US2823622A - Turn table for model electric trains - Google Patents

Description

Feb. 18, 1958 B. F. PREWITT 2,82

TURN TABLE FOR MODEL ELECTRIC TRAINS Filed April 4, 1951 4 Sheets-Sheet 1 IN V EN TOR.

Feb. 18, 1958 B. F. PREWlTT TURN TABLE FOR MODEL ELECTRIC TRAINS 4 Sheets-Sheet 2 Filed April 4, 1951 w w m W m j z Feb. 18, 1958 B. F. PREWITT TURN TABLE FOR MODEL ELECTRIC TRAINS Filed April 4, 1951 4 Shets-Sheet 3 IN V EN TOR.

v \mM in Efremii} Feb. 18, 1958 B. F. PREWITT TURN TABLE FOR MODEL ELECTRIC TRAINS 4 Sheets-Sheet 4 INVENTOR.

B.ZTzraza'z'i2 Filed April 4., 1951 wmk x United States Patent 2,823,622 TURN TABLE FOR MODEL ELECTRIC TRAINS Ben F. Prewitt, Norfolk, Va. Application April 4, 1951, Serial No. 219,248 12 Claims. (Cl. 10438) More particularly it is an object of the invention to 7 provide in such a turntable remote control, and substantially automatic operation, permitting the operator to select the desired end of the turntable to be associated with any track leading to the turntable, to automatically polarize the several tracks, to regulate the energization of these tracks and to indicate operation of the turntable track rotating means.

An important object of the invention comprises the arrangement of stationary contacts corresponding to each turntable rim track, together with brushes at the several ends of the bridge, for cooperation therewith to provide for indexing and locking the bridge in the desired register with a selected rim track. a Y a An important feature of the invention resides in the turntable bridge indexing and locking mechanism carried by and rotatable with the bridge and adapted to insure proper registration of the pit rim and bridge track sections after these have been preliminarily selected by the operator.

Another important feature of the invention resides in the arrangement for delivering the current to the several locking and track energizing circuits movable with the turntable bridge and including track potential reversing means.

A further important feature of the invention resides in the arrangement of a composite switch and push button unit correlating all of the selector, control, circuit closing and reversing, potential regulating and motion initiating means for the many circuits of the system into one unitary structure.

Other objects and features of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specification wherein is disclosed a single exemplary embodiment of the invention, with the understanding that such changes and modifications may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawings:

Fig. 1 is a plan view of a turntable for model electric trains constructed in accordance with the present invention;

Fig. 2 is a vertical central section through'the device of Fig. 1 showing the contacting and operating mechanism on an enlarged vertical scale for the sake of clarity;

Fig. 3 is a vertical central section through a multipurpose switch and regulator for use with the turntable, wires havin been omitted from the first three figures for the sake of clarity;

2,823,522 Patented Feb. 18, 1958 "ice Fig. 4 is a schematic and diagrammatic showing of all of the parts of the complete turntable system and its wiring circuits;

Fig. 5 is a fragmentary horizontal section, on an enlarged scale, of the bridge locking and indexing means;

Fig. 6 is a fragmentary horizontal section, on an enlarged scale, of the cooperating bridge and pit-wal contacts arranged at each track end; and a Fig. 7 is an enlarged schematic view of the bridge locking and controlling mechanism.

In the construction and operation of model electrically operated railway systems the modern enthusiast strives for realism in appearance as well as in operation. The quantity of equipment used for the sake of appearance and operational quality of trains on some of the more complex systems built to simulate all of the characteristics of real or imaginary railway systems, requires remote control of most of the equipment, both because of the desirability of adhering so far as possible to the principle of full scale equipment, and second because "such equipment is often remote from positions where it can be readily controlled otherwise. The modern prac- "tice in model electrically operated railways eliminates the earlier third rail and supplies the current for operating through the two main rails. Alternating current has given way to direct and electrically energized motor fields to permanent magnetic fields, whereby the direction of operation of the locomotive or other motor vehicle can be controlled by determining the polarity of 'the rails on which it is running.

, In accordance with the present invention the contribution to such a railway system comprises a turntable *for reversing locomotives, cars and the like and directing them from one onto any of a plurality of other tracks.

