US3296394A

US3296394A - Air powered current reversing contactor

Info

Publication number: US3296394A
Application number: US428671A
Authority: US
Inventors: Corniello John Patrick
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-01-28
Filing date: 1965-01-28
Publication date: 1967-01-03
Anticipated expiration: 1984-01-03

Description

J. F. CORNIELLO AIB POWERED CURRENT REVERSING CONTACTOR 3 Sheets-Sheet l Filed Jan. 28, 1965 ai mi. l

INVENTOR.

JOHN P. CORNIELLO ATTORNEY Jan. 3, 1967 J. P. coRNn-:LLO

` AIR POWERED CURENT REVERSING CONTACTOR 3 Sheets-Sheet 2 Filed Jan. 28. 1965 INVENTOR. JOHN P. CORNIELLO Jan. 3, 1967 J. P. coRNlELLo 3,296,394

AIR POWERED CURRENT REVERSING CONTACTOR Filed Jan. ze, 1965 s sheets-sheet a INVENTOR JOHN P. CORNIELLO ATTORNEY United States Patent O 3,296,394 AIR PUWERED CUENT REVERSING CONTACTR .lohn Patrick Corniello, New Haven, Conn., assignor of one-half to Rocco Iezzi, New Haven, Conn. Filed Jan. 28, 1965, Ser. No. 428,671 15 Claims. (Cl. 20D-82) This invention relates broadly to current reversing contactors, and more particularly to a heavy duty air powered current reversing contactor.

One of the objects of the invention is to provide a construction of uid operated polarity reversing contactor which is designed so as to prevent both positive and negative contactor elements from closing at the same time.

Another object of the invention is to provide a construction of air operated circuit breaker and maker device movable by air pressure to two different states and which moves to a third state, or open condition, when air pressure is completely removed from the device.

Still another object of the invention is to provide a novel construction of fluid operated polarity reversing contactor which utilizes oppositely acting fluid operated pistons for moving the contactor elements.

Still a further object of the invention is to provide a compact air operated current reversing contactor which is simple and rugged in construction, economical to manufacture, and readily lends itself to mass production techniques.

Other and further objects of the invention are set forth more fully in the specification hereinafter following, and will become manifest to one skilled in the art, as the description proceeds with reference to the accompanying drawings, in which:

FIG. l is a perspective view of the air operated current reversing contactor of the invention, with associated circuitry and air control means shown in schematic form;

FIG. 2 is a top plan view of the current reversing contactor of FIG. l, with parts broken away, and on a somewhat reduced scale;

FIG. 3 is a transverse sectional view taken substantially along line 3 3 of FIG. 2, showing the contactor in one energized state;

FIG. 4 is an enlarged fragmentary transverse sectional View taken substantially along line 4-4 of FIG. 2, with parts omitted for clarity;

FIG. 5 is a fragmentary top plan view of the center portion of the contactor insulation body portion, shown on an enlarged scale, with parts broken away, showing the input ports on two different levels with the associated air passages shown in phantom;

FIG. 6 is a side elevational view of a modified form of air operated current reversing contactor according to the invention, with parts broken away and a portion shown in transverse section;

FIG. 7 is a bottom plan view partly in section, taken substantially along line 7-7 of FIG. 6; and

FIG. 8 is a cross sectional view taken substantially along line 8--8 of FIG. 7.

Referring to the drawings in greater detail, wherein similar reference numerals indicate similar components throughout, the main body portion of the current reversing contactor comprises a pair of

insulation body portions

1 and 2, each having a pair of

apertures

3 and 4 therethrough, respectively disposed in registration with each other when

body portions

1 and 2 are disposed in overlying relation. A pair of air inlet and exhaust ports 5 and 6 are machined in one side surface of

insulation body portions

1 and 2, with inlet and exhaust port 5 machined into insulation body portion 1 and having a connecting passage 7 extending in communication with aper- Patented Jan. 3, 1967 ICC ture 3 adjacent its outer end, and a connecting passage 8 extending through

