US2587948A - Electric switch - Google Patents

Description

March 4, 1952 J. W. WooLF 2,587,948

ELECTRIC SWITCH Filed Aug. 30, 1949 2 SHEETS--SHEET l @YQVQYM March 4, 1952 1 W, WOOLF 2,587,948

ELECTRIC SWITCH Filed Aug. 50, 1949 2 SHEETS-SHEET 2 72 50 JMP Patented Mar. 4, 1952 ELECTRIC SWITCH James W. Woolf, Franklin,

Manufacturing Company,

Pa., assigner to Joy Pittsburgh, Pa., a

corporation of Pennsylvania Application August 30, 1949, Serial No. 113,154

f 11 Claims.

This invention relates to an electric switch, especially to a latch type reversing switch.

In mine haulage practice, it is common to use trolley shuttle cars in a great many applications. Where such shuttle cars have to operate on a grade or slope, it is desirable to provide them with dynamic braking. When two cars have to pass on a hill or slope, the car going downhill must get off the trolley in order that the car going uphill may continue under power. With controlling circuits heretofore in use in shuttle cars, it has not been possible to provide dynamic braking during the time that the shuttle car is oiT the trolley, because with the power removed the reversing switch contacts would drop out and interrupt the armature circuit of the drive motors.

It is, accordingly, an object of this invention to provide a reversing switch suitable for mine shuttle car applications which will not open its contacts upon failure of the power source for any reason. This and other objects are accomplished in a reversing switch having latch means so arranged that the contacts are latched against opening and are opened when the latch is released upon operation of the switch to reverse the contacts.

In the drawings:

Fig. l is a top plan view of a reversing switch made according to this invention.

Fig. 2 is a side elevation of the switch, with the mounting panel in section.

Fig. 3 is a view in section on line 3 3 of Fig. 2.

Fig. 4 is a view in section on line 4 4 of Fig. 2, but shown without the movable contacts.

Fig. 5 is a view in section on line 5-5 of Fig. 4; and

Fig. 6 is a partial View in side elevation, similar to Fig. 2, but showing the contacts reversed from the position shown in Fig. 2.

' A mounting panel of any suitable non-conducting material is shown at 2, and serves as a non-conducting member on which a nonmagnetic support 4 is mounted by any suitable fastener means 6. The support 4 is preferably an inverted U and may be provided with a stiftening member 8 to brace the legs of the U.

A fixed electrical contact I, which may be referred to as a rst contact, is mounted on the non-conducting member 2 by any suitable means such as screws I2. In a preferred form of the invention, the Xed or rst contact I0 takes the shape of a U, one leg of which is secured to the panel 2 as aforesaid, and provides a terminal to which a conductor I4 may be secured in good electrical contact relation. The actual fixed or first contact referred to thus constitutes the other leg of the U and is spaced a substantial distance from the panel 2. Preferably, there are two such contacts IIJ, as is best seen in Figs. l and 3.

Two magnetic base members I6 are provided, one for each of a pair of electromagnets I8 and 20. In a preferred form of the invention, magnets I8 and 2D and magnetic base members I3 are secured to the support 4 by fastening means shown at 22. The fastening means 22 may consist of threaded members passing through openings in the base members I6 and threadedly engaging cores 24 and 25 of magnets I8 and 20, respectively. The details of the engagement of cores 24 and 2S by screws 22 will be well understood by those skilled in the art and need not be shown here.

An armature is provided for each magnet as shown at 28 and 30. These armatures are pivotally mounted on the non-magnetic support 4 by means of bolts 32 passing through and clamping bifurcated members 34 of the armatures and passing freely through openings 36 in the non-magnetic support 4. In a preferred form of the invention, the non-magnetic support 4 is made of brass and the bolts 32 are made of iron or steel, whereby a good bearing is provided for the pivoting of the armatures 28 and 30. A light spring 38 is provided to bias the armatures 28 and 30 away from their respective magnet cores 24 and 28. Springs 38 are preferably L-shaped, one leg of the L being placed against the non-magnetic support and the other leg being clamped between a latch member and the armature.