It will be appreciated that in physical shape and form the equipment may take many characteristics not illus- 'trated in the simple illustrative embodiment of Fig. 1,

where the turntable comprises a pit 10 defined by' the vertical cylinder wall 11,and housing a bridge structure '12 carrying a track including two rails 13 and 14 rotatable about a central vertical axis so that either end thereof, A or B, may cooperate with any one of the radial or pit rim track sections, C, D, E, F, G, H, K and L. Obviously these tracks may be of any number capable of being accommodated about the rim and of any desired disposition but need not be in diametrically opposed pairs as shown.

In vertical section the turntable is illustrated in Fig. 2, and the bridge 12 will be seen to be formed of any suitable structural material having the requisite strength and ease of manufacture. The same is true of the pit rim wall 11 and the closing bottom plate 17, which houses a radial ball bearing 18 whose inner race is secured to the periphery of a tubular shaft 19, coaxial with the bridge and depending therefrom. It is suitably rigidly secured to the bridge in any desired manner. Slightly above its lower end the tube 19 carries one race of a suitable roller thrust bearing 20, the other race of which is carried by any convenient structural element 21 secured by members 22 to the pit bottom 17. This arrangement insures proper stability of the turntable bridge and enables it to travel smoothly and accurately for the desired critical alignment necessary, with the small tracks used, to insure against derailment of vehicles moving from the bridge to any of the radiating tracks.

Below the lower thrust bearings a flexible coupling in the form of a rubber tube or the like 23 connects the member 19 to suitable speed reduction gearing in the housing 24 which is driven by means of a suitable elec? tric motor 25 supported from the structure 21, as is the reduction gear housing. The motor speed and gear reductron is such that the turntable bridge will move at a rate of approximately 1 to 1 /2 R. P..M.

It is desirable, for obvious reasons,=to beable to'align end A or selectively end B of the bridge withany of the radlating track sectionsand to lock it there. For 'this purpose the pit rim wall is provided with sockets 28, one for each pit rim track section and at a position in each case identical in respect to the central line of the track section. For selective cooperation with these sockets each end of the bridge is equipped with a plunger 30 .which may be projected radially :into a socket when ,proper alignment is achieved, serving to lock the bridge in place and index it in respect to the corresponding vtrack. The plungers are selectively and preferably electrically actuated and their mechanism is coordinated with the-drive motor whereby they must be released before the motor starts in operation. Clearly'the-plungers 30 mightbe di rectly connected to magnets in the ends of the bridge but to facilitatetthe construction, adjustment and connections it is found more satisfactory to have these 'plungers .com-

prise the ends of the cores of Bowden wires 31, com-.

prising relatively flexible sleeves slidably housing the cores. These wires are brought down through the tubular shaft for the bridge, as shown, and midway of itsheight extendout through the walls to cooperate with actuating devices generally designated 34 and 35 therefor. These devices are mounted on a platform 36 or otherwise suitably attached to tubular shaft 19.

In greater detail the operating mechanism for'a single one of the locking Bowden wires is illustrated in Fig. 7, where the inner end of the core 30 is seen projecting below the sleeve 31 and having permanently secured thereto the spaced discs 37 and 38. Each of the operating devices 34 and 35 comprises a pair of magnets 40 and 41 each con structed to rotate its core 42 in a clockwise direction through about 20, as shown by arrows. Radially projecting from each core is an arm 43 forked at its outer end to fit over the wire 39. With the relative parts positioning shown in Fig. 7 constituting a locking condition, energization of magnet 40 causes its arm 43 to engage disc 38 and pull wire 30 down so that its end is withdrawn from the socket 28 with which it is engaged. As soon as the magnet 40 is tie-energized arm 43 returns to the position shown in Fig. 7 under the action of a spring (not shown). This movement of 39 has brought .the disc 37 down into proximity to plate 43 of magnet 41 so that when this magnet is energized disc 37 is'returned to the position shown. The :friction of the core wire .30 in its flexible sleeve is sufficient to hold it wherever positioned. Obviously the end of thecore'wire 30 acting as a plunger is pointed, as clearly shown in enlarged scale in Fig. 5, and the socket holexis flared :for'ease of engagement.