body portions

1 and 2 and into cornmunication with aperture 4 in insulation body portion 2 adjacent its outer end. In like manner, air inlet and exhaust port 6, machined in insulation body portion 2, is provided with a connecting passage 9 communicating with aperture 3 therein adjacent its outer end, and a connecting passage 10 extending through

body portions

1 and 2 and into communication with aperture 4, adjacent its outer end, in body portion 1. The outer ends of air inlet and exhaust ports 5 and 6 are enlarged, as shown in FIGS. 2 and 5, to receive the male fluid or air supply and exhaust members 11 and 12 which carry sealing rings 13 to provide airtight connections when the members are inserted in the ports. The functioning of supply and exhaust members 11 and 12 is explained later in the specification.

Gasket 14 having corresponding apertures in registration with the apertures and connecting passages in

insulation body portions

1 and 2 is disposed between the body portions to provide an airtight seal therebetween.

Insulation body portions

1 and 2 are secured together by means of pairs of

angle brackets

24, 25 and 26, 27 disposed on opposite ends of

body portions

1 and 2, having stud bolts 28 extending through

angle brackets

24, 25 and

body portions

1 and 2 therebetween, and stud bolts 29 extending through

angle brackets

26, 27 and

body portions

1 and 2, thus securely clamping opposite ends of

body portions

1 and 2.

Angle brackets

24, 25, 25 and 27 are each provided with a raised electrical contact surface 24', 25', 26 and 27', respectively, and a pair 4of

load connecting lugs

30 and 31 are respectively connected between opposite pairs of

angle brackets

24, 25 and 26, 27, respectively, by means of

bolts

32 and 33, respectively. Lug 3i) is thus placed in electrical contact with

angle brackets

24, 25 and the electrical contact surfaces 24' and 25' connected therewith, while load connecting lug 31 is placed in electrical contact with

angle brackets

26, 27 and the respective

electrical Contact surfaces

26 and 27.

Lugs

30 and 31 thus represent the output terminals of the current reversing contactor to which the load 34, indicated schematically in FIG. l, to be energized by the D C. power source 35, is connected. Although the current or polarity reversing switch of the invention has been designed mainly for reversing the polarity of high D.C. current to a load, such as required at different intervals in metal cleaning and metal plating processes, the switch which actually performs as an air powered relay may also have application for other purposes. Since it is mainly used for reversing the polarity of high DC. i

currents, the angle brackets, load connecting lugs and other electrical contact members, are shown constructed of relatively heavy electrically-conductive material. The DC. power source 35, such as a battery, rectier, or the like, is connected to

input terminals

36 and 37 which are secured to

insulation body portions

1 and 2, respectively, by means of bolts 38, extending outwardly from interior recessed bores 39 in the body portions. The interior recessed bores 39 are of such a depth that the bolts 38 are spaced a considerable distance from each other so that they are well insulated from each other. This is vital since the bolts and the terminals to which they are connected are of opposite polarity.

Input terminals

36 and 37 may be of any length and for purposes of explaining the operation of the device, terminal 36 is connected as an anode connected to the positive terminal of the power source, while input terminal 37 is shown connected as a cathode to the negative terminal of the D.C. power source 35.

Input terminals

36 and 37, as shown more particularly in FIGS. 1 and 3, each provides a pair of raised electrical contact surfaces 36 and 37', respectively, on the outer surfaces thereof, disposed in 3 respective longitudinal alignment with electrical contact surfaces 24', 26' and 25', 27.

A pair -of cylindrical members 15 and 16, carrying recessed sealing rings on the outer surfaces thereof, as shown in FIG. 3, are disposed in

apertures

3 and 4, respectively, of

body portions

1 and 2. Piston members 17 and 1S having sealing rings about their outer peripheries, as shown in FIG. 3, are slidably disposed within cylindrical members 15 and 16, respectively, for reciprocation therein.

