Transmission control

Claim 2

In a control system for a transmission the combination of transmission means including gearing and a plurality of fluid pressure operated drive establishing means fOr providing a plurality of different transmission drives to drive a load on selective delivery of fluid pressure to said fluid pressure operated drive establishing means, a source of fluid pressure, shift valve means for determining selective delivery of fluid from said source to said fluid pressure operated drive establishing means to effect establishment of and shifting between said transmission drives, said gearing including a member that undergoes a load reversal when one of said transmission drives is released and another of said transmission drives is established to transmit torque to drive the load, and transition valve means controlled by said gearing member on shifting from said one transmission drive to said another transmission drive for maintaining fluid pressure in the fluid pressure operated drive establishing means establishing said one transmission drive to maintain said one transmission drive until said another transmission drive is established with sufficient torque capacity to drive the load.

Claim 3

In a control system for a transmission the combination of transmission means including gearing and a plurality of fluid pressure operated drive establishing means for providing a plurality of different transmission drives to drive a load on selective delivery of fluid pressure to said fluid pressure operated drive establishing means, a source of fluid pressure, shift valve means operable in one condition to provide for delivery of fluid from said source to one of said fluid pressure operated drive establishing means to establish one of said transmission drives and operable in another condition to provide for delivery of fluid from said source to another of said fluid pressure operated drive establishing means to establish another of said transmission drives while providing for exhaust of fluid from said one fluid pressure operated drive establishing means to release said one transmission drive, transition valve means operable in one condition to prevent exhaust of fluid from said one fluid pressure operated drive establishing means when said shift valve means is in its said other condition to effect maintenance of said one transmission drive while said shift valve means is in its said other condition providing for establishment of said other transmission drive, said transition valve means operable in another condition to exhaust said one fluid pressure operated drive establishing means when said shift valve means is in its said other condition to effect release of said one transmission drive when said another transmission drive is established, means normally yieldingly holding said transition valve means in its said one condition, said gearing including a member that undergoes a load reversal on shifting from said one transmission drive to said other transmission drive, and bias means controlled by said gearing member for biasing said transition valve means to its said other condition to permit release of said one transmission drive only when said other transmission drive is established with sufficient torque capacity to drive the load.

Claim 4

In a control system for a transmission the combination of transmission means including gearing and a plurality of fluid pressure operated drive establishing means for providing a plurality of different transmission drives to drive a load on selective delivery of fluid pressure to said fluid pressure operated drive establishing means, a source of fluid pressure, shift valve means operable in one condition to provide for delivery of fluid from said source to one of said fluid pressure operated drive establishing means to establish one of said transmission drives and operable in another condition to provide for delivery of fluid from said source to another of said fluid pressure operated drive establishing means to establish another of said transmission drives while providing for exhaust of fluid from said one fluid pressure operated drive establishing means to release said one transmission drive, transition valve means operable in one condition to prevent exhaust of fluid from said one fluid pressure operated drive establishing means when said shift valve means is in its said other condition to effect maintenance of said one transmission drive while said shift valve means is in its said other condition providing for establishment of said other transmission drive, said transition valve means operable in another condition to exhaust said one fluid pressure operated drive establishing means when said shift valve means is in its said other condition to effect release of said one transmission drive when said another transmission drive is established, means normally yieldingly holding said transition valve means in its said one condition, said gearing including a member that undergoes a load reversal on shifting from said one transmission drive to said other transmission drive, and bias means controlled by said gearing member for biasing said transition valve means to its said other condition to permit release of said one transmission drive only when said other transmission drive is established with sufficient torque capacity to drive the load.

Claim 5

In a control system for a transmission the combination of transmission means including gearing and a plurality of fluid pressure operated drive establishing means for providing a plurality of different transmission drives to drive a load on selective delivery of fluid pressure to said fluid pressure operated drive establishing means, a source of fluid pressure, shift valve means operable in one condition to provide for delivery of fluid from said source to one of said fluid pressure operated drive establishing means to establish one of said transmission drives and operable in another condition to provide for delivery of fluid from said source to another of said fluid pressure operated drive establishing means to establish another of said transmission drives while providing for exhaust of fluid from said one fluid pressure operated drive establishing means to release said one transmission drive, transition valve means oPerable in one condition to prevent exhaust of fluid from said one fluid pressure operated drive establishing means via said shift valve means when said shift valve means is in its said other condition to effect maintenance of said one transmission drive while said shift valve means is in its said other condition providing for establishment of said other transmission drive, said transition valve means operable in another condition to exhaust said one fluid pressure operated drive establishing means via said shift valve means when said shift valve means is in its said other condition to effect release of said one transmission drive when said another transmission drive is established, means normally yieldingly holding said transition valve means in its said one condition, fluid chamber means connected through a fluid restriction to receive fluid from said source for effecting a fluid pressure bias to urge said transition valve means to its said other condition, exhaust passage means connected to said fluid chamber means, and said gearing including a member that undergoes a load reversal on shifting from said one transmission drive to said other transmission drive and is operable when said one transmission drive is driving the load to provide for opening said exhaust passage means to exhaust said fluid chamber means to permit maintenance of said transition valve means in its said one condition by said biasing means and is further operable on establishment of said other transmission drive with sufficient torque capacity to drive the load to then close said exhaust passage means to permit pressure buildup in said fluid chamber means so that said transition valve means is pressure biased to its said other condition to only then permit release of said one transmission drive whereby said one transmission drive is maintained until said other transmission drive is established with sufficient torque capacity to drive the load.

Claim 6

In a control system for a transmission the combination of transmission means including gearing and a plurality of fluid pressure operated drive establishing means for providing a plurality of different transmission drives to drive a load on selective delivery of fluid pressure to said fluid pressure operated drive establishing means, a source of fluid pressure, shift valve means operable in one condition to provide for delivery of fluid from said source to one of said fluid pressure operated drive establishing means to establish one of said transmission drives and operable in another condition to provide for delivery of fluid from said source to another of said fluid pressure operated drive establishing means to establish another of said transmission drives while providing for exhaust of fluid from said one fluid pressure operated drive establishing means to release said one transmission drive, transition valve means oPerable in one condition to prevent exhaust of fluid from said one fluid pressure operated drive establishing means via said shift valve means when said shift valve means is in its said other condition to effect maintenance of said one transmission drive while said shift valve means is in its said other condition providing for establishment of said other transmission drive, said transition valve means operable in another condition to exhaust said one fluid pressure operated drive establishing means via said shift valve means when said shift valve means is in its said other condition to effect release of said one transmission drive when said another transmission drive is established, means normally yieldingly holding said transition valve means in its said one condition, fluid chamber means connected through a fluid restriction to receive fluid from said source for effecting a fluid pressure bias to urge said transition valve means to its said other condition, exhaust passage means connected to said fluid chamber means, and said gearing including a member that undergoes a load reversal on shifting from said one transmission drive to said other transmission drive and is operable when said one transmission drive is driving the load to provide for opening said exhaust passage means to exhaust said fluid chamber means to permit maintenance of said transition valve means in its said one condition by said biasing means and is further operable on establishment of said other transmission drive with sufficient torque capacity to drive the load to then close said exhaust passage means to permit pressure buildup in said fluid chamber means so that said transition valve means is pressure biased to its said other condition to only then permit release of said one transmission drive whereby said one transmission drive is maintained until said other transmission drive is established with sufficient torque capacity to drive the load.