ways upon the regulation and braking of a loom namely 1 obtain a regulation of maximum movement give up introducing an increase in the inertial to be overcome at the moment of braking with a brake of the sufficiently powerful motor by using the third proposition set out hereinbefore 2 obtain a sufficiently large regulation of movement without however having perceptibly to modify the braking conditions which are at the approved limit in this case use will be made of the second or third proposition pointed out hereinbefore and the increase in inertia to be overcome at braking will be compensated by reduction in weight of the part of the kinematics with constant inertia crankshaft transmission pulleys etc 3 maintain without modification the irregularities in movement if of course they would be acceptable and reduce considerably the inertia to be overcome at the instant of braking the invention is then brought into play as indicated in paragraph 2 above with however much greater reductions of constant inertia in one practical embodiment there are obtained by putting the invention into practice and without modification of the initial braking conditions a reduction of the order of 35 in the irregularities in movement as well as a lessening by about 20 of the horizontal vibrations introduced by the forces of inertia of the sley this has enabled the nominal speed to be increased by about 25 it has been possible to bring about the reduction in the constant inertia by straightforward action on the driven pulley of the crankshaft of course the invention is not limited to the embodiments described and illustrated and it is.