EP0855468A1

EP0855468A1 - Roller-crusher

Info

Publication number: EP0855468A1
Application number: EP96933627A
Authority: EP
Inventors: Shigeru Oyama Factory of Komatsu Ltd. SHINOHARA; Takayuki Oyama Factory of Komatsu Ltd. MUTOU; Tadao Oyama Factory of Komatsu Ltd. KARAKAMA; Mitsuru Oyama Factory of Komatsu Ltd. ARAI; Koichi Oyama Factory of Komatsu Ltd. MORITA
Original assignee: Komatsu Ltd
Current assignee: Komatsu Ltd
Priority date: 1995-10-13
Filing date: 1996-10-11
Publication date: 1998-07-29
Also published as: WO1997013925A1; EP0855468A4; KR970021536A; JPH09111810A

Abstract

There is disclosed a combined ramming and breaking work machine which includes a boom member (6) mounted on a vehicle body (3) so as to be capable of being vertically swung and to be driven by a boom cylinder assembly (7), and an arm member (8) mounted to the boom member so as to be capable of being swung vertically and to be driven by an arm cylinder assembly (9). A fluid pressure driven vibration generating unit (12) is operatively coupled to the arm member whereas a breaker chisel (15) and a ramming tool (16) are adapted to be interchangeably and each operatively coupled to the vibration generating unit. The machine further includes a floating state switching device for rendering the boom cylinder assembly in a floating state, selectively where a ramming operation is being carried out.

Description

TECHNICAL FIELD

The present invention relates to a combined ramming and breaking work machine for carrying out a ramming operation as well as a breaking operation by the use of a power shovel or the like.

BACKGROUND ART

There has hitherto been known a ramming work machine using a power shovel, in which a cylinder assembly thereof is operated to reciprocate with a small amplitude to impart small vibrations to a bucket operatively associated therewith, thereby carrying out a given ramming work.

There has also been known a breaking work machine using a power shovel, in which an arm member thereof has a vibration generating device attached thereto, which acts to periodically strike a breaker chisel operatively coupled therewith, thereby carrying out a given breaking work.

As described above, a ramming work machine and a breaking machine have so far each been a dedicated machine. To install two such different work machines has, therefore, been a common facilities' requirement where both ramming and break operations must each be carried out.

It is accordingly an object of the present invention to provide a combined ramming and breaking work machine that is designed to carry out both a ramming and a breaking operation with a single machinery installation.

SUMMARY OF THE INVENTION

In order to achieve the above mentioned object, there is provided in accordance with the present invention in a general aspect thereof a combined ramming and breaking work machine, which comprises: a boom means mounted on a vehicle body so as to be capable of being vertically swung and adapted to be driven by a boom cylinder means; an arm means mounted to the said boom means so as to be capable of being swung vertically and adapted to be driven by an arm cylinder means; a fluid pressure driven vibration generating means operatively coupled to the said arm means; a breaker chisel and a ramming tool which are adapted to be interchangeably and each operatively coupled to the said vibration generating means; and a floating state switching means for rendering the said boom cylinder means in a floating state selectively where a ramming operation is carried out.

According to the construction in the general aspect of the invention described above, it can be seen and should be understood that either a breaker chisel or a ramming tool can selectively be employed in a single working machine for carrying on a breaking operation or a ramming operation, respectively, as desired at a given work site. Yet, the machine is designed, where a ramming operation should be selectively performed, to render the boom cylinder assembly in a floating state, thus permitting such a ramming work to be carried out efficiently on a single dual purpose working machine.

In a first subsidiary construction of the generic aspect of the invention mentioned above, the said floating state switching means may desirably comprise: a first operation sensing means for detecting a condition representing the said vibration generating means being in an operating state; a selector switch means for selectively providing a breaking command and a ramming command; a float valve means disposed in a circuit lying between the said boom cylinder means and a boom valve means for delivering a pressure fluid thereto; a floating switch valve means for controlling the said float valve means to change its position from one to another; and a timer relay means operative, only when both a condition representing signal from the said first operation sensing means and the said ramming command from the said selector switch means are inputted, for acting on the said floating switch valve means to establish a floating position in the float valve means.

