US3727968A

US3727968A - Lumber grabbing apparatus

Info

Publication number: US3727968A
Application number: US00146636A
Authority: US
Inventors: A Tsuchihashi; K Honma
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1970-06-12
Filing date: 1971-05-25
Publication date: 1973-04-17
Anticipated expiration: 1990-04-17
Also published as: DE2128712A1; GB1342526A; FR2095208B1; CA948672A; JPS4923180B1; NO132471B; DE2128712B2; FR2095208A1; DE2128712C3; NO132471C

Abstract

An apparatus for grabbing a material closely stacked in a compartment such as a hold, which is provided with means for smoothly and easily penetrating its grabbing arms into the interspace of the material so as to enable said grabbing arms to grab a large amount of the material at a time.

Description

Tsuchihashi et al.

[451 Apr. 17, 1973 [541 LUMBER GRABIBIING APPARATUS 2,743,954 5/1956 )stluno ..294/106 x l I [75] nventors Akira Tsuchl aS'hl' Kazuo ll-llonma Primary Emmmer Gerald M. enza both of Tokyo, Japan Assistant ExammerFrank E. Werner Assignfiei Hitachi, TOkYO, Japan Attorney-Craig and Antonelli [22] Filed: May 25, 197R [57] ABSTRACT 21 Appl. No.: 146,636

An apparatus for grabbing a material closely stacked D 0 0 in a compartment such as a hold, which is provided [30] Apphcatmn Prion Data with means for smoothly and easily penetrating its June 12, 1970 Japan ..45 503|s grabbing arms the interspace of the material so as to enable said grabbing arms to grab a large amount of 52 us. (:1. ..294/88, 294/106, 214/658 the malerlal at a [51] Int. Cl ..B66c 1/42 [58] Field of Search ..294/88, 106, 86.29

[ 56] References Cited 3 Claims, 4 Drawing Figures UNITED STATES PATENTS 247,829 10/1881 Johnson ..294/83 PATENTEDAPR 1 1 727. 968

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BY mug Mk. r AS L ATTORNEYS PATENTEUAPR 1 11915 5.727. 968

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ATTORNEYS,

PATENTEU 1 71975 3.727, 968

SHEET 0F 4 1N VENTOR$ BY Qml HM er" NM ATTORNEY$ LUMBER GRABBING APPARATUS This invention relates to a grabbing apparatus capable of grabbing a large amount of material, e.g., lumbers, at a time by penetrating its grabbing arms deep into the interspace of the lumbers.

A prior art grabbing apparatus well-known in the art, as shown in FIG. 1, includes a grab 1 having a pair of cooperating grabbing arms 1a, 1b; a reciprocating cylinder unit 2 for opening and closing said grab 1; a rotary cylinder unit 3 for rotating said grab 1 and another reciprocating cylinder unit 4 for moving the entire assembly of said elements in a vertical direction; said grabbing arms la, lb of said grab 1 being pivotally connected at their middle portions to said cylinder unit 2 by means of

rods

5a, 5b respectively and also being pivotally connected at their roots to the lower end extremity ofa piston rod 2a of said cylinder unit 2.

In the operation of the prior art apparatus described above, the piston rod 2a of the reciprocating cylinder unit 2 is extended or retracted, whereby the grabbing arms 1a, lb are opened or closed to grab the logs T.

In such a prior artapparatus, however, when the grabbing arms la, lb are opened or closed by the cylinder unit 2, the tips of said grabbing arms 1a, llb are displaced in a vertical direction. Namely, when the grabbing arms 1 a, lb are opened, the tips of said grabbing arms 1a, 1b move outwardly upwardly, whereas while they are closed, the tips thereof moves inwardly downwardly.

Even with such grabbing arms, the logs stacked in a lumber yard or floating on the water surface can be sufficiently grabbed, because the logs are movable horizontally and hence the grabbing arms can be easily penetrated into the interspaces of the logs.

However, with the amount of lumber being exported and imported increasing in recent years, ships have been used for the transportation of the lumber and it is usual that the logs are closely stacked in a hold of the ship.

