Height control of a harvester cutting mechanism

A harvester comprises a ground-tracking cutting mechanism which is fastened to a height-adjustable conveyor shaft to be pendulating. The reaching of limits of the range of pendulation is signalled by an initiator assembly which comprises two initiators (20S, 20H) and is associated with a shaft height initiator (26). The shaft height initiator checks the shaft movement and activates the two initiators (20S, 20H) of the initiator assembly by means of a logic circuit (27). The logic circuit (27) is followed by a two-channel switching amplifier (28) and two electromagnetic valves (33, 34) for raising and lowering of the conveyor shaft. The outputs of the initiators (20S, 20H, 26), manual control keys (29, 30) connected with the inputs of the switching amplifier (28), and a switch (31) blocking the signals of the initiators (20S, 20H) of the initiator assembly, are connected to the inputs of the logic circuit (27). After switching-on of the height control system and lowering of the conveyor shaft through brief actuation of one of the keys (30), the movement of the shaft is controlled by the signals of the two initiators (20S, 20H) only after they have been activated by the shaft height initiator (26) in the working range.