Speed controller for harvesting machine - has circuit for providing rate control and limits on command signal to hydraulic pump motor

The controller is fitted to a harvester having a motor (20) driving a variable flow hydraulic pump (16) which supplies pressurised fluid to hydraulic drive motors (12). The drive speed is controlled by control of the pump motor. The controller (26) includes a speed setting potentiometer (32), an impulse counter (38,40) serving as a speed detector on the principal hydraulic drive motor, a frequency-to-voltage converter producing an analogue voltage signal proportional to the principal motor speed a comparator which compares the measured speed signal against the reference signal, and an electronic circuit with rate control and limit circuits which combines fast responding and slow responding signals to form a command signal for the pump motor. - The command signal forces the hydraulic motor to slow quickly when the principal motor slows, and to accelerate rapidly until the limits are reached as the load is decreased on the harvester. Un dispositif régulateur de vitesse de déplacement automatique pour une moissonneuse, dont un moteur principal entraine une pompe pour fournir du fluide sous pression à un moteur hydrostatique, comprend un dispositif de commande de puissance pour modifier le débit de fluide parvenant au moteur hydrostatique en réaction à un signal de commande, à l'intervention de deux signaux d'ordre réagissant à la vitesse du moteur principal, dont l'un varie à une allure rapide et l'autre à une allure lente.