Patent ID: 8562472

Claim:
A travel drive device for a dump truck comprising: an axle housing mounted in a non-rotating state on a vehicle body of a dump truck and having an end side opened to form a cylindrical spindle; a rotational shaft provided to axially extend in said spindle of said axle housing and driven and rotated by a drive source; a wheel mounting cylinder which is rotatably provided on an outer peripheral side of said spindle through wheel support bearings and to which wheels are mounted; a planetary gear reduction mechanism provided between said wheel mounting cylinder and said spindle to decelerate rotation of said rotational shaft, which is transmitted to said wheel mounting cylinder; and lubricant oil accommodated in a bottom side of said wheel mounting cylinder in a state of being reserved therein to lubricate said planetary gear reduction mechanism, said planetary gear reduction mechanism comprising: a sun gear arranged on an outer peripheral side of said rotational shaft and rotating with rotation of said rotational shaft; a plurality of planetary gears meshing with said sun gear for rotation; and a carrier rotatably supporting each of said plurality of said planetary gears through a support pin, said carrier being mounted in a non-rotating state on an open end side of said spindle, wherein: a cylindrical coupling member formed as a coupling member for connecting said spindle and said carrier is provided between said spindle and said carrier and said rotational shaft is inserted in an inner peripheral side of said cylindrical coupling member, said cylindrical coupling member is provided with an opposing surface portion positioned higher than a liquid surface level of said lubricant oil and, opposing through an axial gap, a meshing part is provided between said sun gear and each of said planetary gears, an oil guide path is formed between each of said planetary gears and said opposing surface portion and guides said lubricant oil ejected from said meshing part between each of said planetary gears and each of said support pins, said sun gear is configured such that an axial one-side end surface projects closer to an axial one side of said opposing surface portion of said cylindrical coupling member than an end surface of each of said planetary gears, said gap being formed narrower than said oil guide path, and said gap is configured to form a dam in such a manner that said lubricant oil ejected from said meshing part flows toward said oil guide path.