US2986630A

US2986630A - Switch machine for railroads

Info

Publication number: US2986630A
Application number: US600988A
Authority: US
Inventors: Wheeler D Maynard
Original assignee: General Railway Signal Co
Current assignee: SPX Corp
Priority date: 1956-07-30
Filing date: 1956-07-30
Publication date: 1961-05-30
Anticipated expiration: 1978-05-30

Description

y 30, 1961 w. D. MAYNARD 2,986,630

SWITCH MACHINE FOR RAILROAD-S Filed July 50, 1956 4 Sheets-Sheet l N m N O) CO IN VEN TOR.

, W.D.MAYNARD imw z HIS ATTORNEY y 1961 w. D. MAYNARD 2,986,630

SWITCH MACHINE FOR RAILROADS Filed July 30, 1956 4 Sheets-Sheet 2 u? 1 I (D w l0 3? r g F M g g (I) 2 2 P0 5'3 INVENTOR. 5 W.D.MAYNARD Ll.

Hi8 ATTORNEY May 30, 1961 w. D. MAYNARD SWITCH MACHINE FOR RAILROADS 4 Sheets-Sheet 3 Filed July so, 1956 FIG. 4.

W.D.MAYNARD ZNMMJ HIS ATTORNEY y 30, 1961 w. D. MAYNARD 2,986,630

SWITCH MACHINE FOR RAILROADS Filed July 50, 1956 4 Sheets-Sheet 4 IN V EN TOR.

W.D.MAYNARD BY zmw HIS ATTORNEY United States Patent SWITCH MACHINE noR RAILROADS Wheeler D. Maynard, Holcomb, N.Y., assignor to General Railway Signal Company, Rochester, N.Y.

Filed July 30, 1956, Ser. No. 600,988

4 Claims. (Cl. 246-240) This invention relates to switch machines for railroads, and it more particularly pertains to electrically operated switch machines of the compact light weight type.

Switch machines of this type are generally used in place of hand operated machines mostly located in railroad yards or at commercial sidings and the like where shorter switches and lighter weight rails are commonly used and where no lock rods, point detectors or the like are required. Operation of the switch machine may be controlled either remotely or locally and provision must also be made for cutting off power locally so that the switch machine may be hand crank operated for purposes of adjustment, maintenance or any other reason. Provision must also be made to assure that the switch machine be retained in a locked-up position after each movement in either direction.

Generallyspeaking, the switch machine comprising the present invention is powered by an instantly reversible gear-head motor which provides an approximate twentyto-one speed reduction to its output shaft. This motor output shaft is connected to a pinion shaft through a dog type flexible coupling and a torque-limiting clutch. The pinion shaft in turn drives a switch machine drive shaft through a single pinion and gear reduction at approximately one-sixth speed. Both the pinion shaft and the drive shaft each have one end extending through the switch machine housing. The outside portion of the pinion shaft is adapted to receive a ratchet type crank to facilitate hand operation of the switch machine; whereas, the outside portion of the drive shaft is fitted with a crank arm having a pivotally mounted jaw connector thereon to facilitate connection to a switch point operating rod.

An inside portion of the drive shaft is provided with a detent cam which cooperates with a spring biased detent device to comprise a means for locking the switch machine in either one of its extreme operated positions. The inside end of the drive shaft is provided with a double cam and contact switch arrangement which operates to cut-off motor energy as the switch machine movement approaches either one of its locked-up fully operated positions. Appropriate mechanically interlocked relay type contactors, a control switch and a terminal board are mounted within the switch machine casing to facilitate the control of the switch machine.

Due to railroad yard conditions where the roadbed is level with the tops of the ties, yard switch machines are usually mounted on top of the ties to keep them above ground level. Also, Where space is limited, it may be necessary to mount the switch machine on either side of the switch without reversing the direction of its mounting. The switch machine of the present invention is adaptable to these varying mounting conditions, the crank arm having different mounting positions to assure the proper alignment With respect to the switch point operating rod.

An object of the present invention is the provision of a power operated switch machine for railroad yard use which is sturdy and compact in design, which is economical to build and maintain, and which is quick acting and instantaneously reversible.

