Method of monitoring filter rod sections in filter tipping machines

In a method of producing filter cigarettes or analogous smokers' products wherein one end of a tobacco-containing first rod-shaped component is connected with a coaxial rod-shaped filter component by an adhesive-coated uniting band which is convoluted around the filter component and the adjacent end of the first component, the steps of transporting successive pairs of spaced-apart first components sideways along a first path so that the first components of each pair define a gap having a width at least equal to the length of a filter component of double unit length;

• transporting a series of discrete filter components of double unit length along a second path and introducing successive filter components of said series into a first portion of said first path so that each filter component is located in the gap between a pair of first components;
• draping discrete adhesive-coated uniting bands around successive filter components of double unit length and the adjacent ends of the first components of the respective pairs in a second portion of said first path;
• monitoring one of said paths ahead of said second portion of said first path for the presence of filter components of double unit length;
• generating signals in response to detection of the absence of filter components of double unit length;
• and moving at least one of the first components of the respective pairs axially toward the other in response to said signals and ahead of said second portion of said first path.