CA2085518A1 - Dc motor reversing control - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A DC motor reversing control utilizes two single-pole double-throw relays which share two stationary contacts.
The control includes connector studs connected to the relay contacts and adapted to be connected to the DC motor and DC
power supply. The control includes a connector socket which is adapted to receive a selector switch for controlling the direction of rotation of the DC motor. The relays, connector studs, and connector socket are secured in a housing of said control in a close tolerance fit, and various electrical connections in the housing are provided by interference fit.
The housing comprises two identical plastic members secured together after assembly of all the internal components.

Description

WR-342 2 0 8 ~ 8 DC MOTOR _EVERSING CONTROL

BACKGROUND OF THE INVENTION
This invention relates to reversing controls for providing bidirectional control of the output of Dc motors, and particularly of high amperage DC motors.
In mobile environments, the prime mover for devices such as winches, pumps, hoists, elevators and the like is generally a DC (direct current) motor. The reason for using a DC motor rather than an AC (alternating current) motor is that AC is not always readily available whereas DC is available in, for example, the typical 12 volt electrical system, of a motor vehicle. Typically, the DC motor in such applications may draw as much as 100 amperes at 12 volts DC.
Prior art reversing controls for such applications typically include two totally-enclosed, commercially-available solenoids. The solenoids -are mechanically and electrically connected together and are enclosed in a housing. Means for connecting the DC motor and the power source are provided on the housing. The housing also includes means for connecting a selector switch, which switch is cooperative with the reversing control for determining the direction of rotation of the output of the DC motor. While such reversing controls generally function satisfactorily, they are relatively large in physical size and relatively expensive to produce.
SUMMARY OF THE INVENTION
The primary object of this invention is to provide a reversing control for high amperage DC motors which overcomes the above-stated disadvantages of the prior art devices.
In accordance with the present invention, there is provided a DC motor reversing control which utilizes two single-pole double-throw relays which share two stationary contacts. The control includes connector studs connected to the relay contacts and adapted to be connected to the DC motor and DC power supply. The control includes a connector socket which is adapted to receive a selector switch for controlling the direction of rotation of the DC motor. The relays, connector studs, and connector soc~et are secured in~0~
of the control in a close tolerance fit, and various electrical connections in the housing are provided by interference fit. The housing comprises two identical plastic members seeured together after assembly of all the internal components. Such construction provides a reversing control whieh is relatively small in physical size, electrically and meehanieally stable, simple to assemble, and relatively inexpensive to produee.
The above-mentioned and other objeets and features of the present invention will beeome apparent from the following description when read in eonjunetion with the aeeompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front plan view of the reversing control eonstrueted in accordance with the present invention;
FIG. 2 is a side plan view of the reversing control of FIG. l;
FIG. 3 is a plan view showing a lower housing with all internal components in place;
FIG. 4 is a plan view of the lower housing of FIG.
;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4;
25FIG. 6 is a partial plan view of the lower housing taken along line 6-6 of FIG. 4;
FIG. 7 is a partial eross-seetional view taken along line 7-7 of FIG. 4;
FIG. 8 is a plan view of a eontaet strip to which 30the relay eoils and a mounting braeket of the reversing eontrol are eleetrieally eonneeted by interference fits;
FIG. 9 is a front plan view of one of the stationary relay eontaets with an external-wiring eonneetor stud attaehed;
35FIG. 10 is a side plan view of the assembly of FIG.
9 also showing an eleetrieal lead attaehed;
FIG. 11 is a front plan view of the other of the i~
stationary relay contacts with an external-wiring connec.or ~~
stud attaehed; r.:

