US1510176A - Automatic lifting grab - Google Patents

Description

Sept. 30', 1924. 1,510,176

s. c. KNIGHT AUTOMATIC LIFTING GRAB Filed June 30, 1922 3 Sheets-Sheet l g 28 FIG. 1. l

FIG. 3.

Susan-V NVE/VTOR;

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S. C. KNIGHT AUTOMATIC LIFTING GRAB Se t. 30 1924.

Filed June 50, 1922 3 Sheets-Shaet 2 vl IL PIC-3.6.

N YE/VTORZ L 7 77 Wm WM ATTY.

Sept. 30, 1924.

S. C. KNIGHT AUTOMATIC LIF'I'ING GRAB Filed June 30, 1922 3 Shan -Sheet 5 b.. urvv FIG. 7.

i atented Sept. 30, 1924;

UNITED STATES STANLEY CHRISTIE KNIGHT, OF GOSFORTH, ENGLAND.

AUTOMATIC LIF'IING GRAB.

Application filed June 30, 1922. Serial No. 572,000.

To all 107mm it may concern:

Be it known that I, STANLEY CHRISTIE Kmcrrr, a subject of the King of Great liritain and Ireland, residing at Gosforth, in the county of Northumberland, England, have invented new and useful Improvements in Automatic Lifting Grabs, of which the following is a specification.

This invention relates to automatic grabs for lifting plates, girders, bars, shells, bar- I'cls, rectangular cases and other bodies, and has for its object to provide an improved construction.

In an automatic lifting grab in accordance with my invention relative movement occurs, when the grab engages the body to be raised, between the frame of the grab wherein the gripping jaws are mounted and the member with which the lifting tackle co-acts and which takes the weight of said body, and said relative movement in one direction is utilized through levers to cause the jaws to approach and grip the body, the gripping power being proportional to the weight of the body being raised, relative movement between said parts in the reverse direction when the grab is lowered and the body is supported by the ground or otherwise retracting the jaws and releasing the body. Means may be provided whereby the retraction of the jaws and consequent release of the body is prevented until desired.

I will more fully describe my invention with reference to the accompanying draw iugs wherein a Figure 1 is an elevation of a plate-lifting grab constructed in accordance with my invention, one side of the frame being removed for clearness;

Figure 2 is a section on the line XX in Fig. 1 to a larger scale;

Figure 3 is a section on the line Y-Y in Fig. 2; and

Figure 4 is a part similar view to Fig. 1 illustrating the parts in the gripping position.

Figures 5 and 6 are two elevations at right angles of a barrel-lifting grab constructed in accordance with my invention; and

Figure 7 is a part central section to a larger scale.

. Referring first to Figs. 1 to 4 of the accompanying drawings, the lifting grab therein illustrated is intended for lifting steel or like plates or slabs of marble, slate or stone. In this example the gripping jaws 10 are pivoted at 11 to the inner ends of two oppositely-disposed levers 12 pivoted at 13 between the side members 14 of the frame, the outer ends of the levers 12 carrying pins 15 working in slots 16 in the outer ends of pairs of levers 17 pivoted at 18 between the frame members 14 and having slots 19 at their inner ends (which cross) engaging pins 20 projecting from a central block 21, the arrangement being such that upward movement of the block 21 moves the jaws 10 together and downward movement of said block moves the jaws apart, said movements of the block being in relation to the frame 14. The block 21 is provided with a central downward extension 22 adapted to engage the upper edge of the plate to be lifted and is guided in the frame members 14 by the engagement of the block 21 with a vertical spindle 23 carried by cross bars 24 mounted between the frame members 14 and by the engagement of the pins 20 with ribs 25 on the inside of the frame members 14. The block 21 and extension 22 are hollow, and passing through them is a central spindle 26 which normally projects below the extension 22. The spindle 26 has a head 27. The lifting tackle 28 is attached to a collar 29 loose on the spindle 26 and normally resting on the upper cross bar 24.

The collar 29 is provided with opposite one-way catches 30 mounted on oppositelysliding plates 31. When the catches 30 are projected they engage stops 30 on the frame members 14, but they are adapted to be retracted by side bars 32 attached by pivoted links 33 (Fig. 2) to the spindle 26 and at their bottom ends by links 34 to feet 35 engaging recesses in the block 21 whereby said bars are anchored to the block, movement of the spindle 26 relative to the block 21 (which occurs when the spindle 26 engages the top of the plate to be lifted), moving said bars outwards and, through the sliding plates 31, retracting the one-way catches 30 against the action of springs 36 (Fig. 3) attached at one end to the plates 31 and at the other to the collar 29. It will be seenthat the right hand bar 32 retracts the left hand catch (and vice versa), the bars engaging pivoted projections 31 on the plates 31, said projections being mounted so that they are free to turn up on their pivots against the action of springs 31".

