US3598059A

US3598059A - Tow truck conveyor system

Info

Publication number: US3598059A
Application number: US736781A
Authority: US
Inventors: Edward J Carney; Karl R M Karlstrom; Ivan L Ross
Original assignee: American Chain and Cable Co Inc
Current assignee: FKI Industries Inc
Priority date: 1968-06-13
Filing date: 1968-06-13
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10
Also published as: DE1929395A1; GB1273395A; DE1929395C3; DE1929395B2

Abstract

The tow truck conveyor system wherein a switch tongue is pivotally mounted at the area of juncture of a slotted main track portion and a slotted branch track portion and is movable from a first position, wherein it is held by a permanent magnet, which permits a tow truck having a tow pin extending downwardly in the slot to be carried by engagement with a chain conveyor undisturbed past the area of juncture. Upon signal from signal means on the two truck as it approaches the area of juncture, an electromagnet is energized which counteracts the force of the permanent magnet to permit a spring to move the switch tongue to a second position causing the tow truck to be deflected along the branch track portion.

Description

United States Patent [72] Inventors Edward J. Carney Pittsburgh, Pa.; Karl R. M. Karlstrom, Roseville, Mich.; lvan 1.. Ross, Birmingham, Mich. [211 Appl, No. 736,781 I22] Filed Juno 1.1, 1968 MSI Patented Aug. 10, I971 |73| Assiguec American Chain & Cable Company Inc.

New York, N.Y.

[54] TOW TRUCK CONVEYOR SYSTEM 15 Claims, 11 Drawing Figs.

[52] US. Cl 104/88, 104/170 [51] int. Cl ..B65g 17/44, B61 j/3/04 [50] Field 01' Search 104/88, 172,178,96,103, 130; 246/265; 335/229, 230

[56] References Cited UNITED STATES PATENTS 3,418,944 12/1968 Hansford et a1. 104/130 2,915,681 12/1959 Troy 335/229 3,261,300 7/1966 Johnson 104/88 3,373,698 3/1968 Bishop 104/88 3,406,638 10/1968 Braun 104/88 FOREIGN PATENTS 149,115 1962 U.S.S.R. 104/130 Primary Examiner"- Drnyton E. Hoffman Ami-ran! Ia'xumim'r Robert Sailor Almrm'y Barnes, Kissclle, Raisch & Choatc ABSTRACT: The tow truck conveyor system wherein a switch tongue is pivotally mounted at the area of juncture of a slotted main track portion and a slotted branch track portion and is movable from a first position, wherein it is held by a permanent magnet, which permits a tow truck having a tow pin extending downwardly in the slot to be carried by engagement with a chain conveyor undisturbed past the area of juncture. Upon signal from signal means on the two truck as it approaches the area of juncture, an electromagnet is energized which counteracts the force of the permanent magnet to permit a spring to move the switch tongue to a second position causing the tow truck to be deflected along the branch track portion.

HIIIKA noon PATENTEUAUGIOISYI 3.598.059

SHEET 1 BF 4 INVENTORS DWARD J. CARNEY ATTORNEYS PATENTED Am; 1 0 [an SHEET 2 BF 4 ATTORNEYS PATENTEI] AUG! 0 1911 SHEET 3 UF 4 II I F H I I'I I Ix ATTORNEYS PATENTED AUG] 0 I97! SHEET 0F 4 FIG. ll

P /t gig i om $4 k dd?) ATTOR NE VS TOW TRUCK CONVEYOR SYSTEM This invention relates to conveyor systems and particularly to tow truck conveyor systems having switches for causing a tow truck to be guided from a main track to a branch track.

It has heretofore been common to provide mechanical switches for moving a carrier such as a tow truck having a tow pin from a main track to a branch track.

Among the objects of the invention are to provide a novel electrical switch operating mechanism which is simple, inexpensive, easy to maintain and relatively low in cost.

