US3044418A - Anti-collision system - Google Patents

Description

July 17, 1962 R. o. BEI-:Rs

ANTI-COLLIsIoN SYSTEM 2 Sheets-Sheet l Filed Dec. 2, 1960 July 17, 1962 R. o. BEERS ANTI-COLLISION SYSTEM 2 Sheets-Sheet 2 Filed Dec. 2, 1960 Unite 1.,

Filed Dec. 2, 1960, Ser. No. 73,312 6 Claims. (Cl. 10S-163) This invention relates to apparatus for preventing collisions between two relatively movable members and more particularly relates to apparatus for preventing collisions between two or more overhead cranes operable on the same overhead track and for preventing the collision of any one crane with stationary abutments, such as building walls and the like.

Overhead cranes are manufactured in various sizes and designs. Common to all such cranes is the considerable cost involved in their manufacture even for the smallest cranes. For example, the retail price of cranes ranges from a few thousand dollars to ten thousand dollars and more.

An overhead crane is usually movable along parallel horizontal tracks. The crane has wheels that are guided by the tracks, and there is a power supply and gear train for driving the wheels to move the crane along the tracks. Because the crane is designed to lift heavy loads, it must itself be constructed of heavy material. Usually adding to the weight and the momentum of a moving crane is the weight of material that is suspended from the crane as the crane is used for its intended purpose.

Many cranes are operable in both forward and reverse directions. Often they are controlled upon actuating of a portable switch box carried by an operator walking on the floor of the building in which the crane is installed. For larger cranes, the controls may be installed in a cab supported by the crane itself. In either case, because the operator must focus his attention upon the load to be picked up, moved and deposited, he is unable to maintain an awareness of the precise position of the crane on its tracks. The result is, as it has been for years, that cranes are often inadvertently driven into obstructions. Such obstructions may he a Wall at the end of the tracks. The obstruction may be another crane. It two cranes are moving toward one another and collide, the force of the impact is even more severe.

Collisions have caused a great amount of damage. Usually, the minimum wreckage involves stripping of the gears of the drive train and damage to the drive shaft, requiring shutdown of the crane and costly repair and replacement of expensive parts. An additional source of damage is the inertia and momentum of a .swinging load suspended from the crane. For example, when two cranes carrying loads collide, the loads may swing against one another causing severe damage to the loads. If the crane collides with the end of the track runway, the load may swing against the wall causing damage to the building and the load.

While it is true that in certain instances bumpers have been provided at the end of the track runway so that the crane will not actually collide with the building wall, such bumpers do not eliminate damage to the crane when it collides with the bumper. Such bumpers do not eliminate damage resulting from the collision of two cranes operable along the same track runway.

Various means have been provided for indicating an imminent collision between a moving object and another object. For example, bumpers have been provided on railroad cars for energization of the brakes of that car when the bumper contacts an adjacent car. Proximity to curbs can be sensed by devices placed on automobiles. However, none of the prior art devices has been found satisfactory for use With overhead cranes. An important ire defect of the prior art devices insofar as their potential adaptability for preventing crane collisions is inherent in the very nature of cranes. Because of their great bulk and weight, and because of the added weight of a heavy load, the brakes that are operable to lock the wheels of the crane are ineffective to immediately stop the crane. Instead, the crane will continue its travel for a number of feet. Another peculiar feature of crane operation is the fact that they are, ordinarily, operated Without regard to the position of the crane along the track. In other words, Whereas the driver operating an automobile may rely upon a proximity indicator to a certain extent, he is also employing his own faculties to determine the position of the vehicle as it approaches an obstruction. In most of the prior art anti-collision devices, there is an additional facility employed for preventing the collision so that, even if the anti-collision device fails to operate, a collision will not necessarily occur. Hence the anticollision devices of the prior art may be satisfactory for their intended purposes. To the contrary, in the crane art, the anti-collision device must be totally reliable so that the operator of the crane can focus his entire attention upon the Work that the crane is doing rather than upon the position of the crane above the head of the operator.

