Zf Friedrichshafen Ag

Wolfgang Groener

Peter Herter

Joachim Staudinger

Ulrich Reith

A method of operating a transmission positioned between a drive aggregate and an axle drive, a transmission input shaft is connected, via a clutch, with the drive aggregate, and a transmission output shaft is connected with the axle drive and power can be diverted from the transmission to drive a power take-off. The PTO is activated by an engine intervention, shifting the transmission to neutral and disengaging the clutch. Thereafter, the clutch is partially engaged at either a position dependent or distance dependent clutch speed while monitoring the input rotational speed and drive aggregate rotational speed. When the input rotational speed approximately equals the drive aggregate rotational speed and the idle rotation speed of the drive aggregate, the clutch is no longer being engaged at the position dependent or distance dependent clutch speed, but is fully engaged at a maximum clutch speed.

Method for operation of a transmission

The invention relates to a method and a device for controlling a standstill circuit of an automatic transmission of the vehicle, comprising a decision unit for selection of the target gear, a low-speed monitoring unit and a standstill circuit, which, when the vehicle is standing still or when its speed falls below a predetermined limit speed, brings about or prepares the activation of a starting gear. The method and the device are intended to enable a vehicle to start up safely even under the influence of considerable tractive resistance. Furthermore, they should be characterized by solutions which are as simple, inexpensive and easy to implement as possible by way of available methods and devices. To this end, the low-speed monitoring unit reads data concerning at least one state of the vehicle and, if necessary, additional data, and, on the basis thereof, as a function of decision rules, renders the standstill circuit ineffective.

Growing community of inventors

Friedrichshafen, Germany

Wolfgang Groener