Travel drive device for dump truck

There are provided a rotational shaft (17) provided in a spindle (14), a wheel mounting cylinder (18) which is mounted through wheel support bearings (20, 21) on an outer peripheral side of the spindle (14), and a planetary gear reduction mechanism (25, 33) for decelerating rotation of the rotational shaft (17), which is transmitted to the wheel mounting cylinder (18). A carrier (38) forming a part of the planetary gear reduction mechanism (25, 33) is mounted in a non-rotating state on an open end side of the spindle (14). A cylindrical coupling member (53) is provided between an open side of the spindle (14) and the carrier (38). An oil guide path (55) is formed between a one-side end surface of each of planetary gears (36) and an opposing surface portion (53E) of a cylindrical coupling member (53) for guiding lubricant oil ejected from a meshing part (40) therebetween to a planetary gear bearing (39).