US1368678A - Resistance unit - Google Patents

Description

W. ZABEL, DECD.

a. 2mm, AnmmsTn/n'mx.

RESISTANCE UNIT.

APPLICATION FILED JULY 15. m9.

Patented Feb. 15, 1921.

I INVENTOR. mm

A 1 ATTORNEY.

' Swissvale UNITED STATES i a'rei-rr OFFICE.

WILLIAM ZABEL, OE SWISSVALE, PENNSYLVANIA; BERTH A ZABEL, ADMINISTRA- TRIX OF SAID WILLIAM ZABEL, DECEASED, ASSIGNOR TO THE UNION SWITCH &'

SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA.

Specification of Letters Patent.

. Application filed July 15, 1919. Serial No. 311,017.

To all whom it may concern."

Be it known that I, WILLIAM ZABEL, a citizen of the United States, residing at in the county of Allegheny and State of lennsylvania, have invented certain new and useful Improvements in Resistance Units, of which the following is a specification.

My invention relates to-resistance units for use in electrical circuits. and particularly to units which are adjustable to vary the value of the resistance imposed'by the unit.

One object of my invention is the provision of a resistance unit which can be manufactured economically, and which embodies adequate support for the resistance conductor with maximum capacity for radiation. A further object of my invention is the provision of a resistance unit having the aforesaid characteristics and also capable of the maximum number of variations in resistance value. v

I will describe one form of resistance unit embodying my invention, and will then point out the novel features thereof in claims. I

In the accompanying drawings, Figure 1 is a view showing in side elevation, one form of resistance unit embodying my invention. Fig. 2 is a sectional view on a plane indicated by the line II--II in Fig. 1 and looking in the direction of the arrows.

Similar reference characters refer to similar parts in each of the views.

Referring now to the drawings, the reference character 1 designates a base, preferably of insulating material such as porcelain, carrying two spaced terminal posts 2 and 3. Also mounted on the base 1 are two angular brackets 4 and 5, preferably of 'brass, each having a horizontal portion with a plurality of longitudinal recesses 8 which, as here shown, are circular in crosssection. As best illustrated in Fig. 2, these Patented Feb. 15, 192 1.

recesses are so located with respect to thesurface of the drum that they are nearly closed, there being only a narrow slot along the surface at each recess. The drum is also provided with a circumferential groove 9 midway between its ends, as best shown in Fig. 1, the purpose of which will appear hereinafter.

Mounted in the recesses 8 is a resistance wire 10 which, as here shown, is in the form of a continuous helix. This wire is threaded back and forth through the recesses 8 with successive strands lying in adjacent recesses. The resistance wire 10 is of course substantially inclosed by the recesses near the ends of the drum 6, but each strand is exposed at the middle of the drum because of the circumferential groove 9. Go-acting with these exposed portions of the several strands is a contact finger 11 which is riveted to a brass strip 12, this strip being supported by and in electricalcontact with the terminalpost 3.

One terminal of the resistance wire is electrically connected with the brass pivot 7 as indicated at 10 and so with the bracket 4 and terminal post 2. This connection is preferably effected by placing two washers 13011 the reduced end portion of the pivot 7 and turning the wire end 10 around the pivot between these washers. The other end of the resistance wire is suitably anchored in the drum 6. g It will be evident, therefore, that. when the two terminal posts are connected in an electric circuit, the amount of resistance which is interposed in the circuit by the unit may be varied by turning the drum 6 on its axis. The number of adjustments is obviously the-same as the number of longitudinal strands of wire, that is, there are two adjustments for each complete loop of wire. It follows that. the unit permits of twice as many adjustments as would be possible-if the contact finger 11 were mounted for engagement with the wire at one end of the drum or the other. The brackets 4 andf5 are flexible, so that when necessary they can be spread apart far enough to permit the removal of the drum 6 and the insertion of a new drum.

A resistance unit embodying my invention provides adequate support for the resistance wire on the drum, and at the same time it provides for maximum heat radiat- "on said drum with the strands parallel to the axis of the drum and with consecutive strands adjacently located, and a contact mounted to engage with said strands.

2. An adjustable resistance unit comprising a drum mounted to rotate, a continuous resistance conductor threaded back and forth on said drum with the strands parallel to the axis of the drum and with the consecutive strands adjacently located, and a contact mounted to engage said strands at a point substantially midway between the ends of the drum.

3. An adjustable resistance unit comprising a drum mounted to rotate and having longitudinal recesses in -its periphery, a resistance conductor threaded back and forth in said recesses with consecutive strands lying in adjacent recesses, and a contact mounted to engage said strands at a point substantially midway between the ends of the drum.

4. An adjustable resistance unit comprising a drum mounted to rotate, said drum having a plurality of longitudinal recesses inv its periphery and a circumferential groove between the twoends, a resistance conductor threaded back and forth in said longitudinal recesses with consecutive strands lying in adjacent recesses, said conductor being substantially inclosed by the longitudinal recesses except where it intersects said circumferential groove, and a contact mounted to engage the strands of said conductor where they are exposed by the circumferential groove.

5. An adjustable resistance unit comprising a drum mounted to rotate, a continuous helical resistance conductor threaded back and forth on said drum with the strands parallel to the axis of the drum and with consecutive strands adjacently located, and a contact mounted to engage with said strands.

6. A resistance unit comprising a cylindrical member of insulating material having longitudinal recesses in its periphery, and

a resistance conductor threaded back and forth in said recess with consecutive strands located in adjacent recesses.

7. A resistance unit comprising a cylindrical member of insulating material having longitudinal recesses in its periphery, and a circumferential groove between its two ends, and a resistance conductor threaded back and forth in said recesses with consecutive strands lying in adjacent recesses, said conductor being substantially inclosed by the longitudinal recesses except where it intersects said circumferential groove.

8. An adjustable resistance unit-compris ing a supporting block, two terminal posts mounted therein, brackets carried on said block and held in place by said terminal posts, a drum pivoted to rotate in said brackets, a resistance conductor mounted on the periphery of said drum, one terminal of said conductor being electricallyconnected with one of said terminal posts through one of the brackets, and a contact finger supported by the other terminal post and engaging with said resistance conductor.

9. A resistance unit comprising a supporting block, two spaced brackets mounted on said block, a drum pivoted to rotate in said brackets, and'a resistance conductor carried by said drum, said brackets being flexible to permit the removal and insertion ofsaid drum without disturbing the mounting of the brackets.

In testimony whereof I afiix my signature in presence of two witnesses.

WILLIAM ZABEL.

Witnesses VVALTIER P. NEUBERT, A. L. VENOILL.

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