Coupling system of an elevator car door drive

An elevator car door drive including a coupling system, the coupling system comprising:

• a traction means;
• a coupling unit that can be coupled to the traction means;
• and
• an adapter element having a first interlock adjustment structure that cooperates with interlock elements of the traction means to form a first interlocked unit, wherein the first interlocked unit secures a relative position, which is settable in defined interlocking adjustment positions, of the adapter element with respect to the traction means, comprising a second interlocked unit included in the coupling unit that secures a relative position, which is settable in defined interlocking adjustment positions, of the adapter element with respect to the coupling unit, wherein at said second interlocked unit a second spacing between directly adjacent interlocking adjustment positions is smaller than a first spacing between directly adjacent interlocking adjustment positions of the first interlocked unit, and wherein the first interlock adjustment structure and the interlock elements of the traction means are coupled by positive interlocking and the adapter element and the coupling unit are coupled by positive interlocking.