<PICT:0773781/IV(a)/1> <PICT:0773781/IV(a)/2> <PICT:0773781/IV(a)/3> <PICT:0773781/IV(a)/4> <PICT:0773781/IV(a)/5> <PICT:0773781/IV(a)/6> <PICT:0773781/IV(a)/7> <PICT:0773781/IV(a)/8> In spinning machines, for the production of artificial filaments of varying denier, having a number of spinning positions each having its own pump for delivering spinning solution, the pumps being driven with a right-angle drive comprising a worm gear and a worm wheel engaging therewith from a common driving shaft on which the worm gear is fixedly mounted, means are provided for periodically moving the driving shaft lengthwise to and fro to vary the flow of spinning solution delivered by each pump. The shaft may be moved at irregular intervals to give a random spacing of slubs on the filaments and, in addition, the length of movement of the shaft may be variable to give slubs of random length. The movement of the shaft may be controlled by an electronic unit operated by cosmic rays. The movement of the shaft may be rapid for the initiation of a slub and gradual for the return stroke, and the duration of the slub stroke may be less than the duration of the return stroke. The shaft may be moved by a piston operated by compressed air. As shown in Fig. 1, in the spinning assembly shown generally at A, the spinning solution is led from a main supply line 1 through pipes 2 to pumps 3 which feed the solution to jets 4 by way of non-expansible tubes 5, which replace the filter candles normally used, in order to prevent the variations in supply from the pumps from being evened out. The pumps 3 are driven by worm wheels 6 in turn driven by worms 7 fixedly mounted on a common driving shaft 8 which is rotated at a constant speed by a shaft 9 driven by a motor (not shown). The drive is transferred from shaft 9 to shaft 8 by splines 10 on shaft 9 co-operating with grooves 11 cut in the interior of a hollow extension of shaft 8. In this way the lengthwise reciprocation imparted to shaft 8 by the mechanism shown generally at B and in Fig. 3 is not transmitted to shaft 9 and the motor. The lengthwise movement of the shaft 8 to the left accelerates the spinning pumps and, on the return stroke, the pumps are decelerated. An irregular periodicity in the lengthwise reciprocation of the shaft 8 is effected by mechanism shown generally at C and in Fig. 2. Referring to C, a shaft 12 is driven at a constant speed by a motor (not shown) and this drive is transmitted to shaft 13 by bevel gear-wheels 14 and 14a. A second shaft 15 also driven at constant speed drives the gear train 16-20. Thus a bevel gear-wheel 16 on shaft 15 drives a bevel gear-wheel 16a which is attached to a gear-wheel 17 mounted on another shaft, and in turn gear-wheels 18 and 19 mounted on a third shaft drive a gear-wheel 20. Gear-wheel 20 has a stud 21, eccentrically mounted on it, which slides in a slot 22 of an arm 23 pivoted at one end 24. The constant rotational speed of shaft 15 imparts a uniform oscillatory movement to the free end 24a of arm 23. This movement is transmitted by link rods 25 to an arm 26 fixed in a radial position to a bevel gear-wheel 27 so that the oscillatory movement of the arm 23 causes the bevel gear-wheel 27 to rotate to and fro. The bevel gear-wheel 27 meshes with the bevel gear 28 which is the crown-wheel of a differential gear 29. The latter comprises, in known manner, the crown-wheel 28, two planet bevel wheels 30 rotatably mounted on extensions 31 of wheel 28 and two bevel wheels 32, 33 fixed to shafts 13, 34 respectively. Wheel 32 is driven by shaft 13, while wheel 33 drives shaft 34. The combination of the constant rotational speed of wheel 32, and the oscillatory movement of crown-wheel 28 and the planet wheels 30, imparts to shaft 34 a continuously varying rotational speed which can be expressed as a sine wave. The varying speed of shaft 34 is transmitted by bevel gear-wheels 35,36 to a wheel 37 which is fixed on the same shaft as the bevel wheel 36 and which drives an endless belt 39 running round wheel 37 and a non-driven wheel 38. Belt 39 has irregularly spaced teeth projecting from it which strike the end 41 of a lever 42 pivoted at 43 as they pass it. To effect a random spacing of slubs it is necessary that the teeth 40 strike the lever 42 at irregular intervals or at least at intervals the pattern of which repeats only after several complete cycles of the endless belt. For this to happen the period of oscillation of arm 23 and hence gear-wheel 28 must be a prime number with respect to the length of time for one complete cycle of the endless belt. This can be ensured by choosing suitable relative speeds of rotation of shafts 12 and 15. Each time a tooth 40 passes the end 41 of lever 42 it rocks the lever, and the screw 44 on the other end of lever 42 actuates a valve for a compressed air system shown on a larger scale in Fig. 2. Compressed air from a supply line 46 (Fig. 1) enters a chamber 