Textile raising machines

1,119,138. Finishing fabrics. T. W. RILEY (ROCHDALE) Ltd. 12 May, 1967, No. 22134/67. Heading D1S. A textile raising machine having rollers 8 to which driving or braking force is applied through an electro-magnetic coupling 19, is provided with control means comprising means 36 for producing an electrical signal dependent upon the speed of the fabric, means 34 for producing an electrical signal dependent upon the speed of rotation of the rollers 8, and means 43 for comparing the two signals and controlling. in dependence upon the comparison, the driving or braking force applied through the electro-magnetic coupling 19 in order to maintain a predetermined speed differential between the fabric and the rollers. As shown, the machine comprises a barrel 5, Fig. 1, mounted on a motor-driven shaft 6 and carrying alternate pile and counterpile rollers 7, 8, respectively, driven by belting (not shown) from pinions 9, 12. The points of of the card clothing of the rollers 7 extend in the direction of rotation of the barrel 5 and those of the rollers 8 in the opposite direction and the fabric is passed around part of the barrel periphery in the direction opposite to the direction of rotation thereof. The pinions 9, 12 mesh with pinions 13, 17 driven through gear boxes 14, 18 and electromagnetic couplings 15, 19 from constant speed motors 16, 20, respectively. The coupling 19, Fig. 2. comprises drive and brake units 23, 24, respectively. In the unit 23. the shaft 25 of the motor 20 is connected to a member 26 of magnetic material extending about a winding 27 and about a member 28 of magnetic material. In the unit 24, a member 32 of magnetic material extends about a winding 33. A tachogenerator 34 is mounted on the output shaft 29 of the coupling 19 to produce an electrical signal in dependence upon the speed of rotation of the rollers 8. By energizing the winding 27 or 33, respectively, a driving or braking torque is exerted on the shaft 29. The coupling 15 is identical with the coupling 19 and incorporates a tachogenerator 35 to produce an electrical signal in dependence upon the speed of the rollers 7. A tachogenerator 36 is driven by a roller (not shown) over which the fabric passes either before or after raising to produce a signal dependent upon the fabric speed. The output from the tachogenerator 36 is fed to potentiometers 37, 38 and the voltages tapped off therefrom are fed to error units 43, 44. The voltages produced by the tachogenerators 34, 35 are also fed