Operation breaking apparatus for construction equipment

Abstract: An operation breaking apparatus for construction machine wherein said cutoff bar (21) has a spring core member with a equipment which is capable of improving its controllability. A cutoff bar (21) is arranged to cut off the entryway (20) to an operator cab (17) of the construction equipment. This cutoff bar (21) is operationally linked with a locking mechanism for a hydraulic valve system of the construction equipment. Further, a displacement enlarging mechanism is provided between an operating knob (28) and the cutoff bar (21).

Description: BACKGROUND OF THE INVENTION [Filed of the Invention] The present invention relates to an operation breaking apparatus for use in construction equipment such as a power shovel. [Description of the Prior Art] There has been known an operation breaking apparatus, for example a cutoff bar, placed commonly at a doorway for the operators within an operator cab of such a construction equipment as a power shovel. An operation breaking apparatus, known from JP-A-5-57052 and JP-A-6-67560, will be described hereinbelow with reference to Fig 7. The description will begins with the purpose of incorporating the operation breaking apparatus. An operator cab 1 is equipped with an entryway 2 open to one side of the machine body, so that the operator get in and out of the construction equipment through the entryway 2. An operating box 4 is disposed in the front and side of an operator's seat 3 and is provided with an operating lever 5 for operating cylinders (not shown) for driving booms and arms. In case that the operating lever 5 is operated in error when the operator approaches and separates from the operator's seat 3, any one of the cylinders can work accidentally. In addition, even in the case that the engine is in no operation, if the operating lever 5 is operated by mistake when the booms or the arms are in lifted conditions, a bucket, together with the booms and the arms, can move accidentally. For these reasons, in the prior construction equipment, a cutoff bar 6 is set in the entryway to the operator's seat to protrude and to be returnable. This cutoff bar 6 is designed to be operationally linked with a locking mechanism for a hydraulic valve for driving the cylinders so that an operating mechanism for the cylinders gets into a deactuated condition when the cutoff bar 6 is in the protruding state toward within the entryway. There is a problem which arises with such a prior cutoff bar, however, in that difficulty is encountered to easily lift the cutoff bar. That is, the cutoff bar is made to work between a generally vertical position and a generally horizontal position, and is moved manually to take the generally horizontal position when to gate the entryway while taking the generally vertical position when to allow the passing of the operator, besides the operated angular range of the cutoff bar needs to be a rotational range (stroke) of approximately 90 degrees. Accordingly, the prior cutoff bar involves a difficult raising operation. Moreover, since a pivot shaft of the cutoff bar is situated under the operator cab 1, the operation of the cutoff bar requires that the operator's body bends forward, thus lowering its controllability. Furthermore, since the cutoff bar is placed within a space defined between the operating box 4 and an inner wall of the operator cab, a further problem arises in that the formation of the space reduces the effective space within the operator cab. SUMMARY OF THE INVENTION The present invention has been developed to eliminate the above-mentioned problems, and it is therefore an object of the present invention to a cutoff bar, being made to protrude within the entryway and retreat therefrom, which is capable of being held up with a short operating stroke. Another object of this invention is to prevent the cutoff bar from being damaged by providing a flexibility to the cutoff bar. For the first-mentioned purpose, in accordance with a preferred form of this invention, there is provided an operation breaking apparatus for construction equipment in which an operating box is located beside an operator's seat within an operator cab of the construction equipment and an operating lever of the operating box operates a cylinder of a working member, and a cutoff bar is situated in an entryway to the operator's seat to protrude and retreat and is linked with a locking mechanism of a hydraulic driving system for driving the cylinder to unlock the locking mechanism when taking a gating condition, the operation breaking apparatus being equipped with a first lever 26 pivotally supported by a base plate 23, a second lever 30 similarly pivotally supported by the same base plate 23, a connecting section 29, 31 for transmitting a rotating force from the first lever 26 to the second lever 30, an operating knob 28 attached to the first lever 26, and a cutoff bar 21 fitted onto the second lever 30, wherein a displacement enlarging mechanism is provided so that the distance between the supporting point 24 of the first lever 26 and the connecting section 29 exceeds the distance between the supporting point 25 of the second lever 30 and the connecting section 29 and a switch 37 is operated to unlock the locking mechanism when the cutoff bar 21 takes a position to cut off the entryway. Furthermore, in accordance with another form of this invention, there is provided an operation breaking apparatus for construction equipment in which the cutoff bar 21 accommodates a spring core member 41 with a flexibility so that a portion of the cutoff bar 21 is flexible. Thus, the displacement enlarging mechanism allows the cutoff bar to protrude toward the entryway and to retreat from the entryway with a smaller operating stroke, with the result that the controllability of the cutoff bar improves. In addition, even if an impulsive force works on the