According to the construction mentioned in the preceding paragraph, it can be seen and should be understood that the advantage is gained that even if the vibration generating unit happens to be in an operative state, the boom cylinder assembly is effectively prevented from being rendered in a floating state unless the selector switch means provides a ramming command. Thus, no time can make the boom cylinder assembly be brought into a floating state as long as a breaking operation is desired or in progress. In addition, control is effected electrically, thus keeping the machine free from a malfunction.

In the construction described just above, the said first operation sensing means may preferably comprise a pressure switch means responsive to a pressure in a pilot circuit means lying between a service valve means for delivering a pressure fluid to the said vibration generating means and a hydraulic pilot valve means for controlling the said service valve means.

Also, in a second subsidiary construction of the generic aspect of the present invention noted previously in the first paragraph of this section hereof, the said floating state switching means may desirably comprise: a selector switch means for selectively providing a breaking command and a ramming command; a float valve means disposed in a circuit lying between the said boom cylinder means and a boom valve means for delivering a pressure fluid thereto; a floating switch valve means for controlling the said float valve means to change its positions from one to another; a second operation sensing means for detecting a condition representing the said boom cylinder means being in an operating state and proving an output signal in response to the said condition; and a timer relay means selectively operative, only when the said output signal from the said second operation sensing means is not inputted and the said ramming command from the said selector switch means is inputted, for acting on the said floating switch valve means to establish a floating position in the said float valve means.

According to the construction of the invention mentioned in the preceding paragraph, it can be seen and should be understood that the advantage ensues that by virtue of the fact that the operation of a fluid pressure operated pilot valve means for the boom valve means during a ramming work causes the said float valve means to be switched to take a position other than the said floating position, the said boom cylinder assembly can be quickly elongated and retracted to allow the boom means to be so vertically swung.

In the construction just mentioned above, the said second operation sensing means may preferably comprise: a shuttle valve means responsive to a higher of pressures of pressure fluids acting on a first pressure receiving portion and a second pressure receiving portion of the said boom valve means from a fluid pressure operated pilot valve means that operates said boom valve means in a controlled manner; and a pressure switch means responsive to a pressure of the said shuttle valve means at its output side.

Further, in the construction just mentioned above, it may be desirable that there be further provided a float switch means, and the said timer relay means be selectively operable, only when both an ON signal from the said float switch means and the said ramming command from the said selector switch means are inputted and further an output signal from the said pressure switch means is not inputted, for acting on the said floating switch valve means to establish the floating position in the said float valve means.

According to the construction just mentioned above, it can be seen and should be understood that switching the said fluid pressure operated pilot calve means for the said boom means to its neutral position during a ramming work may not bring the said boom cylinder assembly into a floating state unless the said float switch is turned ON, thus assuring an enhanced safety of the machine being operated.

Still further in the generic construction mentioned previously in the first paragraph of this section hereof, it should be noted that the said floating state switching means may desirably include: a boom valve means adapted to deliver a pressure fluid to the said boom cylinder means and having a floating position; and a fluid pressure operated pilot valve means for operating the said boom valve means in a control manner, the said pilot valve means having a detent mechanism and further adapted, when operated in a full stroke mode, to switch the said boom valve means to take the said floating position.

Still further in each of the constructions mentioned above, it should be noted that the said vibration generating means preferably has a body portion formed with a bore adapted to accept a working tool, the said bore having a cap adapted to be detachably fitted thereto, the cap having a hook appended thereto.

According to the construction just mentioned above, it can be and should be understood that a foreign matter can be effectively prevented from entering into a cylinder bore by closing the cap where neither a breaking operation nor a ramming operation is carried out, the construction also permitting a suspending operation to be performed by means of the said hook.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will better be understood from the following detailed description and the drawings attached hereto showing certain illustrative embodiments of the present invention. In this connection, it should be noted that such embodiments as illustrated in the accompanying drawings are intended in no way to limit the present invention but to facilitate an explanation and understanding thereof.