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~-FlG. 12 is a side plan view of the assemQ~y o~ ~IG.
11;
FIG. 13 is a plan view of a relay frame and an external-wiring connector stud attached;
FIG. 14 is a plan view of a portion of one of the relay assemblies taken along line 14-14 of FIG. 3;
FIG. 15 is a partial cross-sectional view illustrating an interference fit electrical connection between a relay coil terminal and the contact strip of FIG. 8;
FIG. 16 is a partial cross-sectional view taken along line 16-16 of FIG. 3;
FIG. 17 is a plan view of the connector socket taken along line 17-17 of FIG. 1;
FIG. 18 is a diagrammatic illustration of the reversing control of the present invention, showing the relay contact positions and circuit connections which effect rotation of the output of a DC motor in a certain direction;
and FIG. 19 is a diagrammatic illustration of the reversing control showing the relay contact positions and circuit connections which effect rotation of the output of the DC motor in the opposite direction from that shown in FIG. 18.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, shown therein is the reversing control 10 of this invention. Control 10 comprises a housing 12 out of which extend four connector studs 14, 16, 18 and 20, a connector socket 22, and two mounting brackets 24 and 26. The overall dimensions of control 10 are relatively small as compared to prior art devices utilized for the same applications, such overall dimensions being approximately 2 1/32 inches by 3 5/32 inches by 6 27/32 inches.
Referring to FIG. 2, housing 12 comprises a lower housing 28 and an upper housing 30 joined together at 32.
Lower housing 28 and upper housing 30 are identical in construction. Therefore, while the lower housing 28 will hereinafter be described in detail, it will be understood that the description also applies to upper housing 30.
Referring to FIG. 4, lower housing 28 comprises a generally rectangular plastic member having a bottom wall 34, - :

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side walls 3~ and 3~, end walls 40 and ~2, and a plura~t'~ o~
openings, cavities, ledges, recesses, and projections defined therein which will hereinafter be described in detail. Side walls 36 and 38 and end walls 40 and 42 extend upwardly from bottom wall 34 to define a top edge portion 44 which is in a plane parallel to bottom wall 34. With reference to FIGS. 4 and 7, the top edge portion 44 of the lower one-half of lower housing 28 is provided with a small projection 46 extending upwardly therefrom. The top edge portion 44 of the upper one-half of lower housing 28 is slightly textured. It should be apparent that when lower housing 28 and upper housing 30 are joined, the projection 46 on one of the housings overlies that portion of the top edge portion 44 of the other housing that is slightly textured. Such construction of top edge portion 44 enhances the joining of lower housing 28 and upper housing 30 by ultrasonic welding.
Referring to FIG. 3, internally, control 10 includes two single-pole double-throw relays. A first one of the two relays includes a frame 48, an operating coil 50, an armature 52, and a movable contact 54 carried by armature 52.
Connector stud 20 is secured, preferably by welding, to a leg 56 of frame 48. A flexible braided wire 58 is secured, preferably by welding, to leg 56 of frame 48 at 60 and to armature 52 at 62. A second one of the two relays includes a frame 64, an operating coil 66, an armature 68, and a movable contact 70 carried by armature 68. Connector stud 14 is welded to a leg 72 of frame 64. A flexible braided wire 74 is welded to leg 72 and armature 68.
Providing stationary or fixed contacts cooperative with movable contacts 54 and 70 are a pair of spaced apart contact strips 76 and 78. Referring also to FIGS. 9 and 10, connector stud 16 is secured to contact strip 76 by a staking operation at 80 which also secures a ring terminal 82 to connector stud 16. One end of an electrical lead 84 is provided with a push-on type terminal 86 for connection to ring terminal 82. Referring also to FIGS. 11 and 12, connector stud 16 is secured, preferably by welding, to contact strip 78.
Referring to FIG. 8, shown therein is a contact strip 88. A flat portion 90 of contact strip ~8 lS pro~i~de8d with extended tab portions 92 and 94 having rectangular openings 96 and 98, respectively, therein- One end 100 of eontact strip 88 is bent at slightly less than a ri~ht angle to flat portion 90.
Referring to FIG. 4, bottom wall 34 is provided with recesses 102 and 104 for receiving tab portions 92 and 94, respeetively, of contact strlp 88. Recesses 102 and 104 are also provided with recesses 106 and 108, respectively. Bottom wall 34 is also provided with several T-shaped projections 110 whieh help align eontaet strip 88 when it is initially plaeed into lower housing 28.
Contact strip 88 provides interference fit eleetrieal eonnections with relay eoils 50 and 66 and with mounting braeket 24. Specifically, referring to FIGS. 14 and 15, relay eoil 50 is provided with a terminal 112 to which one end of the relay coil 50 is conneeted and a terminal 114 to whieh the other end is eonnected. Terminal 114 has a tapered portion 116 whieh eooperates with opening 96 in tab portion 92 of contact strip 88 to provide a reliable interferenee fit eleetrieal eonnection with contaet strip 88 as terminal 114 is foreibly inserted into opening 96. Reeess 106 in bottom wall 34 provides a suffieient spaee for tapered portion 116 to freely extend so as to enable sueh insertion of terminal 114.
Relay eoil 66 is provided with terminals identieal to terminals 112 and 114. However, the location of such terminals is reversed. Speeifieally, referring to FIG. 3, relay coil 66 is provided with a terminal 118 which is identieal to terminal 112, and with another terminal, not shown, whieh is identieal to terminal 114. The terminal identieal to terminal 114 cooperates with opening 98 in tab portion 94 of eontact strip 88 to provide an interferenee fit eleetrieal eonneetion with eontaet strip 88 in the same manner as deseribed above for terminal 114.
Referring to FIGS. 3, 4 and 16, mounting braeket 24 ineludes a flat portion 119 having an opening 120, and a U-shaped portion extending at a right angle to flat portion 119 and having opposing leg portions 121 and 122 joined by curved portion 123. End wall 40 of lower housing 28 is notched at .

