US1205425A - Grab. - Google Patents

Description

D. .I. BARNARD.

GRAB.

APPLICATION FILED MAY 4, 1912.

1,205,425. Patented Nov. 21, 1916.

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D. J. BARNARD.

GRAB.

APPLICATION FILED MAY 4, I9I2.

Patented Nov. 21, 1916.

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D. J. BARNARD.

G RAB. APPLICATION FILED MAY 4,1912.

1,205,425. Patnted Nov. 21, 1916.

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DUDLEY JaMEs BARNARD, 01 EAST HAM, ENGLAND.

GRAB.

Specification of Letters Patent.

Patented Nov. 1916.

Application filed May 4, 1912. Serial No. 695,069.

To all whom it may concern:

Be it known that I, DUDLEY JAMES BAR- NARD, a subject of the King of Great Britain and Ireland, residing at East Ham, England, have invented a new and useful Improvement in Grabs, of which the following is a specification.

This invention relates to grabs of what is known as the single chain type, that is to say, in which the hoisting chain or rope is employed for also closing and opening the bucket. In such grabs of this type as concern the present invention the hoisting chain or rope is wound upon a wheel or drum which is automatically locked and unlocked at the proper times and cooperates with or controls the bucket closing and tipping'de-- vice. V

The main object of the present invention is to provide means for increasing the. mun

ber of windings of the hoisting chain on the drum thus enabling the digging action to take place through a greater number of revolutions of the winding mechanism than heretofore, without increasing the length of the closing chains, a greater ratio between the hoisting and closing chains being thus obtained thereby giving the grab greater facility in working upon dense substances such as iron ore; further objects of the invention are to provide an improved tipping device; to insure the bucket closing chains both working and sharing the working strain equally; and to provide the bucket.

sections with a suitable buffer.

According to the invention the ratio between the winding capacity of the hoisting drums and the drums upon which the bucket closing chains are wound is increased thereby causing the winding drum to make .an increased number of revolutions, for

which purpose means are provided for preventing or delaying the locking together of the co-actmg parts of said winding device while the grab is discharging or tipping its contents. The other improvements will be set out hereinafter.

The invention will'now be described more fully with reference to the examples thereof illustrated in the accompanying drawings,

in which Figure 1, is a side elevation, partly in section, of one example of grab constructed in accordance with this'invention showing the position of the parts after tipping, but prior to the hoisting chain being slackened. Fig. 2 is a side elevation thereof with the bucket sections closed and when hoisted with its load to the elevation to which it is to be raised prior to tipping. Fig. 3 is a side elevation, partly in section, illustrating the drum locking means and part of the tipping means in the positions which these parts occupy after the hoisting chain has been slackened, and after the drum, acting under the influence of a spring, has wound said hoist ing chain on its periphery. Fig. 4 is a similar view of the same parts in the positions they occupy when the grab is in the condition shown in Fig. 2,that is, prior to being tipped. Fig' 5 illustrates the relative positions of the fast and loose cams when the grab has been landed on the material to be picked up but prior to the hoisting chain being slackened. Fig. 6 'is an elevation, partly in section, of. a detail showing the lower stop on the hoisting chain.

I In the drawings, the bucket sections at a are shown pivoted together at a by means of brackets a a furnished at both ends of the bucket. Said sections a are pivoted at a to the lower ends of arms 6 b and the left hand bucket section is pivoted at a to a box or casing c, loosely mounted on a shaft 6, which casing partly incloses a drum (Z also loosely mounted on the shaft 6. right hand bucket section is pivotally connected at the point a to a link 5 the upper end of which is loosely mounted on the shaft pivoted together at their upper ends to a pivot pin Z2 carried by a bridge piece which allows them to spread or approach each other according to the movements of the bucket sections.

The links 5 transmit the up and down" movements of the drum rl to the right hand bucket section to which they are connected and thereby also assist the opening and clos- The ing of the grab, thecasingc yielding to this I action by tilting about the pivots a This tilting of casing 0 serves to bring'a tipping lever 7' into position forengaging a tipping.

device Z as hereinafter described.

lVithin thedrum (Z a coiled spring cl is arranged, the outer end of which, as shown at Fig. l, is secured to the drum while the inner end is secured to some non-rotatable part which is fast with, say the links Z) or with the casing c. The drum (Z, is provided at one end with a gravity catch or slide (Z adapted to cooperate with a cam 0 fixed to the shaft 6, and a cam h, loosely mounted on said shaft, as hereinafter more particularly described.

