US3037651A - Automatic handling apparatus - Google Patents

Description

June 5, 1962 J. K. SMITH 3,037,651

AUTOMATIC HANDLING APPARATUS Filed Aug. 22, 1958 4 Sheets-Sheet l INVEN TOR. (hi 1V EJ212115 June 5, 1962 J. K. SMITH 3,037,651

AUTOMATIC HANDLING APPARATUS Filed Aug. 22, 195B 4 Sheets-Sheet 2 INVENTOR. film "1. JZIITH June 5, 1962 J. K. SMITH 3,037,651

AUTOMATIC HANDLING APPARATUS Filed Aug. 22, 1958 4 Sheets-Sheet 3 INVENTOR. JbA IVJK ,ZMJIH BY aw/zm June 5, 1962 J. K. SMITH AUTOMATIC HANDLING APPARATUS 4 Sheets-Sheet 4 Filed Aug. 22, 1953 I NV EN TOR JZIJK J l/7H ATTORNEY 3,037,651 AUTOMATIC HANDLDIG APlARATU John K. Smith, Dundalk, Md., assignor to .l. K. Smith Research 8: Development Company, Baltimore, Md. Filed Aug. 22, 1958, Ser. No. 756,717 15 Claims. ((31. 214-653) The present invention relates to an automatically controlled material-handling apparatus, and more specifically to a grab-type fork lift truck that has means for producing beams of light or similar wave energy and cooperating photoelectric cells or similar wave-receiving means associated with the grab arms and electric circuitry connected therewith to effect automatic movement of th arms for grabbing and lifting an article.

In the materialand article-handling field, wide use is made of various types of apparatus for handling material by grabbing or grasping it with some mechanical or other means and then moving the article held by the grabbing or grasping means from one place to another. After the article is in position adjacent or above its destination, it must be released by the grasping or grabbing means. In present day practice, there is often much difficulty in both the engagement of the grab means with the article and in the release of the article by the grab means.

In some instances, the operator of the material-handling apparatus relies upon his own judgment, experience and skill to properly engage the apparatus with the article, this usually involving moving the apparatus or a part of it in three transverse directions in order to properly position it with respect to the article to be handled. Similarly, when releasing the article, the same or opposite movements must be effected in the apparatus in order to release it without damage.

It has been found through experience that the abovedescribed procedure has not always proven satisfactory because either an undue amount of time was consumed in the positioning of the handling apparatus with relation to the article to be handled or else if the operator endeavored to hurry the movements of this apparatus, he often caused damage to the article when moving the engaging means into position in or on the article.

In some installations, in order to overcome the abovedescribed deficiencies with the available material-handling apparatus, resort has been had to one or more assistants stationed on the ground near the article or otherwise adjacent to it, in order to closely observe the articleengaging means as it was operated to approach the article and to give proper directions to the operator of the apparatus to enable the operator to cause his apparatus to engage the article properly and without damage to it. Obviously, the utilization of two or more men in addition to the equipment is not as economical an operation as is desirable, especially in view of the fact that damage still occurs to the article to be handled due to misunderstanding by the operator of the instructions of his assistant; also, the assistant has not always been able to produce the desired results of enabling the operator to guide his apparatus in the desired manner so as to avoid damage or injury to the article to be grasped.

As a particular example of the material-handling situation discussed in general above, the following is cited: In rolling mills which produce very long and thin strips or sheets of metal, the metal is coiled or rolled on a mandrel at the end of the production process or during an intermediate stage thereof. These rolls of sheet metal must be taken from the rolling mill machine area to storage or to other locations, and it is the practice to use ram-lift trucks to perform this function. The ram extends forwardly of the truck and is movable vertically as a unit. Thus, the ram enters into the axial hole in the e atent ice roll that was previously occupied by the mandrel, and it is during this part of the operation that most of the damage has occurred in the past, because if the rain was not properly aligned with the hole, it would strike the side of the roll and thus damage it.

An object of the present invention is to provide handling apparatus that will automatically properly engage an article.

Another object of the present invention is the provision of a handling apparatus in which light-emitting means or other similar wave-emitting means and cooperating photoelectric cells or similar wave-responsive means are used to obtain alignment of the article-engaging means with the article.

A further object of the present invention is to provide a handling apparatus that will eliminate the possibility of human error in the engagement of the apparatus with an article.

Yet another object of the present invention is the provision of a handling apparatus that will properly engage an article to be handled with a minimum of human participation.

