US3807783A

US3807783A - Cable-operated mechanical grapple

Info

Publication number: US3807783A
Application number: US00296209A
Authority: US
Inventors: Huuksloot L Van
Original assignee: Nemag NV
Current assignee: Nemag NV
Priority date: 1971-10-07
Filing date: 1972-10-10
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: DE2248386A1; DE2248386B2; GB1357275A; JPS4846106A; FR2156135A1; JPS568179B2; NL7113803A; NL171690C; DE2248386C3; NL171690B; FR2156135B1

Abstract

A grab includes a set of movable receptacle devices or scoops to which link-arms are pivotally attached on both sides of the longitudinal symmetry plane of the grab. The arms are mutually connected at some distance from their free end and are provided at their free ends with a grab-controlling means. Each scoop on the side thereof opposite the side contacting the opposite scoop during closing of the grab is pivotally connected to the associated link-arms. This same side of each scoop is at the same time connected to a tensile point situated in the transversely symmetry plane of the grab. The contact side of each scoop has a point which is connected with a fixed point on the link-arm of the not-associated or opposite scoop between the pivot connection of the link-arms and their free ends.

Description

Van Huuksloot CABLE-OPERATED MECHANICAL GRAPPLE [75] Inventor: Leendert Van Huuksloot,

Rotterdam, Netherlands [73] Assignee: Nemag N.V., Rotterdam,

Netherlands [22] Filed: Oct. 10, 1972 [21] Appl. No.2 296,209

[30] Foreign Application Priority Data Oct. 7, 1971 Netherlands 7113803 [52] US. Cl 294/70, 37/185, 294/112 [51] Int. Cl. B66c 3/12 [58] Field of Search 294/69, 70, 71, 111, 112; 37/183 R, 184,185, 188; 214/147 G, 656

[56] References Cited UNITED STATES PATENTS 3,544,150 12/1970 Huuksloot 294/71 991,473 5/1911 Ballard 37/188 479,149 7/1892 Gale 37/185 2,617,211 11/1952 Olson 37/185 Apr. 30, 1974 FOREIGN PATENTS OR APPLICATIONS 286,248 7/1915 Germany 37/188 Primary ExaminerEvon C. Blunk Assistant ExaminerJohnny D. Cherry Attorney, Agent, or FirmWenderoth, Lind & Ponack [5 7] ABSTRACT A grab includes a set of movable receptacle devices or scoops to which link-arms are pivotally attached on both sides of the longitudinal symmetry plane of the grab. The arms are mutually connected at some distance from their free end and are provided at their free ends with a grab-controlling means. Each scoop on the side thereof opposite the side contacting the opposite scoop during closing of the grab is pivotally connected to the associated link-arms. This same side of each scoop is at the same time connected to a tensile point situated in the transversely symmetry plane of the grab. The contact side of each scoop has a point which is connected with a fixed point on the link-arm of the not-associated or opposite scoop between the pivot connection of the link-arms and their free ends.

6 Claims, 2 Drawing Figures 1 CABLE-OPERATED MECHANICAL GRAPPLE BACKGROUND OF THE INVENTION The present invention relates to a grab of the type comprising a set of receptacle devices or scoops to which pairs of link-arms are attached on opposite sides of the longitudinal symmetry plane of the grab. The arms are mutually connected at some distance from their free ends and provided at their free ends with the grab controlling means. Such a device is known from the older Netherlands Pat. application 671 1272 in Applicants name.

In order to discharge the load of the grab as quickly as possible it is important that the bottoms of the scoops be positioned as nearly vertical as possible. This also facilitates the loading of a grab e.g., with sand or ore.

In known devices of the type mentioned the by-pass pulleys of the controlling means for the grab are positioned substantially in the same horizontal plane as the fulcrum of the link-arms when each scoop is rotated by 70 percent out of the vertical plane.

The initial force which has to be exerted in closing the scoops is thus relatively great. Also, due to the less favourable distribution of forces, the connection of the link-arms has to be of a relatively heavy construction.

