EP0887475B1

EP0887475B1 - Linkage for a power shovel arm

Info

Publication number: EP0887475B1
Application number: EP97304570A
Authority: EP
Inventors: Rinta Denda
Original assignee: Takeuchi Manufacturing Co Ltd
Current assignee: Takeuchi Manufacturing Co Ltd
Priority date: 1995-12-28
Filing date: 1997-06-26
Publication date: 2003-09-10
Anticipated expiration: 2017-06-26
Also published as: EP0887475A1; JPH09177112A; JP3172668B2

Description

The present invention relates to an excavator and a power shovel having the excavator, more precisely relates to an excavator, which comprises a boom whose one end is pivotably connected to a base section, an arm whose one end is connected to the other end of the boom, and a bucket being attached to the other end of the arm, and a power shovel having said excavator.
A conventional power shovel having a conventional excavator is shown in Fig. 4. The power shovel includes: a boom 1; a boom cylinder 2; a boom foot section 3 on a vehicle section having crawlers; an arm 4; a bucket 5; and a boom pin 6. Note that, the boom foot section 3 acts as a base section for supporting the excavator. By extending and shortening the boom cylinder 2, the boom 1 turns upwardly and downwardly about the boom pin 6. The turning angle of the boom 1 is about 140 ° or less because the linear movement of the boom cylinder 2 is directly and merely converted into the turning movement of the boom 1.
In the case of the power shovel which is used in a narrow space, an upper part of the power shovel, which includes the excavator, an operator's cabin, etc., can be rotated within the width of the vehicle section having the crawlers. The conventional power shovel usually have a long boom 1, so the arm 4 and the bucket 5 are retracted in an inner space of the crooked boom 1 (see Fig. 4) when the excavator is not operated. By retracting the arm 4 and the bucket 5 as shown in Fig. 4, the excavator can be located within the width of the vehicle section. When the power shovel is conveyed by a truck, etc., it is advantageous to locate the excavator within the width of the vehicle section.
However, even the excavator is located within the width of the vehicle section, the boom must be extended upwardly. So the height of the power shovel must be relatively high due to the long boom. In some cases, e.g., conveying the power shovel by a truck, the high boom accidentally interferes with an electric power line, etc. which are existed in the air. Thus, a lower excavator or a lower power shovel has been required.
The present invention seeks to provide an excavator, which is capable of widely moving a boom and limiting the total height of the excavator when the excavator is retracted, and a power shovel having said excavator.
According to the present invention there is provided an excavator boom assembly comprising: the features according to claim 1.
The power shovel of the present invention comprises the excavator boom assembly of the invention.
In the excavator and the power shovel of the present invention, the boom can be widely moved or widely turned by the first link and the second link, so the total height of the excavator can be made lower when the excavator is retracted and located within the width of the power shovel.
An embodiment of the present invention will now be described by way of an example and with reference to the accompanying drawings, in which:

Fig. 1 is a side view of a power shovel of an embodiment of the present invention;
Fig. 2 is a side view of the power shovel whose boom cylinder is extended;
Fig. 3 is a side view of the power shovel whose boom cylinder is shortened; and
Fig. 4 is a side view of the conventional power shovel.