With the prior art apparatus, however, it is impossible to remove from the hold a large number of logs closely stacked in said hold at one time since little space is available for the lateral movement of the logs due to the limited space in the hold and, therefore, the amount of penetration into the stack of logs of the grabbing arms is small. For grabbing a large number of logs at a time, the apparatus itself must be large in size.

The object of the present invention is to provide a lumber grabbing apparatus which is small in size and hence enables the weight of the entire loading machine to be reduced, and which is operable with high efficiency even in a narrow space.

FIG. 1 is a view showing the construction of a conventional lumber grabbing apparatus;

FIG. 2 is a view showing the construction of the lumber grabbing apparatus according to the present invention;

FIG. 3 is a diagramshowing the hydraulic circuit of the lumber grabbing apparatus of the invention; and

FIG. 4 is a vertical sectional view of a position command pressure reducing valve used in the present invention.

The lumber grabbing apparatus of the invention is shown in FIG. 2.

Referring to FIG. 2, reference numeral 6 designates a grabbing apparatus elevating hydraulic cylinder, in which a piston 7 is slidably disposed. The piston 7 is connected to the lower end of a piston rod 8, the upper end of which is fixed to a machine frame. The fluid pressure in the cylinder varies incident to the vertical movement of the piston rod 8. Reference numeral 9 designates a grabbing apparatus rotating hydraulic cylinder and 10 generally designates a grab. The grab 10 includes grabbing members 11, 11' and

arms

12, 12, and said grabbing members and said arms are operable independently. Reference numeral 13 designates a grabbing members opening and closing hydraulic cylinder. The grabbing members 11, 11' are pivotally connected to the lower end of a piston rod of the cylinder 13 at one ends by means of a hinge pin 14. They are also connected at their mid portions to one ends of rods 15, 15', the other ends of which are connected to the side walls of the cylinder 13 respectively. Reference numerals 16, 16' designate rotary cylinders for opening and closing the arms 12, 12', and the arms can be pivotally moved to the left and right by varying the fluid pressure in said cylinders respectively.

Referring to FIG. 3 there is shown the hydraulic circuit of the subject apparatus for operating the arms. The hydraulic circuit comprises a manually operable position command pressure reducing valve 17, a servo directional control valve 18, the hydraulic cylinder 16, a position feedback pressure reducing valve 19, the arm 12 and pipes communicating said elements with each other.

Now, each of the elements mentioned above will be described in detail hereunder: First of all, the servo directional control valve 18 includes a casing 20 which is provided with a port 20a communicating with a first fluid pressure generator P1 of large capacity, a port 20b communicating with the position command pressure reducing valve 17,

ports

20c and 20d communicating with

ports

16a and 16b of the hydraulic cylinder 16 respectively, a port 20 communicating with the position feedback pressure reducing valve 19 and

discharge ports

20f, 20g communicating with a tank (not shown). Reference numeral 21 designates a valve spool slidably disposed in the casing 20, which has a land 21a for establishing orbreaking the communication between the

ports

20c and 20g, a land 21b for establishing or breaking the communication between the

ports

20a and 20d, and a land 210 for establishing or breaking the communication between the

ports

20d and 20f.

The position command pressure reducing valve 17 which is operated by the operator at his own will, is constructed as shown in FIG. 4. Namely, this pressure reducing valve 17 includes a casing 22 which is provided with a port 22a communicating with a fluid pressure source, a port 2212 communicating with the servo directional control valve 18, and a drain port 22c through which the pressurized fluid flowing into the casing 22 from the port 22a is returned to the tank. In the casing 22 is slidably disposed a valve spool 23 which has two

lands

23a and 23b for establishing or breaking the communication between the

ports

22a and 22b. A push rod 24 is inserted into the casing 22 on one side of the valve spool 23 adjacent the land 23a and a spring 25 is provided between said push rod 24 and said land 23a, by which the valve spool 23 is constantly urged downwards. In the inner surface of the casing 22 are formed an annular groove 26 communicating with the port 22a and an annular groove 27 communicating with the port 22b.

A passage 29 is formed axially in the land 23b of the valve spool 23, for communicating a chamber 28 formed below the lower end of the valve spool 23, with the annular groove 26 and an orifice 30 is formed in said passage 29 at the central portion thereof.

