Control of starting and stopping of a PTO shaft in an agricultural vehicle

The tractor has an internal combustion engine (2) connected to a change-speed transmission (4). The transmission drives a hydraulically-actuated clutch (7) with an output shaft (10) a brake (11) and a power take-off fitting (12). The clutch is controlled by a magnetic valve (9) with an input from a control computer (16). The computer includes a data processor (17).