cutoff bar, the flexibility of the cutoff bar absorbs the impulsive force to prevent the cutoff bar from being damaged therefrom. BRIEF DESCRIPTION OF THE DRAWINGS The object and features of the present invention will become more readily apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings in which: Fig. 1 is a side elevational view showing the whole arrangement of a construction equipment operation breaking apparatus according to an embodiment of the present invention; Fig. 2 is a perspective view showing an operating box including the operation breaking apparatus according to the embodiment of this invention; Fig. 3 is an illustration available for describing an internal structure of the operation breaking apparatus according to the embodiment of this invention; Fig. 4 is a plan view showing the same structure of the operation breaking apparatus as in Fig. 3; Fig. 5 is a cross-sectional view showing a structure of only a cutoff bar according to the embodiment of this invention; Fig. 6 is a cross-sectional view showing a structure of a cutoff bar according to another embodiment of this invention; and Fig. 7 is an illustration useful for explaining a prior construction equipment operation breaking apparatus. DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, a detailed description will be taken hereinbelow of embodiments of this invention. Fig. 1 illustrates the whole configuration of a power shovel 11 equipped with an operation breaking apparatus according to an embodiment of this invention. The power shovel 11 is shown as comprising a crawler 13 driven by an engine placed on a base 12 for movement, a bucket 14 for carrying out a work, an arm 15 and a boom 16 for movably supporting the bucket 14, which are driven under the control of a hydraulic control means. An operator cab 17 is placed on the base 12 and an operating box 19 is provided at both sides of an operator's seat 18 located within the operator cab 17. Designated at numeral 20 is an entryway formed in the operator cab 17 to allow the operator to get in and out. In this entryway 20 and in the front side surface of the operating box 19, there is provided the operation breaking apparatus 22 equipped with a cutoff bar 21 which is made to protrude and return or retreat (see Fig. 2). Secondly, the structure of the operation breaking apparatus 22 will be described with reference to Figs. 3 and 4. In the illustrations, numeral 23 represents a base plate positioned vertically, with first and second pivot shafts 24, 25 being attached thereto. The first pivot shaft 24 pivotally supports a central portion of a first lever 26 having a generally L-like configuration. An operating knob 28 is attached through a fitting screw 27 to a tip portion (one end portion) of the first lever 26, whereas a connecting pin 29 is fixedly secured to the other end portion of the first lever 26. On the other hand, the second pivot shaft 25 pivotally supports a second lever 30 integrally formed with a proximal portion of the cutoff bar 21, and the second lever 30 has an elongated hole 31 which is loosely engaged with the aforesaid connecting pin 29. In addition, numeral 32 denotes a spring supporting pin fitted into the aforesaid base plate 23, and between the spring supporting pin 32 and the connecting pin 29 there is provided or stretched a spring 33 having a generally Ω-like configuration in its side elevation. The elastic action of the spring 33 can make the cutoff bar 21 held appropriately without wobbling when the cutoff bar 21 is at the vertical position indicated by a solid line in Fig. 3 and at the horizontal position indicated by a chain line in the same figure. More specifically, in accordance with the movements of the operating knob 28 the connecting pin 29 is displaceable up and down in Fig. 3 with respect to an axis 34 connecting the spring supporting pin 32 to the first pivot shaft 24, and when the connecting pin 29 is above the axis 34, the second lever 30 is pressed and moved counterclockwise with respect to the second pivot shaft 25 by the elastically pressing force of the spring 33, and the cutoff bar 21 is then maintained in a vertical state (hang-down state) because a stopper 35 exhibits its movement limiting action. On the other hand, when the connecting pin 29 comes to under the axis 34, the second lever 30 is pressed and moved clockwise with respect to the second pivot shaft 25 by the elastic action of the spring 33 and the cutoff bar 21 is maintained in the horizontal state by means of the movement limiting action of another stopper 36 (indicated by a chain line in Fig. 3). Still Further, numeral 37 depicts a microswitch attached to the base plate 23. When the first lever 26 moves to the chain-line indicated position so that the cutoff bar 21 comes to the horizontal position, the microswitch 37 takes its closed state in conjunction with the movement of the first lever 26 so that a solenoid valve or the like (not shown) is actuated to operate a hydraulic system of the construction equipment to permit the construction equipment to work. On the other hand, when the cutoff bar 21 gets into the vertical state, the construction equipment can fall into an operation-inhibited condition. In the illustrations, numeral 38 signifies a connector, numeral 39 stands for a cover of the operation breaking apparatus, and numeral 48 designates an operating lever. As obvious from the above description, in the operation breaking apparatus 22 according to the embodiment of this invention, in response to the operating knob 28 being rotationally moved in opposite directions with respect to the first pivot shaft 24, the cutoff bar 21 is displaceable between the horizontal position and the vertical position. When the cutoff bar 21 is at the horizontal position, it blocks the passing of the operator through the entryway 20 of the construction equipment, and when the operator displaces the cutoff bar 21 