The ends of cylindrical member 15 are closed by a pair of end brackets 19 which extend into sealing engagement with the bore of apertures 3 and overlie the outer surfaces of

body portions

1 and 2 adjacent apertures 3 to form a fluid or air cylinder. End brackets 19 are constructed of insulation material, such as the plastics Debrin, Cilcon, Lexan, or other suitable insulation material, and are provided with radial air passages 20 therethrough, placing opposite ends of the air cylinder thus formed in communication with connecting passages 7 and 9 which are in communication with inlet and exhaust ports and 6, respectively. End brackets 19 are centrally apertured, with the aperture bores provided with sealing rings to form airtight sliding connections between the end brackets and shafts 21 extending therethrough from opposite ends of piston member 17 and outwardly of brackets 19. The air cylinder is secured in

insulation body portions

1 and 2 by stud bolts 22 extending through opposite end brackets 19 and

body portions

1 and 2. These stud bolts draw the end brackets tightly into contact with the ends of cylindrical member l15 and also aid in securing

body portions

1 and 2 together. The sealing rings, shown on FIG. 3, connected about end brackets 19 and cylindrical member 15 prevent air leakage from the current reversing contactor from the connections of

passages

7, 9 and 20 and the air cylinder joints.

In a similar manner a second fluid or air cylinder is formed by a pair of end brackets 40 connected to opposite ends of cylindrical member 16 with the assembly secured together and secured to

body portions

1 and 2 by means of stud bolts 41. Portions of the end brackets 4t) are sealed in the bore of apertures 4 by sealing rings and these portions of the end brackets are provided with radial air passages 42, disposed in registration with connecting passages and 3, placing opposite ends of the air cylinder thus formed in communication with inlet and exhaust ports 6 and 5, respectively. Cylindrical member 16 is provided with sealing rings about its outer periphery to prevent air leakage from the connection between passages 8, 10 and 42.

End brackets 40 are constructed of insulation material to prevent shortcircuiting of the contactor between the input terminals and the angle brackets. Each end bracket 40 is centrally apertured and shafts 43 connected to opposite ends of piston member 18 extend therethrough and outwardly thereof. Sealing rings are provided in the central apertures of end brackets 40 to provide an airtight sliding connection between shafts 43 and the brackets when piston member 18 reciprocates within cylindrical member 16.

Spring members 44, of equal strength, are connected etween opposite sides of both piston members 17 and 18 and the

end brackets

19 and 40 on opposite ends of the respective cylinders, such that when no air pressure is supplied to the contactor device, or when air pressure is released therefrom, spring members 44 cause piston members 17 and 18 to seek centralized positions within cylindrical members and 16, thus positioning all of the electrical contact members in open position, as explained more fully hereinafter following.

A pair of longitudinally extending

movable contactors

45 and 46, having contact surfaces registerable with electrical contact surfaces 24', 36 and 25', 37', respectively, are connected by means of a spring connection indicated generally at 47 to the ends of shafts 21. In like manner a pair of longitudinally extending

movable contact members

48 and 49 are connected to the ends of shafts 43 by similar spring connections 47, such that the contact surfaces carried thereby are adapted to shunt electrical contact surfaces 36', 26 and 37', 27', respectively.

Movable contactors

45, 46, 48 and 49 are maintained in parallel position by insulated bracket rib (not shown), extending from a protective covering which ts over the contactor device of the invention, thus preventing any radial movement of the movable contactor members.

