electrical control system being designed and linked to the pressure sensing device and the controllable valve devices in such manner that actuation of at least one of the controllable valve devices can be rendered dependent upon at least the signals of the pressure sensing device;
- the third controllable valve device includes a pressure medium outlet and a pressure medium input connected to the pressure medium source and a pressure medium pipe;
- the pressure medium input of the first controllable valve device and the pressure medium input of the second controllable valve device are connected to each other via a pressure medium pipe and to the pressure medium outlet of the third controllable valve device;
- the pressure sensing device includes a pressure medium connection which is connected to the pressure medium pipe which connects the pressure medium input of the first controllable valve device and the pressure medium input of the second controllable valve device to each other and to the pressure medium outlet of the third controllable valve device;
- the pressure medium input of the first controllable valve device, the pressure medium input of the second controllable valve device and the pressure medium connection of the pressure sensing device can be connected via the third controllable valve device selectively to the pressure medium source or can be closed off from said pressure medium source;
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- the pressure sensing device being comprised of a pressure sensor which can be subjected to the pressure of the first pressure medium chamber, to the pressure of the second pressure medium chamber of the gearshift, or to the pressure of the pressure medium source, as a function of a switching position of the first, second and third controllable valve devices, said pressure sensor producing electrical signals representing the pressure in the first pressure medium chamber, the pressure in the second pressure medium chamber, or the pressure in the pressure medium source.