Patent GB-190924041-A (GB)
Title: Improvements in Flexible Drive and Variable Speed Mechanism for Motor-propelled Vehicles, Velocipedes and the like.
Inventor: LASERSON FREDERICK MAURICE
IPC: B62M25/00
Filed: 1909-10-20
Granted: 1910-10-20
Abstract: 24,041. Laserson, F. M. Oct. 20. Cranks, adjustable-throw.-Relates to devices applicable to motor-propelled vehicles, velocipedes, &c., in which the throw of a driving- crank or eccentric is automatically reduced, and the gear thereby lowered, with increase of resistance in the vehicles. The slotted crank b, Fig. 1, on the engine shaft a carries a spring g on which bears the crank-pin z connected by a connecting-rod f to a reciprocating frame d carrying pawls e, which engages a driven ratchet-wheel c. Under increased resistance, the pin x moves into the slot against the resistance of the spring g, and the throw of the crank is decreased, the pin being returned to the end of the slot by the spring when the crank passes its dead-centre. The crank may be formed in two pivoted parts, Fig. 2, normally kept in a straight line by a spring g, increase of resistance folding the crank so as to shorten its throw. In order to prevent the action of the spring during the idle part of the stroke, an arrangement such as is shown in Figs. 3 and 4 may be used. The divided crank is kept in its position of greatest throw by a spring i, which also tends to separate the two pivoted parts, and disengage ratchet teeth h formed on their adjacent faces. A cam j on the connecting-rod is so placed that, during the idle stroke of the crank, it actuates a lever k which bears on the pivot pin a' and keeps the ratchet teeth h in engagement so that the crank cannot straighten out. In the form shown in Figs. 10 and 11, the crank-shaft a carries a pinion n gearing with a toothed wheel m which is secured to a spindle o<1>, pivoted in a casing l and carrying the arm o to which the connecting-rod f is secured. A spring p, secured to the casing l, bears on a block m<1>, on the wheel m, and allows the wheel m to rotate to shorten the throw when the resistance decreases. The parts are retained by a pin q in the casing l engaging ratchet teeth on the wheel m when operated by a stationary cam r. The pawls e may be disengaged from the ratchet-wheel c by a segmental ring s adapted to engage pins e<1> on the pawls, and operated by links t. The crank-pin may slide in a radial slot u<4> in a loose disk u<2>, Fig. 7, and a curved slot u<5> in a disk u<1>, secured to the crank-shaft, a spring u<3> resisting rotation and also separating the disks. A fixed cam v<2> engages the disk u<2> and retains the parts during the idle part of the stroke. As shown in Fig. 8, the crankshaft carries a bevel pinion w' engaging bevelwheels w<2>, w<3> on spindles x, x<1> in a casing x<3>. The spindle x<1> is connected to the casing by a spring x<2>, and the spindle x has a screw-thread engaged by the crank-pin. Teeth on the spindle x may be engaged by a pawl on a lever projecting through the casing and operated by a cam on the boss of the connecting-rod, to retain the parts. In the form shown in Fig. 9, a pinion y<1> on the crank-shaft engages a rack y in a slot in an eccentric, which slot contains a spring bearing on the crank-shaft. This arrangement of rack and pinion may be applied to a crank. The driven part may be connected to the engine shaft by chain gearing and a free-wheel device, so that the ergine may be started from the machine. According to the Provisional Specification, the pawls engaging the ratchet-wheel may be disengaged by the use of an eccentric disk. Also the spring, instead of being applied to the crank, may be applied for cushioning the two parts of a telescopic connecting-rod.