It is to be noted that air inlet and exhaust ports 5 and 6 are connected to each of the two air cylinders but to respective opposite ends of the air cylinders. Air pressure is supplied to the contactor of the invention from a flow-reversing-type valve, known in the art, and schematically illustrated at Sil, which operates to rst supply air pressure to supply member 12 and inlet port 6, while simultaneously exhausting or releasing air pressure from port 5 through member 11, and next reversing the action to supply air pressure to port 5 through member 11 and simultaneosuly exhausting pressure from port 6 through member 12. When air pressure is supplied to the current reversing contactor of the invention, in the mode iirst mentioned above, valve Si) supplies air pressure through member 12 to port 6 which communicates this pressure through connecting passages 9 and 10 to respectively opposite ends of the air cylinders through the radial air passages 20 and 42. The increased air pressure within the cylindrical members 15 and 16 move piston members 17 and 18 in respective opposite directions against the pressure of the opposing springs 44. This causes: movable contactor 46 to move into contact with, and to shunt, electrical contact surfaces 37' and 25 to place the negative polarity of input terminal 37 on output lug 30 and thus on the right side of load 34 as shown in FIG. l; movable contactor 45 to move out of contact with electrical contact surfaces 24' and 36' to open that circuit; movable contactor 48 to move into contact with and to shunt contact surfaces 36 and 26' to connect the positive polarity of input terminal 36 to load connecting lug 31 and thus to the left side of load 34; and movable contactor 49 to move out of contact with electrical contact surfaces 37' and 27'. Simultaneously, with this operation, air or fluid from the opposite sides of piston members 17 and 18 are exhausted from the air cylinders through radial air passages 20 and 42, connecting passages 7 and S, exhaust port 5, exhaust member 11, and valve 50 to the atmosphere, or other suitable place. When it is desired to reverse the polarity of the current on the load from that shown in FIG. 1, valve 50 is operated to supply air pressure to port 5 through member 11 and from thence through

passages

7, 8, 20 and 42 to the air cylinders to simultaneously move piston members 17 and 18 to the opposite position than shown in FIG. 3, while exhausting pressure from the opposite sides of the pistons through passages 20, 42, 9 and 10, port 6, member 12 and valve Sil to the atmosphere, or other suitable place. This causes

movable contactors

46 and 48 to move out of contact with contact surfaces 25', 37' and 36', 26', respectively, while causing

movable contactors

45 and 49 to move into electrical contact with contact surfaces 36', 24' and 37', 27', respectively, making load connectinglug 30 positive and load connecting lug 31 negative, thus reversing the polarity of the D.C. current supply to load 34 from power source 35.

The current reversing contactor of the invention thus provides the power actuators between the pairs of contacts, with the pair of power actuators or fluid cylinders operating in opposite directions. The arrangement enables applicant to provide a very compact structure where movement of the contactors is lateral of the longitudinal axis of the device.

A modified form of the current reversing contactor according to the invention is shown in FIGS. 6-8, which form utilizes a pair of Huid or

air cylinders

52, 53 and 54,

55 in conjunction with the movable contactors 56 and 5'7, respectively, which are positioned between the respective pairs of air cylinders. The

insulation body portions

1 and 2 are connected in a manner similar to that described in the preferred form of the invention, forming a main insulation body having open pocket-

like recesses

58 and 59 therein disposed in side-by-side relation along the longitudinal axis of the body portion.

Movable contactors

56 and 57 are respectively suspended within

open recesses

58 and 59 by contactor shafts 60 extending into sliding engagement with apertures through insulation body portions 1' and 2', respectively, with opposite ends of the shafts connected to the ends of pistons 61, in the respective pairs of

air cylinders

52, 53 and 54, 55 connected on opposite sides of the insulation body portion, through spacers 62 of insulation material such as Delrin. The uid or

air cylinders

52, 53 and 54-55 in which the pistons 61 operate, to in turn laterally shift

movable contactors

56 and 57 in

recesses

58 and 59, respectively, are mounted on the insulation body portions by means of flanges 63. The

movable contactors

56 and 57 are maintained in an open circuit position substantially centrally located within the

recesses

58 and 59 by means of compression spring members 64, of equal strength connected between the insulation body portion and each piston 61 to outwardly bias the piston members. The

air cylinders

53 and 54 are provided with combination inlet-outlet ports 65 connected to flow reversing valve 50 While

air cylinders

52 and 53 are provided with inlet-outlet ports 66, commonly connected to the ow reversing valve, the operation of which is explained hereinafter following.

The insulation body portion formed by

portions

1 and 2 also houses a plurality of stationary contact members.

