Apparatus for controlling gear box

Abstract

During shift change, a discrimination is made as to a load, a quantity of residual hydraulic oil in respective shift change clutches (F, R, 1 to 4) and a state of shift change which has been effected from what speed stage to what speed stage so that a pattern of electrical commands to be issued to pressure control valves (51 to 56) for required shift change clutches is variably controlled depending on results derived from the above discrimination. Thus, smooth shift change can always be achieved regardless of running conditions. Electrical commands (C.sub.1 to C.sub.6) to be fed to the respective pressure control valves (51 to 56) are compared with electrical currents (I.sub.1 to I.sub.6) outputted from drive circuits and outputs (S.sub.1 to S.sub.6) from clutch pressure detecting means (101 to 106) for each clutch, whereby an abnormality is detected with the relevant clutch based on results derived from the comparison. Once an abnormality is detected, an adequate disposal for processing the abnormality is executed so as to reliably prevent double engagement from taking place with clutches.

Dependencies are inferred from the claim text.