' q 124 to accept end lO0 of contact strip ~8. As2 ~ s~y described, end 100 of contact strip 88, in its unassembled state, is at an angle slightiy less than a right angle to flat portion 90. Therefore, when mounting bracket 24 is assembled to lower housing 28 with contact strip 88 in place, end loo of contact strip 88 is forcibly biased by leg portion 122 to i.:
essentially a right angle to flat portion 90 thereby providing a reliable interference fit electrical connection between contact strip 88 and mounting bracket 24. End wall 40 is notched at 125 to receive the curved portion 123 of mounting bracket 24. Mounting bracket 26 is identical to mounting bracket 24, and end wall 42 is notched at 126 to receive the r curved portion, shown at 127 in FIG. 3, connecting the two opposing leg portions of mounting bracket 26.
Referring to FIGS. 3-6 and 13, lower housing 28 is provided with a ledge defined by a narrow flat surface 130 in a plane parallel with bottom wall 34 and a wall portion 132 :-extending slightly upwardly from surface 130. Such ledge receives, in a close tolerance fit, frame 64 of one of the relays. Lower housing 28 is also provided with a square-shaped recess 134 in side wall 36 which receives, in a close tolerance fit, the base portion 136 of connector stud 14.
Centered within recess 134 is a circular opening 138 for receiving an unthreaded portion 140 of connector stud 14.
Lower housing 28 is provided with an elongated recess 142 which receives, in a close tolerance fit, contact strip 76. Referring also to FIGS. 9 and 10, side wall 36 of lower housing 28 is provided with a recess 144 and circular opening 146 similar to recess 134 and opening 138, respectively, for receiving the base portion 148 and unthreaded portion 150 of connector stud 16.
Lower housing 28 is provided with a ledge defined by surface 152 and wall portion 154 for receiving, in a close tolerance fit, frame 48 of the other of the two relays. The ledge defined by surface 152 and wall portion 154 is identical in construction to the ledge defined by surface 130 and wall portion 132. Lower housing 28 is also provided with an elongated recess 156 which receives, in a close tolerance fit, contact strip 78.

