High efficiency, high output transmission having an aluminum housing

1. A high output transmission comprising:

an aluminum housing;

an input shaft and an output shaft disposed in the aluminum housing, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing a torque output to a driveline;

a pair of twin countershafts including helical forward drive gears disposed in the aluminum housing and selectively coupled to the input shaft at a first end, and selectively coupled to the output shaft at a second end via a main shaft selectively coupled to the output shaft; and

a planetary gear set comprising a sun gear and a ring gear, wherein the ring gear is coupled to the output shaft, and wherein the sun gear is selectively coupled to the ring gear, the transmission further comprising a ball bearing operatively positioned between the sun gear and the ring gear, and wherein the helical gears are configured to apply thrust loads to the ball bearing.

2. The transmission of claim 1 , wherein a driveline of the transmission does not include any tapered bearings, and wherein enclosure bearings of the housing of the transmission do not take thrust loads of the transmission.

3. The transmission of claim 1 , further comprising:

a controller, the controller comprising a friction brake control circuit structured to provide a friction brake engagement command;

wherein the transmission further comprises a friction brake responsive to the friction brake engagement command to engage one of the twin countershafts; and

wherein the friction brake control circuit is further structured to determine a speed differential between the one of the twin countershafts and an engaging shaft to slow the countershaft during a shift.

4. The transmission of claim 1 , further comprising a controller comprising a shift control circuit, wherein the shift control circuit is structured to:

interpret a shift rail velocity;

provide a first opposing pulse command in response to the shift rail velocity, the first opposing pulse command comprising a first predetermined amount of air above an ambient amount of air in a first closed volume, wherein pressure in the first closed volume opposes movement of a shift actuator in a shift direction;

to determine a second predetermined amount of air in response to at least one of a speed of at least one of the shafts, an air supply pressure, and a transmission temperature value, the second predetermined amount of air comprising an amount of air above an ambient amount of air in a second closed volume, wherein pressure in the second closed volume promotes movement of the shift actuator in the shift direction; and

provide a first actuating pulse command, the first actuating pulse command comprising the second predetermined amount of air.

5. A high output transmission comprising:

an aluminum housing;

an input shaft and an output shaft disposed in the aluminum housing, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing a torque output to a driveline; and

a pair of twin countershafts including helical forward drive gears disposed in the aluminum housing and selectively coupled to the input shaft at a first end, and selectively coupled to the output shaft at a second end via a main shaft selectively coupled to the output shaft;

wherein a driveline of the transmission does not include any tapered bearings, and wherein enclosure bearings of the housing of the transmission do not take thrust loads of the transmission.

6. The transmission of claim 5 , further comprising:

a controller, the controller comprising a friction brake control circuit structured to provide a friction brake engagement command;

wherein the transmission further comprises a friction brake responsive to the friction brake engagement command to engage one of the twin countershafts; and

wherein the friction brake control circuit is further structured to determine a speed differential between the one of the twin countershafts and an engaging shaft to slow the countershaft during a shift.

7. The transmission of claim 5 , further comprising a controller comprising a shift control circuit, wherein the shift control circuit is structured to:

interpret a shift rail velocity;

provide a first opposing pulse command in response to the shift rail velocity, the first opposing pulse command comprising a first predetermined amount of air above an ambient amount of air in a first closed volume, wherein pressure in the first closed volume opposes movement of a shift actuator in a shift direction;

to determine a second predetermined amount of air in response to at least one of a speed of at least one of the shafts, an air supply pressure, and a transmission temperature value, the second predetermined amount of air comprising an amount of air above an ambient amount of air in a second closed volume, wherein pressure in the second closed volume promotes movement of the shift actuator in the shift direction; and

provide a first actuating pulse command, the first actuating pulse command comprising the second predetermined amount of air.

8. A high output transmission comprising:

an aluminum housing;

an input shaft and an output shaft disposed in the aluminum housing, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing a torque output to a driveline;

a pair of twin countershafts including helical forward drive gears disposed in the aluminum housing and selectively coupled to the input shaft at a first end, and selectively coupled to the output shaft at a second end via a main shaft selectively coupled to the output shaft; and

a controller, the controller comprising a friction brake control circuit structured to provide a friction brake engagement command;

wherein the transmission further comprises a friction brake responsive to the friction brake engagement command to engage one of the twin countershafts; and

wherein the friction brake control circuit is further structured to determine a speed differential between the one of the twin countershafts and an engaging shaft to slow the countershaft during a shift.

9. The transmission of claim 8 , further comprising a controller comprising a shift control circuit, wherein the shift control circuit is structured to:

interpret a shift rail velocity;

provide a first opposing pulse command in response to the shift rail velocity, the first opposing pulse command comprising a first predetermined amount of air above an ambient amount of air in a first closed volume, wherein pressure in the first closed volume opposes movement of a shift actuator in a shift direction;

to determine a second predetermined amount of air in response to at least one of a speed of at least one of the shafts, an air supply pressure, and a transmission temperature value, the second predetermined amount of air comprising an amount of air above an ambient amount of air in a second closed volume, wherein pressure in the second closed volume promotes movement of the shift actuator in the shift direction; and

provide a first actuating pulse command, the first actuating pulse command comprising the second predetermined amount of air.