In use, the grab is lowered onto the plate which is indicated at 37 in Fig. 4, so that the jaws 10 He en either side thereof, the weight of the grab being supported by the lifting tackle 28 through the one-way catches 30 which engage'the stops 30' on the frame members 14. When the lower end of the spindle 26 engages the upper edge of the plate 37, the spindle is moved upwards relatively to the block 21 and the catches 30 are retracted by the consequent outward movement of the bars 32 and disengaged from the stops 30. The downward extension 22 of the block then engages the upper edge of the plate 37, and as the downward movement of the grab continues, the consequent upward movement of the block relatively to the frame causes the levers 17, 12 to move the jaws 10 together to grip the plate 37 between them. The grab can now be raised. Upward move ment of the lifting tackle 28 lifts the collar 29 past the stops 30 (the catches 30 being still retracted) into engagement with the head 27 of the spindle 26. This is-the position illustrated in Fig. 4. Further upward movement of the lifting tackle picks up the grab with'the plate 37 securely held .be-

' tween the jaws 10. On the grab being subsequently ,lowered until the plate 37 is supported by the ground or otherwise and the downward movement of the lifting tackle being continued, the collar 29 falls on the spindle 26, the pivoted projections 31 turning up when they strike the tops of the side bars 32 so that the catches 30 are not retracted by said bars although the bars are still in the extended position. The one-way catches 30 pass the stops 30 as the collar falls. When the lifting tackle is again raised, the catches 3O engage the stops 30 and the frame is raised but the weight of the block 21 keeps its downward extension in engagement with the upper edge of the plate 37 until the frame 14 has moved upwards relatively to the block which movement, through the levers 17, 12, causes the jaws 10 to disengage the plate. As the grab leaves gie plate 37, the block 21 and spindle 26 r urn to their normal positions and the bars 32 are retracted allowing the pivoted projections 31 to resume their original position.

If desired, a rack 38 (Figs. 1 and 4) may be provided, said rack being carried by cross members 39 between the frame members 14.

and a spring pawl 40 mounted upon the block 21, said pawl permittin upward movement of the block relative y to the frame but automatically locking the block in its raised position until said pawl is disengagedfrom the rack 38 by pulling a chain 41. Where this rack and pawl is fitted, the plate 37 will not be automatically disengaged upon being supported by the ground or otherwise when the grab is raised again. Disengagement of the plate 37 will not occur until the pawl 40 is disengaged from the rack 38.

Figures 5 to 7 illustrate a modified construction of, grab intended for lifting barrels. In this example the jaws 10 are pivoted at 11 between the lower ends of the side members 14 of the frame and are provided with tail pieces 42 pivoted at 43 to links 44 pivoted to a block 21 sliding on the centre spindle. 26 so that upward movement of the block 21 moves the jaws 10 together and downward movement of said block moves the jaws apart said movement of the block being in relation to the frame 14. The lifting tackle is attached to a shackle 28 bolted to the collar 29 loose on the spindle 26. In a slot 45 in the spindle 26 is pivloted a catch 46 which is weighted at its upper end and provided at its lower end. with a step 47 adapted to engage the bottom of 'a sleeve 48 loose on the spindle 26. Normally the lower end of thecatch 46 lies within the bore of the block 21. A flange 49 around. the top of said sleeve engages stops 50 on the frame members 14 and limits the downward travel of said sleeve. The sleeve 48 is goned internally as shown at 51 (Fig. 7), and said coned portion coacts with pawls 52 pivoted at 53 to the collar 29, said pawls normally engaging stops 54 on the frame members 14.

In use, the grab is suspended by the shackle 28, the frame 14 bein supported by the engagement of the paw s 52 with the stops 54 as shown, the lower end of the spindle 26 projecting below its frame. The grab is lowered onto the barrel to be lifted so that the jaws 10 embrace said barrel. The lower end of the spindle 26 comes against the top of the barrel, and, the downward movement of the grab continuing, the spindle 26 rises relatively to the frame. This upward movement of the spindle disengages the lower end of the catch 46 from the bars of the block 21, and, by reason of the greater weight of the upper end of said catch, its lower end is projected beyond the spindle 26 whereby the step 47 thereon is caused to engage the bottom of the loose sleeve 48. A spring may, if desired, be provided behind the catch 46 to project its lower end when it clears the bore of the block 21. Simultaneously therewith the enlarged lower end of the spindle 26 picks up the block 21 and, the upward movement of Ill) the spindle 26 relative to the frame 14 continuing, the jaws 10 are moved together to grip the barrel by the co-action of the links 44 with their tail pieces 42, and the coned internal face 51 of the sleeve 48 disengages the pawls 52 from their stops 54 thus freeing the collar 29 from the frame. The grab can now be raised. On the grab-being lifted, the collar 29 engages the head 27 of the spindle 26, the lower end 'of said spindle keeping the block 21 in its ralsed pos1t1on whereby the jaws 10 are caused to grip the barrel. Upon subsequently lowering the grab until the barrel rests on the ground or otherwise, the collar 29, the block 21 and the sleeve 48 will all move downwards relatively to the frame and the parts will resume their normal positions with the pawls 52 engag ing their stops 54 so that, when the grab is again lifted, the collar 29 will be locked by the pawls 52 to the frame and the jaws will disengage the barrel and be lifted clear away therefrom.