At a suitably different levelin the pit rim 'wall than the sockets are arranged the stationary contacts 45 each of which is likewise identically positioned in respect to the center line of its track. Each end of .thebridge mounts a brush 46 for cooperation with .the corresponding contact when the tracks on the relatively movable parts are aligned. These elements are shown in .plan on ail'arger scale in Fig. 6 and may'take any desired form'to insure good electrical conductivity at the time of-exact alignment. These contacts, properly selected, as will :be -later described, determine when the turntable end reaches the position selected for it and actuate rnechanism tost'op the drive motor and engage the locking mechanism.

Threaded on the axle tube 19 just below'the upperbearing and clamped between lock-nuts-Si), Stare a plurality of conductor discs 52, 53, 54, 55, 56, 57 and 58. As shown each is insulated from the shaft-by a central annular washer andthey are respectively spaced apart by'intervening washers 6th. Suitable-spring contacts 61, one for each of discs 53 to 58 "inclusive, are insulated'frorn each other and supported by post 62 carried beneath the pit bottom 17, as shown. A corresponding and shorter insulatmg post 63 carries one of the two diametrically disposed contacts 64 and 65 engaging the larger upper disc 52, which is divided into two 180 sections insulated from each other and each connected to one of the track rails on the bridge. It will be recognized that this is a mechanism for reversing thecurrent'delivered to the bridge as it'passes'the positionwhere one:discxhalf leaves one :contact 64, 65 and engages the other.

Fig. 4 illustrates*schem'aticaIIy thecircuit arrangements for the .whole turntable system :anditscontrol .devices as well as the several tracks arranged in combination therewith. In the upp'erle'ft hand corner -is seen the turntable itself with the rails 13, 14, on the bridge. These rails are connected respectively by conductors 67 and 68, to the two halves of disc 52 which provides for reversing the current to these rrails when the bridge .is rotated beyond a position determined bythe relative location of.the..dividing line between the halves ofdisc 52.

A source of track voltage is shown as battery-70, con- .nected through double pole, double-throw switch-71 to conductors 72 and 73 for-onepole andconductor .74.for the other. Conductor 74 leads through rheostat 75, for controlling ithe'potential'applied to the tracks and hence the speed of the motor vehicle driven therefrom. Conductor 76 .leadingtrom .the rheostat has a plurality of branches 77 which energize the most clockwise rail of each track-section-leading from the pit rim to .the left of arbitrary line -xy, Fig. 4, and the least clockwise ones on the other side thereof, Furtherbranch .78 from this conductor leads to'the brush 65 on the :left .side of the divided disc 52 on the bridge structure whereby it serves to energize the rail-14- connected thereto by con- 80 of a track selector switch T'having as many stationary contacts as there are track sections .A,:B, C, etc. Each of these contacts 81 isconnected by .a conductor to the remainingrailof its corresponding track section whereby appropriate'settingof-the arm of the selector switch causes 'energization of the rails of-only a chosen rim track section. The conductor 73 also leading from the double-pole double-throw switch is connected to brush 64 on the reversing disc52rand iserves to-provide current to rail 13 throughconductor167.

The. second selector-switch? is provided with rotatable arm: 83tand stationary contacts 84 which are connected respectively to the rim wall contacts 45. The two switch arms :84) and Q83 :are connected together for movement in unison and .sthe stationary contacts are so .arranged that the one engaged :by :.arm 80 corresponds intrack section position #torthe one. engaged by .arm-83 whereby both .a selection ofthe track and -the pit rim contact to be energized is simultaneously made. Current from a source :86ipasses through conductor 87 to the switch arm 83 while the other-:s'ide of this'source deliversthrough conductor .88 connected to the .arm of reversing switch L, the alternate stationary :contacts of which are connected respectively to the :brushes for discs .53 and 54 onthe tubularashaft of the:turntable-bridge. The operator for this switch iisrconnected, as shown by dotted line, to that of P and-Tiand'thecontacts are .only half as far apart so that one of either set may be engaged simultaneously with ranycontact of P and T.

Theturntableloperatingimotor 25, shown at the lower right in Fig. 4, is connected, through a manually operable reversingswitch. 89:to determine its rotational direction, toa source ofpotential90. Interposed in the connectionisacircuitiincluding. conductors 91 and 92, the first of which leads to conductor disc 57 and the second-to co nductor disc .58. These discs are connected by 'conductors 93 and 94. respe'ctivelywo a terminal of switches Z95and 96' which are. normally spring biased open as shown. 7

tion unless the switches 95 and 96 are both closed;

which can only happen when both locking wires are in their released position. This prevents applying voltage to the motor for its operation when the turntable bridge is locked.