SUMMARY OF THE INVENTION According to the invention the above disadvantages are overcome by providing that each scoop on the outer side thereof opposite the side in contact with the other scoop during closing of the grab, is pivotally connected to the associated link-arms. Adjacent this pivotal connection is a point on the scoop connected to a tensile point situated in the transverse symmetry plane of the grab. On the inner side of each scoop in contact with the other scoop-during closing of the grab is a point which is connected with a fixed point on the linkarm of the not-associated scoop between the pivot of the link-arms and their free ends.

Now in order to be able to open the grab to a position such that thebottom faces of the grabs are substantially in a vertical position, the opening angle,'or the angle of rotation of the link-arms, can be chosen considerably smaller with the device of the invention than with previous devices. Also, the link between the link-arms may be of a lighter construction since one of the link-arms need not be staggered inwardly from the pivot as was necessary in previous devices.

An inexpensive and efficient construction is obtained when the connection between the pivot of the scoop and the tensile point in the transverse symmetry plane of the grab is formed by a cable.

In the same manner the connection between the contact side of the scoop and the opposite link-arm can be formed inexpensively by a cable.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is discussed in more detail below with reference to the accompanying drawings, in which FIG. 1 shows a grab according to the invention in its closed position; and

FIG. 2 shows the grab in its opened position.

DETAILED DESCRIPTION OF THE INVENTION The grab or scoop device of the present invention comprises the receptacle devices or scoops l and 2. A link-arm 3 is attached to the scoop l and a link-arm 4 is attached to the scoop 2. At the end of the link arm 3 remote from the scoop 1 a by-pass pulley 5 is provided, and at the end of the link-arm 4 remote from the scoop 2 a by-pass pulley 6 is provided. To link-arm 4 is also attached a by-pass pulley 7.

The controlling cable 9 for opening and closing the grab is fixed at a point 10 on link-arm 4 and as clearly shown in FIG. 2 passes in an upward direction after passing over and along the pass-by

pulleys

5, 6 and 7. The link-

arms

3 and 4 are provided in pairs disposed on both sides of the longitudinal symmetry plane of the grab (i.e., a plane parallel to the plane of the sheet of drawings). The pivot between the link-

arms

3 and 4 is indicated in the drawing by 8. The connection between link-arm 3 and the associated scoop 1 consists of a pivot 11, whereas the connection between link-arm 4 and the associated scoop 2 is formed by a pivot 12. Adjacent the pivot 11 there is a 'point 13 which is connected to a cable 15, whereas adjacent the pivot 12 is a point 14 which is engaged by cable 16. The

cables

15 and 16 are united at a point 17 situated in the transverse symmetry plane of the grab construction (i.e., a plane perpendicular to the plane of the sheet of drawings). Adjacent the upper end of the inner side of the scoop l which contacts scoop 2 during closing of the grab is a point 18 which is connected through a cable 20 to a point 22 situated on the not-associated linkarm, i.e., link-arm 4. Likewise, a point 19 is situated adjacent the upper end of the inner side of the scoop 2, which contacts scoop 1 during closing of the grab. Point 19 is connected through a cable 21 to a point 23 situated on the not-associated link-arm, i.e. link-arm 3.

In order to move the scoops apart, one away from the other, starting from the closed position shown in FIG. 1, the tension on cable 9 is relaxed so that the cable 9 is reeled out and in doing so, apart from a mutual separating movement of the scoops l and 2, also a tilting movement of the scoops around the

pivots

11 and 12 will take place due to the tensile forces produced at the

points

13 and 14 by

cables

15 and 16, respectively. The tilting movement is restricted by the

cables

20, 21 which act on the sides of the

scoops

1 and 2, respectively, which are in contact during closing of the grab. As a result of this combined motion, the bottoms of the

scoops

1 and 2 will reach, at a relatively small pivoting or turning angle of about in total of link-

arms

3 and 4, the position shown in FIG. 2 in consequence of which the discharge of the load from the grab can be more quickly achieved. In the completely opened position shown in FIG. 2 the by-

pass pulleys

5 and 6 of the link-

arms

3 and 4, respectively are above the pivot 8. This facilitates subsequent closing of the scoops l and 2, since a smaller initial force will be required than in prior art grabs. Moreover it is possible that the

linkarms

3 and 4 may extend beyond the pivot 8 linearly. In other words, one pair of the arms need not be staggered inwardly as in known devices. This results in a simpler pivot which also results in a costs-saving factor in the manufacture and assembly of the grab. The pivot connection of each scoop to the associated pair of linkarms also results in a more simplified assembly.

