Transmission system with planetary gearing operable in forward and reverse modes

A method of selectively transmitting torque between an input and an output in either a forward rotational direction or a reverse rotational direction utilizing planetary gearing that includes a ring gear, single-pinion planet gears, a carrier, and a sun gear, the method comprising:

• accepting an input torque with the ring gear;
• transmitting torque between the ring gear and the carrier through a forward clutch that, when engaged, rotationally couples the ring gear and the carrier to rotate in the same direction and at the same or substantially the same speed;
• delivering an output torque to the sun gear through the planetary gearing in the forward rotational direction;
• receiving a common control signal with a control subsystem;
• producing an actuation stroke with the control subsystem in response to receipt of the common control signal, wherein the actuation stroke concurrently disengages the forward clutch and engages a reverse brake;
• braking the carrier against rotation when the reverse brake is engaged;
• and
• delivering the output torque to the sun gear through the planetary gearing in the reverse rotational direction when the reverse brake is engaged and the forward clutch is disengaged.

A transmission system for transmitting torque to a final drive in forward and reverse operational modes, the transmission system comprising:

• planetary gearing including:
• a ring gear rotatable about an axis of rotation, wherein the ring gear is configured as a torque input to the transmission system;
• a plurality of planet gears;
• a carrier, wherein the planetary gears are rotatably connected to the carrier in a single-pinion configuration;
• and
• a sun gear rotatable about the axis of rotation, wherein the sun gear is configured as a torque output of the transmission system, and wherein the planetary gears each mesh with both the ring gear and the sun gear;
• a journal bracket having a rotationally stationary shaft, wherein the ring gear and the sun gear are each rotatably supported on the shaft;
• a mount rotationally fixed to the sun gear, wherein the mount is externally exposed;
• a forward clutch operatively connected between the ring gear and the carrier, wherein engagement of the forward clutch rotationally couples the ring gear and the carrier, and wherein the forward clutch comprises a wet friction clutch;
• a reverse brake operatively connected between the carrier and a rotationally fixed location, wherein engagement of the reverse brake causes braking of the carrier relative to the rotationally fixed location, wherein the reverse brake comprises a wet friction clutch, and wherein the forward clutch and the reverse brake are arranged concentrically relative to the axis of rotation and at least partially overlap each other in the axial direction;
• and
• a control subsystem that is selectively actuatable to switch the transmission system between a forward operational mode, in which the ring gear and the sun gear are rotatable in the same rotational direction about the axis of rotation, and a reverse operational mode, in which the ring gear and the sun gear are rotatable in opposite rotational directions about the axis of rotation, the control subsystem comprising:
• a pressure chamber;
• a piston positioned at least partially with the pressure chamber and operably connected to both the forward clutch and the reverse brake to selectively transmit axial forces therebetween;
• and
• a spring that spring-biases the piston to a default axial position in the pressure chamber, wherein a common fluidic control signal selectively pressurizes the pressure chamber to translate the piston against the spring-bias of the spring to an actuated axial position, wherein in the forward operational mode the piston is in the default axial position, the forward clutch is engaged, and the reverse brake is disengaged, and wherein in the reverse operational mode the piston is in the actuated axial position, the forward clutch is disengaged, and the reverse brake is engaged.