| 摘要 |
856,504. Weighing apparatus. BARTELT ENGINEERING CO. March 18, 1959 [March 26, 1958], No. 9416/59. Class 143 [Also in Group XIX] A' force-measuring device comprises a cantilever spring supported on a base with a rigid member dis- - posed adjacent the free end of the spring in a plane transverse to the longitudinal axis of the spring, the rigid member being in connection with the spring and resiliently supported by the base in such a way that movement of the member with deflection of the spring under load is confined to a single direction transverse to the longitudinal axis of the spring. The invention is described with reference to a weighing apparatus whose load-supporting platform 10 (Fig. 2) is attached to the rigid member 23 of the device. This member comprises an apertured rectangular plate disposed in a vertical plane adjacent the free end of the horizontal cantilever spring 13. The resilient supporting means for the member 23 consists of flat springs 28 connecting the four corners of the member 23 to the casing 12 of the apparatus by means of the arrangement shown in Fig. 4. The free end of the cantilever is connected to the rigid member by a wire 39. The casing 12 enclosing the device is fitted with an inlet 62 for the admission of air under pressure which escapes through the aperture 27 through which the connection between the rigid member 23 and the load platform 10 extends, thereby excluding dirt. The casing also supports an hydraulic damper 53. Indicating means. The free end of the cantilever 13 carries the armature 20 of an electromagnetic transducer 19 of conventional type for recording the displacement of its end. Temperature compensation. Those parts of the device which extend transversely to the cantilever's longitudinal axis all have substantially the same coefficient of thermal expansion as each other and those extending parallel to the cantilever are made to have the same coefficient of expansion as the cantilever. The circulation of the compressed air in the casing also serves to reduce temperature gradients within the apparatus. The electromagnetic indicating transducer is also constructed to avoid errors due to temperature changes, being constructed so that the non-magnetic frame of the transducer has the same expansibility as the magnetic core thereof and arranged so that the whole construction is symmetrical about the gap in which the armature 20 moves.
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