565,699. Converting rotary into reciprocating motion and vice versa. CULBERTSON, W. J. Oct. 29, 1942, No. 15196. Convention date, Oct. 17, 1941. [Class 80 (i)] [Also in Group XXVII] Although of general application, the invention is particularly directed to the connecting of the pistons to the crank-shafts in radial cylinder, opposed cylinder, or opposed-piston single or double-acting opposed or tandemcylinder types of engines, pumps, compressors, &c. Perfect balance is obtained and the reciprocating parts move with simple harmonic motion. In its simplest form it comprises two crank-shafts geared together to rotate in opposite directions at equal speeds, a crank-pin on each shaft, an eccentric sheave rotatably mounted on each crank-pin, the eccentricity of the sheaves and the throw of the cranks all being equal to one another, and a rigid link in which the eccentric sheaves are mounted, both crank-pins reaching an identical point in the revolution simultaneously. Two crank-shafts 2, 3, Fig. 1, are geared together by gears 5. An eccentric sheave 8 integral with a sleeve 9 is rotatably mounted on each crank-pin 6. The eccentricity e of the sheaves and the throw T of the cranks are all equal. Both eccentric sheaves rotate within a rigid link 10 to which a piston-rod 11 is secured. To ensure that the link 10 will move so as to remain always parallel to itself, each sheave 8 carries a gear 13, these gears meshing with one another in such manner that each sheave 8 rotates on its crank-pin 6 in a direction opposite to its pin, so that both sheaves and both crank-pins reach a point of extreme travel simultaneously. In a modification, Fig. 2 (not shown), the link member 10 is maintained parallel to itself by a linkage instead of by the gears 13. In Fig. 3, two crank-shafts 25, 26 are connected by gears 30. Two eccentric sheaves 31, 32 are secured, 180 degrees apart, to a sleeve 33 rotatably mounted on the crank-pin 34 and, on the crank-pin 39 are similarly mounted two sheaves 36, 37. The eccentricities of the sheaves and throws of the crank-pins are all equal to one another, as before. The sheaves 32, 37 are rotatably mounted. in a rigid link 41. A piston-rod 42 of an opposed-piston type engine or pump is connected to a strap 43 of the sheave 36. Two other piston-rods 44 are connected to a strap 45 rotatably mounted on the sheave 31. Under an exact balance of forces the link 41 would move so as to remain parallel to itself, but, in practice, it is desirable to constrain the movement of this link by shoes 53 mounted on one or more of the straps 43, 45 or on the link itself, the shoes sliding, e.g. in guides 54 in the casing. For correcting any mis-alignment of the line of movement of the eccentrics and piston-rods due to wear of gear teeth, one of the gears 30 is in the form of a ring gear adjustably secured to its crank-shaft by bolts and elongated holes. The link 41 is mounted on the eccentric sheaves which rotate in opposite directions. In a further modification, Fig. 5 (not shown), three crank-shafts are geared together, with a pair of eccentric sheaves at 180 degrees apart rotatably mounted on the crank-pin of each, a link member connecting three eccentric sheaves, the outer two of which rotate in the same direction which is opposite to that of the inner sheave. In Fig. 6, four crank-shafts 90 ... 93 carry respectively crankpins 97, 101, 105, 109, on each of which are mounted, at 180 degrees apart, eccentric sheaves 94, 95 ; 98, 99 ; 102, 103 and 106, 107. Crank-shafts 90, 91 are geared by gears 110, 111, crank-shafts 92, 93 by gears 112, 113 and crank-shafts 91, 93 by gears 114, 115, the gears 110, 111 being located in a different transverse plane from that of gears 112, 113. Two links are provided, one, 116, being mounted on the three sheaves 98, 102, 107 and the other, 117, on the three sheaves 94, 99, 103. Piston-rods 118, 119 are connected to link 116, piston-rods 120 ... 122 to a strap 123 on sheave 95, pistonrods 124, 125 to link 117 and piston-rods 126 ... 128 to a strap 129 on sheave 106. One of the three crank-pins 97, 101, 105 of one of the three, 101, 105, 109, rotates in a direction opposite to that of the others. As before, all the crank-pins and sheaves of each set reach an extreme point of travel at the same time. In a further modification, Fig. 7 (not shown), three geared crank-shafts are located at the corners of a right-angled triangle, eccentric sheaves are, as before, mounted at 180 degrees on each of the three crank-pins and two link members are employed. The arrangements of Figs. 6, 7 make it possible to group a large number of closely spaced coaxial opposedpiston single- or double-acting cylinders in two or more perpendicular cylinder banks.