Patent GB-832590-A (GB)
Title: Improvements in or relating to looper lubricating systems for sewing machines
IPC: D05B71/02
Filed: 1958-02-12
Abstract: 832,590. Sewing machines. PFAFF A.G., G. M. Feb. 12, 1958 [Feb. 13, 1957], No. 4535/58. Class 112 [Also in Group XXXIV] In a lubricating system, for the looper race 7 of a sewing machine, a lubricant supply line 4 leading from a tank 2 with a removable lid 5, Fig. 1 (not shown), delivers lubricant to a valve 5 connected by a supply line 6 to a lubricant dropping member 8 which supplies lubricant to the looper race, the feed from the valve 5 being controlled by a centrifugal device 33, 34, 42 which is secured to the looper shaft 23 and operates at a predetermined speed of the shaft. Shells 33, 34 of the centrifugal device enclose balls 42, the shell 33 being made fast with the shaft 23 and the shell 34 being fixed to a pin 35 which is movable axially in a slot 36 in a hollow part 37 of the shaft 23. A thrust rod 38, having a piston shaped end 39 abutting the pin 35, is located in the axial bore 37, its other end extending through a hole in a bearing 40 which is adjustably screwed into the corresponding end of the bore 37. A compression spring 41, constrained between the piston shaped end part 39 and the bearing 40, urges the shell, with a force which can be regulated by screw adjustment of the bearing 40, toward the shell 33. The shaft 23, mounted in ball bearings 24, 25 in a housing 26 carried by a moulded portion 27 of a machine base plate 11, carries pinion 29 in mesh with a toothed gear 30 on a drive shaft 31 which is rotatably mounted in a ball bearing 32 carried by moulded portion 10 of the plate 11 housing the valve 5. The lubricant supply line 4 is connected to a bore 12 in the valve 5 which communicates with a bore 13 of smaller diameter to form a seat 14 for a valve ball 15 which is urged towards its seat by a spring 16. A radial bore 18, leading from the bore 13, is connected to a threaded nipple 19 of the lubricant feed line 6. An operating pin 20 for the valve ball 15 extends through the bore 13 and is surrounded by a gasket ring 21 sealed in position by an insert member 22 through which the operating pin passes. The free end of a lever 44 is disposed between the laterally offset and neighbouring ends of the thrust rod 38 and the operating pin 20, the other end being linked by a bolt 45 to a threaded spindle 46 which is slidably mounted in a sleeve 48 secured by a screw 49 to the moulded portion 27  of the base plate 11. Adjustment of a knurled nut 52, threaded on to one end of the spindle 46, adjusts the tension of a spring 51 located between the sleeve 48 and an abutment 50 of the spindle 46 and varies the position of the linkage point 45 of the lever 44. This determines the angular location of the lever 44 and thus the effective length between the free end 43 of the lever, which is adapted to engage the operating pin 20, and an abutment face 56 on a pressure member 55 which is pivoted to the lever 44 and is engaged by the thrust rod 38. At a predetermined speed of the shaft 23 the balls 42, as a result of the centrifugal force developed, overcome the force of the spring 41 so that the shell 34 and the thrust rod 38 are moved along the shaft 23, the movement being transferred, through the adjustable lever 44, to the pin 20 which opens the valve ball 15 by an amount corresponding to the speed of the shaft.