In the accompanying drawings:

Fig. 1 is a diagrammatic explanatory view that shows the construction of a first embodiment of the combined ramming and breaking machine according to the present invention;

Fig. 2 is a diagrammatic explanatory view that shows the specific structure of a vibration generating unit that may be employed in the first embodiment of the invention noted above;

Fig. 3 is a diagrammatic view in cross section that shows a portion of the body part of the above noted vibration generating unit;

Fig. 4 is a diagrammatic explanatory view that shows the construction of a second embodiment of the combined ramming and breaking machine according to the present invention; and

Fig. 5 is a diagrammatic explanatory view that shows the construction of a second embodiment of the combined ramming and breaking machine according to the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, suitable embodiments of the present invention with respect to a combined ramming and breaking work machine will be set forth with reference to the accompanying drawings hereof.

An explanation will now be given with respect to the first embodiment hereof.

As shown in Fig. 1, a working vehicle comprises a an upper vehicle body 3 that is turnably mounted on a lower vehicle body 2 having a traveling body 1 equipped therefor. The upper vehicle body 3 has a driver's seat 4 with a plurality of driving members 5. The upper vehicle body 3 also has a boom member 6 mounted thereon as capable of being swung vertically and being driven by a boom cylinder assembly 7. The boom member 6 has an arm member 8 mounted thereto as capable of being vertically swung and being driven by an arm cylinder assembly 9. Further, the arm member 8 has a bucket member 10 mounted thereto as capable of being turnable vertically and being driven by a bucket cylinder assembly 11. And it is these component that constitute a power shovel.

The arm member 8 has a vibration generating unit 12 securely received therein. The vibration generating unit 12 has a body portion 13 in which a piston 14 is slidably received having a pair of pressure receiving chambers at its both end sides. The piston 14 is adapted to be reciprocated with a pressure fluid supplied alternately into these chambers. And its body portion 13 is designed to accommodate a breaker chisel 15 and a ramming tool 16 interchangeably.

A hydraulic pump 18 is adapted to be driven by means of an engine 17 mounted on the upper vehicle body 3. It has its discharge outlet connected to a boom valve 19, an arm valve 20, a bucket valve 21 and the inlet port of a service valve 22. The boom valve 19 has a first and a

second actuator port

23 and 24 which are connected via a first and a

second fluid circuit

25 and 26 to the boom cylinder assembly 7 at its elongating and retracting chambers 7a and 7b, respectively. The service valve 22 has an actuator port 27 that is connected to the vibration generating unit 12 via a fluid circuit 28.

It is seen that a float valve 29 is provided at a site both midway of the first circuit 25 and midway of the second circuit 29. The float valve 29 is held by spring means to take its position of fluid communication a and is adapted to be switched to a floating position b under a pressure fluid supplied into its pressure receiving chamber 30 to establish a fluid communication of the elongating and retracting chambers 7a and 7b of the boom cylinder assembly 7 with a reservoir 31.

It should be noted that a boom valve controlling hydraulic pilot valve 32 is provided on the upper vehicle body 3, and is here designed to be switched from its neutral position c to either an elongating position d or retracting position e by manipulating a lever 32a to feed pressure fluid either the first or the second

pressure receiving portion

19a or 19b of the boom valve 19, thereby switching the boom valve 19 to either the elongating or the retracting position from its neutral position.

A service valve controlling hydraulic pilot valve 33 is also provided on the upper vehicle body 3 to operate in such a manner that if a pedal 34 is depressed a pressure fluid may be supplied from a service valve controlling pilot circuit 35 to the pressure receiving portion 22a of the service valve 22 to switch the service valve 22 to its fluid supply position for providing pressure fluid from the actuator port 27. It is seen that a pressure switch 36 is connected to the service valve controlling pilot circuit 35.