Another object of the present invention is to provide a grab-type fork lift truck having means thereon to sense the position of grab arms of the truck and to automatically move the grab arms into proper position with respect to an article to be engaged by the grab arms.

Yet another object of the present invention is the provision of a fork lift truck equipped with grab arms that will sense the relative position of the arms and an article to be handled and will move the grab arms into proper engagement with the article.

Other objects and the nature and advantages of the instant invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a fork lift truck embodying the present invention;

FIG. 2 is a perspective view partly in section of the carriage and grab arms of the fork lift truck of FIG. 1 and showing certain constructional details thereof;

FIG. 3 is an enlarged perspective View of the structure supporting the grab arms shown in FIG. 2;

FIG. 4 is a view taken on line 4-4 of FIG. 3;

FIG. 5 is a rear view of the element shown in FIG. 4;

FIG. 6 is a rear perspective view of the apparatus shown in FIG. 2 with certain parts omitted;

FIG. 7 is a perspective view of a part of the apparatus shown in FIG. 2; and

FIG. 8 is a schematic View of the electric and hydraulic circuits for actuation and control of the apparatus of this invention.

Referring now to the drawings, wherein like reference characters are used for like or corresponding parts throughout the several views, there is shown in FIG. 1 a fork lift truck generally designated 10 having a prime mover compartment 11 with a motor therein and an operators compartment 12. Two forwardly extending grab arms 13 and 14- may be seen to be in engagement with a roll 15 of metal, although it will be understood that other materials than a roll of metal may be handled by the truck 10.

A guide frame 16 is mounted on the truck and carries an upstanding lifting jack 17 having at its top a horizontal member 18 with sprockets 19 on both ends. Chains 21 are trained over the sprockets 19 and are secured to a carriage 2.2.

As shown in FIG. 2, the carriage 22 comprises an upper slideway 23 and a lower slideway 24, these slideways being joined by a plate 25.

Slidably supported in a downwardly facing and transversely extending channel 26 in upper slideway 23 is a 3 pair of sliding guide blocks 27, each of which has a downwardly facing channel 28 and an end plate 29.

Referring to FIG. 3, there may be seen the lower slideway 24 having sliding guide block 27 slidably positioned in an upwardly facing channel 30. The sliding guide blocks in lower slideway 2% are generally similar to the sliding guide blocks in upper slideway 23 and have upwardly facing channels 23 therein.

In the channels 23 of the sliding guide blocks 27 that are mounted in the upper slideway 23 and lower slideway 2d are two support blocks 33, these support blocks 33 each carrying one of the grab arms 13 and 14, it being understood that the grab arms 13 and 14 extend forwardly between upper slideway 23 and lower slideway 24-.

Referring now to FIG. 6, there may be seen the grab arms 13 and 14, the slideways 23 and 24, and the support blocks 33. At the left rear underface of upper slideway 23 are two depending ears 34 to which are attached a right arm cylinder 35 which has a rod 36 attached to an ear 37 extending from the back of right arm support block 33. Similarly, the right upper face of lower slideway 24 has upstanding ears 38 which are attached to left arm cylinder 39, the rod 41 of which is attached to a rearwardly extending ear 4-2 of left arm support block 33. As will be understood, actuation of pistons in cylinders 35 and 39 will cause the arms 13 and 14 to move inwardly and outwardly to open and close them.

From the lower front face of left arm support block 33 there may be seen in FIG. 3 a forwardly extending rotatable stub shaft 50 that carries thereon a locking member 51. As may be seen in FIG. 4, locking member 51 has a hole 52 at one end thereof in which is received the stub shaft 50 and has also a recess 53. The recess 53 is clearly shown in FIG. 5.

When the piston in left arm cylinder 39 is actuated to move the left arm support block 33 to the left, the left arm support block 33 will slide in the channel 28 in lower sliding guide block 27, which will remain stationary with respect to lower slideway 24-. The left hand face of support block 33 will strike and engage the inner face of end plate 29 and will cause it and sliding guide block 27 to which it is attached to move outwardly (to the left as shown in FIG. 6) to thus carry the arm 13 to the fully open position. When it is desired to close the arm, the piston in cylinder 39 will be actuated in the opposite direction to cause left arm support block 33 to move inwardly, or to the right as shown in FIG. 6. The vertical face of recess 53 of locking member 51 will come into engagement with the outer face of end plate 29 and thus carry inwardly the sliding guide block 27'.

