Abstract: A manually-shifted synchronized compound transmission (10) is provided with a relatively simple and inexpensive mechanism for warning the operator that an inappropriate gear ratio has been selected. Sensors (110, 112, 114) provide input signals (116) to a logic unit (118) indicative of the rotational speed of the transmission input shaft (118) and the logic unit will issue command signals (120) to an alarm member (122) if sensed input shaft speed is not within an acceptable range to warn the vehicle operator that reengagement of the vehicle master clutch (C) in the currently engaged ratio (GR) will result in undesirable overspeeding and/or underspeeding of the vehicle engine (E).

Abstract: An auxiliary transmission section (14) shift control system (230)/method is provided which include a residual pressure valve (246) and a one-way restricted flow pressure relief valve (250) to prevent an auxiliary section high speed ratio synchronized clutch (92) damage if the main transmission section (12) is engaged during an auxiliary section upshift. The chamber (224A) of the actuator (220) associated with the high speed synchronizer clutch is constantly gradually vented to a reference pressure through a severely restricted orifice in the one way restricted flow pressure relief valve (250) and the residual pressure valve (246) will block fluid flow from the source (234) to the slave valve (238) whenever the main transmission section is shifted to the not neutral condition thereof.

Abstract: Shift control system (300)/method for a splitter type auxiliary section (14/102) is provided which includes control members (328) to prevent auxiliary section synchronized clutch (92, 136) damage if the master clutch (C) is engaged during an auxiliary section shift. Upon sensing master clutch engagement during a shift into the auxiliary section high-speed ratio, the force is used to engage the high speed ratio is reduced from a first (p*a.sub.224) to a considerably lower second (p*a.sub.224 -a.sub.222)) level.

Abstract: An auxiliary transmission section (14) shift control system (230) method is provided which includes control members (246) to prevent auxiliary section synchronized clutch (92, 128) damage if the main transmission section (12) is engaged during an auxiliary section shift. Upon sensing (254, 256) synchronized jaw clutch assembly blocked position during a shift into the auxiliary section high-speed ratio, the force used to engage the high speed ratio is gradually reduced from a first (p*a.sub.224) to a considerably lower second (p*(a.sub.224 -a.sub.222)) level.

Abstract: A fluid pressure actuated auxiliary transmission section (14) shift control system (3230/270)/method is provided which includes a control member (246) to prevent auxiliary section synchronized clutch (92, 128) damage if the main transmission section (12) is engaged during an auxiliary section shift. A range synchronizer protection valve (246) is effective to exhaust at least the high speed ratio chamber (224) of the piston actuator (220) whenever a main section engaged condition is sensed.