The bucket sections a a are closed by means of chains 9 the ends of which are connected to spools e fixed to the spindle e, the chains being suspended from the bridge piece 5 For the purpose of limiting the unwinding action of the drum (Z, a stop '5 is fixed upon one of the links of a hauling chain the position of such stop on the chain being such that it comes into contact with the bridge piece when the chain f has been hauled up to completely close the buckets, after which the grab is hoisted the parts being arranged as shown in Fig. 2.

The mechanism will now best be further described by referring to its operation.

Figs. 1, 5 and 6, represent the relation of the parts when the empty grab has just landed onto the material, with its jaws fully opened, and prior to the hoisting chain being slackened, the stop 2' on the chain as shown in Fig. 6, bearing against the bridge piece, with one or more convolutions of the hauling chain still on the drum, and the cams on shaft 0 occupying the position shown in Fig. 5. f, with the parts in the positions above indicated the hoisting chain 7'' is relaxed the drum under the influence of its spring revolves, in this-instance in a counter-clockwise direction as indicated by the arrow to, Fig. 1, carrying with it the sliding catch (Z which at the commencement of such movement is hearing on the cam h and falls away therefrom as the drum turns, said cam it, by reason of the fact that the heaviest part of the cam is to the right of the center, being held by gravity in the position shown in Fig. 5, in which its radial face abuts against the radial face of the fixed cam 6 until the catch (Z again approaches approximately to a vertical position above the shaft 6. The loose cam h as shown is somewhat higher in contour at its highest point than the fixed cam e and therefore the catch (Z in its travel around the shaft 6, after it has dropped toward the faces of the cams when approaching its up per vertical position will strike the project ing part of the cam 7L and knock it away so that said cam will then fall into its lowermost position, as shown in Fig. 3. By this movement of rotation, under the action of its spring (Z, the drum (Z will wind on to its periphery a length of the hoisting chain 7', the length of chain wound on the drum being determined by the provision of means for limiting the rotation of the drum in this particular direction even as the stop 71 limits the movement in. the reverse direction. The means employed may for example be either of the means illustrated in the drawings o British patent specification No. 9132 of 1908. To close the bucket sections and hoist the grab the hoisting chain f is pulled by the 'rane and is thereby unwound from the drum (Z until the stop 2' comes into engagement with the bridge 6 said drum being thereby rotated, in this instance, in a clockwise direction in opposition to its spring. Considering the closing action particularly, the parts being in the position shown in Fi 3 the sliding catch (Z is at the commencement of such rotation of the drum brought up against the radial face of the fixed earn 6 so that the spools 6 will turn with the drum and wind up the bucket closing chains 5, thereby raising the shaft c'and with it the parts carried thereby toward the bridge piece L. When the stop i comes into engagement with the bridge 6 the jawsof the grab have been closed as just described, and the bucket closing members occupy the position indicated in Fig. 4. The continued hauling upward of the chain will elevate the entire gra b. lVhen the grab has reached the top of its ascent a trip pawl j pivoted to the upper end of the tipping lever comes into engagement with and passes the flange Z of the tipping device Z. When the grab has been placed above -the position where it is desired to deposit the contents of the bucket the chain is lowered, and, when the part 7' engages with the flange Z the bell crank lever j is turned about its pivot The outer or free end of the bell crank lever 7' has an are shaped part j which, normally, is more or less concentric with the shaft 6, but which when the lever is tripped will press against the inner face of. an outwardly projecting lug or flange (Z at the head of the sliding catch d. This pulls said catch out of engagement with the cam e and thus releases the drum (Z from the shaft 6 and allows said drum and the other parts of the mechanism to fall by their own weight and tip the buckets a a, the chains g being thereby unwound from the spools c a part of the hauling chain below the stop 2' being also unwound from the drum. 1

This movement is permitted by reason of the fact that the part of the hauling chain 7 which is below the bridge 5 is relieved by the stop a of the weight of the grab.

It is during this last described movement that the loose snail cam it comes into operation, and in order to fully appreciate its use the movements of the several parts will be more particularly described.

