US Patent 9783391 Elevator installation

An elevator installation includes a shaft in which at least two elevator cars are arranged one above the other and are capable of travel upward and downward in a vertical direction separately from one another, wherein each elevator car is assigned a travel drive. The elevator cars are capable of travel with large and small spacings to one another without the risk of collision by coupling at least two elevator cars together by way of a variable-length, releasable coupling device, wherein the spacing between the coupled-together elevator cars can be varied, in a manner dependent on the relative speed between the two elevator cars, with the aid of at least one of the travel drives.