Patent GB-441889-A (GB)
Title: Improvements in or relating to transmission mechanism of the v-pulley type
IPC: F16H9/16
Filed: 1934-08-17
Abstract: 441,889. Tensioning belts; variablespeed gearing. ABBOTT, G. J., 16, Mordaunt House, Larkhall Estate, Albion Road, London. Aug. 17, 1934, Nos. 23758/34 and 12995/35. [Classes 80 (i) and 80 (ii)] In transmission mechanism of the V- pulley type, the flanges of the pulleys are relatively movable away from and towards one another, a rotary member coaxial with the pulley receives from or transmits the drive to the pulley through a connection which also causes relative axial movement of the flanges, and one or more coupling members are provided held from rotation relatively to the flanges, and each of which passes through a pulley flange and acts as a tension member through which the thrust of a spring or springs is transmitted to tend to move the flanges towards one another. Although the invention is applicable to gearing of constant ratio as well as to variable-speed gearing, a form of the latter embodying the invention is described and comprises a driving shaft A and a driven shaft B, Fig. 1, supported in bearings in a casing C. Each shaft has a V-pulley A', B<1>, the flanges of which are relatively movable axially and have radial depressions and projections, a depression on one flange lying opposite a projection on the other as described, for example, in Specification 228,838, [Class 80 (i)]. The flanges A<1> are splined to the shaft A and have thrust collars A<2> acting through bearings A<3> to effect axial movement. The pulleys are connected by a transmission member D in the form of a chain carrying transversely movable slats as described, for example, in Specification 242,416, [Class 80 (i)]. The pulley on shaft B has associated with it mechanism according to the invention. Each flange B <1> is integral with a sleeve free on the shaft B, Fig. 2, each sleeve consisting of a number of splines B<2> which enter slots in the other sleeve. The splines of one sleeve are circumferentially narrower than the slots in the other so as to leave spaces in which coupling bars E are accommodated. The ends of these bars have projections E<1> which serve as abutments for an annular thrust member F between which and the outer face of the adjacent flange is inserted a number of springs F<1>. Alternatively, a single helical spring may be used. Associated with each flange B<1> is a driving member G, mounted so as to slide and be held axially, but not rotate on the shaft B, and comprising a hub G<1> carrying a flange G<3> in the edge of which are mounted three pins H forming supports for rollers H<1>. Each roller is adapted to act upon a ramp or cam-surface J rigid with the outer face of the adjacent flange B<1>. The flanges A<1> are caused to approach one another while the flanges B are moved apart, and vice versa, by levers L, Fig. 1, carrying rollers L<2> to bear on thrust collars K<1>, the levers being actuated by right- and left-handed screws on a shaft L<5> provided with a handle L<6>. For any position of the flanges B<1>, the drive is effected through the ramps J, rollers H<1> and members G, and the force with which the rollers and ramps tend to move the flanges towards one another is sufficient to maintain the correct tension in the chain, the force being proportional to the power transmitted. The springs F<1> serve to exert a wedging action between flanges and chain when little or no power is being transmitted and during reversals of torque. The invention may be applied to both pulleys. In a modification, Fig. 4, the pulley on the driving shaft N has one flange P rigidly secured thereto, the other flange P<1> being slidable by the lever Q for varying the gear ratio. The pulley on the driven shaft is of the type described above, but one of the flanges R is prevented from moving axially, while the other R<1> has ramp surfaces J adapted to engage a member G which is rigidly connected to the shaft. The ramps are longer than in Figs. 1, 2, and are adapted to adjust the distance between the flanges R, R<1> in inverse relation to that between P, P<1> throughout the gear changes.