A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.
Fig. 1 is a side view of the power shovel of the present embodiment; Fig. 2 is a side view of the power shovel in a state of extending a boom cylinder; and Fig. 3 is a side view of the power shovel in a state of shortening the boom cylinder.
In the drawings, a symbol 1 indicates the boom; a symbol 2 indicates a boom cylinder; a symbol 3 indicates a boom foot section of a vehicle section having crawlers for running; a symbol 4 indicates an arm 4; a symbol 5 indicates a bucket; and a symbol 6 indicates a boom pin.
The boom pin 6 is pivotably attached to the boom foot section 3. By the pivotable boom pin 6, one end of an excavator, which includes the boom 1, the arm 4 and the bucket 5, is pivotably connected to the boom foot section 3, which is an example of a base section.
One end of the boom cylinder 2 is pivotably connected to a mid position of the boom 1.
Further, in the drawings, a symbol 8 indicates a first link; a symbol 9 indicates a second link; a symbol 10 indicates a first link pin; a symbol 11 indicates a second ling pin; and a symbol 12 indicates a third link pin.
One end of the first link 8 is pivotably connected to one end of the boom 1 by the first link pin 10; the other end of the first link 8 is pivotably connected to a front end of a rod of the boom cylinder 2, which is the other end of the boom cylinder 2, by the second link pin 11. In the present embodiment, the first link pin 10, which pivotably connects the boom 1 and the first link 8, is shifted to the other end of the boom 1 with respect to the boom pin 6, which pivotably connects the boom 1 and the boom foot section 3. So, the first link pin 10 is located at a position in which the boom 1 is slightly crooked backward in Fig. 1.
One end of the second link 9 is pivotably connected to the boom foot section 3 by the third link pin 12; the other end of the second link 9 is pivotably connected to the other end of the first link 8 by the second link pin 11. In the present embodiment, the third link pin 12 is located at a lower front end of the boom foot section 3 in Fig. 1. The other end of the second link 9, the other end of the first link 8 and the front end of the rod of the boom cylinder 2, which is the other end of the boom cylinder 2, are pivotably connected one another by the second link pin 11. Said three ends are pivotably connected by the second link pin 11, so the structure can be simple, and driving force for moving the boom 1 can be transmitted effectively.
Unlike the present embodiment, if the other end of the first link 8 and the other end of the second link 9 are mutually pivotably connected, the front end of the rod of the boom cylinder 2 (the other end of the boom cylinder 2) need not be connected together with the two ends. In this case, the other end of the boom cylinder 2 may be connected the other end of the first link 8 or the other end of the second link 9 by another link pin. With this structure, the boom 1 can be properly moved as well as the above described embodiment. Note that, it is better to connect the other end of the boom cylinder 2 to the other end of the first link 8.
In the power shovel having above described excavator, the one end of the boom 1 is pivotably connected to the boom foot section 3 by the boom pin 6; the one end of the first link 8 is pivotably connected to the boom 1 by the first link pin 10. The other end of the first link 8, the other end of the boom cylinder 2 and the other end of the second link 9 are mutually coaxially pivotably connected one another by the second link pin 11. The one end of the second link 9 is pivotably connected to the boom foot section 3 by the third link pin 12. Compared with the conventional power shovel, the power shovel of the present embodiment further has: the first link 8; the second link 9; the first link pin 10; the second link pin 11; and the third link pin 12.
The action of the power shovel of the present embodiment will be explained.
The one end of the second link 9 is pivotably connected to the boom foot section 3 of the vehicle section by the third link pin 12; the other end of the second link 9, the rod of the boom cylinder 2 and the one end of the first link 8 are pivotably connected by the second link pin 11; and the other end of the first link 8 is pivotably connected to a position close to the boom pin 6 of the boom 1 by the first link pin 10. With this structure, the first link 8 is upwardly and downwardly turned about the first link pin 10 by extending and shortening the boom cylinder 2. Simultaneously, the second link 9, whose the other end is pivotably connected by the second link pin 11, is turned; the one end of the second link 9 presses the boom foot section 3. Then the boom 1 is upwardly and downwardly turned within angle about 180° by the link action of the first and the second links 8 and 9.
In the present embodiment, a four-joint link mechanism is employed so as to convert the linear movement of the rod of the boom cylinder 2 into the vertical turning movement of the boom 1. In the conventional power shovel, speed of the turning movement of the boom 1 is very high with respect to speed of the linear movement of the boom cylinder 2 at the beginning and at the termination of the movement. On the other hand, in the present embodiment, the first and the second links 8 and 9, etc. are designed to move the first link 8 to a position below the boom pin 6, so the speed of the turning movement of the boom 1 is not very high with respect to the speed of the linear movement of the boom cylinder 2 at the beginning and at the termination of the movement.
Successively, the action of the excavator will be explained with reference to Figs. 2 and 3.
As shown in Fig. 3, in the sate of shortening the boom cylinder 2, angle of the boom 1 with respect to a standard line, e.g., a horizontal plane, of the vehicle section is equal to angle between the standard line and a line "R", which connects the boom pin 6 and the first link pin 10.
When the boom cylinder 2 is extended, the first link 8 is turned about the first link pin 10. Since the boom cylinder 2 and the second link 9 are pivotably connected to the other end of the first link 8 by the second link pin 11, the second link 9 is also turned so that the second link 9 presses the third link pin 12, which is attached to the boom foot section 3. Then the boom 1 is turned about the boom pin 6 by the link action of the first and the second links 8 and 9. Finally, the boom cylinder 2 is extended as shown in Fig. 2, so the angle of the boom 1 with respect to the standard line of the vehicle section is shown as the angle between the standard line and the line "R" in Fig. 2. In Fig. 2, a point "Q" (the first link pin 10) has been moved to the opposite side with respect to a point "P" (the boom pin 6). Namely, the boom 1 can be turned about 180 with respect to the standard line of the vehicle section. Since the boom 1 can be turned within wide angle, the movable range of the boom 1 can be very wide when the excavator is used and when the excavator is retracted. Note that, the movable range of the boom 1 can be adjusted by connecting positions and length of the first and the second links 8 and 9, so the boom 1 can be turned 180° or more.
In the conventional power shovel, each end of the boom cylinder 2 is directly connected to the boom 1 and the boom foot section 3, so the turning angle of the boom 1 is about 140 ° even the boom cylinder 2 is fully extended and shortened.
On the other hand, in the present embodiment, the boom 1 of the excavator can be turned about 180° by employing the first link 8 and the second link 9. With the wide movable angle, the boom 1 can be shortened, and the total height of the power shovel can be lower when the excavator is retracted (see Fig. 1). Construction work can be executed effectively by the excavator having the widely movable boom 1. Further, since the total height of the power shovel can be lower, the power shovel can be easily conveyed by a truck, etc. without interference with, for example, an electric power line in the air.

