Position detector for industrial vehicles

摘要

An apparatus in a forklift (1) for detecting the height of a fork (6) in stages. Two sensors (7) are arranged longitudinally on the mast (3). Each sensor (7) includes a switch (10) that has two states. The state of each switch can be changed by movement of the fork. Each switch (10) is connected to input terminals (T1-T3) of a controller (11). The signal at each input terminal changes between two levels in accordance with the state of a corresponding switch (10). A memory (14) in the controller (11) stores data that defines the relationship between ranges of movement of the fork (6), or zones, and the combination of the signals. The controller (11) judges the height of the fork (6) when the combination of signals corresponds to a combination that exists in the data. The controller (11) judges that there is an abnormality when the combination does not exist in the data. This permits detection of malfunctioning switches and a cut and a short-circuited wiring. <IMAGE>