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Lower housing 28 is also provided with a ~ L~
square-shaped recess 158 for receiving, in a close tolerance fit, one-half of a flange portion 160 of connector socket 22.
The other half of flange portion 160 extends above top edge portion 44 of lower housing 28. Extending from flange portion 160 is a circular portion 162 containing three plug type terminals 164, 166 and 168. Connector 22 is adapted to mechanically and electrically receive a mating connector (not shown) for reasons to be hereinafter described.
Referring to FIGS. 3 and 17, the view of connector socket 22 in FIG. 3 is taken generally along line A-A of FIG.
17. Terminal 164 in socket 22 is connected by a lead 170 to a push-on type terminal 172 which, in turn, is connected to terminal 118. As previously described, terminal 118 is connected to one end of relay coil 66. Terminal 166 in socket 22 is connected by a lead 174 to a push-on type terminal 176 which, in turn, is connected to terminal 112. As previously described, terminal 112 is connected to one end of relay coil 50. Terminal 168 in socket 22 is connected to lead 84. As previously described, lead 84 is connected through terminals 82 and 86 to connector stud 16.
As previously stated herein, lower housing 28 and upper housing 30 are identical in construction. The various internal components are constructed and assembled in such a manner so as to fully utilize such identical construction and thereby provide a relatively simple yet sturdy construction.
Specifically, as illustrated in FIG. 13, connector stud 14 is attached to leg 72 in the bottom portion thereof.
Referring also to FIG. 3, when the relay using frame 64 is placed in lower housing 28, a bottom edge portion 178 of relay frame 64 fits within the ledge defined by surface 130 and wall portion 132, and connector stud 14 fits within recess 134 and opening 138 as previously described. The assembly of relay frame 48 and connector stud 20 is identical to that shown for the assembly of relay frame 64 and connector stud 14 in FIG.
13. Referring to FI~. 3, when the relay using frame 48 is placed in lower housing 28, a bottom edge portion (not shown) of frame 48 fits within the ledge defined by surface 152 and wall portion 154, and connector stud 20 extends above top edge portion ~ of lower housing 28. When upper housi~
assembled to lower housing 28, the ledge in upper housing 30 corresponding to the ledge defined by surface 152 and wall portion 154 in lower housing 28 receives the edge portion 180 of relay frame 64 shown in FIGS. 3 and 13. similarly, the ledge in upper housing 30 corresponding to the ledge defined by surface 130 and wall portion 132 in lower housing 28 receives the edge portion 182 of relay frame 48 shown in FIG.
3. Also, the recess and opening in upper housing 30 corresponding to recess 134 and opening 138 in lower housing 28 receive connector stud 20.
Referring to FIG. 9, connector stud 16 is attached to contact strip 76 in the upper left portion thereof. When this assembly is placed in lower housing 28, an edge portion 184 of contact strip 72 fits within recess 142 of lower housing 28, and connector stud 16 fits within recess 144 and opening 146 as previously described. Referring to FIG. 11, connector stud 18 is attached to contact strip 78 in the lower right portion thereof. When this assembly is placed in lower housing 28, an edge portion 186 of contact strip 78 fits within recess 156 of lower housing 28, and connector stud 18 extends above top edge portion 44 of lower housing 28. When upper housing 30 is assembled to lower housing 28, the recess in upper housing 30 corresponding to recess 142 in lower housing 28 receives edge portion 188 of contact strip 76 shown in FIGS. 3 and 9. Similarly, the recess in upper housing 30 corresponding to recess 156 in lower housing 28 receives edge portion 190 of contact strip 78 shown in FIGS. 3 and 11.
Also, the recess and opening in upper housing 30 corresponding to recess 14~ and opening 146 in lower housing 28 receive connector stud 18.
As previously described, one-half of flange portion 160 of connector socket 22 fits within recess 158 of lower housing 28. When upper housing 30 is assembled to lower housing 28, the recess in upper housing 30 corresponding to recess 158 in lower housing 28 receives the other half of flange portion 160.
Also, as previously described, end wall 40 of lower housing 28 is notched at 125 to receive the curved portion 123 of mountin~ bracket 2~ and end wall 42 is notched ~ 5~ d~
receive the curved portion 127 of mounting bracket 26. When mounting brackets 24 and 26 are attached to lower housing 28, portions of curved portions 123 and 127 extend above top edge portion 44 of lower housing 28. When upper housing 30 is assembled to lower housing 28, notches in upper housing 30 -corresponding to notches 125 and 126 in lower housing 28 receive, in a close tolerance fit, those portions of curved portions 123 and 127 which extend above top edge portion 44.
The above-described close tolerance fits of the various components in lower housing 28 and upper housing 30 thus ensure that when the lower housing 28 and upper housing 30 are joined, the various components are mechanically stable.
A significant advantage of such construction is that it provides mechanical stability without the use of numerous fastening means, such as screws and rivets, thus providing a relatively simple and inexpensive method of assembly. The close tolerance fits, along with the ultrasonic welding of lower housing 28 to upper housing 30, also provides a device which is highly resistant to the ingress of liquids.
Reversing control lO can be used in a variety of applications requiring the reversing function. A typical application is shown in FIGS. 18 and l9 wherein the internal construction of reversing control 10 is simplified to facilitate description of the operation thereof. Reference numbers the same as those in FIGS. 1-17 are used where appropriate.
Referring to FIG. 18,reversing control 10 is shown connected to a DC motor 200. Also connected to reversing control 10 is a DC power source 202 and a selector switch 204.
In the illustrated embodiment, motor 200 is a series wound DC motor wherein its field windings, connected between terminals F1 and F2, and its armature windings, connected between terminals A1 and A2, are electrically in series. As is well known, the direction of rotation of the armature of such a motor is reversible by reversing the direction of current flow through either the field windings or the armature windings. As will hereinafter be described, reversing control 10 is connected so as to effect a reversal of the direction of ~ . .