In the drawings:

FIG. 1 is a fragmentary perspective view of a portion of a system embodying the invention.

FIG. 2 is a fragmentary sectional view taken along the line 2-2 in FIG. 1.

FIG. 3 is a fragmentary sectional view taken along the line 3-3 in FIG. 2.

FIG. 4 is a fragmentary plan view of a portion of the system shown in FIG. I.

FIG. 5 is a fragmentary sectional view on an enlarged scale taken along the line 5-5 in FIG. 4.

FIG. 6 is a fragmentary sectional view taken along the line 6-6 in FIG. 5.

FIG. 7 is a fragmentary part sectional front elevational view of a modified form of system.

FIG. 8 is a fragmentary sectional view on an enlarged scale taken along the line 8-8 in FIG. 7.

FIG. 9 is a fragmentary plan view of a modified form of the invention.

FIG. 10 is a fragmentary sectional view taken along the line 10-10 in FIG. 9.

FIG. 11 is a view similar to FIG. 9 showing the parts in a different operative position.

Referring to FIGS. 1, 2 and 3, the system embodying the invention is shown as comprising a floor 10 having a track 11 defined by slots including a main track portion 12 and a branch track portion 13 extending at an angle to the main track portion 12. A chain 14 is movable along the main track portion 12. One or more carriers 15 in the form of wheeled tow trucks are provided for movement along the track. Each carrier 15 includes a tow pin 16 which extends downwardly into a slot in the floor for engagement with the conveyor 14 to move the tow truck 15 along the main portion 12 of the track. A switch tongue 17, which is generally triangular in shape, is provided at the area ofjuncture of the main track portion 12 and the branch track portion 13 and is movable from a first position shown in solid lines in FIG. 4 which permits the tow truck to move along the main track portion 12 to a second position shown in broken lines in FIG. 4 wherein the tow pin is deflected to cause the tow pin and, in turn, the tow truck 15 to be guided into the branch track portion 13.

As shown in FIGS. 1. 4 and 5, the upper surface 18 of the switch tongue is substantially flush with the surface of the floor 10. Specifically, the switch tongue 17 has a shaft 19 fixed to the underside thereof that extends downwardly through a collar 20 fixed on a portion of a frame 21 on the underside of the floor to pivot the switch tongue 17. The shaft 19 has a collar 22 fixed thereto and a spring 23 is interposed between the collar 22 and a base plate 24 of the frame 21. This yieldingly urges the switch tongue to a position wherein the upper surface of the switch tongue is substantially flush with the floor 10. As shown in FIGS. 5 and 6, a permanent magnet 25 is fixed on the plate 24 beneath the floor and an arm 26 is fixed to the underside of the switch tongue 17 and supports an armature 27 that engages the permanent magnet to hold the switch tongue in its first position. The armature 27 is yieldingly mounted on the arm 26 by an arrangement which includes a shaft 28 fixed to the armature 27 and extending through an opening in the arm 26, nuts 29 threaded on the shaft and a spring 30 interposed between the armature and the arm 26.

A tension spring 31 has one end thereof fixed to the frame by an eye bolt 32 and the other end thereof fixed to a pin 33 on the underside of the switch tongue. The spring 31 thus tends to urge the switch tongue to a second position shown in broken lines in FIG. 4. An electromagnet 34 is wound around the permanent magnet 25 and is adapted to be energized upon proper signal to counteract the force of the permanent magnet 25 permitting the spring 31 to swing the switch tongue 17 to its second position shown in broken lines in FIG. 4 so that the tow pin of the tow truck will be guided into the branch track portion 13.

