US 12,281,701 B2
Transmission and method for producing transmission
Toshifumi Yasuda, Sakai (JP); Jun Yoshida, Sakai (JP); Yusuke Morita, Sakai (JP); and Akihiro Takami, Sakai (JP)
Assigned to Kubota Corporation, Osaka (JP)
Filed by Kubota Corporation, Osaka (JP)
Filed on Mar. 30, 2023, as Appl. No. 18/128,651.
Claims priority of application No. 2022-065180 (JP), filed on Apr. 11, 2022.
Prior Publication US 2023/0323947 A1, Oct. 12, 2023
Int. Cl. F16H 59/10 (2006.01); F16H 63/18 (2006.01)
CPC F16H 63/18 (2013.01) [F16H 59/10 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A transmission for a traveling vehicle, comprising:
a gear change operation tool;
a shift drum configured to rotate in response to an operation of the gear change operation tool and having at least one bent guide groove disposed in a surface of the shift drum and extending in a circumferential direction of the surface of the shift drum;
at least one shifter having a cam pin in the at least one guide groove and configured to be moved by a movement of the cam pin following the rotation of the shift drum; and
a speed change gearbox comprising gears configured to be switched by the movement of the shifter,
wherein the at least one guide groove includes a bent section formed by (i) first end mill machining performed in a direction in which the at least one guide groove extends, with use of an end mill having a diameter corresponding to a width of the guide groove, and (ii) second end mill machining performed in the direction in which the at least one guide groove extends, in such a manner as to increase a curvature radius of an inner wall on an inner side, the inner wall having been formed by the first end mill machining, and
wherein the bent section further has an inner wall on an outer side and a ratio between a curvature radius of the inner wall on the outer side and the curvature radius of the inner wall on the inner side is 2 to 1.5.