More recent developments have produced the photoelectric cell or electric eye type of proximity indicator. The photoelectric cell has found wide application in indicating the presence of a person near a door, so that the door may be opened automatically. There are many other applications of the photoelectric cell, each having the purpose of sensing proximity. In the operation of an `overhead crane, an electric eye arrangement would have distinct disadvantages as an indicator for anti-collision or as a means for operating the brakes of the crane. First of all, the effective operation of an electric eye is dependent upon a clear lens covering the eye. An electric eye will fail to operate when it is covered with dust. Because a crane is operated overhead, often in areas Where there is dirt and dust, dust would quickly collect on the lens of the electric eye causing it to fail. Obviously, the eye being mounted on the crane near the ceiling of the building, it would be highly impractical to continuously wipe away the collection of dust. Another disadvantage `of the electric eye is its extreme sensitivity to mechanical failures. With the continual stopping and starting of an overhead crane, the constant jarring of the electric eye mechanism would cause repeated damage to the mechanism and consequent failure of operation. Furthermore, an electric eye arrangement with all its required equipment and circuitry would be a tremendously expensive installation compared to the invention that will be described.

An important object `of the invention is to provide an anti-collision system for overhead cranes that Will operate to stop the movement of a moving crane in time to avoid a collision.

Another object is to provide an anti-collision system for overhead cranes` having means for stopping the motion -of a moving crane with reference to the distance required to stop the crane Without a collision.

Another object of the invention is to provide an overhead crane with means for preventing collision in either direction of travel of the crane.

Another object of the invention is to provide an overhead crane with means for automatically stopping the crane as it approaches a point of collision in either direction, with means for permitting the operator of the crane to operate the crane in the direction opposite the obstruction yupon actuation of the mechanism conventionally devised to operate the crane in that direction.

Still another object of the invention is to provide a 3 means for automatically stopping a crane prior to a collision, which means is operable independent of dust collections and other environmental inuences.

Yet another object of the invention is to provide an anti-collision device for stopping overhead cranes, which device may `be installed on new cranes or on existing cranes, regardless of the structure ofthe existing cranes.

Yet another object of the invention is to provide an anti-collision system which is durable under various conditions of operation of the crane, but which is, nevertheless, extremely inexpensive -to install and maintain.

Still another object of the invention is to provide an anti-collision system for stopping a crane in either direction of travel when .a collision lin that direction is imrni nent, including means for separately rendering inetective the anti-collision system for either direction of travel, or for both directions of ftravel.

Other objects and advantages will appear.

FIGURE l is a plan View of the invention with parts broken away, the cranes being illustrated in diagrammatic form and the article transporting carriage being omitted;

FIGURE 2 is a side elevation view of the invention taken from the bottom side of FIGURE l, with one of the switch and actuating arm combinations being omitted for clarity;

FIGURE 3 is an end elevationvview taken from the left or right side of FIGURE 2 with parts broken away and with the article transporting carriage shown in schematic form.

The specific structure of the crane with which the invention may be used is not critical. In fact, it may be used with any of fthe cranes presently available, and for that reason the cranes are shown largely in schematic form. Because the cranes illustrated are identical in at least their basic components, one is identified with prime numbers corresponding to the numbers of the other crane.

Referring to the drawings, the crane system 10 includes a pair of parallel tracks 11 that are supported by opposite walls 12 in any well-known manner, such as by the shelves 13 illustrated. There is a crane 15 movable along the tracks 11. i The crane 15 has what may generally be called a pair of wheel carriages 16, and rotatably supported by each wheel carriage 16 are a pair of wheels 17'. The wheels 17 n'de along the tracks or rails 11 and are held from lateral sliding by the reduced center pontions 18 of the wheels 17 as is known in the art.

