US889126A - Automatic safety device for cranes. - Google Patents

Description

No. 889,126. PATENTED MAY 26, 1908.

N. S. HASELTINB. 7 AUTOMATIC SAFETY DEVICE FOR GRANES.

APPLIOATION IILED AUG. 16, 1907.

2 SHEETS-SHEET 1.

INVENTOR No. 889,126. PATENTED MAY 26, 1908.

N.- S. HASELTINE.

AUTOMATIC SAFETY DEVICE FOR GRANES.

I APPLICATION FILED AUG. 16, 1907.

2 SHEETSSHEET 2 wrfnzssas mvzu'ron PATENT ()FFIOE.

NATHAN s.- HAsEL'riNE, or SWISSVALE, PENNSYLVANIA.

AUTOMATIC SAFETY DEVICE FOR CRANES.

Specification of Letters Patent.

Patented May 26, 1908.

Application filed August 16, 1907. Serial No. 388,773.

To all whom it may concern:

Be it known that I, NATHAN S. HASELTINE, a citizen of the United States, and residing in the borough of Swissvale, in the county of Allegheny and State of Bennsylvania, have invented or discovered new and useful Improvements in Automatic SafetyDevices fbr Cranes, &c., of which the following is a specification.

19 My invention consists in a new and improved safety switch for electric cranes and similar mechanisms, whose ofiice is to automatically break the power circuit and stop the operation of the mechanism to prevent accident.

The invention is arranged to be operated automatically by the mechanism without the interference of the operator, so that accident-from the carelessness of the operator or loss of control of the mechanism is avoided.

In illustrating and. describing my invention I have shown it arranged to prevent an overwind of an electric crane but it will be evident that it may also be arranged to prevent too great lowering of the load Without altering the cardinal features of the invention.

, In the construction shown I have illustrated a convenient method-of wiring whereby, when the safety switch has been thrown,

i means where y, after the switch is unlocked,

it is ki ed forcibly out of engagement with the contact thus overcoming any slight ins ing between switch and contact and assisting the sp g which is usuall provided to throw out the switch when'the KJcking means is re leased.

I also shownovel construction and arrangement of parts and'operative connecvtionsto attain the above results which will p aphpgar from-the following description.

the accompanying drawings, which are merelyillustrative ofthe practical adaptation of my inventionand not intended to limit the scope thereof to the construction shown, Fig- 5 5 -ure 1 is a front elevation of myinvention-shown l operativelyconnected to the cable drumof a crane or other mechanism; Fig. 2 is a side elevation of the same looking in the direction of the arrow in Fig. 1, partially in section along the line [III in said figure; Fig. 3 is a rear elevation of the switch board showing the wire connections; Fig. 4 is a diagrammatic figure illustrating a convenient method of wiring a crane for my invention, while Fig. 5

is a front elevation of a modification of the structure of Fig. 1 wherein the switch is operated by the cable block.

The following is a detailed description of the drawings: 1 is a cable drum whose shaft 2 is operatively connected by any convenient means to a Worm shaft 3 j ournaled in a frame 4 attached to the crane.

5 is a switch board, preferably consisting of a triangularwooden board, also secured to the crane. I

6 is a switch lever pivoted to the top of board 5 by stud -7 which passes through said board and to which an electric wire is attached to place said switch in circuit.

. 8 and 9 are contacts of the ordinary spring 30 design placed at either of the lower corners of board 5, into engagement with either of which contacts the switch 6 may be brought.

10 is an arm keyed to stud 7 so as to be stationary. l 8 5 11 is a spiral or other spring attached at one end to arm 10 and at its other end to the switch 6 adjacent to its lower end. The point of connection between said spring and said switch is a handle by means of which said switch may be thrown by hand. It is, evident that spring 11 will automatically throw and maintain switch 6 in engagement with contact 9 unless said switch is lockedin engagement with contact Sin the manner to be described.

13 is an extension plate secured to board 5 -in any convenient manner and tofiwhich is pivoted the bell crank lever 14' provided with three-arms, 15,16 and 17. The lower arm 15 is pivoted at its free end to one end of the link 18 whose outer end is pivoted to the u per end oflever 19 which is pivoted interme iate of its ends to cars 20 mounted on frame 4.