As the lower sliding guide block 27 approaches its inner position, the downwardly depending member 54 that is secured to the stub shaft 58 will strike the detent 55 and thus cause the stub shaft 50 together with the locking member 51 to rotate in a counter-clockwise manner as seen in FIG. 3, to thus remove the vertical face of recess 53 from engagement with the outer face of end plate 29. Thereafter, the lower sliding guide block 27 remains stationary while the left hand support block 33 slides in the channel 28 thereof.

It will be understood that a similar arrangement is provided for the right arm 14 and its supporting structure.

In FIG. 7 is shown the upper slideway 23 and an upper sliding guide block 27 with its end plate 29 secured thereto. Attached to the outer face of support block 33 is a bracket 57 in which is vertically slidably mounted a lock bolt 58. A lever that is L-shaped has one end pivotally secured at 61 to the outer face of support block 33, a screw 62 engages in the lock bolt 58 and extends into a slot (not shown) in the lever 59. A spring 63 has one end secured to the lever 59 to urge it and lock bolt 53 upwardly, the other end of spring 63 being attached to an ear 64 extending from support block 33. The free end of lever 59 has a cam surface 65' thereon that is engageable with the under side of upper slideway 23. In operation, when support block 33 is moved outwardly, the outer face thereof engages with the inner face of end plate 29 to thus carry sliding guide block 27 outwardly; while the support block 33 was sliding in the channel of sliding guide block 27, the lower face of upper slideway 23 engaged with the upper surface of le er 59 to hold it and lock bolt 53 down. After the outer face of supporting block 33 engages with the inner face of end plate 29, the free end of lever 59 is carried beyond the outer end face of upper slideway 23 and thus the spring 63 will urge the lever 59 and the lock bolt 58 upwardly into the position shown in FIG. 7. Thereafter, when the support block 33 is caused to move inwardiy, the lock bolt 5?; will engage with the end plate 29 and cause the upper sliding guide block 27 to move inwardly and this movement will continue until the cam surface 65 engages with upper slideway 23 to move lever 59 and lock bolt 53 downwardly, thereafter support block 33 will slide inwardly in the channel of sliding guide block 27.

Parts 51 and 57 cooperate to increase the positive guidance of the grab arms 13 and 14'. The respective positions of parts 51 and 57 can be reversed, that is, part 51 can be mounted on the upper slideway and part 57 on the lower slideway.

It should be understood that parts 51 and 57 are also mounted on the left block 33. These parts have been omitted on FIG. 6 for claritys sake.

The apparatus is provided with mechanism to automatically control movements of the truck after it has been driven to a position adjacent an article to be handled.

The control circuits and elements comprise, as may be seen in FIG. 2, three photoelectric cells designated A, B and C, these photoelectric cells being located in the right grab arm 14- and receiving light from three sources A, B and C located in grab arm 13. The photoelectric cells and light sources are grouped in a particular manner about inwardly extending, opposed lifting members 70 and 71, lifting member 70 being generally arcuate in configuration and having the photoelectric cell A arranged slightly above it, photoelectric cell B slightly below it, and photoelectric cell C slightly rearwardly thereof. It will be understood that the light sources A, B and C are located in the same relative positions with respect to lifting member 71. In addition, a contact switch 72 is positioned on the grab arm 14 adjacent lifting member '70, and a similar contact switch 73 is similarly positioned on the grab arm 13.

Referring now to FIG. 8, there is shown a source of current 104) connected through a rheostat 101 to a conductor 1&2, the conductor 102 being connected with the neutral contact N of grab arms control lever 103 and to the neutral contact N of a truck traction lever 104. Also engageable by lever 1&3 are an automatic pickup contact CP and an automatic release contact CR. Traction lever 104 is also engageable with forward movement contact F and rearward movement contact R.

Three amplifiers A, B" and C" are connected in parallel with conductor 102 and are connected in known fashion, respectively, to the three photoelectric cells A, B and C. A conductor 106 extends from the other side of amplifier A" and has a relay coil R1 therein and is connected to a return line 150. The amplifiers are of identical design and are each represented by A Similarly, conductors 197 and 108 are connected to the amplifiers B and C", to return line 150, and include the relay coils R2 and R3 respectively.

Contact switch 73 is connected to conductor 102 by conductor we and to return line by a conductor 11% that includes a relay coil R4. Similarly, contact switch 72 is connected by a conductor 111 to conductor 102 and to return line 150 by a conductor 112 that includes relay coil R5.