Another object of the present invention is the provision of a power operated switch machine of the crank arm type which is provided with a spring biased detent device to lock-up the switch machine movement in either of its extreme operated positions, this lock-up means becoming effective shortly before the switch machine movement passes its crank toggle dead center position.

Another object of the present invention is the provision of a double cam and contact arrangement which permits the switch machine movement to control its own motor power cut-off and establish suitable completion of stroke indications at the appropriate time.

A still further object of the present invention is the provision of optional crank arm mounting means to permil: universal mounting of the switch machine in various operating positions with respect to its associated switch operating rod and switch points.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings and in part pointed out as the description progresses.

In describing the invention in detail, reference will be made to the accompanying drawings in which similar reference characters will be used to designate corresponding parts throughout the several views, and in which:

Fig. 1 is a top plan view of the switch machine of the present invention with the cover removed to show the organization of the various parts of the movement;

Fig. 2 is a side elevational sectional view of the switch machine of the present invention taken substantially on the line 2-2 of Fig. l as viewed in the direction of the arrows and shows mainly the alignment of the pinion and motor shafts and their component parts;

Fig. 3 is a side elevational sectional view of the switch machine of the present invention taken substantially on the line 33 of Fig. l as viewed in the direction of the arrows and shows the drive shaft and its component parts as well as the relay and terminal board mounting;

Fig. 4 is an end elevational view of the switch machine of the present invention partly shown in section as indicated by the line 44 of Fig. l as viewed in the direction of the arrows;

Fig. 5 is an end elevational sectional view of the switch machine of the present invention taken substantially on the line 55 of Fig. 1 as viewed in the direction of the arrows and shows the spring biased cam and detent device in its left hand operated locked-up position;

Fig. 6 is an end elevational view taken substantially on the line 6-6 of Fig. 1 as viewed in the direction of the arrows and shows the cam and contact arrangement operated by the drive shaft;

Fig. 7 is a partial sectional view taken substantially on the line 77 of Fig. 1 as viewed in the direction of the arrows and shows the spring bias mounting of the detent lock-up arrangement;

Fig. 8 is a plan view of the entrance end of a typical switch layout showing the switch machine of the present invention mounted on the left hand side of the track switch and connected to the switch points;

Fig. 9 is an end view of the apparatus shown in Fig. 8 drawn at a reduced scale, and also shows in broken lines the switch machine location as it would appear if mounted on the right-hand side of the track switch;

Fig. 10 is an end view of the switch machine crank arm shown mounted on the drive shaft in one of its positions and showing the keyway slots for mounting in its other position; and

Fig. 11 is an illustration of a typical circuit for the control and operation of the switch machine of the present invention.

Referring now generally to the structure of the switch machine as shown in Figs. 1 to 7 inclusive and more particularly to Fig. 2 of the drawings, the housing comprises a casing 15 and a top cover 16 having sponge rubber or cork inserts 17 fitting over the ridge of the casing 15 to render the inside of the housing weatherproof when closed. The cover 16 is fastened to the casing 15 at one end by means of lugs 18 which cooperate with hook-eye bolts 19 mounted in suitable casing lugs. The other end of the cover 16 is provided with a forked lug 20 which cooperates with a pivoted bolt 21 and a wing nut 22 fastened to a suitable lug on the casing 15. With the cover 16 in position on the casing 15, the lugs 18 and hook-eye bolts 19 act as a hinge whereas the pivoted bolt 21 passing through the forked lug 20 with the wing nut 22 on top provides a means for tightening the cover 16 down in place on the casing 15, thus compressing the gasket inserts 17.

Upstanding bosses 23 are provided on the inside of the casing 15 upon which is mounted the motor M by means of bolts 24. The motor M is a conventional instantly reversible gear head type motor having a built-in gear reduction GR comprising a helical planet gear-integral ring gear combination which drives its output shaft 25 at an approximate twenty-to-one speed reduction. This motor M is also provided with a starting winding as well as a running winding and has a capacitor and a centrifugally operated reversing switch in series with its starting winding for operational purposes as will be explained more in detail hereinafter in connection with the control circuit arrangement.

