US2767251A - Dials - Google Patents

Description

Oct 15 1955 H. v. ALExANDERssoN 2,767,251

DIALs Filed March 8, 1955 IN VEN ifo/ HH/Qmp 14% Dimm ,4MM/wmf By bm MyW/14 nited States Patent O DIALS Harald Valdemar Alexandersson, Lidingo, Sweden, as-

signor to Telefonaktiebolaget L M Ericsson, Stockhoim, Sweden, a corporation of Sweden Application March 8, 1955, Serial No. 492,996

Claims priority, application Sweden March 26, 19554 6 Claims. (Cl. 179-90) The present invention relates to a dial for automatic telephone systems. The gear arrangement betweeen the nger wheel and the speed regulator used in a dial is usually a wormor cog-gear. It is diicult to have such gears work silently and in a reliable manner during a long time. Besides, they comprise relatively many details. An object of the present invention is to achieve asimple construction, in which said disadvantages are substantially avoided. In carrying out the objects of this invention, a gear device consisting of a friction gear has a cylindrical friction path fixed to the body of the dial, inside of which, a plurality of balls or rolls, respectively, are arranged so as to engage with the friction path and actuate the speed regulator when the finger wheel is returning to normal position after winding. A special advantage of such a constructionY is that the high bearing pressures common to friction gears are avoided.

The invention will be described more closely with reference to the accompanying drawing, wherein Fig. l is a plan view, in section, taken along line B-B of Figure 2, showing the gear arrangement; Fig. 2 is a side view in section, taken along line A-A of Figure l, showing a dial provided with the gear arrangement according to Fig. 1.

Referring now to the drawing, the rigid body 1 of the dial has a cylindrical inner surface 2. Inside the body and mounted in it there is a driving mechanism 3 rigidly connected with the movable finger wheel 13, three cylindrical rolls 4 being mounted on studs 5 in said driving mechanism. Outside said rolls there is a row of three balls 6, which are kept in position by a ball holder or race 7 fixed to the driving mechanism. In the center of the driving means there is a regulator or governor shaft 3, to the lower part of which a regulator 9 is xed. The regulator shaft 8, which is rotatably mounted between the three rolls 4, is arranged so that it cannot be moved axially. When the regulator rotates its weights l move round studs 11, thereby pressing against a brake-path on the inner surface of the prolongation downwards of the driving mechanism. The exterior surface of said prolongation is shaped as a cam disc for actuating spring sets, which are not shown. The driving mechanism 3 is fixed to the finger wheel 13 by means of a screw 14.

The shown gear arrangement functions in the follow ing manner. If the nger wheel is wound up in the direction shown by the arrow on top of Figure 1, the driving mechanism 3 with the rolls 4 and the balls 6 is also driven in the same direction. The balls then irnmediately come out of mesh with the cylinder surface 2 on the body 1. The gear arrangement 3, 4, 8 is thereby disengaged and the regulator 9 stands still. If the finger wheel is released after winding up, it is in a known manner actuated by a spring device, which is not shown, so that the wheel rotates in the direction opposite to that indicated by the arrow. During that return of the finger wheel the balls mesh between the cylinder surface 2 and the rolls 4, which they press against the regulator shaft 8 located in the centre. If the dimensioning is such that the mesh angle of the balls 6 between the rolls 4 and the cylinder surface 2 is smaller than the friction angle for the used material, the balls cannot slide but roll around and pull the rolls with them, which rolls in their turn wind the regulator shaft 8. Since there is no sliding, the peripheral speed of all the movable parts is equal, and the gear ratio is equal to the ratio between the diameters of the cylinder surface 2 and the regulator shaft 8. Actually, the arrangement is such that the balls function in rolling wedges.

The bearing pressure is usually high in friction gears, but as appears from the drawing the normal pressures on all the parts compensate each other in the proposed construction, so that they appear only as inner tensions in the partaking parts. The bearing friction can therefore be kept at a low value.

In the proposed construction the cylindric surface is rigid and the rolls and the balls movable as well as the finger wheel. An extremely simple construction is thereby obtained. The cylindric surface 2 can then be made a part of the body, which latter is suitably manufactured of iron sheet, in which a cylindrical excavation has been stamped. The body is case-hardened and ground along the cylindrical surface 2.

The main part 3 of the driving mechanism is suitably manufactured of plastic material, for example nylon, and it can be made so as to comprise in one piece both a nave for mounting in the body 1 and a brake path 10 for the regulator as well as an impulse disc 15 and bear ing studs 5 for the rolls 4.

Another great advantage of the proposed construction is that the quickly moving regulator shaft 8 needs only be mounted between the inner row of rolls 4. It is thus squeezed between said rolls in a self centering position.

The invention described above is naturally not limited to the embodiment shown on the drawing, which is only an example of a suitable construction. The gear arrangement may thus be manufactured in some other manner. Among others, the balls 6 may be replaced by rolls. lt is likewise possible to replace the rolls 4 by balls.

I claim:

l. A dial assembly for automatic telephone systems comprising, in combination, a iixed housinghaving an inwardly disposed cylindrical friction surface, a rotatable finger wheel disposed outwardly of one side of said housing, a speed regulator disposed outwardly of another side of said housing, a rotatable shaft carried by said speed regulator and extending into said housing, and friction drive means carried by said linger wheel and disposed within said housing between said friction surface and said rotatable shaft, said friction drive means comprising a rst set of rotatable means in driving engagement with said shaft and spaced from said friction surface, and a second set of rotatable means disposed between said first set of rotatable means and said friction surface and engageable with said friction surface and said first set of rotatable means in response to rotation of said finger wheel in one direction and disengaged therefrom in response to rotation of said linger wheel in an opposite direction.

2. A dial assembly as set forth in claim l, wherein said rst set of rotatable means comprises at least one circular element, and said second set of rotatable means comprises at least one circular element having a diameter greater than the spacing of said first set of rotatable means from said friction surface and being displaceable from a first disengaged position relative to said friction surface and said first set of rotatable means for one direction of rotation of said finger wheel to a second wedge-like engaged position between said friction surface and said first set of rotatable means.

3. A dial assembly as set forth in claim 2, wherein said shaft'is disposed along the central axis of said cylindrical friction surface, said first set of rotatable means comprising three symmetrically arranged friction wheels Vin constant engagement with said shaft, and said second ported by said finger wheel, and said Vballs are rotatably supported by a circular race carried by said finger wheel. Y5. A dial-assembly as set forth in claim 4, wherein 4 Y v said finger wheel supports aV brake assembly adjacent to said speed regulator. f

6. A dial assembly as set forthy in claim 5, wherein Y said brake assembly comprises an inwardly disposed p brake path surrounding said speed regulator, and an exterior peripheral surface having an impulse disc for actuating engagement with dial contact springs.

References Cited in the file of this patent UNITED STATES PATENTS 1,866,669 Rhodes Julyrl2, 1932 WMA

Images