A reduction gear includes an external gear, an internal gear which meshes with the external gear, a first member which synchronizes with a rotation of the external gear, a second member which synchronizes with a rotation of the internal gear, and a main bearing which is disposed between the first member and the second member, in which one of the first member and the second member is connected to a driven member and the other is fixed to an external member, and the first member, the second member, and the main bearing are formed of a material having a larger Young's modulus and larger specific gravity than those of a material constituting the external gear and the internal gear.

A motion device including a carriage for traveling along a rail. The carriage can have at least one rotatable fixed position roller, and at least one rotatable adjustable roller that is movable relative to the at least one fixed position roller for self compensating for play between the rollers and mating surfaces of the rail. Each adjustable roller can be part of a movable roller portion movably mounted to the carriage. The movable roller portion can be adjustably movable by a self adjustment mechanism. The self adjustment mechanism can include a mechanical advantage pushing member for movably engaging the movable roller portion. The mechanical advantage pushing member can be resiliently biased against the movable roller portion by a biasing arrangement. The biasing arrangement can cause movement of the mechanical advantage pushing member and the movable roller portion for moving the at least one adjustable roller for self compensating for play.

A reduction gear includes an external gear, an internal gear which meshes with the external gear, a first member which synchronizes with a rotation of the external gear, a second member which synchronizes with a rotation of the internal gear, and a main bearing which is disposed between the first member and the second member, in which one of the first member and the second member is connected to a driven member and the other is fixed to an external member, and the first member, the second member, and the main bearing are formed of a material having a larger Young's modulus and larger specific gravity than those of a material constituting the external gear and the internal gear.

A motion device can include a carriage for traveling along a rail. The carriage can have at least one rotatable fixed position roller, and at least one rotatable adjustable roller that is movable relative to the at least one fixed position roller for self compensating for play between the rollers and mating surfaces of the rail. Each at least one adjustable roller can be part of a movable roller portion movably mounted to the carriage. The movable roller portion can be adjustably movable by a self adjustment mechanism. The self adjustment mechanism can include a mechanical advantage pushing member capable of movably engaging the movable roller portion. The mechanical advantage pushing member can be resiliently biased against the movable roller portion by a biasing arrangement. The biasing arrangement can be capable of causing movement of the mechanical advantage pushing member and the movable roller portion for moving the at least one adjustable roller for self compensating for said play.

The present application relates to a field of bearing technology and relates to a recirculating roller bearing, including a front cover plate, a rear cover plate, an inner supporter, a sealing covering and a plurality of rolling carriers and at least one connector, in which the front cover plate and the rear cover plate are detachable connected on two sides of the inner supporter respectively; a circulating guiding path is defined by the front cover plate, the rear cover plate, the inner supporter and the sealing covering, the circulating guiding path includes a sealing portion and an opened load-bearing portion; the rolling carriers are filled in the circulating guiding path, each of the rolling carriers forms a rolling fit with the inner supporter, and each of the rolling carrier forms a rolling fit with a retractable fork when passing the opened load-bearing portion of the circulating guiding path.

The present application relates to a field of bearing technology and relates to a recirculating roller bearing, including a front cover plate, a rear cover plate, an inner supporter, a sealing covering and a plurality of rolling carriers and at least one connector, in which the front cover plate and the rear cover plate are detachable connected on two sides of the inner supporter respectively; a circulating guiding path is defined by the front cover plate, the rear cover plate, the inner supporter and the sealing covering, the circulating guiding path includes a sealing portion and an opened load-bearing portion; the rolling carriers are filled in the circulating guiding path, each of the rolling carriers forms a rolling fit with the inner supporter, and each of the rolling carrier forms a rolling fit with a retractable fork when passing the opened load-bearing portion of the circulating guiding path.