As soon as the catch d has been pulled li t out of engagement with the fixed cam 6 the parts will, as above stated, fall by their own weight, the drum, being free from the shaft 0 and that part of the hauling chain 7 between the stop 71 and the crane hoisting the reverse direction to that of the hauling chain on the drum together with the weight of the grab'acting through the shaft 6 cause the shaft 6 andthereby the spools to rotate in a counter-clockwise direction. These opposite rotary tendencies of the drum (Z and spools c. were resisted so long as the drum (Z and shaft 6 were held together by the engagement of the catch d with the cam 6 During the rotation of the shaft 6 the cam 6 will overtake the loose cam h and the catch (Z will travel idly over the peripheral faces of these cams so that a very considerable amount of relative rotation takes place between the drum (Z and the shaft 6, amountingto as many revolutions as are required by the length of the bucket closing chains 9. W hen this movement is completed the cams e and it will again occupy the relative positions shown in Fig. 5, the inner end of the catch (Z bearing on the face of the cam It. But for the provision of the loose cam h the drum (Z and shaft 6 would, after the release of the catch (Z be able to make only a short relative rotary movement because the catch (Z which is a gravity catch, would on reaching its upper position, fall down on to the shaft 6 and would thus very soon lock against the radial face of cam e and prevent the chains 9 being unwound to the full extent and the jaws from opening to the full extent. The provision of the loose cam it however, prevents this and therefore allows of a complete unwinding of the bucket closing chains 9, and, consequently, at the next operation, (after the hoisting chain has been slackenech) of a considerably longer bucket closing movement, thereby giving a greater length of time for the bucket sections to act on the material being lifted.

The tipping lever j between the trip pawl and the bell crank lever or the like y' is rigid and is loosely jointed to said bell crank lever so as to be able to fall laterally one way or the other such lateral motion being limited by stops j j in a bracket y' which serves to guide the rod j. The lever 3' is pivoted at 7' to the casing c, and as previously stated, has an arc-shaped part which partially surrounds and is normally concentric with the shaft 6, and which is normally located between said shaft and the concentric circular path of travel of the lug (Z on the catch 6Z2. Normally, that is to say when not in use, said tipping lever falls laterally out of the way, although restricted in its lateral movements by the stops j and in this position,'as already stated, the arc shaped part of the le ver j lies inwardly of the lug (Z on the catch (Z so that said catch can travel around without being tripped by the said are shaped part; when, however, the buckets close together as aforesaid the tilting of the drum box or casing 0 about its hinge pins a will cause the trip pawl j carried by the tipping lever to be brought into position for engaging flange Z of the tipping device Z. On-the ascent of the grab the trip pawl j strikes the bottom flange Z of the tipping ring Z and yields thereto or tilts so that it can pass said flange, and once past the same it falls back into normal position as shown in Fig. 2. On the descent of the grab, said pawl engages the upper side of said lug but is unable to yield thereto, with the result that the rod j is pulled upwardly and the lever j is tilted so as to move its arc-shaped part outwardly into engagement with the lug (Z on the catch 6Z2 and thereby move said catch out of engagement with the abrupt face of the fast cam c and so release the shaft 0 and the spools c thereon from the spring drum (Z and permit these spools to fall into the bucket opening position shown in Fig. 1, the drum (Z revolving in a clock wise direction and the shaft 0 and spools c in an anti-clockwise direction. The members j y" are arranged to remain at all times within the outside diameter of the bucket so that projecting parts in this portion of the tipping device are avoided. The closing chains are attached to the spools e at points in line with the tip of the fast cam c and therefore when the hoisting chain is slackened, the impact of the catch (Z against the tip of the cam it will occur while the abutting cam faces are vertically above the center of the shaft or are slightly short of this position, approximately as shown in Fig. 5. The cam it therefore, being loose, will fall away partly from said impact and partly by gravity, until it hangs in a position approximately vertically below the center of the shaft. The catch (Z will, when it has passed the tip of the fast cam 6 fall into the space openedup between the two opposing faces, but when in the course of the drums revolution it has passed the horizontal position it will fall radially outward, under the influence of gravity, along its lateral guides. These guides allow the catch d a suflicient length of outward move ment to permit its inner end to clearthe tip of theloose cam 71, when passing around the under side of the shaft 6, so that the drum (Z can revolve, and in revolving of course carry the catch (Z idly around the cams e and it, the drums revolving in an anti-clockwise direction until the predetermined length of hoisting chain has been wound on the drum and until the parts again occupy the position indicated in Fig. 8.