to the vertical position, the operator is allowed to get in and out of the construction equipment, besides the hydraulic driving system of the construction equipment comes into the closed condition. Thus, in this embodiment, the operating knob 28 is fixedly secured to one end portion of the first lever 26 pivotally supported by the first pivot shaft 24, while the connecting pin 29 is fixedly secured to the other end portion thereof, and further the cutoff bar 21 is fixedly secured to one end portion of the second lever 30 pivotally supported by the second pivot shaft 25 and the elongated hole 31 is made in the other end portion thereof to loosely engage with the connecting pin 29, more-over a displacement enlarging mechanism is provided so that the distance between the connecting pin 29 and the second pivot shaft 25 becomes shorter than the distance between the first pivot shaft 24 and the connecting pin 29. With this arrangement, in response to the slight movement of the operating knob 28, the cutoff bar 21 is movable widely from the horizontal position to the vertical position. In addition, for example, the operating knob 28 can be located on an upper part of the operating box 19, thereby providing the operation breaking apparatus with an excellent controllability for use in the construction equipment. Figs. 5 and 6 show concrete structural examples of the aforesaid cutoff bar 21. In the cutoff bar 21 shown in Fig. 5, one end portion of a spring core member 41 involving a coil spring section 40 is fixedly secured to the second lever 30, and the circumferential portion of the coil spring section 40 is covered with a rubber member 42 with a flexibility while the other section of the spring core member 41 is covered with a resin-made pipe 43, thus forming a bar-like configuration. Thus, this cutoff bar 21 can escape from its damage because its portion in the longitudinal directions is constructed to exhibit a flexibility. On the other hand, in the case of the cutoff bar 21 according to another embodiment shown in Fig. 6, a metallic pipe 44 is fixedly secured to the second lever 30 and a spring receiving shaft 45 is fixedly secured through a pin 46 to the tip portion of the metallic pipe 44 and further a spring core member 41 having a coil spring section 40 is fixedly secured to the tip portion of the spring receiving shaft 45 in an extending state, besides the circumferential portion of the coil spring section 40 is covered with a flexible pipe 47 made of a soft material such as a rubber while the other portion of the spring core member 41 is covered with a resin-made pipe 49. Thus, even in the case of the cutoff bar 21 according to this embodiment, a flexible and elastic section comprising the spring section 40 and the flexible pipe 47 is provided as a portion of the cutoff bar 21 in the longitudinal directions, and hence the cutoff bar 21 can be saved from its damage. In the construction according to this invention, since the displacement enlarging mechanism is set between the operating knob and the cutoff bar, irrespective of the slight movement of the operating knob, the cutoff bar is operable widely from the horizontal position to the vertical position. In addition, since, for example, the operating knob 28 can be placed on the upper portion of the operating box 19, the operation breaking apparatus for the construction equipment can exhibit an excellent controllability. Moreover, since a longitudinal portion of the cutoff bar is constructed as a flexible and elastic section, the prevention of damage of the cutoff bar is possible. It should be understood that the foregoing relates to only preferred embodiments of the present invention, and that it is intended to cover all changes and modifications of the embodiments of the invention herein used for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

Claims: An operation breaking apparatus for construction equipment in which an operating box (19) is located beside an operator's seat (18) within an operator cab (17) and an operating lever of said operating box (19) operates a cylinder of a working member, and a cutoff bar (21) is situated in an entryway (20) to said operator's seat (18) to protrude and retreat and is linked with a locking mechanism of a hydraulic driving system for driving said cylinder to unlock said locking mechanism when taking a cutoff condition, characterized in that said operation breaking apparatus comprises : a first lever (26) pivotally supported by a base plate (23) ; a second lever (30) pivotally supported by said base plate (23) ; a connecting section (29, 31) for transmitting a rotating force from said first lever (26) to said second lever (30) ; an operating knob (28) attached to said first lever (26) ; the cutoff bar (21) fitted into said second lever (30) ; a displacement enlarging mechanism arranged so that a distance between a supporting point (24) of said first lever (26) and said connecting section (29) exceeds a distance between a supporting point (25) of said second lever (30) and said connecting section (29) ; and a switch (37) operated to unlock said locking mechanism when said cutoff bar (21) takes a position to cut off said entryway (20). An operation breaking apparatus as claimed in claim 1, characterized in that said cutoff bar (21) has a spring core member (41) with a flexibility therein so that a portion of said cutoff bar (21) is flexible.

Inventors: AKAHANE EIJI, HATA SEIICHI, KURODA KENZO, OHTA MAKOTO, SATO SHOSUKE, AKAHANE, EIJI, HATA, SEIICHI, KURODA, KENZO, OHTA, MAKOTO, SATO, SHOSUKE, Akahane, Eiji, c/o Shin Caterpillar Mitsubishi Ltd, Hata, Seiichi, c/o Shin Caterpillar Mitsubishi Ltd, Ohta, Makoto, c/o Shin Caterpillar Mitsubishi Ltd.
Applicants: CALSONIC KANSEI CORP, CATERPILLAR MITSUBISHI LTD, CALSONIC KANSEI CORPORATION, SHIN CATERPILLAR MITSUBISHI LTD.
Application year: 1996
Main classification: E02F9
IPC codes: E02F9, G05G5