To operate the magnets which provide for unlocking the bridge there is a separate circuit for potential from the source 86 which is energized by pressing the button 100, which disconnects the terminals of the battery from .the conductors 87 and 88 and connects them momentarily with the conductors 101 and 102. The switch actuated by the button 100 is spring biased for normal engagement with conductors 87, 88. Conductor 101 leads to :the brush for disc 55 on the bridge shaft and this is connected to conductor 103 which divides as shown and leads to one terminal each of the two unlocking coils 40, which are illustrated best in Fig. 7, and serve to withdraw the cores 30 of the Bowden wires to release any locking which may be effected by either of their ends engaging in one of the pit rim sockets 28. Such unlocking, as previously mentioned, automatically closes the switches 95 and 96 and permits operation of the motor which rotates the turntable bridge. The opposite terminals of the windings on the unlocking coils 40 are connected by conductor 104 to contact disc 56 whose brush is connected to wire 102, thus completing the bat- .tery circuit for the unlocking coils.

It has already been explained how two way selector :switch L permits the operator to energize disc 53 or ;54 to activate the brush at end A orthe end B of the turntable bridge. Contact discs 53 and 54 engage conductors 105 and 106, leading respectively to the spring contact blades 107 and 108. Referring again to Fig. 7 it will be seen that one of these, 108, is the spring blade of a pair which has an extending end engaged by the disc 37 of Bowden wire core 30 when the wire is in its locking position. At any other time the contact 108 engages contact 109 and this is connected, in the right hand mechanism of Fig. 4, by conductor 110 to locking coil 41. Conductor 111 leads from the opposite terminal of this locking coil to the B brush on the bridge. The A brush is connected by conductor 112 to the locking coil of the left hand assembly whose other terminal is connected to the stationary contact cooperating with spring contact 107.

With the arrangement just described, when the turntable is under rotation by the action of its motor the brushes at A and B sweep the respective stationary contacts 45 on the pit rim. When the brush selected by switch L engages a contact which is energized by means of selector switch P a circuit is completed through the corresponding locking coil 41, its switch 107 or 108 being closed because of the requirement for complete unlocking before the motor can operate. On the instant that a locking coil is energized, its arm 41 rotates to move the corresponding core to a locking position and when this happens the corresponding switch 95 or 96 is instantly opened, breaking the motor circuit and stopping movement of the bridge. As the core is projected into the selected socket 28 in the pit rim the disc 37 on the moving core opens its corresponding upper switch 107 or 108 de-energizing the corresponding locking coil and brings everything to a standstill and de-energized.

.It is thus possible for the operator, by the manipulation of the track selector switch with its associated pit wall contact selector switch and the single-pole double-throw .ewitch L to determine which end of the turntable bridge engages any selected track section leading from the turntable. He is also enabled byswitch 71 to determine the polarity of the current on the bridge tracks to select the direction in which the vehicle thereon is run ofi the bridge. At any time, whether occupied or not, the turntable bridge may be brought to a desired position by first rotating the selector s'witch'combining the parts P and T and then pushing the button until the motor starts in operation. The button can then be released since it has instantaneously released the locking device previously engaged and thus closed the motor circuit. The motor will start and continue to rotate at a slow speed until the brush selected by means of the switch L comes into engagement with the selected pit rim contact, at which time locking is effected by one of the locking mechanisms and the circuits all opened as previously explained.

For the sake of simplicity and ease of operation all the various switches described in connection with Fig. 4 have been combined into a unitary structure, as illustrated in Fig. 3 which may be located remotely from the turn table and connected thereto by a cable. This comprises a large cylindrical unit provided with an annular disc 121 secured to the top thereof and extending as a peripheral rim 121 allowing the unit to be supported from the surface of a table or thelike in which it is set.

The switch includes four separate decks: 122 which com prises the selector switch T,Fig. 4; 123 which comprises the selector switch P of Fig. 4; 124 comprising the singlepole double-throw switch L' of mg. 4; and 14:, a switch which permits delivery of voltage from a separate source to any pit rim track section except that one selected by the selector switch T.