Also mounted inside the casing 15 in concentric alignment with the motor output shaft 25 is a pinion shaft 26. This pinion shaft 26 is rotatably mounted in two hushed

bearings

27 and 28. The bearing 27 is formed in the casing 15 whereas the bearing 28 is a block which is bolted to an upstanding boss 29' provided in the inside of the casing 15. The pinion shaft 26 has a pinion gear 30 formed integral therewith. When mounted, the pinion gear 30 is positioned between the two

bearings

27 and 28 so that the pinion shaft 26 is held in proper linear alignment. The left-hand end of the pinion shaft 26 extends through the bearing 27 to the outside of the casing 15 and is provided with a hex head 31 for receiving a ratchet type hand crank.

The motor output shaft 25 and the pinion shaft 26 are connected together by means of a flexible coupling comprising a jaw and lug type connector and a torque-limiting plate type clutch. The bifurcated jaw 32 is keyed to the motor output shaft 25 by means of a key 33 inserted in suitable keyways so that it turns in either direction with the motor output shaft 25. The bifurcated portion 34 of the jaw 32 co-acts with a lug 35 which projects from a collar 36. This collar 36 is connected by means of a key 37 to the outer clutch casing 38 which is rotatably mounted on the inner clutch casing 39. The inner clutch casing in turn is keyed to the pinion shaft26 by means of a key 40. Suitable clutch plates 41 are interposed between the two

clutch casings

38 and 39 and these clutch plates 41 are alternately keyed to the two

clutch casings

38 and 39 in the usual manner. An adjusting nut 42 and suitable spring washers on the inner clutch casing 39 provides a means for adjusting the clutch plate pressure. Thus, the drive from the motor output shaft 25 to the pinion shaft 26 is through the clutch plates 41.

The pinion gear 30 meshes with and drives at an approximate six-to-one speed reduction a spur gear 45 which is keyed to a drive shaft 46 by means of a key, 47. This drive shaft 46 is mounted in a pair of bushedbearingsYftS and 49 (see Fig. 3) with the gear'45 positioned between the two bearings. The bearing 48 is formed in the casing 15 whereas the bearing 49 is a block which is 4 bolted to an upstanding boss 50 provided on the inside of the casing 15. The left-hand end of the drive shaft 46 extends through the bearing 48 to the outside of the casing 15 where a crank arm 51 is keyed thereto by means of a key 52, a split ring 53 holding the crank arm 51 in place. The free end of the crank arm 51 is provided with a pivot pin 54 upon which is journalled a switch rod connector 55 which is held in place by a split ring 56. This switch rod conductor 55 is provided with a bifurcated jaw portion 57 to which one end of a switch connecting rod 58 is attached by means of a pin 59. The other end of the switch connecting rod 58 is connected to the switch points as shown in Figs. 8 and 9, and described more in detail hereinafter.

The inner end portion of the drive shaft 46 is provided with one cam 61 which is part of a detent locking arrangement and two adjustable

contact operating cams

62 and 63. The cam 61 has an enlarged hub and is keyed to the shaft 46 by means of a key 64 and is held in place by a split ring 65. This cam 61 is provided with two recessess or detents 66 and 67 (see Fig. 5) which are located two hundred degrees apart around its pe riphery and designate the prescribed extreme'locked-up positions of movement of the drive shaft 46 and its associated crank arm 51. It is obvious that the extreme linear movement of the crank arm 51 is through an arc of one hundred eighty degrees which may be termed the toggle or dead center points and these two

cam detents

66 and 67 define the locked-up positions of the crank arm 51 which in this case will be ten degrees past toggle center in each extreme position. As the normal position of the switch machine would be either one of its extreme operated positions, the various parts have been shown in their left-hand operated positions for the purpose of illustration.

