arrangement it is possible to fit replace and or extract the punched paper tape without having to manually disengage and engage the roller 1 as in the past but by simply rotating the spindle 3 of the roller 1 about the pivoting point 8 of the support 5 so as to pass from the position of fig1 to the position of fig2 after axially moving the bush 4 outwardly against the action of the spring 4 39 in order to free the spindle 3 from the support s fig3 a and 3b show a safety element of the device according to the invention it consists of a pair of arcuate lever shaped stops 16 which swivel about an intermediate point 17 and can be controlled at one end 18 in order to lock the roller 1 in the working position of fig1 and 3b by engaging slots 19 in the bushes 4 and 14 or in order to release it into the paper replacement position of fig2 and 3a if the arcuate levers 16 do not engage the slots 19 when in the position of fig1 and 3b this is a sign that the front clutch 15 has not been correctly operated the consequence of which would be that the design on the punched tape would not be read by the appropriate dobby needles the operator then.