Input terminals

36 and 37" are housed in the insulation body portion on one side thereof with each of the input terminals being of bar-type construction and extending substantially the entire longitudinal length of the insulation body portion as shown in FIG. 6, so as to form opposite side walls of the upper portions of

open recesses

53 and 59, as shown particularly in FIGS. 6 and 8. As indicated input terminals 36" and 37 are disposed adjacent and on opposite sides of

movable contactors

56 and 57 so as to make electrical contact therewith when the contactors are moved laterally within the recesses. For purposes of explaining the operation of the device, input terminal 36 is connected to a positive source of D.C. potential and is thus considered the anode, while input terminal 37" is connected to a negative source of D.C. potential and is thus considered the cathode. In operation the power source is continually connected to these input terminals.

The output terminals are connected on the opposite side of the insulation body portion from the input terminal, and are constructed of substantially the same bar-type material,y preferably of copper. A pair of relatively short stationary output contact bars 24 and 25 are housed in the insulation body portion so as to form opposite side walls of recess 59 and extend longitudinally of the body portion a distance just sufficient to allow movable contactor 57 to make electrical contact therewith as it is laterally moved within the recess. Output contact bars 24 and 25" are commonly connected to load connecting lug 30 in substantially the same manner as in the preferred form of the invention. At the opposite end of the insulation body portion a pair of relatively short stationary output Contact bars 26 and 27 are commonly connected to load connecting lug 31 and are housed in body portion, as shown in FIG. 8, so as to form opposite side walls of the lower portion of recess 58 and are disposed adjacent movable contactor 56 such that the movable contactor may move into selective electrical contact therewith when moved laterally of the recess. Output contact bars 26 and 27" extend longitudinally of the block and terminate at substantially the inner edge of recess 58. The output 6 contact bars 24 and 26, and 2.5 and 27" are thus disposed in respective axial alignment in the insulation body portion, but their inner terminating ends are spaced longitudinally from each other.

In operation, the load to be energized is connected across load connecting lugs 30 and 31', and

input terminals

36 and 37 are connected across a D.C. power source as previously described. Flow reversing valve 50 is then actuated to move movable contactors from their neutral positions as shown to positions to energize the load in a selected manner. If valve 50 is actuated to supply air or fluid pressure to ports 66 of

iluid cylinders

52 and 55 while connecting ports 65 of

cylinders

53 and 54 to the exhaust side of the valve, as air simultaneously enters

cylinders

52 and 55 the pistons 61 therein are moved inwardly against the pressure of their springs 64 to slide the shafts 60 laterally of the recesses moving movable contactor 56 into contact with negative input terminal 37" and stationary output contact bar 27, and movable contactor 57 into contact with positive input terminal 36 and stationary output contact bar 24". Lug 31 is then a negative terminal or cathode while lug 30 is a positive terminal or anode.

When valve 5) is reversed from the state as schematically shown in FIG. 6, ports 66 of

cylinders

52 and 55 are exhausted to the atmosphere and air pressure is supplied to

cylinders

53 and 54 through ports 65. This causes opposite lateral movement of the movable contactors, with contactor 56 moving into contact with input terminal 36 and output contact bar 26 while contactor 57 moves into electrical contact with input terminal 37" and output contact bar 25". Lug 31 thus becomes positive and lug 30 becomes negative reversing the polarity of the voltage applied to the load connected across the lugs.

While the invention has been described in certain preferred embodiments, it is realized that modifications can be made without departing from the spirit ofthe invention, and it is to be understood that no limitations upon the invention are intended other than those imposed by the scope of the appended claims.

What is claimed is:

1. A polarity reversing switch comprising, a main body portion, a pair of input terminals connected on said body portion and adapted for connection to opposite terminals of a source of D.C. potential, first and second output terminals connected to opposite ends of said body portion and adapted for connection to a load, iirst and second oppositely acting huid operated means connected in substantially side-by-side spaced relation on said body portion, said first fluid operated means connected between said pair of input terminals and said first output terminal and said second fluid operated means connected between said pair of input terminals and said second output terminal, separate contact members connected to opposite terminal ends of each of said rst and second iluid operated means outwardly of said tluid operated means, and means connecting said first and second ui-d operated means for opposite movement simultaneously whereby the contact members of said first iluid operated means and the contact members of said second fluid operated means are moved in opposite directions, each to two switching positions connecting the respective output terminal to one or the other of said pair of input terminals, whereby said rst and second output terminals are alternately connected to opposite input terminals of said pair of input terminals upon operation of said fluid operated means.

