Patent GB-478946-A (GB)
Title: Improvements in or relating to oscillating mechanical systems for the transmission of power
IPC: B06B3/00
Filed: 1936-04-24
Abstract: 478,946. Rubber springs. SCHIEFERSTEIN, G. H. April 24, 1936, Nos. 11750 and 11751. Convention dates, April 24, 1935 and Jan. 14, 1936. [Class 108 (iii)] [Also in Groups XXIV, II, X, and XXX] Relates to oscillating mechanical systems for the transmission of power, applicable to screening-apparatus, road-ramming appliances, jig-conveyers, frame saws, &c. of the type in which a driving mechanism is connected to an elastically constrained driven mechanism adapted to oscillate with a pronounced natural frequency and variable amplitude through an interposed loose coupling, and consists in providing elastic means for the loose coupling to produce pseudo-harmonic oscillations involving large forces with small amplitudes while the space occupied by the elastic means is small. Large amplitudes may also be obtained by the employment of levers. According to the invention. the elastic means consists of at least one rubber body, e.g. in the form of a segment of a sphere, which in one longitudinal section, at least, tapers towards the surface by which it is pressed, in such manner that on being compressed, the greater of its contacting surfaces remains substantially constant while the smaller contacting surface quickly changes from a small to a large area, means being provided for adjusting the frequency and amplitude of the system. A mass m, Fig. 1, of finite dimensions is mounted on a lever h<1> pivoted to a mass M of infinite dimensions, and rubber bodies b of approximately hemispherical form are interposed between the masses. The system is oscillated by the crank i through connecting-rod k, lever h<2> and rubber bodies c. By varying the length of the lever h<1> the amplitude and frequency are varied, and by increasing the length of the lever h<2> the coupling is made looser. When the mass m cannot be moved, the frequency can be varied by adjusting the pre-compression of the bodies b by the bolts g. The pivot points o, x<1>, x<2> may have elastic bearings. The rubber bodies may, as an alternative, be connected to their respective levers at their bases. A load-displacement curve, and suitable dimensions for the rubber blocks are given. As applied to a road-making machine, Fig. 3, the mass m which represents the ramming and cambering member is connected through the rubber blocks b and the levers h<1>, pivoted at x<1> to the frame of the machine, with a mass M in phase opposition to balance force and inertia effects. The mass m is energized by synchronized cranks i, the leverage being adjusted by moving the rubber blocks c. The masses m, M are constrained, except in the vertical direction, by springs f. The coupling may, if desired, act upon the mass M as shown in broken lines. As applied to a shaking trough, Fig. 5, with a long stroke, the rubber bodies b engage the levers h<1> pivoting at x<1>. To eliminate pivot friction, the levers h<1> may be connected to the troughs m<1>, m<2> by flexible members n of leather, steel &c. A coupling for giving the large amplitudes comprises the rubber bodies c, a fixed pivot x<2> and a pivot o to the trough m<1>. The frequency can be varied by varying the initial compression of the blocks b by the bolts s. In a modification, Fig. 6, a screen m<1>, m<2> is energized with high frequency, i.e. oscillations up to 4000 per minute by an eccentric i. The rubber bodies b engage angle brackets h<1>, h<2> on the screens which are oscillated with a phase displacement of 180‹ and guided by springs f. In a further modification, Fig. 7 (not shown), the pivots x<1> in Fig. 5, are on the screens. The rubber bodies may be arranged in pairs on opposite sides of the pivot of the lever h<11>. The rubber bodies should preferably be secured on both sides, Figs. 10, 11 (not shown), by vulcanizing where they are employed to produce circular oscillations. In Fig. 12 is shown the application to a screening or conveying trough M flexibly supported by springs f on both sides, wherein energization takes place only in the longitudinal plane of symmetry. The drive consists of a crank i and connecting-rod k terminating in a plate e held by spring strips n and acting upon the pre-compressed hemispherical rubber blocks b. In a modification, the potential coupling of Fig. 12 is replaced by a kinetic coupling consisting of an adjustable mass located between the rubber bodies and vibrated by a weight revolving about the centre of the mass. Where long conveyers are used, the formation of nodes in the conveyer is prevented by energizing it in the direction of its longitudinal axis. If the conveying capacity is to be increased, with larger amplitudes, the guide springs f are replaced by link supports. Where the conveyers are portable, the basal points of the guide springs or the links are connected to the basal point of the driving mechanism by a chain or the like. Specifications 188,633, 237,934, [both in Class 80 (iv)], and 404,685, [Group VIII], are referred to.