The cam recesses or

detents

66 and 67 as well as the cam surface 68 cooperate with a roller 69 which is journalled on a pin 70 mounted on a spring biased lever arm 71. This lever arm 71 is substantially U-shaped in cross section and extends lengthwise across the vw'dth of the casing 15 and is located directly under the cam 61. The right hand end of the lever arm 71 is journalled on a pivot pin 72 and is mounted in a bracket 73 which is suitably bolted to the base of the casing 15. The left hand end of the lever arm 71 is forked into two arms 74 to form a U-shaped extremity which partly surrounds an inverted cylindrical cup shaped spring housing 75. The two arms 74 bear on two projecting lugs 76 formed integral with the spring housing 75, as more clearly shown in Figs. 1 and 7, the bearing surfaces 77 providingsuitable pivot points.

The spring housing 75 rests on top of and surrounds a compression coil spring 78, the spring housing 75 having a downwardly extendingboss 79 which fits inside the compression spring 78. The compression spring 78 in turn fits over and is positioned by an upstanding boss 80 formed integral with the base of the casing 15. When assembled, the compression spring 78 is placed under initial compression so that the roller 69 always bears against the surface of the cam 61 even when the roller 69 is in one of the

detents

66 or 67 as shown in the draw: ings. In effect, the construction provides a form of saddle for the free end of the lever arm 71, the coinpression spring 78 providing an upward bias. A down ward movement of the lever arm 71 will compress the compression spring 78 to an equal extent, up to a limit, as defined by the spacing between the opposing ends of

bosses

79 and 80. The design of the cam 61 is such that when the cam surface 68 is in contact with the roller 69, the lever arm 71 will further compress the spring 73 but there will still be a slight clearance'between the

bosses

79 and 80. However, the unused surface 81 of the cam .61 is of greater radii than that of the cam surface 68 so that if for any reason, as explained hereinafter, the'carns 61 should continue to be turned, the bosses 79 and '80 (see Figs. 5 and 7) would come together and stop all movement before the top portion of the rear incline of the

detents

66 and 67 could ride past the roller 69.

The two

contact operating cams

62 and 63 are alike and are mounted on a reduced end portion of the drive shaft 46 so that their cam surfaces 82 and 83 are spaced approximately two hundred degrees on their centers to correspond to the spacing of the

detents

66 and 67 in the cam 61. These earns 62 and 63 are held in position on the shaft 46 by a structure comprising a cutaway portion in the cam block and a cross plate 88 screw fastened to the cam block in a manner whereby the structure surounds the shaft 46 and is clamped thereto when the screws are tightened down. The cam surface 82 of the cam 62 contacts a suitable normally closed snap acting contactor 84 when the switch machine is in its left hand position as shown; whereas, the cam surface 83 of the cam 63 will contact another normally closed snap acting contactor 85 when the switch machine is operated to its right hand position. The edges of the cam surfaces 82 and 83 are spaced approximately one hundred and sixty degrees apart so that they operate their

respective contactors

84 and 85 prior to the entrance of the roller 69 into the

cam detents

66 and 67, as will be explained more in detail hereinafter. These

snap acting contactors

84 and 85 are mounted on an upstanding angle bracket 86 which is bolted to the bottom of the casing.

These cam operated

contactors

84 and 85 are provided with two sets of contacts which control the current to the motor M and suitable indication signals as will be explained hereinafter. The

cams

62 and 63 are adjustable on the drive shaft 46 and are preferably so adjusted that the motor current is cut off at the contactors at about the same time the roller 69 is about to enter one of the

detents

66 or 67, just before the end of the stroke of the switch machine movement. The overrun of the motor M and the trapped pressure of the spring 78 will now permit the switch machine movement to be forced into its locked up position wherein the roller 69 is spring biased into one of the

cam detents

66 or 67. At the same time, an indication signal is lighted by a normally open micro-switch contact to indicate that the switch machine movement has completed its stroke.

' Having thus described the mechanical organization of the switch machine of the present invention, it is believed that a brief description of the operational movements of the switch machine as it travels through a cycle of operation will facilitate a better understanding of the mechanism. As previously stated, the switch machine has been shown in a so-called left hand position, that is, with its drive shaft 46 operated to its full clockwise position, as viewed in Figs. 4, 5 and 6.