As further shown in FIGS. 4 and 6, the switch tongue 17includes a projection 35 that extends into the path of the tow pin when the switch tongue is in second position and the tow pin is moving along the branch track portion 13. When the tow pin engages the projection 35, it swings the switch tongue 17 to return the armature 27 into position for engagement with the permanent magnet thereby returning the switch tongue 17 and holding the switch tongue I7 in the first position. The spring mounting of the armature permits sufficient overtravel in the return movement of the switch tongue to insure that the armature will engage the permanent magnet. As shown in FIGS. 5 and 6, a vertically extending stop 36 is provided on the base plate 24 and is operable to engage the arm 26 when a weight is placed on the switch tongue 17 to prevent the switch tongue I7 from being forced to the second named position. Specifically, for example, if a wheeled vehicle such as a lift truck were to move across the upper surface of switch tongue 17 and at the same time were to turn as it moves across the switch tongue 17, there might be a tendency to move the switch tongue 17 away from the permanent magnet 25 causing an inadvertent operation of the switch tongue 17. However, by the arrangement disclosed, any weight upon the switch tongue 17 moves the switch tongue 17 downwardly against the action of the spring 23 into position where the stop 36 will prevent pivotal movement of the switch tongue to the second position.

In the form of the invention shown in FIGS. 1-3, the operation of the electromagnet is achieved by providing the electromagnet in series circuit with reader means such as electrical contact members 40, 41 disposed at laterally spaced positions along the main track portion 12. Where several switches are proved in a conveyor system, the position of the contacts 40, 41 can be at different distances laterally so that each switch will have a particular orientation of the contacts. The tow truck, in turn, has b. means in the form ofa pair of

signal members

42, 43 mounted thereon in laterally adjustable position and having electrical brush contacts 44 (FIG. 2) in series by a wire 45. If the position of the

signal members

42, 43 is proper so that the contacts 40, 41 are contacted as the tow truck is moved toward the switch tongue 17, a circuit is completed energizing the electromagnet 34 and thereby overpowering the permanent magnet 25 to permit the spring 31 to move the switch tongue 17 to the second position for guiding the tow pin along and into the branch track portion 13.

Specifically, as shown in FIGS. 1, 2 and 3, the tow truck 15 includes vertically spaced laterally extending

brackets

46, 47 that have forwardly and outwardly extending openings 48 for receiving the

signal members

42, 43. Each signal member has collars 49, 50 thereon for engaging the openings to hold the signal member in one of the plurality of positions laterally of the tow truck. Thus, the signal members can be manually adjusted to correspond with the positioning of the contacts 40, 41 for a particular switch in a conveyor system.

In the form of the invention shown in FIGS. 7 and 8, reader means in the floor comprises reed switches 50 which are electrically connected and in series with the electromagnet and a source of power and have their

contacts

51, 52 normally open. The signal means on the tow truck 15' comprise laterally adjustable members 53 having permanent magnets 54 on their lower ends. Each signal member 53 is movable along a rod 54 and has an inwardly extending pin 55 engaging one of a plurality of openings 56 to hold the signal member in position laterally of the tow truck. If the signal members 53 on the tow truck are properly positioned laterally of the tow truck, the simultaneous movement of the permanent magnets 54 thereof over the reed switches 50 along the floor will cause an energization of the electromagnet 34 to overpower the permanent magnet 25 and permit the spring to move the switch tongue to its second position.

In each form of the invention, as the tow pin moves along the branch track portion, it engages the projection 35 to return the switch tongue to its original position.

In the form of the invention shown in FIGS. 9, l and II, switch tongue 60 is provided at the area of juncture of the main track portion 61 and branch track portion 62 and is movable from the position shown in FIG. 9 to the position shown in FIG. II The upper surface 63 of the switch tongue is substantially flush with the surface of the floor 64. A shaft 65 on the underside of the switch tongue 60 extends downwardly through a collar 66 fixed on a portion of the frame 67 on the underside of the floor 64 to pivot the switch tongue. The shaft has a collar 68 fixed thereto and a spring 69 is interposed between the collar and the base of the frame 67 to yieldingly urge the switch tongue upwardly so that the surface of the switch tongue is substantially flush with the floor.