In the thick cover plate 132 is incorporated rheostat 75 for regulating the speed of the vehicle on the turntable bridge and this is actuated by a knob moving the pointer 131 over an appropriate scale on the surface of the disc 121. At 134 is shown a double-pole-throw switch of the progressively rotatable type which is used in lieu of switch 71 to determine the forward and reverse direction of the locomotive on the turntable. At 136 isshown a second double-pole double-throw switch including an operating ring for the switch mechanism. Such ring is set into an annular channel in the top cover plate of the switch assembly and has a plurality of arcuate slots there- 'in which uncover direction arrows at the bottom of the channel. Movement of this ring determines the direction of rotation of the turntable motor and exposes the proper arrows through the slots to indicate what the direction will be.

A rotatable insulating operating shaft 137 is journaled through the center of the switch assembly and carries a knob at its upper end as well as a long pointer 139 sweeping over the surface of the cover plate and cooperating with a suitable scale at 140 on the inner periphery of the mounting plate 121. This scale indicates rim track positions each with an A or B designation whereby the desired end of the bridge is selected simultaneously with the track section. Through the center of the operating shaft is a rod 141 surmounted by button 100 projecting above the operating knob. This rod 141 is biased up by helical spring 142 so that disc 143 at its lower end engages the bottom of the shaft. Below the disc the rod carries an insulation block on which are mounted the movable contacts 145 connected to the bridge locking voltage source 86 and normally engaging the terminals 87 and 88 under the action of the spring. Momentary contact is made with the terminals 101 and 102 when the rod is pushed down by button 100.

The exact construction of the several switches simultaneously actuated by the central rotatable shaft 137 is relatively unimportant. They may be of any desired style but as shown the assembly comprises four separate layers of annular discs. The upper two of these each have a seriesof inset contact blocks .14! and 148 the inner ends.

r 7 of which" are exposedto-be engaged by*the-contact*arms Sit-and 83*ontherotatable' shaft. Thesea'rms' along with others" also on 'the sha-ftare supplied with currentthrough conductors 'ladingffroma series ofcontact discs- 150 near the-bottom-of the insulatingshaft, which" are'-'engaged=hy" spring brushes" 151 in an obvious manner: The conduc" tors leading from the circumferentially spaced contacts 147" and 148 are clearly illustrated and reach to the" peripheryofthe'switch assembly through"suitablegroovesi The equivalent of the sin'gle-p'ole double-throw switch 10 L is incorporated'in the annular' disc-1 24*ofthe-composite control unit which contains a series 'of" contact ele ments- 152 arranged in insulated-pairs; one'paiFforeach of the contactelements 147 *or "148 in theswitches'aboveit. Alternate ones of" these"contacts are'connected to gether and thus= act: as a multiple single-pole doublethrow switch so that the selection of the end of theturn table 1 bridge which *is tobe" engaged with thedesired track section is: effected by" merelystopping'the rotatableinsulating shaft at the position indi cated'by the index 140 corresponding to the desired track section and*using' the A or B position thereat: Theblock contacts147 and Mfr-each cover arr-angularextent' equalto-that of a pair of contactblocks 1523 The lowermost of therotary selector switches is in 5 the annularring-IZS and-is of the excluding'type; that is, it selects all'butone track sectionto'beenergized: This is to permit thetrack-sections independent of the one with which the bridge'is-aligned -'to-be-energized from a'separate source so that motive unitsthereon maybe operated independent of the 1 one being-handled*on-- the turntable. lnthis switch each ofthecontact blocks 154 contains aspring pressed plunger 155 having-limited inward move= ment and these-areall adapted to engage the'outerperiphcry of aconductor disc 156 exceptwhere the disc is notched as sh'ownat 157. This-notch is of such' depth that 'thetplungen 155-does not project sufliciently far'tomake electrical contact with-the disc beneath 'it in alignment. Naturally this notch is aligned with" the contact arms80and 83.:

It .will .be recalled from the description of the operation of the present inventionthat nothingtakes--placeduring rotation of switch-shaft--137 eventhbugh-switch arms '89 and. 83 sweep' over a great number ofterminals. Only by stopping-.theswitch' arms -in-;.engagement-'with*selected contact bl'ocksand: then-pushing the button 100 isthere any operation .ofT'the-system. However; in order to 'pre-' vent an; accident; which might occurif the-button-were" pressed.while= thershaft is being rotated;- andthus'move a locomotive situated on the turntable, a switch may'be' arranged; ifv desired for; interposition-in the rheostatcircult tomsureagainstany possibility of applying potential to the;tracksl on:the bridge -except by a-positiveaction on thepart'of the operator; Such a switch 157' shown at H the upper rightin Fig.3 is-a:single-pole swit'ch- -biased toward closure.butnormallyiheld in the'openjposition. It includes a stationary'contact 158 on =the-sur-face -of-cover plate 132 andLacOoperat-ingspring-contact 159held in the open position shown byrod-l160 =having its'inner end engaging the Slll'fflCfi'Ofithfi insulated-switch-shaft137. The rod operates in a-radi'al tunnel asshown-n A'single notch l61-in a predetermined and selected p'osition onthe surface of the insulatingshaft 137 permits" the rod to drop therein under the'action ofspring-159so that the" switch is closed when the shaft is properly positioned for the purpose; The notch 160 is'so positioned that-none of the switch arms 89; 83 engages any' of -its stationary spaced contacts when this notch is*'in"aiignn1ent" within the rod 160. An index on the'-scale:advisesof'this; This switch; if "used,1adds to the operating; procedure then a further'motionofjthe knob"138"after theturntable has moved to' the required"position-followingthe operation of the button'ltlfl; at which time' the 'rheostat'circuit is then properly energized so that the. locomotive on the turntable cambe rolled'foft"onto the selected track sectioni 1 asaama Itwillbe apprecia'tedth'atmany changes and-modifiea' tions canhe made'sin -the" device as shownand that the' invention resides primarily in the broadcircuit" and ge* gage cooperating means on the pit rim allotted-onefor each radiating track to lock the bridge in position-when a selected" radiating track and bridge track end are aligned, means to rotate thebridg'e; contact means on- -thepit rim allot-ted one to-each-radiating track a -contact on each end of' the bridge adapted'to successively engagethe rim contacts as the bridge is rotated,' means to manually selectively energize a'singlepit rim contact corresponding to asingle selected radiating track to indicate 1 by engagement; thereof by a selected bridge contact-of proper bridge-radiatingtr'ackalignment and acircuit associating the engaged, selected contacts and the corresponding lockingmeans to actuate the latter.

2. The turntableof claim'-1 in which a nlotor 'is arranged to rotate the bridge and a circuit is provided between'said motor and asource of power therefor, a

switch int-said circuit {and mean-s actuated by the locking means -to open said switch? on -completion of operation of said-"locking means;

3. In a turntable' for'electric railways in which the rails are polarized for direction control, in combination,

a" turntable pit havingtrack sections radiating from the rim thereof, a source of power'havin'g one pole'conn'ected'to one rail of'each-section, a selector swit-chhaving a plurality/ of fixed and a ntovable contact arranged to'connect th'e opposite pole of said isource to the op posite rail-bf any selected one of saidsections; abridge having: a: track and -rnounted for rotation -in said pit-t0.

have either end selectivelyv aligned-=with anyone ofsaid contact. brushes mounted for .rotation in. correspondence to the bridge and eachireprescntative of Lthe1positi0n of one end; ofthexbridgeirack, means to select one of said brusheszfor cooperation with said stationary contacts, a motori'for rotatingxsaidsbridge, .a power. circuit for'said motor and means actuated by said second power sourcev tov openthe.motor powerrcircuit uponrengagement of the selectedstationary contact and brush.

4'. The: turntable: oficlairn 3: inwhich' means is providedon the bridgerto' index. and lock said bridge with the :selectedend thereof corresponding tozthe selected rim track, and apparatus for actuating said lock means when said selected contact andbrush engage.

5. Theturntable of claim: 3 in which the track rails of the bridgezarekinsulated from the pit rim track sec-' tions at all times, said first source of power being direct-current and a-current'reverser electrically connected betweensaid source and. bridge track rails and mechanically. driven by the bridge motor to be actuated in unison with movement of thebridge to match bridge rail and pit rim V-traclzrail polarity when dilferent bridge ends are selected for rim-track: section: alignment.