Assuming now that the switch machine is to be operated to its right-hand position, the motor M is energized causing its output shaft 25 to rotate clockwise at a 20 to 1 speed reduction due to its built-in gear reduction GR. The output shaft 25 drives the jaw and lug type connector which comprises the bifurcated jaw 32, the lug 35 and the collar 36. The collar 36 drives the outer clutch casing 38 which in turn drives the inner clutch casing 39 through the clutch plates 41. As the inner clutch casing 39 is connected to the pinion shaft 26, the pinion 30 drives the spur gear 45 and its drive shaft 46 at an approximate six to one speed reduction in a counter-clockwise direction.

As the drive shaft 46 turns, it will rotate its associated detent cam 61, the two adjustable

contact operating cams

62 and 63 and the crank arm 51. The initial move ment of the drive shaft 46 will operate the crank arm 51 through its,10 past toggle center position and start the linear movement of the throw rod 58. At the same time, the cam 61 will be moving out of its locked-up position wherein the lever arm roller 69 is positioned in the cam detent 66, thus forcing the lever arm 71 downward against the bias of the compression spring 78. As the drive shaft 46 continues to turn, the crank arm 51 will be going through its operating movement and the cam surface 68 will be hearing against the roller 69, thus holding the lever arm 71 down against the bias of the spring 78. At about the same time that the edge of the detent 67 in the cam 61 reaches the roller 69, the cam surface 83 of the contact operating cam 63 will come in contact with the operating arm of the contactor 85, thus cutting off current to the motor M. The kinetic energy of the motor M and the momentum of the switch machine movement along with the trapped pressure in the compression spring 78 will continue to rotate the drive shaft 46 so that the spring biased roller 69 will enter the cam detent 67 The trapped pressure of the compression spring 78 will also force the lever arm 71 upward causing the roller 69 to bear against the bottom of the detent 67, wherein the switch machine movement will again be in a locked-up position. Any overrun movement of the drive shaft 46 in a counterclockwise direction is opposed by the bias of the compression spring 78 as any attempt of the roller 69 to ride up the back inclined surface of the detent 67 will tend to compress the spring 78 still further.

The switch machine casing 15 also houses double unit relay contactors RL and RR, a suitable terminal board TB, a knife switch KS, and a motor capacitor MC. The relay contactors RL and RR are mounted on the side wall of the casing 15 and they have their armatures mechanically interlocked so that under any condition only one contactor can close its contacts at a given time. The terminal board TB is of the usual type insulation board and supplies a mounting for the wire connecting terminal blocks 87, the knife switch KS and the motor capacitor MC. These relay contactors RL and RR, the knife switch KS, and the motor capacitor MC are used to control the motor circuit as will be explained more fully hereafter. A conduit fitting 89 is provided in the casing 15 to facilitate the entrance of external wiring.

Referring now more particularly to Figs. 8 and 9, there has been shown a simple typical railroad switch layout with the switch machine of the present invention con nected thereto in operational position, the switch machine as a whole being referred to and designated as SM. The switch layout comprises the two

main rails

90 and 91 and the two

switch points

92 and 93 which rest on and are fastened to the tie plates 94 and ties 95. The switch points 92 and 93 are fastened together at their free ends by suitable switch lugs and a switch rod 96 which has a switch rod connector 97 mounted thereon. The other ends of the switch points 92 and 93 are hingedly connected to anchored stock rails (not shown) so that the free ends of the switch points may be moved back and forth between the

main rails

90 and 91. The adjustable switch connecting rod 58 is then connected between the switch machine SM and the switch rod connector 97 as previously mentioned, so that operation of the switch machine crank arm 51 will move the switch points 92 and 93 to set up the proper track route.

As previously mentioned the switch machine has been shown in its left-hand operated position and has also been shown mounted on the left-hand side of the switch layout. The switch layout has been shown to correspond with the position of the switch machine, that is, with the switch point 92 against the main rail 90, which is its left-hand operated position. Also, as previously mentioned, the switch machines for use in railway yard layouts are usually mounted on top of the ties to keep them above ground level. This mounting is accomplished by having two of the ties extending outward from the main rail 90 and bolting the switch machine SM thereto by means of bolts 98. These bolts 98 preferably pass through holes 99 located in the base of the switch machine casing 15 (see Fig. 1), but it should be understood that lugs could be provided on the outside of the switch machine casing 15 for mounting purposes.