Each armature is thus provided with a latch member, armature 28 being provided with a latch member 40, and armature 38 having a latch member 42. Suitable fastening means, such as screws 44, secure each latch member to its armature.

A second armature is provided for each magnet, armature 46 being shown as associated with magnet I8 and armature 48 being shown as associated with magnet 23. The two armatures 45 and 48 are mounted for pivotal movement on support 4 by means of bolts 5E?, in much the same manner as armatures 28 and 38 are mounted by means of bolts 32. Movable contacts 52 and 54 are mounted on armatures 46 and 4B, respectively. Inasmuch as Contact I was referred to above as a first contact, contacts 52 and 54 may be referred to as second and third contacts.

Although the details of mounting the second and third contacts 52 and 54 do not per se form a part of this invention, it may be pointed out briefly that the contacts 52 and 54 are carried on contact holders 56, which are pivotally mounted at 58 on brackets 60. Brackets 6D are mounted on transverse insulating blocks 64 and 66, which in turn are mounted on the armatures 46 and 45 respectively, Springs 68 are provided between one end of each contact holder 56 and its respective bracket 68 to provide a yielding pressure or bias of the contacts 52 and 54 against the xed contact IU, or against a stop 68 when the movable contact is not engaging the fixed contact.

54. There are preferably twomovable contacts 52 and two movable contacts 54, one on each side of the switch, for engagement with the two fixed contacts I0. Correspondingly, there are two flexibleconductors and two exible conductors 12, as may best be seen in Figs. 1, 3 and 4. Thetwo flexible conductors 10 engage terminals 14 and 1B, and the two exibleconductors 12 engage terminals 18 and 88. The terminals are mounted on an insulating panel member 8|. In order to provide the conventional reversing-switch circuit, terminals 14 and 80 are cross-connected by a conductor strap 82, and terminals 16 and 18 are cross-connected by a conductor strap 84. The conductor strap 84 is insulated in any suitable manner from the strap 82, as for example by means of a non-conducting sheath 86.

Latch members 48 and 42 were referred to above. A third latch member 81, consisting of a block 88 and side members 89, is supported by both of the armatures 46 and 48 by means of bolts 98. Thus, the latch member 81 serves as a link connecting the two armatures 46 and 48. As

Flexible conductor 10 engages contact 52, and a similar flexible conductor `12 engages contact 4 ture in its attracted position, the ux path for armature 48 is through the upper end of armature 48, magnetic base member I6, magnet core 26 and part of armature 30. The air gap then exists between the lower end of armature 48 and the left end of armature 3E. Armature 48 is thereupon attracted toward armature 38, disengaging the contacts I8 and 54. vInasmuch as latch member 81 serves as a link connecting the armatures 46 and 48, armature 46 is also moved Atoward the right as seen in Fig. 2, causing engagement of contacts l0 and 52. With the parts in this position, latch member 40 is free to drop into the recess .92, whereupon the parts take the position ,shown in Fig. 6 and the contacts 52 and I8 are latched in engagement.

is best seen in Fig. 5, block 88 of latch member 81 is notched out to provide recesses 92 and 94 for the engagement respectively of latch members 48 and 42. Thus, the latch members 48, 42 and 81 form latch means for holding the contacts in a selected engagement, as will be more fully brought out in the description of the operation.

Operation Let ,it be assumed that a shuttle car with a reversing switch, made according to the invention, is proceeding downhill with its switch parts occupying the relative positions shown in Fig. 2 and Fig. 5. With the switch parts as thus shown, latch member 42 engages recess 94, thus cooperating with the latch member 81 to hold it in its extreme leftward position and to keep the movablecontact 54 in engagement with fixed contact l0. If then the shuttle car has to get off the trolley for any reason, taking the electromagnet I8 oi the power source, contacts I8 and 54 will, nevertheless, remain in engagement, because of the latch means just described. The armature circuits of the drive motors thus remain closed and the vehicle continues to operate with dynamic braking.