A permanent magnet 70 is fixed on the frame 67 beneath the switch tongue 60. A toggle lever means comprising a t0ggle lever 71 is pivoted at one end to the switch tongue as at 72 and at its other end to one end of a lever 73 as at 74. The lever 73, in turn, is pivoted at 75 to the underside of the floor 64. Lever 73 supports a spring loaded armature 76 through an integral sleeve 71a and lever 71b. Armature 76 is yieldingly urged outwardly of the lever 71 by a spring 77 surrounding a shaft 78 which supports the armature. An electromagnet is wound around the permanent magnet 70 as in the previous forms of the invention so that when it is energized upon proper signal, it counteracts the force of the permanent magnet 70. A tension spring 80 extends between the pivot 74 and a fixed point 81 on the underside of the floor so that when the elec tromagnet is energized, the spring swings the lever 73 pulling the switch tongue in the position shown in FIG. 9.

As shown in FIG. 9, when the armature 76 is in engagement with the permanent magnet 70, the

levers

71, 73 are aligned. In this position, any force on the upper surface of the switch tongue 60 tending to rotate the switch tongue is opposed by the alignment of the levers II, 73. Thus, the levers 7], 73 serve the further function of preventing inadvertent movement of the switch tongue. After the electromagnet has been energized to move the switch tongue 60 to the position shown in FIG. 10, the tow pin of an oncoming tow truck will be diverted into the branch track 62. As the tow truck moves through the branch track, the tow pin engages the projection 82 returning the tow pin to its original position.

We claim:

I. In a conveyor system, the combination comprising a track,

a carrier movable along said track,

said track having a main portion and a branch portion ex tending at an angle to the main portion,

switch means at the juncture of the main portion and brancl portion of said track movable from a first position wherein the carrier is permitted to move along the main portion to a second position wherein said carrier is guided for movement from said main portion to said branch portion,

an armature yieldingly mounted on said switch means,

a permanent magnet associated with said armature and operable to hold said switch means in one of said posi tionti,

spring means for urging said switch means toward the othc position,

and an elcctromagnet associated with said permanent mag net and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch means to said other position,

means operable to prevent inadvertent movement of said switch means,

means operable to energize said electromagnet,

said last-mentioned means comprising signal means on the carrier and reader means along said track operable to read said signal means and energize said electromagnet,

said signal means on said carrier comprising spaced electri- V cal signal contact members connected in series,

said reader means comprises electrical contacts along said track connected in series with said electromagnet whereby when said signal contacts simultaneously engage said reader contacts, a circuit is completed to said electromagnet.

2. The combination set forth in claim I wherein said signal members include resilient contact brushes for engaging the contacts alongside said carrier.

3. In a conveyor system, the combination comprising a track,

a carrier movable along said track,

said track having a main portion and a branch portion extending at an angle to the main portion,

switch means at the juncture of the main portion and branch portion of said track movable from a first position wherein the carrier is permitted to move along the main portion to a second position wherein said carrier is guided for movement from said main portion to said branch portion,

an armature yieldingly mounted on said switch means,

a permanent magnet associated with said armature and operable to hold said switch means in one of said positions,

spring means for urging said switch means toward the other position,

and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch means to said other position,

means operable to prevent inadvertent movement of said switch means,

said track being defined by a slot in said floor,

said carrier having a tow pin extending downwardly in said slot,

said means at the area of juncture comprising a switch tongue movable between said first and second positions,

said switch tongue having an upper surface substantially flush with said floor and forming a part of the surface of said floor,

means for pivotally supporting said switch tongue for move ment between said first and second positions,

said means for preventing inadvertent movement of said switch tongue comprising means yieldingly urging said switch tongue in upwardly disposed position with the upper surface thereof substantially flush with the surface of said floor,

and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said one position wherein it is held by said permanent magnet to said other position.

4. The combination set forth in claim 3 wherein said switch tongue has an arm fixed thereto,

said armature being yieldingly mounted on said arm,

said permanent magnet being positioned alongside said track for engagement by said armature.