In order to obviate a strain not properly divided between the two bucketclosing chains the latter are dispensed with and a single chain is employed: such chain has hereinbefore been referred to as chains, but that expression was used as referring to the two portions of the single chain which are wound on to the two spools 6. Instead of being fixed to the frame above the bucket, as was thecase with the two chains formerly employecL-or of running freely over two sheaves at the top of the grab to wind from a drum on one side to a drum on the other side as has been proposed in connection with a difierent type of apparatus,the single chain 9 may be supported in any way, in this instance by means of eyes 9, 9, that will permit it to adjust itself toward one side or the other, and thus prevent a onesided strain coming upon it. This adjustment would usually be Very small in amount, but suflicient for its purpose. Such supporting device would be so arranged as to leave a clear way for the hoisting chain or ro e.

The brackets (0 a or the top beams or shoulders, of the bucket sections may be provided with means, in the example illus trated, a buffer is, to prevent their mutual shock when opened suddenly.

It will be obvious that, in place of the hoisting chain 7 or the chains 9 of the bucket members, rope might in either case be used if preferred, and accordingly in the following claims the word chain is to be understood as including either a. chain or a rope.

To assist in furnishing a clear understanding of the operation of the improved grab, the present drawings illustrate and the foregoing description refers to a number of features not specifically claimed as a part of the present invention, the same being substantially those shown and described in British Patent 9132 of April 27th 1908, issued to myself and James MacDonald.

What I claim is 1. In a grab, the combination with hinged complementary bucket members of a drum or wheel, a hoisting chain adapted to be wound thereon, a shaft upon which such drum is freely mounted, bucket closing means normally disconnected from said drum carried by said shaft and means for operatively connecting said bucket closing means with said drum, comprising a sliding locking catch carried by the drum, a fast cam carried by and rotating with said shaft positioned to co-act with said locking catch, and a loose cam positioned to co-act with the locking catch and shroud said fast cam during a certain period of the revolution of the drum.

2. In a grab, the combination of a plurality of complementary bucket members, a spring drum, an axle therefor, a shield or casing for said drum, a pivotal connection between said shield or casing and one of the aforesaid bucket members, and a link pivotally connected to said axle and to the other bucket member.

3. In a grab, the combination of a plurality of complementary bucket members, of a drum, a hoisting chain adapted to be wound thereon, bucket closing means normally disconnected from said drum, means for operatively connecting said bucket closing means with said drum, comprising a locking catch carried by the drum, a fast cam carried by and rotating with the bucket closing means positioned to co-act with and engage said locking catch and a loose cam positioned to co-act with the locking catch and shroud the fast cam and trip means for releasing said locking catch from the fast cam, one member of said trip means being carried by the grab, and another co-acting member thereof being supported in the path of travel of said first named trip member, and means connected with the aforesaid bucket members for bringing said first named trip member, when said bucket members are closed, into a path of travel where it can come into operative relation to said second named trip member.

at. In a grab, the combination with hinged complementary bucket members of a drum, a hoisting chain adapted to be wound thereon, bucket closing means normally disconnected from said drum, means for operatively connecting said bucket closing means with said drum, means comprising a sliding locking catch carried by the drum, a fast cam carried by and rotating with the bucket closing means positioned to co-act with and engage said locking catch and a loose cam positioned to co-act with the locking catch and shroud the fast cam during a period of the revolution of the drum, and means comprising a tipping ring carried separately from the grab, and a loose tripping lever carried by the grab engaging with said tipping ring,

, for throwing said locking catch out of engagement with the fast cam.

5. In a grab, the combination with hinged complementary bucket members of a hoisting chain, a shaft supporting said bucket members, a drum mounted loose on said shaft actuated by said chain, bucket-closing means normally disconnected from said drum, means including a sliding locking catch on the drum and a fast cam on the shaft for operatively connecting said bucket-closing means with said drum, and means for delaying such connection, com- 7 prising a loose cam positioned to co-act with the lockmg catch and shroud sald fast cam during a certain perlod of the drums revolution and to be pushed away therefrom In witness whereof I have hereunto set during an opposite revolution of the drum, my hand in the presence of two subscribing the bucket-operating parts being so adjust- Witnesses.

ed or proportioned to each other that such DUDLEY JAMES BARNARD. pushing away will take place when said lVitnesses:

cams are at the upper part of their circular ARCHIBALD ERNEST HARRISON, path. ALEXANDER J OSEPH PLATON.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, 13.70.

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