With the switch machine SM mounted on top of the ties 95 and the switch rod 96 located below the base of

therails

90 and 92, it is obvious that the switch connecting rod 58 must be provided with a downward offset as shown at 100 in Fig. 9. This places the line of thrust, which is shown by a line 101drawn between the two connected ends of the switch operating rod 58, on an upward angle of 4 /2 with respect to the horizontal. This line 101 designates the toggle center position of the crank arm 51and the locked up position of this crank arm 51 is past the toggle center position. Therefore, with the switch machine movement and the crank arm 51 in their left-hand locked-up positions, the angle position of the crank arm as shown in Figs.'4, 9, and 10' is actually 14% with respect to the horizontal.-

Assume now that the track layout conditions demand that the switch machine SM be mounted on the righthand side of the switch layout as indicated by broken lines in Fig. 9. This would call for a diiferent angular position for location of the crank arm 51 as the line 102 which designates the toggle center position of the crank arm 52 would place the crank arm 51 on a downward angle'of 4 /2 with respect to the horizontal. This obviously makes a difference of 9 in the angular location of the crank arm 51 when the switch machine SM is moved from one side of the track switch to the other. Provision is made for changing the angular position of this crank arm 51 by providing two sets of keyways in the crank arm 51 and its drive shaft 46. As shown in Fig. 10; the key 52 is placed in the

keyways

103 and 104 When'it is desired'to mount the switch machine SM on the right-hand side of'the track switch, his only necessary to remove the key 52 from the

keyways

103 and 104, .turnthe crank arm 9 in a counterclockwise direction and place the key 52 in the

keyways

105 and 106. This will permit the crank arm 51 to assume its toggle center positionon a downward angle of 4 /z with respect to the horizontaland allow the crank arm Sl to operate to its locked-up position which is 10 past toggle center position, .the drive shaft '46 and the balance of the switch machine mechanism remaining unchanged.

Referring now to Fig. 11, there has been shown a A typical circuit for theoperation of the switch machine 'of' the present invention. This circuit illustrates the electrical components of the switch machine SM in a conventional manner andincludes the two relay contactors RL and RR, the two cam operated

snap acting contactors

84 and 85, the knifeswitch K S, t he motor M and its associated windings, thernotor capacitor MCand a motor operating centrifugal reversing switch RS. This centrifugally operated reversing switch RS is of a type wherein the motor, after attaining" a certain speed, will cut out the circuit forthe starting winding for that particular direction of rotation only. The circuit for the starting winding remains closed for the other direction of rotation so that when the motor is instantly reversed it willfind the starting Winding circuit closed.

Assume now that the switch rn-achine' SM is in its last operated position, which is the left-hand position as shown on the drawings, and it is desired to operate the switch machine SM and the track switch to their other lockedup: right-hand positions.

Upon operation of the remote controllswitch CS to its right-hand position, a circuit will be established through the-winding of the relay contactor RR which may be traced from a source of alternating current'supply BX, remote control switch contact CS, wire .110 to the winding of relay contactor RR, wire 111, contact 85a ofthe contactor .85 and wire 112 to the cjommonreturn NX. With the relay contactor RR energized, its contacts 113,114 and 115 are picked upthus establishing energizing circuits for both the starting winding 116 and the running winding 117 of the motor M. The circuit for the starting winding 116 may be traced from the alternating current source BX, wire 118, contact 114 of the relay contactor RR,

wires

119 and 120, starting winding 116 of the motor M, motor capacitor MC, wire 121 to the common connection to the reversing switch RS, contact 122 and wire 123 to the contact 113 of the relay contactor RR, wire 124 to 'the' knife switch KS and thence to the common return NX. The circuit for the running winding 117 may be traced from the same alternating current source BX,

Wires

118 and 125, contact of the relay contactor RR, wire 126'to the running winding 117 of the motor M,

wires

127 and 128 to the knife switch KS and thence to the commonreturn NX. Energization of both of the motor windings will cause the motor to speed up rapidly until a certain speed is attained, whereupon its centrifugal unit will open the reversing switch RS at contact 122, thus cutting out the starting winding.

