to the other it is not practicable for the bellows structure to embrace a full 180 u00b0 of arc nevertheless the structure of the invention enables the end extremities of the bellows structure to project as far as practicable to the midpoints of the suction drums because of the relatively restricted areas in the regions where the suction drums approach each other air losses in these regions are relatively modest the system of the invention makes it commercially practicable for the first time to provide for effective selectively adjustable width control of suction drum dryers so that the effective width of the suction drums can be quickly adjusted to a width appropriate to the fabric being processed by simply actuating the drive motor 34 the machine operator can precisely expand or contract the bellows structures and thereby increase or reduce the width of the open central portion of the suction drums over an entire processing line in a practical commercial embodiment of the invention it has been shown possible to achieve both higher processing speeds and substantial increases in productivity up to 30 in addition it has been found that by being able to direct significantly greater proportions of the processing air through the fabric the temperature of the processing air may be lowered with respect to the requirements of a conventional suction dryer not only does this result in a savings in energy but the lower operating temperatures also reduce the possibility of damaging the fabric it should be understood of course that the specific forms of the invention herein illustrated and described are intended to be representative only.