Patent GB-133974-A (GB)
IPC: F16H35/16
Abstract: 133,974. Barr & Stroud, Barr, A., and Stroud, W. Aug. 22, 1917. Logarithmic calculators; gunnery calculators.- Relates to epicyclic gearing for use in converting motion according to one law or scale into motion according to another law or scale, especially applicable for converting motion according to a uniform scale of ranges into that of the working head of a constant-base range-finder, or into a logarithmic scale, or into a scale of gun-sight elevations. One member of an epicyclic gear is driven according to one law, that member is geared to a second member through an appropriate variable-speed device, and the third member moves according to the second law, the first two members being so rotated as to tend to drive the third member in opposite directions so that the speed of the third member may pass through zero. In a modification, the driving-member of an auxiliary epicyclic gear employed to drive the first and second elements of the main gear is arranged to move according to the first law. The bevel-wheel 1 or 3, Fig. 2, moves according to one law and the wheels carry spur-wheels 8, 9 geared together by wheels 14, 11, a wheel 12 on a stationary spindle, a wheel 13, and spiral toothed. wheels 15, 16, so varying the speed of the wheel 3 or 1 that the shaft 10 carrying the planet-wheel 2 is driven at a speed corresponding to the second law. The wheels 8, 9 are driven by wheels 6, 7, one driving through an idler 4, on bevel-wheels 1<1>, 3<1> driven by a planet-wheel 2<1> on a shaft driven by a handle 5. The bevel-wheel 1 or 3 is connected to the part moving according to the first law, or, in a modification, the handle 5 may move according to this law, the shaft 10 in each case moving according to the second law. Any two epicyclic members tending to drive the third member in opposite directions may form the connected members. Fig. 4 shows a gear for converting range-finder working-head motions to ranges in which gearing 20, 21 of the kind described in Specification 15294/14, [Class 80 (i), Gearing, Belt &c.], is used to connect the bevel-wheels 1, 3. The gear 20, loose on the shaft 10, is secured to the bevel-wheel 3 and drives through an idle wheel 22 the gear 21, which is connected by a flexible coupling to the gear-wheel 14 engaging the wheel 8 on the bevelwheel 1. The shaft 10 carrying the planet-wheels 2 is connected to the working-head. A shaft 30 operating a scale of ranges is secured to the wheel 3' which, with the wheal 1<1>, is operated by planetwheels 2' turned by the handle 5, the wheels 1, 3 being driven by gearing 6, 8', and 7, 4, 9, respectively. The gearing 20, 21, 22 may be arranged as in Specification 15294/14, [Class 80 (i), Gearing, Belt &c.], or, as shown, the gear 20 may drive, through gearing 33, 34, 35, the shaft 36 which is screwed to engage the gear 21, so that the gear is moved laterally as required to keep the parts 20, 21, 22 in engagement. The wheel 22 is carried on a bracket sliding on a rod moved laterally by screw-and-nut means operated by the gear 20. The gearing 8, 14, 21, 22, 20 is so proportioned that the wheel 1 always rotates more quickly in one direction than the wheel 3 rotates in the other, so that the velocity of the shaft 10 never passes through zero. The handle 5 may operate the scale of ranges. Specifications 15480/10 and 11772/11, [both in Class 97 (i), Optical systems &c.], and 618/14 are referred to.