On worm shaft 3 moves screw block 21 whose up er extremity extends through longitudina'slot 22 in frame 4, thus preventing saidf block from rotating with the worm and causing it to move lengthwise; ofsaid slot. The

ing'up' the drum the block moves toward the depending end of lever 19 and in unwinding worm and block are arranged so that in windthe drum the movement of the block is in the other direction. The lever 19 extends downwardly sufiiciently to be engaged by said block 21 when the drum has been wound up to a predetermined limit where the drum must be stopped to prevent accident. When 'theblock comes into contact with lever 19, it kicks the lower end thereof toward the right iii-Fig. 1, thus moving the link 18 longitudinally toward the left, rocking the bell crank lever 14 toward the right on its pivot point. The arm 16 of lever 14 is provided at its outer end with a lateral stud 23 which engages a slight notch in the lower portionof switch 6 thus locking theswitch when the lever 14 is in the position shown in Fig. 1. It is evident that the rocking of said lever 14, as above described, will depress the arm 16 and release the switch so that the spring 11 may throw the same out of engagement with contact 8 and into engagement with contact 9. As it frequently happens that the switch refuses to respond to the tension of the spring owin to a slight fusing of metal between the switch and the contact 8, I provide the following means for disengaging the switch from said contact to permit the spring to work efi'ectually.

The upper arm 17 is provided with a lateral roller stud 24 which when the lever 14 is rocked as described, comes into forcible contact with the switch 6 thus kicking it out of engagement with the contact 8 it is thus evident that when the cable drum has been wound up to a predetermined point, beyond which. there is danger of an accident, the block 21 throws lever 19, thus rocking lever 14, releasing the locking pin 28, kicking the switch 6 out of engagement with contact 8 and allowing the spring 11 to throw said switch into engagement with contact 9.

in Fig. 1 l have shown a convenient method of wirin for my invention. 35 represents the motor and 26 its iield. 27 represents the positive main and 28 the ne ative main. The controller .is represented by points a, b, c, and (Z. The positive main 27 is connected to controller point d while the negative 11min 28 is connected to hold 26. The motor 25 is connected by wire 3-9 to switch 6 and also to point I) by wire 30. The contact 8 connected by wire 31 to point 0, and the contact 9 is comicctcd to point a by wire 32 which is also connected to hold '26 by wire :53. When the switch 6 is in engagement with contact 8, as shown in full lines in Fig. 4, as is its position in the normal operation of the crane or other mechanism titted with my invention, by scttin g the controller so that point a is connected with point Z ,'aiid point c with point (1 the motor will be dri\ on in one direction, say, in the proper direction to wind up the cable on the drum. ii, on the other hand, the points a and c be connected, and likewise the points b and d, the motor will be reversed and the cable unwound. When the points a and b, and the points 0 and d are, respectively connected, as the drum winds up ,the cable, the screw block 21 will gradually approach the lever 19 until, when the predetermined danger point is reached, the block 21 will force aside said lever 19, unlocking the switch 6 and kicking it out of engagement with contact 8 and throwing it into engagement with contact 9. It is evident that since the former circuit through switch 6, contact 8 and wire 31 is broken, the motor will come to a stop and the winding up of the cable cease. By throwing the controller to reverse the motor so that points a, and c, and Joints 6 and (Z, are respectively connected, t us unwinding the drum, a circuit is established through main 27, wire 30, motor 25, Wire 29, switch 6, contact 9, wire 32, wire held 26 and main 28, thus allowing the motor to operate. It is thus evident that while the load may be lowered, it can not be raised further while the switch 6 is in contact with contact 9. If contact 9 be omitted, it is evident that when switch 6 ceased to engage contact 8, no circuitcould be established through the motor and the crane could not be operated until the switch 6 is again set in engagement with contact 8.

After the operation of the switch 6 as above described, the load is lowered, retreating screw block 21 to the left thus allowing the switch 6 to be swung back, by the operator seizing handle 12, into engagementwith con tact 8 and the bell crank lever to be swung back into its normal position, by means oi handle 34. formed thereon for the purpose, locking switch 6 in place by means of pin 23. The crane is now once more in condition to be operated either for elevating or lowering loads.