10. A high output transmission comprising:

an aluminum housing;

an input shaft and an output shaft disposed in the aluminum housing, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing a torque output to a driveline;

a pair of twin countershafts including helical forward drive gears disposed in the aluminum housing and selectively coupled to the input shaft at a first end, and selectively coupled to the output shaft at a second end via a main shaft selectively coupled to the output shaft; and

a controller comprising a shift control circuit, wherein the shift control circuit is structured to:

interpret a shift rail velocity;

provide a first opposing pulse command in response to the shift rail velocity, the first opposing pulse command comprising a first predetermined amount of air above an ambient amount of air in a first closed volume, wherein pressure in the first closed volume opposes movement of a shift actuator in a shift direction;

to determine a second predetermined amount of air in response to at least one of a speed of at least one of the shafts, an air supply pressure, and a transmission temperature value, the second predetermined amount of air comprising an amount of air above an ambient amount of air in a second closed volume, wherein pressure in the second closed volume promotes movement of the shift actuator in the shift direction; and

provide a first actuating pulse command, the first actuating pulse command comprising the second predetermined amount of air.

11. The transmission of claim 10 , wherein the shift control circuit is further structured to interpret a shift actuator position, and to provide a second opposing pulse command in response to the shift actuator position indicating an engaging synchronizer is off the block.

12. The transmission of claim 10 , wherein the shift control circuit is further structured to provide the first opposing pulse command after the first actuating pulse command, and further in response to an expiration of a predetermined opposing pulse delay time.

13. The transmission of claim 10 , wherein the shift control circuit is further structured to interpret a shift actuator position, a second opposing pulse command in response to the shift actuator position indicating an engaging synchronizer is off the block, and to interrupt at least one of the first actuating pulse command and the second opposing pulse command to synchronize pressure decay in the first closed volume and the second closed volume.

14. The transmission of claim 10 , wherein the shift control circuit is further structured to:

interpret a shift actuator position;

modulate the first actuating pulse command in response to a previously determined gear departure position value; and

wherein the modulating comprises providing the first actuating pulse command as a full open command in response to a position of the shift actuator being on an engaged side of a gear departure position value, and providing the first actuating pulse command as a pulse-width modulated (PWM) command in response to the position of the shift actuator being one of approaching or exceeding the gear departure position value.

15. The transmission of claim 10 , wherein the controller further comprises:

a backlash indication circuit structured to identify an imminent backlash crossing event at a first gear mesh by performing at least one operation selected from the operations consisting of;

determining that an imminent rotational direction of the first gear mesh in the transmission is an opposite rotational direction to an established rotational direction of the first gear mesh;

determining that a speed change between a first shaft comprising gears on one side of the first gear mesh and a second shaft comprising gears on an opposing side of the first gear mesh is likely to induce a backlash crossing event;

determining that a gear shift occurring at a second gear mesh is likely to induce a backlash crossing event at the first gear mesh;

determining that a transmission input torque value indicates an imminent zero crossing event; and

determining that a vehicle operating condition is likely to induce a backlash crossing event; and

a backlash management circuit structured to reduce engagement force experienced by the first gear mesh in response to receiving a backlash crossing indication event from the backlash indication circuit by performing at least one operation selected from the operations consisting of:

disengaging the first gear mesh during at least a portion of the backlash crossing event;

disengaging a clutch during at least a portion of the backlash crossing event; and

slipping a clutch during at least a portion of the backlash crossing event.

16. A high efficiency, high output transmission, comprising:

an aluminum housing;

an input shaft and an output shaft disposed in the aluminum housing, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing a torque output to a driveline;

twin countershafts disposed in the aluminum housing and comprising helical forward drive gears, the twin countershafts selectively coupled to the input shaft at a first end, and selectively coupled to the output shaft at a second end;

wherein the twin countershafts are selectively coupled to the output shaft at the second end via a main shaft selectively coupled to the output shaft, wherein a driveline of the transmission does not include any tapered bearings, and wherein enclosure bearings of the housing of the transmission do not take thrust loads of the transmission.

17. The transmission of claim 16 , further comprising a friction brake on one of the twin countershafts; and

a controller including a friction brake control circuit structured to determine a speed differential between the one of the twin countershafts and an engaging shaft to slow the countershaft during a shift.

18. The transmission of claim 17 , wherein the controller further comprises a shift control circuit, wherein the shift control circuit is structured to:

interpret a shift rail velocity;

provide a first opposing pulse command in response to the shift rail velocity, the first opposing pulse command comprising a first predetermined amount of air above an ambient amount of air in a first closed volume, wherein pressure in the first closed volume opposes movement of a shift actuator in a shift direction;

to determine a second predetermined amount of air in response to at least one of a speed of at least one of the shafts, an air supply pressure, and a transmission temperature value, the second predetermined amount of air comprising an amount of air above an ambient amount of air in a second closed volume, wherein pressure in the second closed volume promotes movement of the shift actuator in the shift direction; and

provide a first actuating pulse command, the first actuating pulse command comprising the second predetermined amount of air.

19. The transmission of claim 18 , wherein the controller further comprises:

a backlash indication circuit structured to identify an imminent backlash crossing event at a first gear mesh by performing at least one operation selected from the operations consisting of;

determining that an imminent rotational direction of the first gear mesh in the transmission is an opposite rotational direction to an established rotational direction of the first gear mesh;

determining that a speed change between a first shaft comprising gears on one side of the first gear mesh and a second shaft comprising gears on an opposing side of the first gear mesh is likely to induce a backlash crossing event;

determining that a gear shift occurring at a second gear mesh is likely to induce a backlash crossing event at the first gear mesh;

determining that a transmission input torque value indicates an imminent zero crossing event; and

determining that a vehicle operating condition is likely to induce a backlash crossing event; and

a backlash management circuit structured to reduce engagement force experienced by the first gear mesh in response to receiving a backlash crossing indication event from the backlash indication circuit by performing at least one operation selected from the operations consisting of:

disengaging the first gear mesh during at least a portion of the backlash crossing event;

disengaging a clutch during at least a portion of the backlash crossing event; and

slipping a clutch during at least a portion of the backlash crossing event.