531,128. Lapping crank-shafts. NORTON CO. July 12, 1939, No. 20329. Convention date, July 20, 1938. [Class 60] A crankshaft lapping machine has a number of lapping arms supported on a movable frame and clampable relatively to the frame while the work is supported between a headstock and a tailstock, separate fluid pressure motors being provided for operating the tailstock centre and the movable frame under the control of one manual valve and for operating the lapping arms and the clamping means under the control of a second manual valve. The base 20 is fitted with a plate 26 which is grooved to form the inner raceways of ball bearings 29, 30 for guiding the reciprocating work table 21. The headstock 22 driven from a motor 34 through multiple belts 36 and the rotation of the headstock spindle effects reciprocation of the table 21 in the manner described in U.S.A. Specification 2,092,734. The outer end of the crankshaft 24 is supported on a ball-bearing tail-centre 51 carried in a slidable sleeve 55 actuated by a fluid pressure cylinder 58. The piston rod 60 of this cylinder actuates a pair of toggle links 63, 64, the former of which is connected to a sliding sleeve 67, the motion of which is transferred through a spring 70 to the sleeve 55. A pair of spaced supporting arms 80 pivotally mounted on a shaft 81, are connected by spaced bars 82, 83 which support the lapping arms. The entire lapping assembly may be moved to an inoperative position by means of a fluid-pressure cylinder 84 the pistonrod 87 of which is connected to a link 89 connected by a link 92 and toggle levers 94, 95 to an arm 98 on the rock-shaft 81 so that when the cylinder 84 is actuated, the linkage is shifted from the full-line to the dotted-line position in Fig. 2 to rock the arms 80 so as to withdraw the lapping assembly from the work. A pump 99 in the base draws fluid from a reservoir 100 and delivers to a control valve 102 operable by a lever 106. In the position shown, Fig. 3, fluid from the valve passes through line 114 to the cylinder 84 and moves the lapping arms into their operative position, while exhaust from cylinder 84 passes through lines 117, 101 to the reservoir. The valve 102 also admits fluid to the tail-centre operating-cylinder 58 just prior to the movement of the lapping arms into operative position. Three lapping arms 130 ... 132 are provided for the main bearings and four, 133 ... 136, for the crank pins. Each lapping arm, such as 132, Fig. 2, has a pair of pivoted arms 140, 141 fitted with part-cylindrical lapsupporting blocks 142, 143. The arms 140, 141, are connected by a pair of toggle levers 146, 147, the stud 148 of which moves in a slot 149, the toggles being in the straight line position, Fig. 2, to maintain the lapping blocks in operative position. To move the blocks away from the work, the piston rod of a fluid pressure cylinder is connected by a link 151 to the pine 148 to operate the toggles, which are broken to withdraw the lapping blocks by outward movement of the piston rod, Fig. 2. Fluid is supplied to the cylinder by lines 132d, 132f. All the lapping elements are operated simultaneously by joining their supply pipes to manifolds 153, 154. Each lapping arm is pivoted to an arm 155 which at its lower end is pivoted to a member 156, in the manner shown in Fig. 12. The arm 155 is yoked at its lower end and flanged nuts 161, 163 on a screw 160 may be adjusted to take up lost motion between the arm 155 and the member 156. The upper pivot on the arm 155 is of similar construction, the lapping arms being free to follow the movement of the crank pins. Each lapping arm is provided with a separate continuous strip of abrasive paper which passes from a reel 172, through guides 174, 175, round for instance a crank pin 24 where it is held by the members 143, 142, and is finally wound on a reel 178 which moves with the lap supporting arm 140 and has a pawl 181 which prevents unreeling of the worn paper. The paper may be fed manually by turning the reel 178. The members 142, 143 may float in their supporting arms. Each lapping arm has a separate abrasive paper supply reel similar to that described above. Guide plates such as 200 are fixed on the bracket 156 to provide lateral guiding means for the lapping arms. All the lapping arms may be simultaneously clamped in an operative position and for this purpose each guide plate such as 200 has a guide 214 for a member 215 having cam depressions 216 coacting with cams 217, 218 on the plate 200 so that upward movement of the slide 215 causes the slide to move to the right, Fig. 10, so as to clamp the arm 132 in a fixed position. Each lapping arm has similar clamping means and all the arms are clamped simultaneously by means of a shaft 221 carrying a number of eccentrics engaging elongated slots in the clamping slides 215. A fluid motor 230 having a vane 232 operates the shaft 221. A control valve 250 is supplied by the pipe 101 and is actuated by a control lever 253. In the position shown in Fig. 3, pressure fluid passes along the line 255 and closes all the lapping elements. Fluid also passes to a chamber 257 to unclamp the lapping arms so that the crank shaft may be rotated. After completion of the operation the lever 253 is shifted to clamp the lapping arms in a definite position and finally fluid is admitted to the upper ends of cylinders 130 ... 136, to open the lapping elements for withdrawal of the lapping arm assembly. The control lever is associated with a notched quadrant 267 for determining the positions of the control valve.