With the motor M energized, it will drive the switch machine mechanism and its cam operating shaft 46 to their right-hand posiitons until such time as the cam 83 opens the contact 85a, whereupon the relay contactor RR will become deenergized and open its contacts, thus cutting off current to the motor M. As previously explained, at this point of the operation of the switch machine mechanism, the spring biased roller 69 is about to enter thecam detent 67 so that even though the kinetic energy of the motor and the momentum of the switch machine movement will help, the trapped pressure of the compression spring 78 alone would be great enough to carry the switch machine movement on through'to the end of itsstrok'e.

During the movement of the cam operating shaft just described, it should be noted that the cam- 82 has moved away from the contact 84a, thus allowingit to close its circuit to the relay contactor RL and condition said relay contactor for the next operation of the switch machine to a left-hand position. Also, with the motor stopped, the reversing switch contact 122 will again be closed Suitable indication or signal lamps are provided to indicate the position of the switch machine and the track switch. As shown on the drawing, with the switch machine and track switch in their left-hand operated positions, the contact 84b is closed and the signal lamp SL is lighted through an obvious circuit. During the movement of theswitc-h machine and trackswitch to a right-hand position as'just described above, thecontact 84b wasopened thus eirtinguishing the lamp SL, whereas the contact 85b was closed to light up the'flam'p SR. 3

With the switch machine SM operated to its right-hand position as justdesc ribed, remote control switch CS'w'ill be in its right-hand position, th'e'relay contactors RL and RR will both be decnergized, the contact 85a is open arid b is closed; whereas, the contact 84a is closed and 84b is open. A movement of a remote control switch CS to its left-hand position will now ope-ratethe'switch machine SM to its left-hand position through circuits similar to those described above in connection with"ari'ght-'hand operation and it is not believed necessary to describe'these circuits in detail. It should be understood, of course, that in this left-hand movement, the relay contactoriRL will be energized and its cont-

acts

130, 131, and 1 32' will be closed. Also, the motor starting winding116 will be'cut out due to the centrifug ally operated reversing switch contact 133 being open. During the operationof the switch machine movement, contact 85a will beclosed' whereas contact 84a will be opened.

The manually operated knife switch KS, as previously mentioned, ismourited on the terminal board TB inside theswitch machine casing l's and is" accessible only" when the cover 16 is removed. This knife switch KS is in series with the motor circuit and is used primarily when/maintenance work s being done on the switch machineor when it is found necessary to hand crank the fsw itch In such event, or possibly for other reasons, it is advisable to cut out the motor circuit so that the switch machine motor can not be operated from a remote source while an authorized person may be working on the switch machine. It should be understood that an automatic type of cut out switch could be used, as for example, a switch which would automatically cut off the motor circuit when the cover was removed. Hand cranking of the switch machine is accomplished by applying a ratchet type crank wrench to the hex head 31 on the pinion shaft 26, whereby the switch machine drive shaft 46 may be rotated through approximately 180 by several hitches of the hand crank wrench.

With reference again to the spring housing 75, the compression spring 78 and the two extending

bosses

79 and 80 located within the compression spring 78 as shown in Fig. 5, as previously explained, the two

bosses

79 and 80 provide a positive stop for the switch machine movement beyond either of its extreme locked-up positions. Such a movement would tend to occur, for example, due to the failure of a motor cut-

out contactor

84 or 85, thus allowing the motor M to continue to drive. In this instance, the detent cam 61 would continue to rotate past the center of its detent position thus forcing the roller 69 and the lever arm 71 downward against the force of the compression spring 78 until the two

bosses

79 and 80 came together and stopped the movement. No damage would occur to the motor M, the switch machine mechanism or the track switch as the torque-lirniting clutch would now permit slippage with the motor still rotating. A time elemen relay could also be provided to cut off the motor energy after a certain set time interval to prevent burning out the clutch.

Having thus described one specific embodiment of the present invention, as applied to the control of a track switch, it is desired to be understood that the form shown has been shown and described more for the purpose of illustrating the principles and mode of operation involved rather than for indicating the scope of the present invention, and it is to be further understood that the various modifications, adaptations, and alterations may be applied to the specific form shown within the scope of the present invention, except as limited by the appending claims.