A conductor 113 extends from the forward contact F for truck traction lever 104 to the fixed contact of a switch S51 that is controlled by the relay coil R5. The movable contact of switch S51 is connected by conductors 114 and 115 to a junction 116. A conductor 114A extends from conductor 113 to one contact of a switch $41 that has the movable contact thereof controlled by the relay coil R4. Switch S41 is connected by conductor 115 to junction 116. Also connected with junction 116 is a conductor 117 that is connected to the movable contact of a double-throw switch 831 that is controlled by the relay coil R3. One of the fixed contacts of switch S31 is joined by conductor 118 to conductor 113, and the other fixed contact of switch S31 is connected by conductor 119 to the movable contact of a switch S62, the fixed contact of which is connected by conductor 120 to the contact 01 of lever 1113. Lever 103 is electrically connected to lever 1% by a conductor 121.

Also connected with the junction 116 is a conductor 122 that is connected to return line 1511 and has therein a forward control winding 123.

All of the switches above described as well as the switches to be described that are part of relays are shown in the positions they occupy when the relays are not energized, and it will be understood that these switches are moved to their opposite positions when their respective control relays are energized.

A conductor 125 extends from the contact GP to the fixed contact of a switch S61, switch S61 and switch S62 both being controlled by relay coil R6. A conductor 126 is connected to conductor 125 and to the fixed contact of switch S32, the movable contact of which is under the control of relay coil R3 and is connected by a conductor 127 to the movable contact of a double-throw switch 811. One fixed contact of switch S11 is connected by conductor 123 to the movable contact of a switch S21 that is under the control of relay coil R2. The fixed contact of switch S21 is connected by conductor 129 to a conductor 1313. Conductor 130 is joined to a conductor 131 that is connected at one end to the movable contact of switch S61 and is connected to return line 150 through the relay coil R6. 7

Attention is now invited to left arm cylinder 39, right arm cylinder 35, and jack cylinder 45, each of these cylinders being connected in known manner to the three position valves VL, VR and VV respectively. The control valves are each connected to a source of fluid under pressure generally designated 135. Flow controllers FC and a pressure controller PC are provided. Each of the valves VL, W and VR is solenoid controlled, having one solenoid to urge it out of a neutral position in one direction and another solenoid to urge it out of a neutral position in another direction. Thus, it may be seen that upon energization of one or the other of the solenoids, the valve will be moved in one or the other direction from its neutral position in which it permits no fluid to flow therethrough. These solenoids can be actuated at will, manually, or automatically according to this invention by appropriate switching.

Referring again to the wiring diagram, it may be seen that the conductor 139 is connected to the movable contact of a two-position switch S42 that has one of the fixed contacts thereof connected by a conductor 136 to return line 150 through a solenoid SLC that serves when energized to move the control valve VL to a position to connect the left end of cylinder 39 to the pressure source and the right end to the exhaust conduit to cause the left grab arm 13 to move inwardly towards the right grab arm 14. The other fixed contact of switch S42 is connected by a conductor 137 to the fixed contact of a switch S52 that has a movable con-tact controlled by the relay coil R5 and which is connected by a conductor 138 to the movable contact of a switch S22. Conductor 138 is also joined to a conductor 139 that is connected to return line 150 through a solenoid SVU that serves to shift valve VV to a position to connect the lower end of jack cylinder 45 to the fluid under pressure and the upper end of this cylinder to the exhaust conduit whereby the carriage and arms 13 and 14 will move upwardly. The fixed contact of switch S22 is connected by a conductor 141 to the conductor 127.

The other fixed contact of switch S11 is connected by conductor 142 to a fixed contact of switch S43 that has a movable contact under the control of relay coil R4 and which is connected by a conductor 143 to return line 150 through the solenoid SVD that serves to shift valve W to connect the upper end of cylinder 45 to the fluid under pressure and the lower end to exhaust to effect downward movement of the carriage and grab arms 13 and 1-4. The other fixed contact of switch S43 is con'- nected by conductor 144 to a fixed contact of switch S12, switch S12 having a movable contact under the control of relay coil R1 and connected by a conductor 145 to contact CR of the lever 103. A conductor 146 extends from the other fixed contact of switch S12 through solenoid SRO that shifts valve VR to connect the left end of the cylinder 35 to the source of fluid under pressure and the right end to the exhaust to effect the opening movement of the right arm 14. A second conductor 147 extends from said other fixed contact of switch S12 through the solenoid SLO to return line 150, and it will be understood that solenoid SLO controls the flow of fluid into and out of cylinder 39 to effect opening movement of the left arm 13.