While I have described the above construction as used to prevent an overwind, by reversing the conslruction it may be used to prevent a too great lowering of tho load. All that would be required would be a reversal of the pitch of the thread in block 21 to permit its approach to lever 19 when the drum is beingunwound and such change in the wiring as to break the lowering circuit when the switch 6 is thrown out oi contact with contact 8. ()r if desired a second switch mechanism may be installed to control the lowering o'l' loads which may be actuated by the block 21 when it approaches its limit of travel to the left of Fig. 1. The consiruc tion in all cases would be the same but a slight and sell" evident change in wiring would be rermircd. I 7

In ll 5 i show a modilicd form of switch actuating mechanism wherein the switch is thrown by the cable block instead of the drum shalt, a method found especially applicable to some types of cranes. Herein '35 is the cable block mounted on cable 36'wound crane. 39 is a lever pivoted intermediate of wardly extending 20 e on drum'l and 37is the" equalizing sheave mounted on stationary portion 38 of the its endsto portion 38 and provided at its outer end with weight 40. On the other side of the pivot point a weight 41 is suspended from said lever by means of aphain 42, said weight being heavy enough to'overbalan'ca weight 40. A stop 43 is p ovided to prevent the lever 39 swinging-'below the horizontal through the influence of We ht 4-1. The

Weight 41-is provided "at its si es with vertical rooves or'recessesj4 {14 in which travels t e cable 36, thus main aining said weight in alinement with and above the cable block weight .41 and 'ari'ies "the same up with-it,

thus allowing t e weilght 40 to'draw down the outerend of the ever 39,- thus in turn raising the inner end of .said lever which operates to raise "the outer end of arm 15 of lever 1 ,releasin .lockin pin 23 from the switclfufi and kic ing sai switch over, into engagement withc'o'ntactQ with the results above described. By arranging the lever 39 to be thrown by the 'descent of'the cable block, this m'odification.inay be 'ada ted to arrest the descent of the load as we as the elevation thereof.

-- Many modifications of themechanis m used illpstrate thepractical adaptabilit' of my 'broadly:' V T 1. In electric cranes-and similar mechanisms, a safety switch, means for locking and invention will occur to those skille in the art but' I do not iimit'mgselfto the construction shown in the rawings but claim switch in its closed position, means actuated by the operation ofsaidcrane beyond a predetermined point for disengaging said locking'means and means also actuated the operation of saidzcranebeyond a pre etermined point for disengaging said switch from the contact. y

2. In electric cranes and similar mechanisms, asafety switch, means for locking said switch in its closed position,.means actuated by the operation of said c'rane'beyond a predetermined point for discn'g agin said lockmg means, means also actuated y the operat on of said cranebeyond a predetermined point for disengaging said switch'from' the contact and spring actuated means for throwing said-switch out of its'closed position. i

3. In electric cranes and similar mechark isms, a safety switch, means for locking said switch in its closed position, means actuated by the operation or" said crane beyond a re determined point for disengaging said 100 ing means and a member also actuated by the operation of said crane beyond a predetermined point adapted to kick said switch out of e agement with the contact.

4. 11 electric cranes and similar mechanisms, a safety switch means for locking said bwitch in its closed position, means actuated by the operation of said crane beyond a pre determined point for disengaging said locking means, a meinber-also actuatedb the mined point adapted to kick said switch out of enga ement with the contact and spring actuate means-for throwing said switch ont of its closed position.

5. In electric cranes and similar mechanoperation of said crane beyond a pre eter= isms, a safety switch, means whereby when said switch is closed said crane may be operated in either direction, means whereby when saidswitch is open said crane may be operated in but on direction and means whereby t e operation of said crane-beyond a predetermined oint throws said switch.

Signed at Pitts urg, Penna this 14th day .of August, 1307.

r NATHAN Witnesses: I

WALTER FAMARISS', ,ED'WARD LAURENCE.

s. HASELTINE.

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