Now, when the length I from the lower end of the position command pressure reducing valve 17 to the top end of the push rod 24 is shortened by pushing said push rod, the valve spool 23 is moved down by the spring 25, so that the communication is established between the

ports

22a and 22b and the pressurized fluid flows through the pipe to act on the servo directional control valve 18. On the other hand, the pressurized fluid in the annular groove 27 flows into the chamber 28 through the orifice 30 to build up the pressure in said chamber against the biasing force of the spring 25. When the fluid pressure in the chamber 28 and the biasing force of the spring 25 are balanced by each other, the valve spool 23 is located in a position to break the communication between the

ports

22a and 22b. In other words, the fluid pressure in the port 22a is proportional to the amount of downward movement of the push rod 24.

Next, the arm opening and closing rotary cylinder 16 has a port 160 communicating with the port c of the servo directional control valve 18 and a port 16b communicating with the port 20d of said directional control valve 18. The arrangement is such that when the pressurized fluid is supplied into the rotary cylinder 16 from the port 1611, an output shaft is connected directly with the arm is rotated in a clockwise direction, causing the arm in a clockwise direction, whereas when the pressurized fluid is supplied thereinto from the other port 160, the output shaft is rotated in the opposite direction, causing the arm to rotate in a counterclockwise direction. The angle of rotation of the output shaft is limited to not more than 360.

The position feedback pressure reducing valve 19 is identical in construction with the position command pressure reducing valve 17 previously described with reference to FIG. 4, and the outer end of a piston rod 19a of the valve 19 is held in contact with the side face of the arm connected to the output shaft of the rotary cylinder 16. The push rod is displaced in proportion to the angle of rotation a of the arm 12. Further, the position feedback pressure reducing valve 19 is in communication with the first fluid pressure generator P1 and also with the servo directional control valve 18 as will be described later.

The piping of the hydraulic circuit will be described with reference to FIG. 3. In FIG. 3, reference numeral 31 designates a pressurized fluid feed pipe extending from a second fluid pressure generator P2 and connected to the port 22b of the position command pressure reducing valve 17, 32 a remote control pipe for feeding the pressurized fluid from the port 22a of the position command pressure reducing valve 17 to the port 20b of the servo directional control valve 18 therethrough, and 33 a pressurized fluid feed pipe extending from the first fluid pressure generator P1 to the port 20a of the servo directional control valve 18.

Reference numeral 34 designates a pipe communicating the port 20c of the servo directional control valve 18 with the port 16a of the rotary cylinder 16, 35 a pipe communicating the port 20d of the servo directional control valve 18 with the port 16b of the rotary cylinder 16, 36 a pipe branched from said pressurized fluid feed pipe 33 and connected to the position feedback pressure reducing valve 19, and 37 a pipe communicating the port 20e of the servo directional control valve 18 with the position feedback pressure reducing valve 19.

In the above-described hydraulic circuit, when the position feedback fluid pressure from the feedback pressure reducing valve 19 and the fluid pressure supplied from the position command pressure reducing valve 17 into the right end chamber of the servo directional control valve 18 through the pipe 32 are equally balanced, i.e., when the valve spool 21 of the servo directional control valve 18 is in a neutral position as shown in FIG. 3, the servo directional valve 18 does not supply the pressurized fluid to either port of the rotary cylinder 16, so that the grab continues its grabbing motion when it is in the grabbing operation or its opening motion when it is in the opening operation.

The lumber grabbing apparatus of the invention will operate in the following manner:

First of all, the rotary cylinder 9 shown in FIG. 2 is actuated to set the

arms

12, 12 in positions parallel to the longitudinal direction of the logs and at right angles to the surface of the ground, and then the loading machine is lowered to penetrate the arms 12, 12' into the first layer of logs. Successively thereafter, the

arms

12, 12 are penetrated into the second layer of logs. In this case, the angular positions of the

arms

12, 12 are respectively adjusted by means of the rotary cylinders l6, 16 while holding the hydraulic cylinder 9 and the grab opening and closing cylinder 13 in the fixed state and lowering the grab elevating cylinder 6. The adjustment of the angle of opening a of each arm 12 or 12' can be achieved by projecting or retracting the push rod of the position command pressure reducing valve 17. In more detail, when the valve spool 23 is moved down by pushing the push rod 24 in FIG. 4, the