I claim:

1. A grab comprising:

a first scoop having a closed bottom, an outer side,

and an inner side;

a first pair of link-arms pivotally connected at first ends thereof to said first scoop at said outer side thereof;

a second scoop having a closed bottom, an outer side,

and an inner side,

a second pair of link-arms pivotally connected at first ends thereof to said second scoop at said outer side thereof;

said first and second pairs of link-arms being pivotally connected at a fulcrum point adjacent the midpoints thereof;

control cable means for selectively pivoting said pairs of link-arms about said fulcrum point from a closed position wherein said inner sides of said first and second scoops are in contact, to an open position wherein said bottoms of said first and second scoops are vertically positioned;

tension means connected to said outer sides of said first and second scoops for causing said first and second scoops to pivot with respect to the respective pairs of link-arms thereof during pivoting of said pairs of link-arms from said closed position to said open position; and

means connected between points adjacent said inner sides of each of said first and second scoops and points on the opposite of said pairs of link-arms for limiting the extent of pivoting of said first and second scoops about the respective link-arms thereof during pivoting of said link-arms from said closed 4 position to said open position.

2. A grab as claimed in claim 1, wherein said tension means comprises a first cable connected to said first scoop, and a second cable connected to said second scoop, said first and second cables being joined at a point vertically aligned above the area of contact between said first and second scoops when in said closed position.

3. A grab as claimed in claim 1, wherein said means for limiting comprises a first cable connected between said first scoop and said second pair of link-arms, and a second cable connected between said second scoop and said first pair of link-arms.

4. A grab as claimed in claim 3, wherein said first cable is connected to said second pair of link-arms at a point thereof between second ends thereof opposite said first ends thereof and said fulcrum point, and wherein said second cable is connected to said first pair of link-arms at a point thereof between second ends thereof opposite said first ends thereof and said fulcrum point. i

5. A grab as claimed in claim 1, wherein the ends of said link-arms opposite said first endsthereof are positioned in a horizontal plane above said fulcrum point when said link-arms are pivoted to said open position.

6. A grab as claimed in claim 1, wherein each linkarm of said first and second pairs of link-arms extends in a single plane throughout the entire length thereof.

Claims

1. A grab comprising: a first scoop having a closed bottom, an outer side, and an inner side; a first pair of link-arms pivotally connected at first ends thereof to said first scoop at said outer side thereof; a second scoop having a closed bottom, an outer side, and an inner side; a second pair of link-arms pivotally connected at first ends thereof to said second scoop at said outer side thereof; said first and second pairs of link-arms being pivotally connected at a fulcrum point adjacent the mid-points thereof; control cable means for selectively pivoting said pairs of linkarms about said fulcrum point from a closed position wherein said inner sides of said first and second scoops are in contact, to an open position wherein said bottoms of said first and second scoops are vertically positioned; tension means connected to said outer sides of said first and second scoops for causing said first and second scoops to pivot with respect to the respective pairs of link-arms thereof during pivoting of said pairs of link-arms from said closed position to said open position; and means connected between points adjacent said inner sides of each of said first and second scoops and points on the opposite of said pairs of link-arms for limiting the extent of pivoting of said first and second scoops about the respective link-arms thereof during pivoting of said link-arms from said closed position to said open position.

4. A grab as claimed in claim 3, wherein said first cable is connected to said second pair of link-arms at a point thereof between second ends thereof opposite said first ends thereof and said fulcrum point, and wherein said second cable is connected to said first pair of link-arms at a point thereof between second ends thereof opposite said first ends thereof and said fulcrum point.

5. A grab as claimed in claim 1, wherein the ends of said link-arms opposite said first ends thereof are positioned in a horizontal plane above said fulcrum point when said link-arms are pivoted to said open position.

6. A grab as claimed in claim 1, wherein each link-arm of said first and second pairs of link-arms extends in a single plane throughout the entire length thereof.