GB878708A - Spring torque torsion balance - Google Patents

Abstract

878,708. Weighing apparatus. TORISON BALANCE CO. Nov. 4, 1959 [May 6, 1959], No. 37391/59. Class 143. A torsion balance-of the type wherein a centre truss 22 mounted on a base 10 carries tensioned bands 32b, 35b to provide torsional fulcra for a pair of beams 23, 24 which are interconnected at their ends by trusses 20, 21-is provided with additional spring means connected to the skeleton 11 comprising the beams and trusses so as to exert thereon a torque tending to rotate the beams about their fulcra and with means to vary this torque connected to the base and to the said spring means. The said spring means is a spiral spring 14 (Figs. 2 and 6) whose outer end is adjustably clamped by screws 72 to an angle bracket 70 carried by a bracket 76 which is mounted on the upper beam 23 of the skeleton. The torque-varying means comprises a shaft 83 to which the inner end of the spring 14 is attached and which is rotatable in a support member 84 against the frictional resistance of a spring- loaded ball 86. The shaft 83 is turned by a knob 94 having a graduated flange 97. In use of the apparatus a load on the pan 13 is opposed by loose weights on the pan 12, the out of balance of the beam being indicated by a pointer 62 carried by the upper beam 23. When approximate balance is achieved with loose weights, rotation of the knob 94 is used to bring the pointer 62 to its zero position when the reading of scale 98 on flange 97 indicates the fractional part of the weight of the load. The skeleton may be arrested by plates 114, 115 engageable with the end trusses and attached respectively to levers 110, 111 (Fig. 3) arranged below the base 10 of the apparatus. A shaft 123, Fig. 4 (not shown) carries an eccentric pin 122 engaged with slots in the levers 110, 111 so that rotation of this shaft raises or lowers the plates 114, 115. The movements of the skeleton are damped by a piston 53 (Fig. 9) comprising two plates 54, 55 whose relative orientation with respect to the shaft 51 on which they are mounted may be varied to adjust the effective piston area. This piston moves vertically in liquid in a dashpot 15 (Fig. 2) with the upper end of the shaft 51 connected to the skeleton. For transporting the apparatus the dashpot may be raised by a screw (not shown) below the base 10 until a conical seating 58b in the dashpot upper cover engages with a neoprene washer 52 carried on the piston shaft 51. The mechanism of the apparatus is enclosed in a casing (not shown) supported by posts 127 attached to the base.