What I claim is:

1. In a switch machine for railroads, a drive shaft and a motor operated driving means therefor, a detent locking device cooperating with said drive shaft comprising a detent cam mounted on said drive shaft having two spaced detents in its cam face and a spring biased lever arm having a roller thereon which co-operates with said cam face, two contact operating cams adjustably mounted on said drive shaft to co-operate in sequence with two contact devices which control the motor current, said roller being forced into one of said detents and an associated contact operating cam operating an afiiliated contact switch when said drive shaft is operated to either one of its locked-up positions, said contact switches cutting off the motor current prior to the entrance of said roller into one of said detents; whereby, the overrun of said motor operated driving means and the biasing force of said lever arm carries the movement through to its extreme position as determined by said roller bearing against the bottom of one of said detents.

2. In a switch machine for railroads, a drive shaft driving means comprising, an instantly reversible motor having a self-contained gear reduction, a pinion shaft connected to the motor shaft by a dog type flexible coupling and a torque-limiting clutch, a pinion gear on said pinion shaft meshing with a spur gear on said drive shaft to produce a gear reduction drive, said drive shaft having a crank arm, a detent cam and two contact operating cams mounted thereon, said detent cam having two spaced detents therein and co-operating with a roller mounted on a spring biased lever arm, said two contact operating cams co-operating each with a contactor to make and break the motor circuits, said crank arm having a connector rod journalled thereon which is connected to a railroad track switch, a positive stop effective to limit the movement of said drive shaft; whereby, said crank arm and said detent cam are driven within the limits of the spacing of said detents in said detent cam as determined by the motor circuit breaking point caused by said contact operating cams operating said contactors, whereupon the overrun of said driving means and the spring bias of said lever arm will force said roller into a cam detent and lock up said driving means and said track switch, said positive stop preventing movement of said driving means beyond said locked-up position.

3. In a switch machine for operating a railroad track switch, a drive shaft and a motor operated driving means therefor, a locking device for at times locking said drive shaft comprising a detent cam mounted thereon with two spaced detents therein and a spring biased lever arm having a roller thereon which cooperates with said two cam detents when said drive shaft is in its extreme operated positions, said detents in said detent cam determining the locked positions of said drive shaft, two contact operating cams mounted on said drive shaft which act to cut ed the current to said motor when said drive shaft reaches an extreme operated position, a crank arm having at least two set mounted positions on said drive shaft and com nected to said track switch, the particular position of the mounting of said crank arm with respect to said drive shaft being selected so that the dead center position of said crank arm can always be on the line of thrust regardless of which side of the track switch said switch machine is mounted.

4. In a switch machine for operating a track switch on a railroad, a reversible motor having a self-contained gear reduction, a pinion shaft connected at one end to the motor by a flexible coupling and a torque limiting clutch, a pinion gear on said pinion shaft, a drive shaft having mounted thereon a spur gear meshing with said pinion gear to produce a gear reduction drive, a toggle drive arm on said drive shaft connected to the track switch, a detent locking device for holding said drive shaft in its extreme operated positions comprising a cam mounted on said drive shaft having two spaced detents on its face, said cam face having a greater radius on one side than on the other side, a lever arm having a roller mounted thereon and pivoted at one end, a spring at the other end of said lever arm biasing said lever toward said cam and said roller against said cam face, said spring biased lever arm forcing said roller into the corresponding one of said detents when said drive shaft is operated to either of its extreme positions, a stop located beneath said other end of said lever to prevent movement of said cam beyond said extreme positions when said roller begins to pass onto said cam face of greater radius, whereby said track switch is positively operable to its extreme positions.

References Cited in the file of this patent UNITED STATES PATENTS 273,450 Brahn Mar. 6, 1883 713,490 Pottin et a1 Nov. 11, 1902 806,299 Snow Dec. 5, 1905 1,889,022 Little Nov. 29, 1932 2,003,382 McWhirter June 4, 1935 2,124,739 Kershaw July 26, 1938 2,566,946 Laze Sept. 4, 1951 2,633,220 Chase Mar. 31, 1953