2. A polarity reversing switch as set forth in claim 1, in which said rst and second fluid operated means each includes a separate uid cylinder, a piston member disposed in said uid cylinder having a rod member extending from opposite ends of the cylinder, and input and output iluid pressure means connected at each end of 7 said cylinder for moving the piston member in opposite directions.

3. A polarity reversing switch as set forth in claim 2 in which a said separate contact member is connected to each end of said rod member of each fluid operated means.

4. A reversing switch of the type adapted for operation at high currents comprising, a main body portion, a pair of input terminals connected on said main body portion, first and second output terminals connected to opposite ends of said body portion, a laterally movable first pair of contacts connected for contacting movement between said first output terminal and said pair of input terminals, a laterally movable second pair of contacts connected for movement between said second output terminal and said pair of input terminals, and lirst and second interconnected oppositely acting spaced iiuid operated means connected to said body portion and operable to two states connected respectively to said first and second pair of contacts to simultaneously impart opposite lateral movement to each pair of contacts, whereby upon operation of said first and second fluid operated means to one state said first pair of contacts connects said first output terminal to one of said input terminals and the said second pair of contacts connects the said second output terminal to the opposite input terminal, and upon operation of said rst and second fluid operated means to the second state the first and second pairs of contacts connect the same respective output terminals to the opposite input terminals of said pair.

5. A reversing switch as set forth in claim 4 in which said first and second fluid operated means are respectively connected between said first pair of contacts and said second pair of contacts, and said first and second fluid operated means having axes disposed substantially parallel with each other.

6. A current reversing switch of the type adapted for operation at high currents comprising, a main body portion, first and second output terminals connected on said main body portion, a pair of input terminals connected on opposite sides of said body portion in spaced longitudinally extending planes, a laterally movable first pair of contacts connected for movement between said first output terminal and said pair of input terminals, a laterally movable second pair of contacts connected for movement between said second output terminal and said pair of input terminals, first and second interconnected oppositely acting spaced air operated means connected to said body portion and operable to two states by air pressure connected respectively to said first and second pair of contacts to :simultaneously impart opposite lateral movement to each pair of contacts, said first and second air operated means connected to said body portion between said first and ysecond output terminals and extending laterally of the body portion between the spaced longitudinally extending planes of said input terminals, and said pair of input terminals connected between said spaced first and second air 'operated means, whereby upon operation of said first and :second air operated means to one state said first pair of contacts connects said first output terminal to one of the input terminals and the said second pair of contacts con- .nects the said second output terminal to the other input terminal, and upon operation of said first and second air operated means to the second state the first and second pairs of contacts connect the same respective output terminals to the opposite input terminals.

7. A current reversing switch as set forth in claim 6 in which said pair of input terminals are connected substantially centrally of said body portion between said first and second output terminals and in spaced relation therewith, and disposed substantially normal to the axes of Asaid first and second air operated means.

8,. A reversing switch as set forth in claim 4 in which said first and second output terminals are' generallyU-` shaped enclosing the opposite ends of said main body of D.C. potential, rst and second output terminals con.

nected on said body portion and adapted for connection to a load, separate first and second oppositely acting spaced fluid operated means connected on said body portion, said first fluid operated means connected between said pair of input terminals and said first output terminal and said second fiuid operated means connected between said pair of input terminals and said second output terminal, first and second movable contact means respectively connected to said first and second separate oppositely acting liuid operated means, said first and second movable contact means connected for simultaneous opposite lateral movement by the respective first and second fluid operated means to two switching positions to conneet the respective first and second output terminals to one or the other of the input terminals of said pair, whereby said first and second output terminals are simultaneously alternately connected to opposite input terminals of said pair of input terminals upon operation of said first and second fluid operated means.