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current flow throu~h the field windings. 2 ~ 8 ~ .
Typically, motor 200 is provided with an output shaft 206 which is connected to the armature of motor 200.
Shaft 206 is mechanically connected by suitable connecting s means 208 to a controlled device 210. Controlled device 210 can be any device, such as a winch, pump, hoist or elevator, whose function requires a reversing operation. In the illustrated embodiment, controlled device 210 comprises a winch such as the type used in vehicles which provide a towing function, such as tow-trucks. Typically, such a winch includes a towing cable wound on a rotatable drum which is rotated in one direction to reel in the cable on to the drum and in the other direction to allow slack in the cable so that it can be pulled away from the drum.
Connector stud 14 is connected by a lead 212 to terminal F1 of motor 200; connector stud 20 is connected by a lead 214 to terminal F2; connector stud 18 is connected by a lead 216 to terminal A1 of motor 200; and connector stud 16 is connected by a lead 218 to the positive side of DC power source 202, which power source comprises the vehicle's 12-volt battery and the electrical generator system cooperative with the battery. The negative side of power source 202 is connected by a lead 220 to co~mon C, common C comprising a metal portion of the vehicle. Terminal A2 of motor 200 is connected by a lead 222 to common C.
Selector switch 204 is connected to reversing control 10 by leads 224, 226 and 228 which are encased to define a three-wire cable 230. One end of lead 224 is connected to terminal 164 in connector socket 22, and the other end is connected to a stationary contact 232 in selector switch 204. One end of lead 226 is connected to terminal 168 in connector socket 22, and the other end is connected to a movable contact 234 in selector switch 204. One end of lead 228 is connected to terminal 166 in connector socket 22, and the other end is connected to a stationary contact 236 in selector switch 204. Typically, cable 230 is provided at one end with a connector socket and terminals (not shown) which are cooperative with connector socket 22 and terminals 164, 166 and 168 therein to effect the above-described electrical connections. Movable contdct 234 in selector switch 2~ :.
manually movable by any suitabl~ operating means 238 so as to select the desired direction of rotation of shaft 206 of motor 200. contact 234 is also movable to an "OFF" position indicated at 240.
Reversing control 10 is attached to the vehicle by means of mounting brackets 24 and 26 whereby at least mounting bracket 24 is electrically connected to common C.
In operation, with selector switch 204 in the position shown in FIG. 18, relay coil 66 is energized, the circuit being: from power source 202, lead 218, connector stud 16, leads 84 and 226, contacts 234 and 232, leads 224 and 170, relay coil 66, contact strip 88, mounting bracket 24, common C, and lead 220 back to power source 202. With relay coil 66 energized, relay contact 70 is in contact with contact strip 76, and motor 200 is energized through the following circuit: from power source 202, lead 218, connector stud 16, contact strip 76, contact 70, armature 68, wire 74, connector stud 14, lead 212 to terminal F1, field windings between terminals F1 and F2, lead 214, connector stud 20, wire 58, armature 52, contact 54, contact strip 78, connector stud 18, lead 216 to terminal A1, armature windings between terminals A1 and A2, lead 222, common C, and lead 220 back to power source 202. Under these conditions, output shaft 206 rotates in a certain direction, shown as clockwise in 242. Such clockwise rotation effects rotation, in a certain direction, of the drum in winch 210. Arbitrarily, the direction of .
rotation of the drum is such that slack is provided in the towing cable so that the cable can be pulled away from the drum. Also arbitrarily, the position of selector switch 204 .
which effects such direction of drum rotation is designated .
"FORWARD." It is noted that with selector switch 204 in the "FORWARD" position, current flows through the field windings and armature windings in the directions shown by arrows 244 and 246.
Referring to FIG. 19, when it is desired to reverse the direction of rotation of the drum in winch 210, mova~le contact 234 in selector switch 204 is moved by operating means 238 so that it is in contact with fixed contact 236. This 1 1 !.