A conductor 143 is connected to the movable contact of a switch S53 that is under the control of the relay coil R5, the fixed contact of S53 being connected by a conductor 149 to-return line 150 through a solenoid SRC that controls the flow of fluid into and out of cylinder 35 to effect closing movement of the right arm 14.

A conductor 151 is connected to the manual grab arms, manual control switch lever 155, and to the manual lifting jack control switch lever 156. Engageable by lever 155 are contacts 159 and 160, and engageable by lever 156 are contacts 157 and 158. Conductor 152 extends from contact 159 to conductor 149 to energize SRC. Conductor 153 extends from contact 159 to conductor 136 to energize SLC. Conductor 161 extends from contact 157 to conductor 139 to energize SVU. Conductor 16-2 extends from contact 158 to conductor 143 to energize SVD. Conductor 154- extends from contact 160 to conductor 147 to energize SLO and SRO.

In operation it will be assumed that the source of pressure 135 is operative and that the truck 10 has a motor or prime mover that is controlled by the forward control solenoid 123. The operator of the truck 10 aligns it generally so that its longitudinal axis is perpendicular to the axis of the roll 15 that is to be picked up. The grab arms control lever 103 is in the neutral position on contact N and the truck 10 is moving forward towards the roll 15 with the truck traction lever 104 in contact with the contact F. Of course, the light sources A, B and C are connected with one or more sources of energy (not shown). The circuit is thus set for automatic operation.

With the parts thus positioned and operating, the truck 10 will proceed forwardly, there being a circuit from source 100 through conductor 102, the contact N for lever 1113, lever 1G3, conductor 121, lever 104, contact F, conductor 113, conductor 118, switch S31, conductor 117, junction 116, conductor 122, and forward control solenoid 123 to return line 150. It will be recalled that movable contact of switch S31 is in the left-hand position since the relay coil R3 is energized due to the fact that the light beam for photoelectric cell C is unbroken. Also, since there is no roll 15 in the grab arms 13 and 14, the contact switches 72 and 73 will be open, relay coils R and R4 will not be energized, and the switches S51 and S41 will be open as shown.

As the truck moves forward, the grab arms 13 and 14 will pass on either side of the roll 15, and when the outer diameter of roll 15 comes into line with the photoelectric cell C and source C, the beam of light will be broken and this will open the circuit through relay coil R3 and thus the movable contact of switch S31 will move to the right; this will break the circuit through the forward control solenoid 123 and the truck will therefore stop. The operator will then shift the truck traction lever 104 to neutral and the grab arms control lever 103 to lift contact CP.

With the levers 103 and 104 positioned as just described, current will flow through conductor 102, contact N, lever 104, conductor 121, lever 103, contact CP, conductor 120, switch S62, conductor 110, switch S31, conductor 117, junction 116, conductor 122, and forward control solenoid 123 to return line 150. With this circuit completed, the truck 10 will again move forward until photoelectric cell C is energized by the passage of light through the axial opening in roll 15. This will cause a circuit to be completed through relay coil R3 to move the movable part of switch S31 to the left and thus break the circuit through the forward control solenoid 123, again stopping the truck 10, but this time with the members 70 and 71 in proper front-to-rear alignment with respect to the roll 15.

Assuming that the arms 13 and 14 are too high, the beam from source A to photoelectric cell A will be broken and this will cause the circuit through relay coil R1 to be broken and relay coil R1 will accordingly not be energized. Switch S11 will have the movable contact thereof to the right, as shown on the drawings. A circuit will then be made from contact CP through conductors 125 and 126 to the fixed contact of switch S32, and because photoelectric cell C is energized, the movable part of switch S32 will be to the left and switch S32 will be closed. Accordingly, the circuit will continue through conductor 127, switch S11 (relay coil R1 being not energized), conductor 142 to the right contact of switch S43. Since the movable contact of switch S43 it to the right, the circuit will continue through conductor 143 and solenoid SVD to return line 150. When solenoid SVD is thus energized, it will move valve VV in the direction to cause fluid to flow into cylinder 45 so as to bring the carriage with the grab arms 13 and 14 downwardly.

When the arms have descended sufficiently, the beam from source A' will energize photoelectric cell A and thus the relay coil R1 will be energized and will move the movable contact of switch S11 to the left. This will break the circuit that previously existed through conductor 125, switch S32, switch S11, switch S43, and solenoid SVD, and consequently solenoid SVD will be deenergized to return the valve VV to neutral and halt the downward movement of the arms 13 and 14.