11. A polarity reversing switch as set forth in claim 10 in which each of said separate oppositely acting first and second fiuid operated means comprises a pair of axially spaced fiuid operated cylinders connected on opposite sides of said body portion and on opposite sides of the respective movable contact means for selectively imparting lateral movement thereto.

12. A polarity reversing switch as set forth in claim 11 in which fluid conduit means interconnecting the axially spaced pairs of fluid operated cylinders for each of said first and second movable contact means for opposite lateral movement of said first and second contact means.

13. A polarity reversing switch as set forth in claim 10 in which said pair of input terminals extend longitudinally of said insulation body portion in lateral spaced relation, and are disposed on the same side of both of said first and second separate oppositely acting fluid operated means.

14. A polarity reversing switch as set forth in claim 10 in which said first and second output terminals each comprises a pair of spaced stationary contacts common to said first and second separate oppositely acting fluid operated means respectively.

1S. A polarity reversing switch as set forth in claim 14 in which the spaced pairs of stationary contacts are disposed longitudinally of said insulation body portion in axially spaced relation, and disposed on the same side of said first and second fluid operated means.

References Cited by the Examiner UNITED STATES PATENTS 2,965,730 12/1960 Regoli et al 200-82 2,988,614 6/1961 Grebe et al 200-82 OTHER REFERENCES 1,089,855, German application, Licentia, 1960. 1,151,588, German application, Brown, 1963.

BERNARD A. GILHEANY, Primary Examiner,

G. MAIER, Assistant Examiner.

Claims

1. A POLARITY REVERSING SWITCH COMPRISING, A MAIN BODY PORTION, A PAIR OF INPUT TERMINALS CONNECTED ON SAID BODY PORTION AND ADAPTED FOR CONNECTION TO OPPOSITE TERMINALS OF A SOURCE OF D.C. POTENTIAL, FIRST AND SECOND OUTPUT TERMINALS CONNECTED TO OPPOSITE ENDS OF SAID BODY PORTION AND ADAPTED FOR CONNECTION TO A LOAD, FIRST AND SECOND OPPOSITELY ACTING FLUID OPERATED MEANS CONNECTED IN SUBSTANTIALLY SIDE-BY-SIDE SPACED RELATION ON SAID BODY PORTION, SAID FIRST FLUID OPERATED MEANS CONNECTED BETWEEN SAID PAIR OF INPUT TERMINALS AND SAID FIRST OUTPUT TERMINAL AND SAID SECOND FLUID OPERATED MEANS CONNECTED BETWEEN SAID PAIR OF INPUT TERMINALS AND SAID SECOND OUTPUT TERMINAL, SEPARATE CONTACT MEMBERS CONNECTED TO OPPOSITE TERMINAL ENDS OF EACH OF SAID FIRST AND SECOND FLUID OPERATED MEANS OUTWARDLY OF SAID FLUID OPERATED MEANS, AND MEANS CONNECTING SAID FIRST AND SECOND FLUID OPERATED MEANS FOR OPPOSITE MOVEMENT SIMULTANEOUSLY WHEREBY THE CONTACT MEMBERS OF SAID FIRST FLUID OPERATED MEANS AND THE CONTACT MEMBERS OF SAID SECOND FLUID OPERATED MEANS ARE MOVED IN OPPOSITE DIRECTIONS, EACH TO TWO SWITCHING POSITIONS CONNECTING THE RESPECTIVE OUTPUT TERMINAL TO ONE OR THE OTHER OF SAID PAIR OF INPUT TERMINALS, WHEREBY SAID FIRST AND SECOND OUTPUT TERMINALS ARE ALTERNATELY CONNECTED TO OPPOSITE INPUT TERMINALS OF SAID PAIR OF INPUT TERMINALS UPON OPERATION OF SAID FLUID OPERATED MEANS.