5. In a conveyor system, the combination comprising a track,

a carrier movable along said track,

said track having a main portion and a branch portion cxtending at an angle to the main portion,

an armature yieldingly mounted on said switch means,

spring means for urging said switch means toward the other position,

means operable to prevent inadvertent movement of said switch means,

said track being defined by a slot in said floor,

said carrier having a tow pin extending downwardly in said slot,

said means for preventing inadvertent movement of said switch tongue comprising means for pivotally supporting said switch tongue for move ment between said first and second positions,

a pair of levers, 7

one of said levers being pivoted to said switch tongue,

another of said levers being pivoted to a fixed portion of said conveyor system,

said levers being pivoted to one another and in one position being normally axially aligned,

said armature being mounted on one of said levers,

said spring means tending to move said levers out of axial alignment.

6. In a conveyor system, the combination comprising a track defined by slots in a floor,

a carrier movable along said track,

said carrier having a tow pin extending downwardly into said slots,

a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion,

an armature yieldingly mounted on said switch tongue,

a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet,

and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position,

means operable to prevent inadvertent movement of said switch tongue,

means operable to energize said electromagnet,

said last-mentioned means comprising signal mean on the carrier and reader means along said track ope 'able to read said signal means and energize said electrom rgnet,

said signal means on said carrier comprising spaced electrical signal contact members connected in series,

said reader means comprises electrical contacts along said track connected in series with said electromagnet whereby when said signal contacts simultaneously engage said reader contacts, a circuit is completed to said electrornagnet.

7. in a conveyor system, the combination comprising a track defined by slots in a floor,

a carrier movable along said track,

said carrier having a tow pin extending downwardly into said slots,

an armature yieldingly mounted on said switch tongue,

and an electromagnet associated with said permanent mag-' net and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position,

means operable to prevent inadvertent movement of said switch tongue,

said switch tongue having an upper surface substantially fiush with said floor and forming a part of the surface of said floor,

means for pivotally supporting said switch tongue for movement between said first and second positions,

and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said first position wherein it is held by said permanent magnet'to said other position,

8. In a conveyor system, the combination comprising a track defined by slots in a floor, I

a carrier movable along said track,

said carrier having a tow pin extending downwardly into said slots,

an armature yieldingly mounted on said switch tongue,

means operable to prevent inadvertent movement of said switch tongue,

said switch means comprising a switch tongue,

said means for preventing inadvertent movement of said last-mentioned means comprising means for pivotally supporting said switch tongue for movement between said first and second positions,

a pair of levers,

one of said levers being pivoted to said switch tongue,

said armature being mounted on one of said levers,

said spring means tending to move said levers out of axial alignment.

9 For use in a conveyor system comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extend ing at an angle to the main portion, the combination comprismg a switch tongue adapted to be positioned at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion,

an armature yieldingly mounted on said switch tongue,

means operable to prevent inadvertent movement of said switch tongue,

said switch tongue having an upper surface adapted to be substantially flush with said floor and forming a part of the surface of said floor,

means yieldingly urging said switch tongue in upwardly disposed position with the upper surface thereof substan tially flush with the surface of said floor,

and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said first position wherein it is held by said permanent magnet to said other position.

10. For use in a conveyor system comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extend ing at an angle to the main portion, the combination comprismg a switch tongue adapted to be positioned at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion,

an armature yieldingly mounted on said switch tongue,

means for preventing inadvertent movement of said switch tongue,

a pair of levers,

one of said levers being pivoted to said switch tongue,

said armature being mounted on one of said levers,

said spring means tending to move said levers out of axial alignment.

ll. In a conveyor system, the combination comprising a track defined by slots in a floor,

a carrier movable along said track,

said carrier having a tow pin extending downwardly into said slots,

:1 switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion,

an armature yieldingly mounted on said switch tongue,

a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent mag net,

and an electromagnet associated with said permanent mag net and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position means operable to prevent inadvertent movement of said switch tongue to said other position,

means operable to prevent inadvertent movement of said switch tongue,

means operable to energize said electromagnet,

said signal means on said carrier comprising spaced electri' cal signal contact members connected in series,

said reader means comprises electrical contacts along said track connected in series with said electromagnet whereby when said signal contacts simultaneously engage said reader contacts, a circuit is completed to said electromagnet,

said signal members including resilient contact brushes for engaging the contacts alongside, said carrier.