Assuming that the grab arms 13 and 14 are too low when the truck has stopped due to the making of the beam C through the inner diameter of the roll 15, the beam to photoelectric cell B will be broken and relay coil R2 will not be energized. A circuit will be made through contact CP, conductors 125 and 126, switch S32, conductor 141, switch S22, conductor 139, and solenoid SVU to return line 150, thus energizing solenoid SVU to move the valve VV in the direction to supply pressure fluid to cylinder 45 so as to raise the carriage and the arms 13 and 14.

When the arms 13 and 14 have been raised sufliciently, the beam from source B will again energize the photoelectric cell B, the beam being made through the inner diameter of the roll 15. This will cause the relay coil R2 to be energized and to thus move the movabl contact of switch S22 to the left, opening switch S22 and the circuit through solenoid SVU, and thus returning the 8 valve VV to neutral and stopping the arms 13 and 14 in the proper position.

The sequence of movement above described, beginning with photoelectric cell C, is exemplary, and obviously changes may be made to begin the sequence otherwise.

Each of photoelectric cells A, B and C is now energized, and thus the arms 13 and 14 are in proper position relative to the inner diameter of roll 15. A circuit will then be made from contact CP through switch S32 (to the left), switch S11 (to the left), switch S21 (to the left), and conductor 129 to conductor 130. The circuit continues through conductor 130, switch S42, and conductor 136 to return line 150 through solenoid SLC, which latter moves the valve VL to close the left arm 13. Also, a circuit is made through conductor 130, conductor 131, conductor 148, switch S53 to return line 150, through solenoid SRC to thus close the right arm 14.

A circuit will also be made from conductor through conductor 131, and relay coil R6 to return line 150, thus causing the movable contacts of switches S61 and S62 to move to the right; switch S61 will be closed and will act as a holding switch for the relay coil R6.

As the grab arms 13 and 14 close by virtue of the circuits noted above, the contact switches 72 and 73 on the grab arms 13 and 14 will contact the sides of the roll 15 and thus will make a circuit through the relay coils R4 and R5. Consequently, each of the movable contacts of the switches S41, S42, S43, S51, S52 and S53 will be moved to the left. Movement of the movable contact of switch S42 to the left will break the circuit through solenoid SLC to stop the closing movement of left grab arm 13, and movement of the movable contact of switch S53 to the left will break the circuit through solenoid SRC, thus stopping the closing movement of the right grab arm 14. The closing movement of each grab arm is stopped as soon as it contacts the side of the coil.

With switch S61 closed, a circuit is made from contact CP through it, through conductor 130, switch S42, conductor 137, switch S52, conductor 138, and conductor 139 to return line 150, through solenoid SVU to effect the raising of the carriage with the arms 13 and 14.

With the roll 15 thus raised, the operator places lever 103 on contact N and places lever 104 on contact F.

A circuit will be completed from contact F to return line through the forward control solenoid 123. The truck traction lever 104 is then used in normal manner to maneuver the truck to the desired position where the roll 15 is to be put down. When the roll 15 is over its delivery position, the lever 104 is returned to neutral and the lifting arms control lever 103 is placed in contact with the contact CR. A circuit will then be made through conductor 102, levers 104 and 103, conductor 145, and switch S12, Photoelectric cell A, which is the upper photoelectric cell, is not energized because of the presence of the roll between it and the source A, and accordingly relay coil R1 is not energized and the movable contact of switch S12 is to the right. Accordingly, the circuit will be made through the switch S12, conductor 144, switch S43 (which is to the left), conductor 143 to return line 150, through the solenoid SVD. This will lower the carriage and with it the grab arms 13 and 14 as above described. As the grab arms 13 and 14 descend, the roll 15 will touch the ground or floor and the arms will continue their downward movement. This will cause the photoelectric cell A to be energized from the source A through the inner diameter of the roll 15, and the movable contact of switch S12 will be moved to the left. There will then be a circuit from the contact CR through conductor 145, switch S12 (which is to the left), and the solenoids SRO and SLO to open the arms 13 and .14. The outward movement of the arms 13 and 14 causes the contact switches 72 and 73 to open.