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position of selector switch 204 is desiynated "RE2 ~ 8 Under this condition, relay coil 66 is de-energized and relay coil 50 is energized. Relay coil 50 is energized through the following circuit: from power source 202, lead 218, connector stud 16, leads 84 and 226, contacts 234 and 236, leads 228 and 174, relay coil 50, contact strip 88, mounting bracket 24, common C, and lead 220 back to power source 202. With relay coil 50 energized, relay contact 54 is in contact with contact strip 76, and motor 200 is energized through the following circuit: from power source 202, lead 218, connector stud 16, contact strip 76, contact 54, armature 52, wire 58, connector stud 20, lead 214 to terminal F2, field windings between terminals F2 and F1, lead 212, connector stud 14, wire 74, armature 68, contact 70, contact strip 78, connector stud 18, lead 216 to terminal A1, armature windings between terminals A1 and A2, lead 222, common C, and lead 220 back to power source 202. It is noted that under this condition, current flows through the armature windings in the same direction as it flowed in FIG. 18; such direction is shown by arrow 246.
However, the direction of current flow through the field windings is now opposite of the direction it flowed in FIG.
18; such direction is shown by arrow 248, Accordingly, the output shaft 206 now rotates in a counterclockwise direction shown at 250 and thus the direction of rotation of the drum in winch 210 is reversed from what it was in FIG. 18. Under this condition, the towing cable is reeled in on to the drum.
When selector switch 204 is moved to its "OFF"
position, dynamic braking is achieved wherein rotation of the armature of motor 200 is quickly stopped, such as within one second. Specifically, when selector switch 204 is moved to its "OFF" position from either its "REVERSE" or "FORWARD"
positions, both relay coils 50 and 66 are in their de-energized states wherein the movable contacts 54 and 70 controlled by coils 50 and 66, respectively, are in contact with contact strip 78. Such condition of contacts 54 and 70 is shown in FIG. 3. Referring to FIGS. 18 and 19, it should be apparent that with contacts 54 and 70 in contact with contact strip 78, current flow from power source 202 to the field windings and armature windings of motor 200 is -- ' . ....................................... ~

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terminate~d and the ~ield windings are electrically 2st~ 8 When selector switch 204 is moved to its "OFF" position, the magnetic flux in the field windings of motor 200 collapses due to the termination of current flow from power source 202, inducing a voltage which causes a momentary surge of current in the field windings in a direction opposite of which current was flowing before selector switch 204 was moved to its "OFF"
position. This momentary surge of current causes the armature of motor 200 to tend to reverse its direction of rotation.
However, since the current surge is momentary and is not sustained, and since the armature windings are no longer energized by power source 202, the armature stops rotating but does not reverse its direction of rotation.
It is to be understood that there are other types of DC motors with which the reversing control 10 of this invention can be used. For example, the DC motor could be a permanent magnet motor. In such a motor, the armature has no winding. Referring to FIG. 18, if such a motor were used, lead 222 would not be provided and lead 216 would connect connector stud 18 to common C instead of to motor 200.
While the invention has been illustrated and described in detail in the drawings and foregoing description, it will be recognized that many changes and modifications will occur to those skilled in the art. It is therefore intended, by the appended claims, to cover any such changes and modifications as fall within the true spirit and scope of the invention.