A cross-member 19 is connected to each `of the wheel carriages 16. The cross member 19 supports an article transporting carriage or dolly 20 which has wheels 21 for allowing i-t to move along the cross-member 19. There may be various ways of guiding the dolly 20 along the cross-member 19. As diagrammatically illustrated in FIGURE 3, -a chain 22 is supported by the dolly 2i) to be raised or lowered thereby upon energization of certain controls which are not shown. s Y

The system for operating the crane 15 along the tracks 11 is shown schematically Vin FIGURE 2. In that system, there are a pair of wires and 31 connected across a 440 v. system. A wire 32 is connected to the wire 30 and to a switch terminal 33. The opposite side 35 of the switch 34 is connected by a wire 36 to one side 37 of a switch 38'. The opposite side 39 of the switch 38v is connected by a wire 40 rto one sideV 41 of a motor 42. The opposite side 43 of the motor isY connected by a wire 44 to one side 45 of a switch 46. The opposite side 47 of the switch 46 is connected by a wire 48 to the other wire 31 of the 440 v. source. 38, rthe motor 42 and the switch 46 are connected in a series circuit.

Connected in parallel by wires 49 vand 50 across the Ymotor 42 is a solenoid 51 for operating a brake (not is connected so that when the solenoid 51 is energized,

Thus the switch 34, the switch thebrakes are released permitting the wheels A17 to rotate freely. When the solenoid 51 is de-energized, the brakes will be applied to lock the wheels 17 against rotation. Because the solenoid 51 is connected in parallel across the motor 42, when the motor is energized to rotate the wheels 17 (through a gear train arrangement that is Well-known in the art and not illustrated) the brakes will be released, and vice versa.

Because the crane 15 must be operable in opposite directions along the tracks 11, :the lmotor 42 is reversible. Therefore, there is a wire 55 connected from the wire 36 to one side 56 of a switch 57, and the other side 58 of the switch 57 is connected by a wire 59 to the wire 44, and thus to the side 43 of the motor 42. From the wire 40 (which is connected to the side 41 of the motor 42) a wire 60 is connected to one side 61 of the switch 62. The other side 63' of the switch 62 is Vconnected by a wire 64 to the wire `48. Hence there is another series circuit including the switch 34, the switch 57, the motor 42 and the switch 62. The connections of the motor 42 across the power source may be reversed in direction according to which of the series circuits is closed by its switches.

The switches 38 and 46 have contact members 65 and 66, respectively. They are connected to a single shaft 67 ingang arrangement for simultaneous operation by an operating element 68. Likewise, the switches 57 and 62 have contact elements 69 and 70, respectively, that are controlled by a common shaft 71 to be simultaneously operated by an operating element 72.

The control circuit described thus far is the basic cir cuit for driving the crane 15 in either direction along the tracks 11. (A similar circuit is provided for the crane 15'.) However, with the basic drive circuit there is no means for preventing a collision between the two cranes 15 and 15 operated along the same track 11, or for preventing the collision of either crane 15 or 15' with the end walls 12. The invention incorporates such anti-collision means. y

`Connected across the 440l v. Source in parallel with the wires 32 and 48 is a transformer 76 having a secondary output of 110 v. A wire 77 is connected to the transformer and to one side 78 of a switch 79. The other side 80 of the switch 79 is connected by a wire 81 to one side 82 of a limit switch -83. The limit switch 83 includes a switch arm 84 pivotally mounted on a block 85, and the block 85 is connected to the wheel carriage 16. The free end of the switch arm 84 has a roller S6 rotatably attached to it. A compression spring 87 normally biases the actuating arm 84 in an upward direction and into contact with the terminal 82. There is a wire 88 connected to the actuating arm 84 and to a solenoid coil 89. The Solenoid coil 89, when energized, draws a Contact bar 90 against the terminals 33 and 3S of the switch 34 to close that switch. The other side of the solenoid coil is connected by a wire 90 to the transformer 76. From the foregoing, it can be seen that one control circuit for the contact bar 90 of the switch 34 is a series circuit including the switch 79, the limit switch VS3, and the coil 89.

