A gear box includes a gear box body of a reducer to which a motor is mounted. The gear box body includes a worm, wheel holding section where a worm wheel of the reducer is held, and a motor holding section, where a part of the motor is contained, the motor holding section having a motor mounting opening. The motor holding section is configured such that a bottom of the motor holding section is provided in a region between a line L1 and a line L2. Here, the line L1 passes through the center C of the worm wheel holding section and is perpendicular to the axis line X of a motor shaft. The line L2 is a tangent line passing through an outer edge portion located near a circular outer peripheral wall of the worm wheel holding section on a motor side and is perpendicular to the axis line X of the motor shaft.

The present invention relates to a transmission (1), in particular for an adjustment drive, comprising a housing (2), a worm shaft (3) which is rotatably mounted in the housing (2) and which can be driven, a worm wheel (4) which is rotatably mounted in the housing (2) and which meshes with the worm shaft (3), an encircling first wedge surface (5) which is formed on the worm wheel (4) or fixedly connected to the worm wheel (4), a brake element (6) which is arranged so as to be rotationally conjoint with respect to the worm wheel (4) and which has a second wedge surface (7), wherein the first wedge surface (5) bears areally against the second wedge surface (7).