6.- The turntable of claim 4 in. which separate means are provided to disengage the lock means, said lock disengaginggmeans being goperatively associated with switch means arranged to=close the 'power'circuit motor con-' nection to actuate the motor automaticallyupon-unlocklngtithe bli'dge- 7. In a turntable for electric railways in which the rails are polarized for direction control, in combination, a turntable pit having track sections radiating from the rim thereof, a source of power having one pole connected to one rail of each section, -a selector switch having a plurality of fixed and a movable contact arranged to connect the opposite pole of said source to'the opposite rail of any selected one of said sections, a bridge having a track and mounted for rotation in said pit to have either end selectively aligned with any one of said rim track sections, a stationary contact on the pit wall at each track end, a second source of power, a second selector switch mounted for movement in unison with the first to connect the stationary contact at the selected track section to one pole of said second source, a contact brush at each end of the bridge, switch means to choose one of said brushes for connection to the other pole of said second source of power, a locking mechanism for each end of the bridge adapted when energized to index and lock said bridge end to the adjacent pit wall with the bridge and rim track in alignment, a locking magnet and an unlocking magnet for each mechanism, each locking magnet being in circuit with said second source and its brush whereby locking is effected when the brush engages the selected and energized contact, a contact actuated by said locking magnet to open its circuit when locking is completed, switch means to transfer the second source of power directly to both unlocking magnets, a motor for rotating said bridge, a circuit connecting said motor to a source of power, and means to open said last mentioned circuit when a locking mechanism is actuated to locking position and vice versa.

8. The turntable of claim 7 in which the bridge tracks are energized independently of the rim tracks and switch means actuated by the bridge to reverse the track polarity at a predetermined angular position of the bridge.

9. In a turntable for a toy electric railway, in combination, a base having a walled and closed bottom pit, track sections on the base radiating from the pit wall, a tracked bridge in said pit, a tubular shaft for said bridge, means carried by the pit bottom journalling the shaft for rotation, whereby the bridge track may present either end to any of said sections, a motor and reduction gear for rotating said bridge, a socket in the pit rim wall corresponding to the position of each track section thereat, a plunger at each end of the bridge adapted to be selectively projected into said sockets to index and lock the bridge with selected track and bridge end alignment, a projecting magnet and a retracting magnet for each plunger, a contact on the pit rim wall adjacent each socket, a brush at each end of the bridge each adapted to engage a contact when the corresponding plunger and socket are in alignment, a selector for connecting a desired contact to a source of power, a selector to connect a desired brush to a source of power, a circuit for .energizing the projecting magnet at the selected brush end of the bridge from said source when the brush engages the selected contact, means for opening said circuit when the magnet stroke is completed and manual means to transfer the source of energy to the retracting magnets.

10. The turntable of claim 9 in which the motor is electric, a source of power connected in circuit to said motor, a pair of switches in series in said motor circuit, means biasing said switches to open position and means actuated in unison with each plunger in its withdrawn position to maintain one of said switches closed.

11. The combination of a turntable having rim track sections, a corresponding number of pit rim contacts and two bridge end brushes for selective cooperation with said contacts, a switch assembly for energizing said tracksections, rim contacts and brushes including a first rotary switch having a selector arm and contacts each connected to one rail of said rim track sections, a second rotary switch having a selector arm and the same number of contacts as the first each connected to one of said pit rim contacts, a third rotary switch having a selector arm and two contacts for each one of the others, alternate contacts of said third switch being connected together and each group to one of the two brushes, a common operator for said three selector arms, said first and said second switches being arranged to connect corresponding contacts simultaneously and having such width contacts that engagement is eifected by their arms when either of the two corresponding contacts on the third switch is selected and sources of direct current connected for control by said switches to selectively energize the several tracks and contacts.

12. The turntable and switch assembly of claim 11 in which the turn table bridge is fitted with a locking magnet and an unlocking magnet, a plunger in the said common switch operator and a double-pole double-throw switch positioned to be actuated by said plunger and adapted to connect one of said sources of power to said magnets alternatively.

References Cited in the file of this patent UNITED STATES PATENTS 606,544 Harting June 28, 1898 1,800,722 Edson Apr. 14, 1931 2,019,182 Gipe et al. Oct. 29, 1935 2,211,220 Verplanck Aug. 13, 1940 2,576,836 Hilsinger Nov. 27, 1951 2,629,336 Seidel Feb. 24, 1953 FOREIGN PATENTS 71,611 Austria Apr. 25, 1916

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