Also connected to the transformer 76 by a connection to the wire 77 is a wire 91, and the wire 91 is connected'to one side 92 of a switch 93. The other side 94 of the switch 93 is connected by a wire 95 to one side 96 of another limit switch 97. The limit switch 97 has an actuating arm 98 pivotally mounted on a block 99 that is connected to the wheel carriage 16. There is a roller 100 on the free end of the actuating arm 98 and a compression spring 101 Vfor normally biasing the switch arm 98 upwardly into contact with a terminal 102. The terminal 102 is connected by a wire 103 to the wire .88. Thus, another control circuit for the contact bar 90 of the switch 34 includes the switch 93, the limit Y switch 97 and the coil 89.

There is a toggle switch 105 in parallel connection across the limit switch 83 and a toggle switch 106 connected across the limit. switch 97. A contact bar 108 isV connected to the rod 67 for closing the switch 79. In like fashion, a contact bar 109 is connected to the rod 71 for closing the switch 93. The contact bar 108 is a ganged switch with the contact bars 65 and 66, and the contact bar 109 is a ganged switch with the Contact bars 69 and 70.

The crane (which is identical to the crane 15), carries a switch actuating member 115 in the form of a T bar that is fastened by a bracket 116 to the wheel carriage 16'. The actuating member 115 has a lower surface 117 that is horizontal and slightly below the upper extremity of the wheel 86 when the switch arm 84 is in its uppermost position in contact with the terminal 82. Therefore, when the cranes 15 and 15 move toward one another, the roller 86 will engage the curved leading end 118 of the actuating member 115 and be forced downwardly against the pressure of the spring 87 and out of contact with the terminal 82. Engagement of the roller 86 by the actuating member 115 depresses the switch arm 84 a sufficient amount to cause the limit switch 83 to open. In addition, because the surface 117 of the actuating member 115 is substantially horizontal, the switch 83 will remain open until the contact between the switch arm 84 and the actuating member 115 is released.

There is a similar actuating arm 120 connected to the wall 12, the actuating arm being an L-shaped T bar with surface 122 is in the path of the roller 100 so that contact of the roller 100 with the leading end 123 of the actuating member 120 will open the limit switch 97, and the switch 97 will remain open until its contact with the actuating member 120 is removed.

If both the cranes 15 and 15' are moving toward one another, there must be means for stopping both cranes when a collision is imminent. crane 15 has a limit switch 130 that includes a switch arm 131 having a roller 132 on its upper end. The structure of the limit switch 130` is the same as that for the switches 82 and 97, and the roller 132 is normally at the same height or elevation as the rollers 86 and 100. The actuator for the switch 130' comprises a T bar 134 that is connected to the crane 15 in a manner similar to the connection of the T bar 115 to the crane 15. The

' actuator 134 is at the same elevation as the actuator 115,

in the path of movement of the roller 132 as the crane 15 approaches the crane 15.

The circuitry for the limit switch 130 is the same as the circuitry for the limit switch 83, as has been described. When the cranes 15 and 15' move toward one another, the actuator 115 will operate the limit switch 83, and the actuator 134 will operate the limit switch 130.

Similarly, the crane 15 includes a limit switch 135 that includes a switch arm 136 having a roller 137 at its free end. There is a T bar actuator 138 fastened to the wall 12 in the path of travel of the roller 137 for depressing the switch arm 136 upon contact with the under surface 139 of the T bar 138.

The operation of the invention is as follows: The gang switch operating element 68 may be regarded as a forward direction operating element and the gang switch operating element 72 may be regarded as a reverse direction operating element. When the crane 15 is not close to the crane 15 or to the wall 12, the limit switches 83 and 97 will be closed with their switch arms at an elevated position and in contact with the terminals 82 and 102, respectively. When the operating element 68 is depressed, the switches 79, 38 and 46 are simultaneously closed. (The arrangement of the switches is such that depression of the forward switch operating element 68 causes the reverse operating element 72 to be raised, and vice versa. The switches would ordinarily be contained within a switch box that is portable to be operated by .a vertical leg 121 attached to the wall 12, The horizontal Therefore, the

