The present invention is an improved apparatus and method for forming a retractable tower or column. The present invention includes pointed hooks wherein the hooks are attached to each section of a section chain, one in a horizontal direction and one in an off-set manner. The section chains are placed on a take up mechanism in an operable position and then raised utilizing a motor. As the section chains are raised, they are guided by a guide tower, rollers, shims, and gear racks into a position whereby hooks from adjacent sections of the section chains form coupled engagements. The coupled engagement of the hooks of the sections of each adjacent section chains thereby form the column.

Thrust chain device, includes a thrust chain with a straight portion along an axis and a curved portion, and links hinged on shafts, a chain guide, a driving sprocket with chain interlocking teeth, the sprocket being in contact with the chain via contact surfaces in the shape of an involute of a circle, the contact surfaces belonging to the teeth, a tooth engaging with the chain while defining a line of action having an angle with the shaft of the straight portion of between ?10? and 10?, the sprocket in contact with the straight portion and not the curved and is mounted such that it can rotate on a shaft on the side of the chain opposite the curved portion's center of curvature, the contact surfaces including a convex front surface directed towards the straight portion and a rear surface directed towards the curved portion when the tooth is interlocking.

Thrust chain device, includes a thrust chain with a straight portion along an axis and a curved portion, and links hinged on shafts, a chain guide, a driving sprocket with chain interlocking teeth, the sprocket being in contact with the chain via contact surfaces in the shape of an involute of a circle, the contact surfaces belonging to the teeth, a tooth engaging with the chain while defining a line of action having an angle with the shaft of the straight portion of between ?10? and 10?, the sprocket in contact with the straight portion and not the curved and is mounted such that it can rotate on a shaft on the side of the chain opposite the curved portion's center of curvature, the contact surfaces including a convex front surface directed towards the straight portion and a rear surface directed towards the curved portion when the tooth is interlocking.

A thrust chain device that induces an open thrust chain with a thrust portion and a housing portion, a thrust chain guide on a thrust portion of the thrust chain, a driving sprocket provided with teeth interlocking with the thrust chain, and a storage space of the housing portion, is provided. The storage space is parallel to the thrust portion and located opposite the thrust portion, the driving sprocket interlocks bilaterally with the thrust chain in a symmetric manner on the side of the thrust portion and on the side of the housing portion, the chain includes a connection portion between the thrust portion and the housing portion, arranged at a distance from the sprocket, the driving sprocket is in contact with the thrust chain by surfaces in the shape of an involute of a circle, the surfaces belonging to the teeth, where one tooth meshes with the chain while defining a line of action having an angle with the thrust portion between 10 and 10, and the guide includes contact surfaces in synthetic material.

A thrust chain device that induces an open thrust chain with a thrust portion and a housing portion, a thrust chain guide on a thrust portion of the thrust chain, a driving sprocket provided with teeth interlocking with the thrust chain, and a storage space of the housing portion, is provided. The storage space is parallel to the thrust portion and located opposite the thrust portion, the driving sprocket interlocks bilaterally with the thrust chain in a symmetric manner on the side of the thrust portion and on the side of the housing portion, the chain includes a connection portion between the thrust portion and the housing portion, arranged at a distance from the sprocket, the driving sprocket is in contact with the thrust chain by surfaces in the shape of an involute of a circle, the surfaces belonging to the teeth, where one tooth meshes with the chain while defining a line of action having an angle with the thrust portion between 10 and 10, and the guide includes contact surfaces in synthetic material.

Disclosed is a tracked lifting platform for vehicles (14), comprising at least two tracks (16), wherein each track (16) engages at least at a respective end region of a lifting platform (18) for lifting and lowering the track (16) between a basic position (19) and a working position (21), wherein the lifting platform (18) comprises a push column (21) with multiple push members (23), which can be arranged one above the other so as to be resistant to pressure in the vertical direction.

Disclosed is a tracked lifting platform for vehicles (14), comprising at least two tracks (16), wherein each track (16) engages at least at a respective end region of a lifting platform (18) for lifting and lowering the track (16) between a basic position (19) and a working position (21), wherein the lifting platform (18) comprises a push column (21) with multiple push members (23), which can be arranged one above the other so as to be resistant to pressure in the vertical direction.

An engagement chain has two chain members. Each of the chain members includes link plates, each of which has two pin holes, and coupling pins. The two pin holes are aligned in the advancing/retreating direction and are sized differently from each other. Each of the coupling pins of each chain member is tightly received in the smaller pin hole of the two pin holes of one of any adjacent two of the link plates in the advancing/retreating direction and is loosely received in the larger pin hole of the two pin holes of the other one of the two adjacent link plates. In a state in which the chain members are integrated with each other, any two of the coupling pins that are opposed to each other are in the same received states in the corresponding pin holes.

An engagement chain has two chain members. Each of the chain members includes link plates, each of which has two pin holes, and coupling pins. The two pin holes are aligned in the advancing/retreating direction and are sized differently from each other. Each of the coupling pins of each chain member is tightly received in the smaller pin hole of the two pin holes of one of any adjacent two of the link plates in the advancing/retreating direction and is loosely received in the larger pin hole of the two pin holes of the other one of the two adjacent link plates. In a state in which the chain members are integrated with each other, any two of the coupling pins that are opposed to each other are in the same received states in the corresponding pin holes.

The present invention is an improved apparatus and method for forming a retractable tower or column. The present invention includes pointed hooks wherein the hooks are attached to each section of a section chain, one in a horizontal direction and one in an off-set manner. The section chains are placed on a take up mechanism in an operable position and then raised utilizing a motor. As the section chains are raised, they are guided by a guide tower, rollers, shims, and gear racks into a position whereby hooks from adjacent sections of the section chains form coupled engagements. The coupled engagement of the hooks of the sections of each adjacent section chains thereby form the column.