If the operator desires to move the carriage up and down, or to close and open the grab arms for manually controlled operation, he may do so by shifting switch levers 155 or 156. By shifting lever 155 to contact 159, a circuit is made from conductor 102 through conductor 151, lever 155, contact 159, conductor 152, through solenoid SRC to return line 150, also from contact 159 through conductor 153 and solenoid SLC to return line 150. The grab arms 13 and 14 will be moved to closed position.

When the lever 155 is moved to contact 160, a circuit will be made from conductor 102, through conductor 151, lever 155, contact 160, conductor 154, conductor 147, and solenoids SLO and SRO to return line 150. The grab arms 13 and 14 will then open.

When the lever 156 is moved to contact 157, a circuit will be made from conductor 102, through conductor 151, lever 156, contact 157, conductor 161, and through solenoid SVU to return line 150. The carriage with the grab arms will then be raised.

When the lever 156 is moved to contact 158, a circuit will be made from conductor 102, through conductor 151, lever 156, contact 158, conductor 162, and solenoid SVO to return line 150. The carriage and with it the grab arms will then be lowered.

The circuitry shown in FIG. 8 is in addition to other circuitry known in the art for operating any or all parts of the truck 10, particularly its traction.

It will thus be seen that there has been provided a fork lift truck particularly adapted for lifting objects having a hole therethrough, especially rolls of metal or the like. The lift truck or other handling apparatus in accordance with this invention is capable of fully automatic engagement and lifting of the article and of fully automatic lowering and disengagement of the article, In addition, ample safety provisions have been included in order to make the operation of the handling apparatus in accordance with this invention substantially foolproof.

The apparatus of the present invention has many advantages over the prior art devices in that articles that may be easily damaged by rough handling may be picked up, transported, and deposited without in any way being damaged by the handling equipment. The automatic control of the arms that engage the article insures that the arms will never be abruptly brought into contact with the article, thereby avoiding damage thereto.

It will be obvious to those skilled in the art that various changes may be made without departing from the spirit of the invention, and therefore the invention is not limited to what is shown in the drawings and described in the specification but only as indicated in the appended claims.

Having described my invention, I claim:

1. Handling apparatus comprising a lift truck having a prime mover, a frame, a carriage mounted for vertical movement on said frame, spaced left and right grab arms extending generally horizontally from said carriage, means mounting said grab arms on the carriage for horizontal movement to open and close the same, said grab arms each having opposed inwardly extending lifting members, first, second and third light sources and first, second and third photoelectric cells paired therewith, said light source of each pair being on one arm and the photoelectric cell of each pair being on the other arm, the light beam path of said first pair extending between said grab arms above said lifting members, the light beam path of said second pair extending between said grab arms below said lifting members and the light beam path of said third pair extending between said grab arms rearwardly of said lifting members, left and right hydraulic cylinders mounted on said truck and connected to move said left and right grab arms, a valve hydraulically connected to each of said cylinders, said valves being connected to a source of fluid under pressure and each having a neutral position in which no fluid is admitted to the cylinder and grab arm opening and closing positions, a vertical hydraulic cylinder mounted on said truck to move said carriage vertically on the frame, a valve hydraulically connected to said vertical cylinder and to a source of fluid under pressure and having a neutral position in which no fluid is admitted to the cylinder and carriage raising and lowering positions, a pair of solenoids for each valve to move it when energized to one or the other non-neutral positions, a contact switch on each of said arms closable upon contact thereof with an article when the arm thereof moves inwardly, a truck traction lever for moving said truck forward or backward and engageable with forward, neutral and reverse contacts, a grab arms control lever engageable with pickup, neutral and release contacts, a source of energy connected with said neutral contacts, a conductor between said levers, first, second and third photoelectric cell circuits connected between said source and a return line and having said first, second and third photoelectric cells therein respectively, first and second contact switch circuits connected between said source and return line each having one of said contact switches therein, circuit means operable when said traction lever is in forward position for deenergizing said prime mover upon opening of said third photoelectric cell circuit, circuit means operable when said traction lever is in neutral position and said control lever is in pickup position for energizing said prime mover while said third photoelectric cell circuit is open to thereby advance said truck, circuit means for deenergizing said prime mover upon reclosing of said third photoelectric cell circuit to thereby stop said truck, circuit means including the carriage lowering solenoid for lowering said carriage when said first photoelectric cell circuit is open, circuit means including the carriage raising solenoid for raising said carriage when said second photoelectric cell circuit is open, circuit means including the arms closing solenoids for closing said arms when said first, second and third photoelectric cell circuits are closed, and circuit means including the carriage raising solenoid for raising said carriage when said first, second and third photoelectric cell circuits and said first and second contact switch circuits are closed.