6. an operator below the crane. Such arrangement is wellknown in the art.) Closing of the switch 108 completes a circuit from the transformer by way of the wire 77, the switch 79, the wire 81, the limit switch 83l (which is closed because it is out of contact with the actuator 115), the wire 88, the coil 89, and back to the transformer. -Thus, energization of the coil is accomplished so that the switch 34 is closed. Closing of the switches 38 and 46 completes a circuit from the wire 32 past the switch 34, the switch 38, through the motor 42 and across the coil 51, returning by way of the wire 44, the switch 46, and the Wire 48 to the power source. Therefore, the motor 4'2 is energized to drive the crane in a forward direction (to the right as illustrated in FIGURE 2) and the coil 51 is energized to release the brakes.

When the crane 15 moves into a position of imminent collision with an obstruction that has van actuator', such as the actuator 115 on the crane 15', that actuator depresses the switch arm 84 opening the switch 83. Therefore, the circuit through the solenoid 89 will be opened so that the contact bar 90 will break contact with the terminals 33 and 35 of t-he switch 3'4.

Consequently, the energy of the motor `42 and to the brake solenoid 51 will be terminated, Vand the brakes will be applied and the motor stopped. Nevertheless, because of the great momentum of the heavy crane 15, it will continue to move even :after the motor has stopped and the brakes have been applied by de-energization of the solenoid 51. However, the length of the bar or actuating member 117 is sufficient to 'allow for the stopping time of the heavy crane. (For example, the actuating member may be as much as ve feet in length 0r more, depending upon the size of the crane with which the invention is to be used.)

When the crane 15 nally comes to a halt in a forward direction, the forward operating element 68 will be ineffective to drive the crane 15 in -a forward direction, even though the operating element 68 is depressed, because the switch 83 will cause the circuit through the solenoid coil to be opened so that the circuit to the motor 42 and the brake solenoid 51 will remain open. However, the crane may be operated in a reverse direction so long as the limit switch 97 is closed. Depression of the reverse operating element 72 will cause the forward op-` erlating element 68 to Ibe raised, opening the switches 79, 38-and 46. However, the switches 93, 62 and 69 will be closed. When the switch 93 is closed, a circuit is completed from the wire 7'7, 4the Wire 91, the switch 93, the limit switch 97, the wire 88, and the coil 89, back to the transformer 76 by way of the wire 90. 'Therefore, the coil 89 will again be energized closing the switch 34. The connection of the motor y42 across the voltage source will be reversed, because the circuit, when the reverse operating element 72 is depressed, includes the Wire 32, the switch 34, the wire 36, the wire 55, the switch 57, through the motor, and back to the power source by way of the wire 60, the switch 62, the wire 64 and the wire 48. Hence, the brake solenoid 51 will again be energized to release the brakes and the motor -42 will operate in la reverse direction to move the crane 15 laway from the obstruction which, as illustrated in the preceding description, is designated by the crane 15.

Should the crane 15 approach the left wall 12 and the actu-ating member 120, the limit switch 97 will be opened by the actuating member 120. In that case, the circuit to the coil 89 will be opened so that the circuit to the motor `and brake solenoid will again be opened. Therefore, the brakes will be applied and the motor stopped. Again, the length of the actuating member is sufficient tov allow the crane to stop before it contacts the Wall 12. But in this case the crane may be moved forward upon depression of the operating element 68 because the limit switch 83 is closed.

If both cranes 15 yand 15' are in operation, and are moving toward one another, the limit switches 83 and 7 130 will be simultaneously opened by the actuating members 115 and 134, respectively. The crane 15 will be -stopped as has been described. The crane wilibe stopped in a similar manner. Because of the momentum of both cranes 15 and 15', yand the stopping distance required for each crane, the length of the actuating members 115 and 134 must be suiiicient to account for the stopping distance of both cranes.

Similarly, if the crane 15 is moved too close to the.

Wall 12 that supports the actuating member 138, the limit switch 135 will be opened to stop the crane 15.