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Claims (8)

1. In a reversing control adaptable for providing bidirectional control of the output of a DC motor by providing for a reversal of current flow through a winding of the DC
motor, a housing;
relay means secured in said housing, said relay means comprising two relays, each of said relays having a coil, an armature, and a movable contact carried by said armature, said relays sharing two stationary contacts cooperative with said movable contacts;
four connector studs secured in said housing, each connector stud being connected to a different one of said contacts, said connector studs being adaptable to be connected to the winding of the DC motor and to a DC power source; and a connector socket secured in said housing and connected to said relay coils and to said DC
power source and adapted to be connected to a selector switch which enables selective energizing of said relay coils by said DC
power source, the arrangement being such that when one of said relay coils is selectively energized, current flows through said winding of the DC motor in a certain direction, and being such that when the other of said relay coils is selectively energized, current flows through said winding of the DC motor in a direction opposite said certain direction.

2. The reversing control claimed in claim wherein said housing comprises two identical plastic members secured together.

3. The reversing control claimed in claim wherein the configuration of said housing is such that it provides a close tolerance fit with said relay means, connector studs, and connector socket.

4. The reversing control claimed in claim 1 wherein each of said relay coils is provided with a terminal on at least one end thereof, and further including a contact strip to which said terminals are electrically connected by interference fit.

5. The reversing control claimed in claim 4 further including a mounting bracket electrically connected by interference fit with said contact strip.

6. In a reversing control, relay means comprising two single-pole double-throw relays, each of said relays having a coil, an armature, and a movable contact carried by said armature;
first and second stationary contacts cooperative with said movable contacts of said relays;
four connector studs, said first stationary contact being connected to a first one of said connector studs, said second stationary contact being connected to a second one of said connector studs, the movable contact of one of said relays being connected to a third one of said connector studs, the movable contact of the other of said relays being connected to a fourth one of said connector studs, said first connector stud being adapted to be connected to the positive polarity side of a DC power source, said third and fourth connector studs being adapted to be connected to electrical windings of a DC
motor;
a connector socket having a first terminal therein connected to said first connector stud, a second terminal therein connected to one end of the coil of said one of said relays, and a third terminal therein connected to one end of the coil of said other of said relays;

means for connecting the other ends of said coils to the negative side of said DC power source, said connector socket being adapted to be connected to a switch for selecting which of said coils is to be energized, the arrangement being such that when said coil of said one of said relays is selectively energized, said movable contact of said one of said relays makes with said first stationary contact so that current flows out of said third connector stud to said windings of said DC motor and back into said fourth connector stud thereby causing a certain direction of rotation of the output of said DC motor, and being such that when said coil of said other of said relays is selectively energized, said movable contact of said other of said relays makes with said first stationary contact so that current flows out of said fourth connector stud to said windings of said DC
motor and back into said third connector stud thereby causing the opposite direction of rotation of the output of said DC motor from the direction existing when said coil of said one of said relays is selectively energized.

7. The reversing control claimed in claim 6 wherein said relay means, connector studs, and connector socket are secured within a plastic housing in a close tolerance fit.

8. The reversing control claimed in claim 7 wherein said means for connecting the other ends of said coils to the negative side of said DC power source includes terminals on said other ends of said coils, a contact strip having openings therein which receive said terminals in an interference fit, and a mounting bracket secured within said housing in a close tolerance fit and receiving said contact strip in an interference fit, said mounting bracket being adapted to be mounted to a surface which is at the electrical potential of said negative side of said DC power source.