2. The apparatus of claim 1 and further including circuit means for permitting energization of said prime mover, when said control lever is in neutral and said traction lever is in other than neutral and said third photoelectric cell circuit is closed, only when said first and second contact switch circuits are closed.

3, The apparatus of claim 1 and further including a circuit for energizing, when said traction lever is in neutral and said control lever is in release, the carriage lowering solenoid to thereby lower said carriage with its arms. 1

4. The apparatus of claim 3 and further comprising circuit means for energizing, when said traction lever is in neutral and said control lever is in release, the arms opening solenoids upon reclosing of said first photoelectric cell circuit.

5. Handling apparatus comprising a lift truck having a prime mover, a frame, a carriage mounted for vertical movement on said frame, spaced left and right grab arms extending generally horizontally from said carriage, means mounting said arms for horizontal movement to open and close the same, said arms each having opposed inwardly extending lifting members, first, second and third paired photoelectric cells and light sources positioned on said arms respectively above, below and rearwardly of said lifting members, means for moving said arms vertically, means for energizing said prime mover upon deenergization of said third photoelectric cell and for de energizing said prime mover upon reenergization of said third photoelectric cell, means for actuating said arms moving means to lower said arms upon deenergization of said first photoelectric cell and for stopping said arms moving means upon reenergization of said first photoelectric cell, and means for actuating said arms moving means to raise said arms upon deenergization of said second photoelectric cell and for stopping said arms moving means upon reenergization of said second photoelectric cell.

6. The apparatus of claim 5 and further including means 1 1 for closing said arms, and means for actuating said arms closing means upon energization of all three of said photoelectric cells.

7. The apparatus of claim 6 and further including a contact switch on each of said arms, said arms closing eans being individually operable, and means for stopping the arms closing means of one of said arms upon closing of the switch on said arm.

8. The apparatus of claim and further including a contact switch on each of said arms, and means for actuating said arms moving means to raise said arms upon energization of said photoelectric cells and closing of said switches.

9. The apparatus of claim 5 and further including means for opening said arms and means for actuating said arms opening means upon energization of said first photoelectric cell.

10. Apparatus for handling articles having a hole therethrough comprising a pair of spaced grab arms, means for opening and closing said grab arms, means for moving said arms in a transverse direction relative to said article, means for moving said arms in the direction thereof, said arms having opposed lifting members adapted to enter the hole in said article, means for raising and lowering said grab arms, and sensing means mounted on said grab arms for sensing the relative position of said lifting members and the hole in said article to move said lifting members and grab arms toward said hole.

11. The apparatus of claim 10, said sensing means comprising photoelectric cell means.

12. The apparatus of claim 10 and further including means responsive to said sensing means for actuating said arms moving and opening and closing means to cause said members to enter said hole.

13. The apparatus of claim 12 and further including means for sensing the full entry of said members in said hole upon closing movement of said arms, and means responsive to said latter-mentioned sensing means for stopping said closing movement.

14. Apparatus for handling easily damaged articles comprising a carriage, means for moving the carriage forwardly and rearwardly, means for raising and lowering the carriage, article engaging arms carried by the carriage, means for shifting the arms towards and away from each other, and sensing means carried by the arms and responsive to positioning of the arms with relation to an article for actuating the means for moving and raising the carriage and for actuating the means for shifting the arms to insure determined engagement of the arms with the article.

15. Apparatus for automatically sensing the configuration of and for handling easily damaged articles comprising a carriage, means for moving said carriage forwardly and rearwardly, means for raising and lowering said carriage, article engaging arms carried by said carriage, means for shifting said article engaging arms towards and away from each other, article engaging members mounted on said article engaging arms to engage an article to be handled, and sensing means carried by said article engaging arms and being responsive to sensing the configuration of said article to be handled and to positioning of said article engaging arms with relation to said article for actuating said means for moving and raising said carriage and for actuating said means for shifting said article engaging arms to insure determined engagement of said article engaging members with said article.

References Cited in the file of this patent UNITED STATES PATENTS 2,143,779 Kaufman Jan. 10, 1939 2,512,409 Adde June 20, 1950 2,602,562 Bresciani July 8, 1952 2,652,167 Havener Sept. 15, 1953 2,900,521 Eames Aug. 18, 1959 FOREIGN PATENTS 1,162,655 France Apr. 14, 1958

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