The variable speed transmission uses multiple fluid couplings to provide a sturdy, durable variable output ratio transmission by using hydraulic fluid to vary the output. Each fluid coupling has an independent output shaft driven by the respective fluid coupling turbine. Output shafts drive alternate gears (i.e., first and third at a first fluid coupling and second and fourth at a second fluid coupling). This configuration alternates gear shifts between the fluid couplings allowing the next gear up or down to be engaged before disengaging the current gear, for uninterrupted gear changes in both up and down shifting. A fifth gear would be driven by a gear connected to the fluid coupling input shafts. Gears could be engaged with hydraulic clutches or syncromesh gears. This combined with variable slip fluid couplings allows for better torque and control.

An actuator system has a power source, an output member, a first fluidic coupling and a second fluidic coupling. The fluidic couplings generate a variable amount of torque transmission. A transmission operatively couples the fluidic couplings to the power source and to the output member in at least first load path and a second load path, the first load path and the second load path being parallel to one another, the first load path including the first fluidic coupling, the second load path including the second fluidic coupling. The fluidic couplings are operable for torque from the power source to be transmitted solely via the first load path, solely via the second load path, and cumulatively via the first load path and the second load path.

An actuator system has a power source, an output member, a first fluidic coupling and a second fluidic coupling. The fluidic couplings generate a variable amount of torque transmission. A transmission operatively couples the fluidic couplings to the power source and to the output member in at least first load path and a second load path, the first load path and the second load path being parallel to one another, the first load path including the first fluidic coupling, the second load path including the second fluidic coupling. The fluidic couplings are operable for torque from the power source to be transmitted solely via the first load path, solely via the second load path, and cumulatively via the first load path and the second load path.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. At least one of the first and second hydraulic units has variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft and the rotatable component of the second hydraulic unit. One of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. A valve having a variable orifice is positioned along the high and low pressure lines, and at least one of the first and second hydraulic units has a variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft of the first hydraulic unit and a rotatable component of the second hydraulic unit. In use, one of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. A valve having a variable orifice is positioned along the high and low pressure lines, and at least one of the first and second hydraulic units has a variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft of the first hydraulic unit and a rotatable component of the second hydraulic unit. In use, one of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. A mechanical torque transfer arrangement transfers torque between the first shaft of the first hydraulic unit and a rotatable housing of the second hydraulic unit. One of the first and second hydraulic units operates as a hydraulic pump and the other operates as a hydraulic motor, and both of the first and second hydraulic units have variable displacement.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. A mechanical torque transfer arrangement transfers torque between the first shaft of the first hydraulic unit and a rotatable housing of the second hydraulic unit. One of the first and second hydraulic units operates as a hydraulic pump and the other operates as a hydraulic motor, and both of the first and second hydraulic units have variable displacement.