Multi-speed countershaft transmission with a planetary gear set and method

A transmission comprising:

• an input member;
• an output member;
• a main shaft operatively connected to said input member;
• a first and a second shaft member, each spaced from and substantially parallel with said main shaft;
• a plurality of gears arranged in not more than five co-planar, intermeshing gear sets, each of said gears concentric about one of said main shaft, said first shaft member and said second shaft member;
• a planetary gear set operatively connected to at least two of said gears and directly connected to said output member, wherein said planetary gear set includes a ring gear member, a carrier member and a sun gear member;
• at least seven torque-transmitting mechanisms selectively engagable to establish at least seven forward speed ratios and at least one reverse speed ratio between said input member and said output member, wherein said torque-transmitting mechanisms include four torque-transmitting mechanisms each of which is a rotating clutch concentric with one of said shaft members and at least two of said four torque transmitting mechanisms being radially nested within the other two of said four torque transmitting mechanisms;
• and
• wherein said plurality of gears includes at least two range gears concentric with said first shaft member and at least two range gears concentric with said second shaft member, said at least two range gears concentric with said second shaft member each being engageable with said main shaft by a gear not engageable by said range gears concentric with said first shaft member.

A transmission comprising:

• an input member;
• an output member;
• a main shaft operatively connected to said input member;
• a first and a second shaft member, each spaced from and substantially parallel with said main shaft;
• a plurality of gears forming different co-planar, intermeshing gear sets, each of said gears concentric about one of said main shaft, said first shaft member an said second shaft member, wherein said gears concentric with said first and second shaft members partially form not more than five of said co-planar, intermeshing gear sets;
• wherein said plurality of gears includes at least two gears concentric with said first shaft member, one of said at least two gears being operatively supported on the other of said at least two gears and not supported by said first shaft member;
• wherein said not more than five of said co-planar, intermeshing gear sets include a first head gear set for transferring torque from said main shaft to said first shaft member and a second head gear set for transferring torque from said main shaft to said second shaft member;
• wherein one of said gears is connected for common rotation with both of said input member and said main shaft and is included in both of said head gear sets, said first and second head gear sets thereby forming a first of said not more than five co-planar, intermeshing gear sets;
• a planetary gear set operatively connected to at least two of said gears and directly connected to said output member;
• and
• at least seven torque-transmitting mechanisms selectively engagable to establish at least seven forward speed ratios and at least one reverse speed ratio between said input member and said output member.

A method of reducing the length and weight of a transmission package including a main shaft member and a pair of secondary shaft members arranged in a substantially parallel, triangular formation with said main shaft member, and a plurality of gears selectively interconnectable with respective clutches to obtain a plurality of selectable ratios, said method comprising:

• nesting at least some of said clutches sufficiently to at least partially reduce the length of said package;
• supporting at least one of said gears on a bearing disposed on an adjacent gear rather than on one of said secondary shaft members so that said one of said secondary shaft members is sufficiently shorter and lighter to fit within and further reduce the length of said package;
• providing a first head gear set for transferring torque from said main shaft member to a first of said secondary shaft members, and a second head gear set for transferring torque from said main shaft member to a second of said secondary shaft members, wherein said first and second head gear sets are coplanar and both include one of said gears that is continuously connected for common rotation with both of said input member and said main shaft member;
• and
• providing that each forward range gear concentric with one of said secondary shaft members directly interconnects with a gear on said main shaft member that does not directly interconnect with another forward range gear concentric with said other secondary shaft member permitting improved flexibility in the selection of said ratios.