Fluid operated transmission control system

A fluid operated transmission control system comprising:

• (a) a source of fluid under pressure;
• (b) a plurality of drive speed establishing devices including a rotary first speed clutch and all adapted to be selectively actuated by the pressurized fluid from the source for selecting a drive speed;
• (c) a pair of drive direction establishing devices adapted to be selectively actuated by the pressurized fluid from the source for selecting a drive direction;
• (d) a series connection of speed select valves associated one with each drive speed establishing device and adapted to be pilot operated individually for directing the pressurized fluid from the source to the associated ones of the drive speed establishing devices, the speed select valves including a first speed select valve associated with the first speed clutch, the first speed select valve being adapted to normally deliver to the first speed clutch a relatively low fluid pressure less than a pressure at which the first speed clutch becomes engaged;
• (e) a pair of direction select valves connected in parallel with each other and associated one with each drive direction establishing device, each direction select valve being adapted to be pilot operated for directing the pressurized fluid from the source to the associated one of the drive direction establishing devices, one of the direction select valves being adapted to place, when pilot operated to actuate the associated one of the drive direction establishing devices, the other drive direction establishing device in communication with a fluid drain;
• (f) a plurality of speed select control valves, associated one with each speed select valve, to be electrically actuated individually for pilot operating the associated speed select valves to cause the same to direct the pressurized fluid to the associated drive speed establishing devices;
• (g) a pair of direction select control valves, associated one with each direction select valve, to be electrically actuated individually for pilot operating the associated direction select valves to cause the same to direct the pressurized fluid to the associated drive direction establishing devices;
• and
• (h) a plurality of emergency control valves connected one between each of the speed select control valves and direction select control valves and the associated one of the speed select valves and direction select valves, each emergency control valve being adapted to be operated manually upon malfunctioning of the associated one of the speed select control valves and direction select control valves to actuate or deactuate the associated one of the drive speed establishing devices and drive direction establishing devices via the associated one of the speed select valves and direction select valves.