Let it now be assumed that the vehicle is again on the trolley and that it is desired to reverse the drive motors. The operator makes the necessary manipulation of manually or pedally operated controls, whereupon electromagnet 28 is energized. The close proximity of the armature 38 to the lower end of magnet core 26 makes it possible for magnet 20 to attract armature 38, pulling the lat-oh member 42 out ci tbe recess ,94. With ama-l The reverse of the operation, i. e., going from the position shown in Fig. 6 to the position shown in Fig. 2, will be readily understood by those skilled in the art from the above description and need not be detailed here.

Ainong the advantages of a switch made according to this invention is that vof maintaining the contacts in engagement, even after the system is disconnected fromV the power source (or in case of a power failure for any reason whatever), making it possible in the application of the invention referred to herein to keep the shuttle car or other vehicle operating with dynamic braking. Other advantages will be apparent to those skilled in the art.

While there is in this application specically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration, and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

I claim:

l. In an electric switch, a first contact, a second contact and a Vthird contact, the contacts being mounted to provide relative movement of two of them with respect to the other whereby said rst and second contacts are engaged to provide a desired electric circuit through the switch and alternatively said rst and third contacts are engaged to provide another desired electric circuit through the switch, latch means for holding the contacts in a selected engagement, the latch means including three `latch members, two electromagnets, a first armature for each of said two magnets, one of the three latch members being supported by one rst armature and another of the three latch members being supported by the other iirst armature, and a second armature for each of said two magnets, the third latch member and the second and third contacts being supported by both of said second armatures.

2. A switch according to claim l, in which the flux path for each second armature includes vat least a portion of its associated rst armature.

3. In combination, a non-conducting member, an electrical contact mounted on the member, a non-magnetic support mounted on the member, a pair of magnetic base members, a pair of electromagnets, means to secure each electromagnet with one of said base members to the support, an armature for each magnet, a second armature for each magnet, an electrical contact mounted on each said second armature and movable thereby into engagement with the first-named electrical contact, a latch member supported by both of the second armatures, and another latch member on each rst-named armature and cooperable with the first-named latch member.

4. The combination of claim 3, in which the flux path for the second armature includes at least a portion of the rst armature.

5. The combination of claim 4, in which the first-named latch member is connected to said second armatures and serves as a link to connect them.

6. The combination of claim 3, in which the rst-named latch member is connected to said second armatures and serves as a link to connect them.

7. The combination of claim 3, in which the armatures are pivotally mounted on the nonmagnetic support.

8. In combination, a non-conducting member, an electrical contact mounted on the member, a non-magnetic support mounted on the member, a pair of electromagnets, means to secure each electromagnet to the support, an armature for each magnet, a second armature for each magnet, an electrical contact mounted on each said second armature and movable thereby into cngagement with the first-named electrical contact, a latch member supported by both of the second armatures, and another latch member on each rst-named armature and cooperable with the first-named latch member.

9. The combination of claim 8, in which the flux path for the second armature includes at least a portion of the rst armature.

10. The combination of claim 9, in which the rst-named latch member is connected to said second armatures and serves as a link to connect them.

11. The combination of claim 8, in which the first-named latch member is connected to said second armatures and serves as a link to connect them.

JAMES W. WOOLF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 938,588 Keely Nov. 2, 1909 1,186,561 Evans June 13, 1916 1,819,061 Bancroft Aug. 18, 1931 1,971,199 Owens Aug. 21, 1934 2,097,335 Memmel Oct. 26, 193'7 2,295,881 Wheelcock Sept. 15, 1942 2,423,116 Price July 1, 1947 2,441,633 Horman May 18, 1948 FOREIGN PATENTS Number Country Date 83,895 Austria May 10, 1921

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