ports

22b and 22a are brought into communication with each other and the fluid pressure from the second fluid pressure generator P2 shown in FIG. 3 is supplied through the pipe 32 into the right end chamber of the servo directional control valve 18 from the port 20b, causing the leftward movement of the valve spool 21. As a result, the communication is established between the

ports

20a and 20d and the fluid pressure from the first fluid pressure generator P1 is supplied into the port 16b of the rotary cylinder 16 through the pipe 35, causing the

arms

12, 12 to rotate in a clockwise direction. By the clockwise rotation of the

arms

12, 12, the push rod 19a of the position feedback pressure reducing valve 19 in contact with said arm is moved, so that the valve spool of said pressure reducing valve is displaced proportionally to the amount of displacement of said push rod 19a and the pressurized fluid flows through the pipe 37 into the left end chamber of the servo directional control valve 18 from the port 20e, causing the valve spool 21 to move to the right. The rightward movement of the valve spool 21 continues until it reaches a position at which the fluid pressures in the right end chamber and left end chamber of the directional control valve 18 are equally balanced. Namely, as the valve spool 21 moves to the right, the communication between the

ports

20a and 20d is gradually broken and the rightward movement of the valve spool 21 stops when the communication is completely broken and the fluid pressure in the left and right end chambers are balanced with each other.

When the pressure is removed from the push rod 24 of the position command pressure reducing valve 17, the valve spool 23 in FIG. 4 is allowed to return its neutral position and the communication between the

ports

22b and 22a is broken. As a result, the fluid pressure in the right end chamber of the servo directional control valve 18 becomes greater than that in the left end chamber thereof, causing the valve spool 21 to move to the right and thus the communication between the ports 20a and 200 is established. The fluid pressure from the first fluid pressure generator P1 is supplied through the pipe 34 into the port 160 of the rotary cylinder 16 and the arm 12 is rotated in a counterclockwise direction.

Incident to the rightward movement of the valve spool 21, the pressurized fluid in the right end chamber of the servo directional control valve 18 is returned to the position command pressure reducing valve 17 through the pipe 32. Namely, the pressurized fluid is discharged from the port 22a and flows into the lower end chamber 28 through the orifice 30 of the valve spool 23 in FIG. 4. Consequently, the valve spool 23 is moved upwards and the land 23a opens the port 22c, whereupon the communication is established between the

ports

22a and 22c and the pressurized fluid is slowly returned to the tank through the port 22c.

As the arm 12 rotates in a counterclockwise direction, the push rod 19a of the position feedback pressure reducing valve 19 is displaced and pressurized fluid supply into the pipe 37 is shut down by the valve spool. Therefore, the fluid pressure in the left end chamber of the servo directional control valve 18 is decreased and that in the right end chamber thereof becomes higher, with the result that the valve spool 21 moves to the left. The leftward movement of the valve spool 21 continues until it reaches a position at which the pressures in the right and left end chambers are equally balanced. Namely, as the valve spool moves to the left, the communication between the

ports

20a and 20d is slowly broken and, when the communication is completely broken, the fluid pressures in the right and left end chambers are balanced with each other and the valve spool 21 stops its leftward movement.

As described above, the position of the valve spool 21 of the servo directional control valve 18 is constantly changed by the axial movement of the push rod of the position command pressure reducing valve 17, directing the fluid pressure from the first fluid pressure generator P1 to flow from the port 200 into the

port

20c or 20d.

It will be understood, therefore, that by axially moving the push rod of the position command pressure reducing valve 17, the arm of the rotary cylinder 16 can be moved pivotally to the left and right and thereby penetrated into the second layer of logs.

After the arms have been penetrated deep into the 11, 11', whereby the logs indicated by the hatched lines in FIG. 2 can be grabbed.

In comparing the prior art lumber grabbing apparatus of FIG. 1 with that of the instant invention shown in FIG. 2, the former is slightly smaller in size than the latter but the latter can grab an amount of lumber twice or more times as much as the amount which can be grabbed by the former, at one time.

The number of logs which can be grabbed by the subject apparatus are indicated by the hatched lines, and the same number of logs are indicated in FIG. 1 by the solid lines.