12. In a conveyor system, the combination comprising a track defined by slots in a floor,

a carrier movable along said track,

said carrier having a tow pin extending downwardly into said slots,

an armature yieldingly mounted on said switch tongue,

a permanent magnet associated with said armature and operable to hold said switch tongue in said first position spring means for urging said switch tongue toward the second position against the force of said permanent magnet, I

and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, 7

means operable to prevent inadvertent movement of said switch tongue,

and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said first position wherein it is held by said permanent magnet to said other position,

said switch tongue including a portion thereof projecting into the path of said carrier as it moves along said branch portion of said track for returning said switch tongue to its position wherein the armature is in contact with said permanent magnet,

13. In a conveyor system, the combination comprising a track,

a carrier movable along said track,

an armature yieldingly mounted on said switch means,

toggle lever means operable upon engagement of said armature with said permanent magnet to prevent inadvertent movement of said switch means due to an external force on said switch means,

spring means operable on said toggle lever means in a direction tending to release the same and urging said switch means toward the other position,

and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said toggle lever means and in turn move said switch means to said other position.

N. In a conveyor system, the combination comprising a track defined by slots in a floor,

a carrier movable along said track,

said carrier having a tow pin extending downwardly into said slots,

an armature yieldingly mounted on said switch tongue,

a permanent magnet associated with said armature and operable to hold said switch tongue in said first position,

toggle lever means operable upon engagement of said armature with said permanent magnet to prevent inadvertent movement of said switch tongue due to an external force on said switch means,

spring means operable on said toggle lever means in a direction tending to release the same and urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said toggle lever means and in turn move said switch tongue to said other position. 15. For use in a conveyor system comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, the combination comprismg a switch tongue adapted to be positioned at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a pennanent magnet associated with said armature and operable to hold said switch tongue in said first position,

toggle lever means operable upon engagement of said armature with said permanent magnet to prevent inadvertent movement of said last-mentioned means due to an external force on said switch tongue,

spring means operable on said toggle lever means in a direction tending to release the sameand urging said switch tongue toward the second position against the force ofsaid permanent magnet,

and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said toggle lever means and in turn said switch tongue to said other position.

Claims

1. In a conveyor system, the combination comprising a track, a carrier movable along said track, said track having a main portion and a branch portion extending at an angle to the main portion, switch means at the juncture of the main portion and branch portion of said track movable from a first position wherein the carrier is permitted to move along the main portion to a second position wherein said carrier is guided for movement from said main portion to said branch portion, an armature yieldingly mounted on said switch means, a permanent magnet associated with said armature and operable to hold said switch means in one of said positions, spring means for urging said switch means toward the other position, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch means to said other position, means operable to prevent inadvertent movement of said switch means, means operable to energize said electromagnet, said last-mentioned means comprising signal means on the carrier and reader means along said track operable to read said signal means and energize said electromagnet, said signal means on said carrier comprising spaced electrical signal contact members connected in series, said reader means comprises electrical contacts along said track connected in series with said electromagnet whereby when said signal contacts simultaneously engage said reader contacts, a circuit is completed to said electromagnet.

2. The combination set forth in claim 1 wherein said signal members include resilient contact brushes for engaging the contacts alongside said carrier.