47 (Fig. 2), through an inlet 46a. A valve 48 is normally held on its seating 49 by a spring 50 surrounding a valve stem 51, and the compressed air cannot escape from the chamber 47. When a tooth 40 rocks the lever 42 a screw 44 bearing on the end of the valve stem 51 lifts the valve 48 from its seating 49, and compressed air is free to pass through an outlet 52a into the pipe 52 (Fig. 1) and, via the inlet 52b, into the cylinder 53, which is shown on a larger scale in Fig. 3. A seal prevents escape of air around the valve stem 51 to the atmosphere. When a tooth 40 has passed the end 41 of lever 42, the action of the spring 50 around the valve stem 51 returns the valve 48 on to its seating 49. Referring to Fig. 3, a fixed cylinder 53 has a floating piston 55 within it making a close but sliding fit and sealed with sealing rings 73. The piston surrounds shaft 8 of the spinning machine, but does not rotate with it, and has valves 58 which are normally held against their seatings 61 by springs 60 around the valve stems 57. Compressed air enters the annular space 54 on one side of the piston 55 while the annular space 62 on the other side of the piston is open to the atmosphere by way of holes 63 in the cylinder head 74. In operation, an impulse of compressed air enters the chamber 54 by the inlet 52b and forces the piston 55 to the left until the ends 56 of valve stems 57 strike the fixed cylinder head 74. This lifts the valves 58 from their seatings 61 and allows the compressed air to escape to the atmosphere by way of chamber 62 and holes 63. The movement of piston 55 is transmitted to shaft 8 by means of a collar 64 fixed by a grub-screw 65 to shaft 8. The shaft 8 and piston 55 are returned to the right by the resistance of the spinning pumps 3 (Fig. 1) acting on the worms 7 of the shaft 8. A stop 75 screwed into the piston 55, and sliding in an angle bracket 75a screwed to the cylinder body 53, prevents any rotation of the piston. The movement of shaft 8 may be further controlled and limited by a spring 66 (Fig. 1), between the bearings 69 and 69a for the shaft. A shoulder 67 is fixed to the bearing housing and a stop 68 is fixed to shaft 8. The spring 66 is fixed to stop 68 by a pin 68a. The shaft 8 is moved to the left by the piston 55. This movement is resisted by the spinning pumps 3, which tend to return the shaft to its original position, the resistance of the pumps being partly balanced by the spring 66. A stop 70 to the left of bearing 69 on shaft 8 may also be used to limit the return stroke. In order to compensate for leakage of compressed air from the space 54, there may be provided a supplementary duct 71 (Fig. 1) through which there is delivered to the space 54 a continuous flow of compressed air, the rate of supply of the supplementary compressed air being regulated by the valve 72 in accordance with the required denier of the filaments to be produced. In an example in which the supply of compressed air, which imparts axial movement to the spinning pump common drive-shaft, is controlled by random electrical impulses and the return stroke is controlled by an hydraulic cylinder, viscose from a main supply line 81 (Fig. 4), is led by branch lines 82 to gear pumps 83, from which it is fed by rounder ends without filter candles to jets 84. A common drivingshaft 85 drives the pumps 83 at a constant speed by means of worms 86 fixedly mounted on the shaft and worm wheels 87 on the pump shafts. The drive for the main shaft 85 is contained in a housing 88, and the shaft is supported by bearings 89, 90 at either end. Movement of the shaft is effected by a compressed air-operated piston 91 which, after a short period of free travel, strikes the end 92 and bearings 90 of the shaft, moving them to the left and thereby momentarily accelerating the gear pumps 83. The shaft is moved against the resistance of a hydraulic cylinder 93 and piston 94 which controls the return stroke of the shaft, giving a gradual assisted return. As shown in Fig. 5, compressed air is conducted by a pipe 95 to a single acting valve 96 of standard construction controlled by a solenoid 97, which receives random electrical impulses from a randomizing unit operated by cosmic rays or a radio-active source. This unit is not shown but may be of the type described in Specification 703,697. On receiving an impulse the solenoid 97 operates, by means of links 98, 99, the valve 96 admitting compressed air into the cylinder 100. The piston 91 is thereby moved to the left and a head 101 on the piston, after a period of free travel, strikes the end 92 and bearings 90 of shaft 85, moving shaft and bearings together to the left until the housing 90A of the bearings 90 (which housing is a close sliding fit in the support member 109) comes up against a stop formed by the main wall 102 of the shaft drive housing 88. The shaft 85 is rotated by an electric motor (not shown) through bevel gear-wheels 103, 104