Claims

An excavator boom assembly comprising: a bucket (5); a dipper arm (4); a boom (1), the proximal end portion of the boom being pivotally connectable to a base section (3) of a power shovel by a first pin (6) so as to be actuatable in use on the forward side of the power shovel,
a boom cylinder (2) being located underneath said boom (1) when the boom is extending horizontally forwardly relative to the power shovel, a first end of said boom cylinder (2) being pivotally connected to a mid portion of said boom (1) so as to turn said boom (1) upwardly and downwardly;
characterized by:
a first link (8) comprising a first end pivotally connected by a second pin (10) to the proximal end portion of said boom (1) towards the distal end of the boom in relation to the first pin (6); the second end of the first link (8) being pivotally connected to the second end of said boom cylinder (2);

a second link (9) having a first end pivotally connectable by a third pin (12) to a part of the base section (3) located forwardly of the power shovel relative to the first pin (6) and underheath said first pin (6); the second end of the second link (9) being pivotally connected to the second end of said first link (8),

the second pin (10) being in use moveable by extending and retracting said boom cylinder (2) between two positions, which are located on radially opposed sides relative to the first pin (6).
The excavator boom assembly according to claim 1,
wherein a part of the boom (1), which is close to the one end thereof, is curved forward, and
wherein the one end of said first link (8) is pivotably connected to the curved part of said boom (1) by the second pin (10).
The excavator boom assembly according to claim 1 or 2,
wherein the other end of said first link (8), the other end of said second link (9) and the other end of said boom cylinder (2) are coaxially pivotably connected by a fourth pin (11).
A power shovel having the excavator boom assembly according to claim 1, 2 or 3.