While I have described as examples of lifting grabs in accordance with my invention, a grab for lifting plates and one for lifting barrels, by suitably modifying the shape and travel of the lifting jaws, the grabs may be adapted for liftin girders, bars, shells, rectangular cases and other bodies. I may suspend a number of lifting grabs from a framework whereby they are retained in suitable relative positions, said framework being ada .rted to be raised and lowered by lifting tac kle, said grabs simultaneously engaging, gripping, raising, lowering and releasing a corresponding number of plates, barrels or other bodies.

By my invention I provide a grab which is entirely automatic in action, and which is locked in the gripping position before the plate or barrel or other body is raised from the ground. My improved grab acts immediately it is lowered onto the plate, barrel or body to be lifted, and releases same immediately the load is taken off the grab (except where the grab is provided with a rack and pawl locking arrangement as hereinbefore described). It does not require to be locked or re-set by hand and is therefore fool-proof. Working automatically and without the need of an attendant, my improved grab may be used for picking up red-hot ingots or for similar purposes where it is not possible for a workman to be near, the jaws and adjacent parts of the grab being suitably protected from the heat;

I wish it to be understood that the details and arrangements of the members of my improved automatic lifting grabs may be modified without departing from the spirit of my invention.

What I claim as my invention and desire to secure by Letters Patent is 1. An automatic lifting grab comprising a frame, jaws ivoted thereto adapted to grip the body to be lifted, a member capable of movement relatively to said frame, pivoted links connecting said member to said jaws, and lifting tackle connected to said member, relative movement in one direction between said member and frame causing the jaws to approach and grip the body which movement automatically occurs when the grab engages the body, and relative movement in the reverse direction between said member and frame causing the jaws to retract and release the body which reverse movement automatically occurs when the weight of the body is taken off the grab.

2. An automatic lifting grab com rising a frame, jaws pivoted thereto adapte Y to grip the body to be lifted, a. member capable of movement relatively to said frame, pivoted links connecting said member to said jaws, lifting tackle connected to said member, relative movement in one direction between said member and frame causing the jaws to approach and grip the body and relative movement in the reverse direction between said member and frame causing the jaws to retract and release the body, and .means whereby the retraction of the jaws and consequent release of the body is prevented until desired.

3. An automatic lifting grab comprising a frame, a pair of oppositely-disposed levers pivoted thereto, gripping jaws carried by said levers, a central spindle capable of movement relatively to said frame, a collar loose on said spindle, lifting tackle attached to said collar, a block loose on said spindle, pivoted links connecting said block to the aw-carrying levers, relative movement in one direction between said block and said framecausing the jaws to approach and in the reverse direction retracting said jaws, means for locking the collar to the frame, and means actuated by the relative movement between the spindle and the block for retracting said locking means when the spindle engages the body to be lifted and for re-locking the collar to the frame when the grab is lowered and the jaws are relieved of the weight of the body.

4. An automatic lifting grab comprising a frame, a pair of oppositely-disposed levers pivoted there-to, gripping jaws carried by said levers, a central spindle capable of movement relatively to said frame, a collar loose on said spindle, lifting tackle attached to said collar, a block loose on said spindle, pivoted links connectingv said block to the jaw-carrying levers, relative movement in one direction between, said block and said frame causing the jaws to approach and in the reverse direction retracting said jaws, means for locking the collar to the frame, means actuated by the relative movement between the spindle and the block for retracting said locking means when the spindle enosition when the gages the body to be lifted and for re-lockmg the-collar to the frame when the grab is lowered and the jaws are relieved of the weight of the body, a rack on the frame and. a spring awl on the block (or vice versa) whereby t e return of said block to normal b' is lowered and the aws are relieved of tl ie wei ht of the body is prevented until said paw is disengaged 10 from said rack by hand.

In testimony whereof I have signal my name to this specification.

STANLEY CHRISTIE KNIGHT.

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