Common Berthing Mechanism

The Common Berthing Mechanism (English, abbreviation CBM ) is a coupling mechanism for space station modules and other spacecraft. The mechanism comes as a connection in all non- Russian modules of the International Space Station for use.

Description

A Common Berthing Mechanism combines a pressurized module with another. It is composed of two components: an Active Common Berthing Mechanism ( ACBM ) and a Passive Common Berthing Mechanism ( PCBM ). The ACBM is the active part of the mechanism, besides the actual coupling ring it has the necessary tabs, leadership, moveable bolt and control panels. Only this part of CBMs has a power and data connections. The PCBM is the passive counterpart. For a connection, a module with a ACBM, its the other with a PCBM. During installation, the module is done with the passive part by a robot arm to the holding device of the ACBM. If the module is in the correct position, the strength and pressure- tight connection is made by 16 pins in the next step. Both parts of the mechanism to create a pressure-tight connection, both sides hatches open a passage for the crew and cargo transfer with a diameter of 50 inches (127 cm). This means that the International used in the American part of the station as a standard fixtures Standard Payload Racks can be moved through. Power, data and other connections between the modules have to be installed manually after Dockvorgang.

Each module with CBM, which is to couple to one that is already in space station part, must itself have a PCBM and dock at a ACBM.

Use

The first coupling of CBMs in space was the connection of the station module Unity with the Z1 Truss element. Since all pressurized, non-Russian station modules were docked using CBM to the ISS. Also used for the transport of extensive inventories MPLMs used CBM.

The three connecting modules Node 1-3 each have four radial docking ports ACBM. With respect to the axial ports, Unity (Node 1) differs from the other two modules. Here are both active ACBM, at Node 2 and Node 3 are each a ACBM and PCBM. The Destiny and Kibo feature one PCBM and ACBM.

Apart from the actual station modules, the mechanism is also used for the coupling of various unmanned transport spaceships: The Japanese H-2 Transfer Vehicle ( HTV ), as well as the U.S. Space Shuttle SpaceX Dragon and Cygnus are each equipped with a PCBM and the Canadarm2 on a the free ACBMs the ISS modules docked.