FIGURE 3 illustrates the application of the invention to the dolly that traverses the cross member 19. Thus, the dolly 20 has limit switches 140' and 141 at its ends, each having circu-itry similar to the circuitry for the limit switches 83 and 97. There are actuating members 142 and 143 at the ends ofthe cross member 19 for actuating the switches 140 and 141, respectively. By the arrangement of FIGURE 3, the dolly 2i) is automatically controlled toV prevent collision with the ends of the cross member 19 if bumpers be otherwiseprovided for the cross member 19, and if such bumpers be eliminated, the arrangement of FIGURE 3 prevents driving of the dolly 20 oli an end of the cross member 19.

Various changes and modifications may be made within the process of this invention as will be readily apparent to those skilled in the art. 'Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

What is claimed is:

l. An anti-collision system for a crane wherein the crane includes track means, an article lifting frame for transporting articles, Wheels on the frame and supported by the track means, drive means for rotating iat least one of the wheels, and brake means `for locking the wheels against rotation, rst switch means for operating the drive means to move the crane in a rst direction, and for rendering the brake means inopenative, second switch means for operating the drive means to move the crane ina second direction land for rendering the brake means inoperative, the system comprising: third and fourth norma-lly closed switches carried lby the crane, the third switch being connected to open the circuit including the iirst switch means, the fourth switch being connected to open lthe circuit of the second switch, a switch arm for opening the third switch and a switch arm for Yopening Vthe fourth switch, ian actuator for eachy switch, each crane includes an article supporting vehicle, a track for guiding the vehicle and means for moving the vehicle along the track, the system comprising a source of electrical power, a motor, a tirst circuit for connecting the motor across the source of power, a first switch means for closing the rst circuit, first actuating means for operating the lirst switch means to close the iirst circuit, a second circuit for reversing the connection of the motorV across the Y source of power, second switch means for closing the actuator being supported by an obstruction against which Y the anti-collision system is to prevent collision by the crane, one of the obstructions being in the path of movement of the crane in the rst direction iand the other `obstruction being in the path of movement of the crane in the second direction the actuator supported by the one obstruction having a substantially horizontal surface for moving 'and holding movedthe third switch arm when the crane is moved in the first direction too near the'one obstruction, the actuator supported -by the other obstruction having a substantially horizont-a1 surface for moving and holding moved thefourth switch arm when the crane is moved in the second direction too near the other obstruction, the horizontal surfaces of the :actuators extending from the obstructions a Ipredetermined distance acsecond circuit, second actuating means for operating the second switch means to close the second circuit, a brake actuating solenoid connected in parallel with the motor for energization when either the rst or second switch means is closed, third switch means in both the iirst and second circuits and in series with the first and second Y switch means, a iirst movable arm supported by the crane and operable when moved to open the third switch means to open the rst circuit, a second movable arm supported by the crane and operable when moved to open the third switch means, means positioned adjacent the limit of movement of the crane in one direction for moving the first arm, and means positioned adjacent the limit of movement of the crane in the other direction for moving the second arm.

4. The anti-collision system of claim 3 with means for limiting the effectiveness of the third switch means to the irst circuit onlywhen the second arm is unmoved and to the second circuit only when the rst arm is unmoved.

5. An anti-collision system for a crane for preventing the collisionof the crane with an obstruction, comprising a drive mechanism for the crane, a switch in the circuit of they drive mechanism for energizing and deener-gizing the drive mechanism, a limit switch carried by the crane for deenergizing the drive mechanism when the limit switch is actuated, a switch arm for actuating the limit switch, and an actuator for actuating the switch arm, the

actuator being supported to extend from the obstruction e toward the crane, the actuator having a switch arm engaging surface parallel to the line of movement and in the path ,of the switch arm as the crane approaches the actuator, the switch arm engaging surface being suciently long to hold the switch arm engaged during the length of travel required to stop the crane before colliding with the obstruction after the switch arrnhas been actuated.

`6. The system of claim 5 where there is a roller on the free end of the switch arm for contacting the switch engaging surface of the actuator.

References Cited in the file of this patent UNITED STATES PATENTS 2,708,715 Meyers May 17, 1955

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