3. In a conveyor system, the combination comprising a track, a carrier movable along said track, said track having a main portion and a branch portion extending at an angle to the main portion, switch means at the juncture of the main portion and branch portion of said track movable from a first position wherein the carrier is permitted to move along the main portion to a second position wherein said carrier is guided for movement from said main portion to said branch portion, an armature yieldingly mounted on said switch means, a permanent magnet associated with said armature and operable to hold said switch means in one of said positions, spring means for urging said switch means toward the other position, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch means to said other position, means operable to prevent inadvertent movement of said switch means, said track being defined by a slot in said floor, said carrier having a tow pin extending downwardly in said slot, said means at the area of juncture comprising a switch tongue movable between said first and second positions, said switch tongue having an upper surface substantially flush with said floor and forming a part of the surface of said floor, means for pivotally supporting said switch tongue for movement between said first and second positions, said means for preventing inadvertent movement of said switch tongue comprising means yieldingly urging said switch tongue in upwardly disposEd position with the upper surface thereof substantially flush with the surface of said floor, and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said one position wherein it is held by said permanent magnet to said other position.

4. The combination set forth in claim 3 wherein said switch tongue has an arm fixed thereto, said armature being yieldingly mounted on said arm, said permanent magnet being positioned alongside said track for engagement by said armature.

5. In a conveyor system, the combination comprising a track, a carrier movable along said track, said track having a main portion and a branch portion extending at an angle to the main portion, switch means at the juncture of the main portion and branch portion of said track movable from a first position wherein the carrier is permitted to move along the main portion to a second position wherein said carrier is guided for movement from said main portion to said branch portion, an armature yieldingly mounted on said switch means, a permanent magnet associated with said armature and operable to hold said switch means in one of said positions, spring means for urging said switch means toward the other position, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch means to said other position, means operable to prevent inadvertent movement of said switch means, said track being defined by a slot in said floor, said carrier having a tow pin extending downwardly in said slot, said means at the area of juncture comprising a switch tongue movable between said first and second positions, said means for preventing inadvertent movement of said switch tongue comprising means for pivotally supporting said switch tongue for movement between said first and second positions, a pair of levers, one of said levers being pivoted to said switch tongue, another of said levers being pivoted to a fixed portion of said conveyor system, said levers being pivoted to one another and in one position being normally axially aligned, said armature being mounted on one of said levers, said spring means tending to move said levers out of axial alignment.

6. In a conveyor system, the combination comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue, means operable to energize said electromagnet, said last-mentioned means comprising signal means on the carrier and reader means along said track operable to read said signal means and energize said electromagnet, said signal means on said carrier comprising spaced electrical signal contact members connected in series, said reader means comprises electrical contacts along said track conNected in series with said electromagnet whereby when said signal contacts simultaneously engage said reader contacts, a circuit is completed to said electromagnet.

7. In a conveyor system, the combination comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue, said switch tongue having an upper surface substantially flush with said floor and forming a part of the surface of said floor, means for pivotally supporting said switch tongue for movement between said first and second positions, said means for preventing inadvertent movement of said switch tongue comprising means yieldingly urging said switch tongue in upwardly disposed position with the upper surface thereof substantially flush with the surface of said floor, and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said first position wherein it is held by said permanent magnet to said other position.

8. In a conveyor system, the combination comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue, said switch means comprising a switch tongue, said means for preventing inadvertent movement of said last-mentioned means comprising means for pivotally supporting said switch tongue for movement between said first and second positions, a pair of levers, one of said levers being pivoted to said switch tongue, another of said levers being pivoted to a fixed portion of said conveyor system, said levers being pivoted to one another and in one position being normally axially aligned, said armature being mounted on one of said levers, said spring means tending to move said levers out of axial alignment.

9. For use in a conveyor system comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extEnding downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, the combination comprising a switch tongue adapted to be positioned at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue, said switch tongue having an upper surface adapted to be substantially flush with said floor and forming a part of the surface of said floor, means for pivotally supporting said switch tongue for movement between said first and second positions, means yieldingly urging said switch tongue in upwardly disposed position with the upper surface thereof substantially flush with the surface of said floor, and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said first position wherein it is held by said permanent magnet to said other position.

