Being accurate is not enough: measuring and optimizing the diversity of recommendations

A tractor for agriculture comprising an engine, a hydraulic stepless speed change mechanism having an output shaft, an input shaft connecting the engine with the hydraulic stepless speed change mechanism and having an extended portion, a PTO shaft connected in association with the extended portion, a running device, a transmission shaft connected in association with the output shaft, and a transmission change mechanism disposed at an intermediate portion of the transmission shaft, said transmission change mechanism being connectable and disconnectable of power transmission from the output shaft to the running device and capable of power transmission from the extended portion to the running device when said power transmission from the output shaft to the running device is cut. The tractor may be running even if the hydraulic stepless speed change mechanism is in trouble.