In FIG. 1, the logs indicated by the cross-hatched lines are those which can be grabbed by the prior art apparatus but cannot be grabbed by the apparatus of FIG. 2 because the grabbing span is smaller than that of the former. From the comparison between the logs indicated by the solid lines and those indicated by the hatched lines, it will be understood that the apparatus of FIG. 2 can grab a larger amount of lumber at a time than the apparatus of FIG. 1, though it is relatively small in size.

According to the penetration type grabbing apparatus of the invention, the grab is composed of the grabbing members and the arms, and said grabbing members and arms are operable independently. Therefore, the apparatus of the invention can grab a large amount of article at one time as compared with the logs by repeating the operation described above, the 2 cylinder 13 is actuated to close the grabbing members conventional apparatus, even though the former is smaller in grabbing span and in size than the latter. By employing the grabbing apparatus of the invention, the weight of the entire loading machine can be reduced and the operational efficiency of the machine can be enhanced even in a narrow space.

What is claimed is:

1. A lumber grabbing apparatus comprising a. a hydraulic cylinder including a piston slidably disposed therein and a piston rod connected to said piston;

. a pair of grabbing members adapted to be opened and closed by said hydraulic cylinder, each of said grabbing members having one end pivotally connected to the outer end of the piston rod of said hydraulic cylinder, the respective mid portions of said grabbing members being pivotally connected to respective first ends of rods, the other ends of said rods being connected to said hydraulic cylinder;

0. arms pivotally connected to the other ends of said grabbing members respectively; and

. hydraulic cylinders provided on said grabbing members respectively for causing said arms to make a pivotal movement about the other ends of said grabbing members.

2, A lumber grabbing apparatus comprising first hydraulic cylinder means having a piston slidably disposed therein, a piston rod having one end connected to said piston, a pair of grabbing members adapted to be opened and closed by said first hydraulic cylinder means, each of said grabbing members having one end thereof pivotally connected to the other end of said piston rod, a pair of connecting rods, each connecting rod having one end connected to said first hydraulic cylinder means and the other end pivotally connected to the mid portion of a respective one of said grabbing members, a pair of arms means, each of said 3. A lumber grabbing apparatus according to claim arm means pivotally connected to the other end of a 2, Whfir in aid nd hydraulic cylinder means inrespective one of said grabbing members, and second cludes a P Of hydraulic Cylinders, each of Said hydraulic cylinder means mounted on said grabbing hydraulic Q'W belng mounted on a respective one members for controlling the pivotal movement of said of Sald grabbmg members f commnlflg the movearm means about the other end of said grabbing memmam of the arm means assoclated therew'thbers

Claims

1. A lumber grabbing apparatus comprising a. a hydraulic cylinder including a piston slidably disposed therein and A piston rod connected to said piston; b. a pair of grabbing members adapted to be opened and closed by said hydraulic cylinder, each of said grabbing members having one end pivotally connected to the outer end of the piston rod of said hydraulic cylinder, the respective mid portions of said grabbing members being pivotally connected to respective first ends of rods, the other ends of said rods being connected to said hydraulic cylinder; c. arms pivotally connected to the other ends of said grabbing members respectively; and d. hydraulic cylinders provided on said grabbing members respectively for causing said arms to make a pivotal movement about the other ends of said grabbing members.

2. A lumber grabbing apparatus comprising first hydraulic cylinder means having a piston slidably disposed therein, a piston rod having one end connected to said piston, a pair of grabbing members adapted to be opened and closed by said first hydraulic cylinder means, each of said grabbing members having one end thereof pivotally connected to the other end of said piston rod, a pair of connecting rods, each connecting rod having one end connected to said first hydraulic cylinder means and the other end pivotally connected to the mid portion of a respective one of said grabbing members, a pair of arm means, each of said arm means pivotally connected to the other end of a respective one of said grabbing members, and second hydraulic cylinder means mounted on said grabbing members for controlling the pivotal movement of said arm means about the other end of said grabbing members.

3. A lumber grabbing apparatus according to claim 2, wherein said second hydraulic cylinder means includes a pair of hydraulic cylinders, each of said hydraulic cylinders being mounted on a respective one of said grabbing members for controlling the movement of the arm means associated therewith.