10. For use in a conveyor system comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, the combination comprising a switch tongue adapted to be positioned at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means for preventing inadvertent movement of said switch tongue, means for pivotally supporting said switch tongue for movement between said first and second positions, a pair of levers, one of said levers being pivoted to said switch tongue, another of said levers being pivoted to a fixed portion of said conveyor system, said levers being pivoted to one another and in one position being normally axially aligned, said armature being mounted on one of said levers, said spring means tending to move said levers out of axial alignment.

11. In a conveyor system, the combination comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold saId switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue, means operable to energize said electromagnet, said last-mentioned means comprising signal means on the carrier and reader means along said track operable to read said signal means and energize said electromagnet, said signal means on said carrier comprising spaced electrical signal contact members connected in series, said reader means comprises electrical contacts along said track connected in series with said electromagnet whereby when said signal contacts simultaneously engage said reader contacts, a circuit is completed to said electromagnet, said signal members including resilient contact brushes for engaging the contacts alongside said carrier.

12. In a conveyor system, the combination comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, spring means for urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said switch tongue to said other position, means operable to prevent inadvertent movement of said switch tongue, said switch tongue having an upper surface substantially flush with said floor and forming a part of the surface of said floor, means for pivotally supporting said switch tongue for movement between said first and second positions, said means for preventing inadvertent movement of said switch tongue comprising means yieldingly urging said switch tongue in upwardly disposed position with the upper surface thereof substantially flush with the surface of said floor, and a stop member operable upon application of a force downwardly on said switch tongue to prevent movement of said switch tongue from said first position wherein it is held by said permanent magnet to said other position, said switch tongue including a portion thereof projecting into the path of said carrier as it moves along said branch portion of said track for returning said switch tongue to its position wherein the armature is in contact with said permanent magnet.

13. In a conveyor system, the combination comprising a track, a carrier movable along said track, said track having a main portion and a branch portion extending at an angle to the main portion, switch means at the juncture of the main portion and branch portion of said track movable from a first position wherein the carrier is permitted to move along the main portion to a second position wherein said carrier is guided for movement from said main portion to said branch portion, an armature yieldingly mounted on said switch means, a permanent magnet associated with said armature and operable to hold said switch means In one of said positions, toggle lever means operable upon engagement of said armature with said permanent magnet to prevent inadvertent movement of said switch means due to an external force on said switch means, spring means operable on said toggle lever means in a direction tending to release the same and urging said switch means toward the other position, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said toggle lever means and in turn move said switch means to said other position.

14. In a conveyor system, the combination comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, a switch tongue at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, toggle lever means operable upon engagement of said armature with said permanent magnet to prevent inadvertent movement of said switch tongue due to an external force on said switch means, spring means operable on said toggle lever means in a direction tending to release the same and urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said toggle lever means and in turn move said switch tongue to said other position.

15. For use in a conveyor system comprising a track defined by slots in a floor, a carrier movable along said track, said carrier having a tow pin extending downwardly into said slots, said track having a main portion and a branch portion extending at an angle to the main portion, the combination comprising a switch tongue adapted to be positioned at the juncture of the main portion and branch portion of said track movable from a first position to permit said carrier to move along the main portion to a second position wherein said carrier is caused to move from said main portion to said branch portion, an armature yieldingly mounted on said switch tongue, a permanent magnet associated with said armature and operable to hold said switch tongue in said first position, toggle lever means operable upon engagement of said armature with said permanent magnet to prevent inadvertent movement of said last-mentioned means due to an external force on said switch tongue, spring means operable on said toggle lever means in a direction tending to release the same and urging said switch tongue toward the second position against the force of said permanent magnet, and an electromagnet associated with said permanent magnet and operable when energized to counteract the field of said permanent magnet to permit said spring means to move said toggle lever means and in turn said switch tongue to said other position.