It can further be seen that a selector switch 37 is provided also on the upper vehicle body 3, say, at the lever 32a of the boom valve controlling hydraulic pilot valve 32. The selector switch 37 has a pair of switchable positions, i. e., the ramming position f and the breaking position g in order to issue a ramming command and a breaking command.

A pressure signal issued from the pressure switch and a ramming command issued from the selector switch are furnished or input to a timer relay 38. The timer relay 38 is designed to electrically energize a solenoid 40 for a floating switching valve 39 a predetermined time interval after receipt of these signal or command inputs.

The floating switching valve 39 is provided in a floating pilot circuit 41 connected to the pressure receiving portion 30 of the float valve 29. It is normally held under a spring pressure at its drain position h and is adapted to be switched to its supply position i when the solenoid 40 is electrically energized.

Next, a certain specific structure of the vibration generating unit 12 will be described.

In Fig. 2, its body portion 13 is shown as being formed with a cylinder bore 43 which consists of a larger diameter cylinder bore 41 and a smaller diameter cylinder bore 42 and in which the piston 14 is slidably received. The piston 14 is formed with a larger diameter section 45, a larger diameter rod section 46, an intermediate diameter rod section 47 and a smaller diameter rod section 48. It is also formed at both sides of the larger diameter section 45 with a first chamber 49 having a smaller pressure receiving area and a second chamber 50 having a larger pressure receiving area, with the addition of a subsidiary chamber 51, thereby together constituting a cylinder portion 52.

There is provided a servo valve 53 having a pump port 54, a principal port 55, a tank port 56 and a subsidiary port 57 and is so constructed that the pump port 54 may communicate with the first chamber 49 of the cylinder portion 52 and the valve 53 may be switched to a neutral position A, a first position B and a second position C as the piston 14 is displaced.

There is also provided a principal switching valve 58 formed with a first, a second, a third and a

fourth port

59, 60, 61 and 62, in which the first port 59 communicates with the circuit 28 shown in Fig. 1, the second port 60 communicates with the subsidiary port 57 of the servo valve 53, the third port 61 communicates with the reservoir 31 and the fourth port 62 communicates with the second chamber 50 of the cylinder portion 52. The valve 58 also has a first pressure receiving portion 63 communicating with the principal port 55 of the servo valve 53 and a second pressure receiving portion 64 communicating with the above mentioned fluid circuit 28 which in turn communicates with both the first chamber 49 of the cylinder portion 52 and the pump port 54 of the servo valve 53. And the principal switching valve 58 is adapted to be switched to its first position D under a pressure applied to the first pressure receiving portion 63 and to its second position E under a pressure applied to the second pressure receiving portion 64.

It should further be noted that the subsidiary chamber 51 of the cylinder portion 52 is adapted to communicate either with the reservoir 31 or with the second chamber 50 by means of a switching valve 70. The switching valve 70 is of a pilot switching type in which it is held at its drain position F under a spring pressure and switched to a fluid communication position G under a fluid pressure applied to the pressure receiving position 71 that is connected to the floating pilot circuit 41. Note here that the switching valve 70 may also be of a manually operated switching type provided with a mechanical detent feature.

An explanation will next be given with respect to a basic operation of the vibration generating unit so far described in its construction.

In the state shown in Fig. 2, it is seen that the piston 14 is located at its neutral position and the servo valve 53 is held at its neutral position A with the pump discharge fluid pressure applied both to its first and second

pressure receiving portions

63 and 64. Then, since the first pressure receiving portion 63 is greater in pressure receiving area than the second pressure receiving portion 64, the principal switching valve 58 will take its first position D, thus permitting the second chamber 50 of the cylinder portion 52 to communicate with the reservoir 31 with the result that the piston 14 will be displaced rightwards under a fluid pressure in the first chamber 49.

If the piston 14 is displaced to reach a rightward stroke end position, the servo valve 53 will assume its second position C, thus establishing a fluid communication between the principal port 55 and the tank port 56 while blocking a fluid communication between the pump port 54 and the subsidiary port 57. As a result, with the pressure fluid in the first pressure receiving portion 63 of the principal switching valve 58 flowing out thereof into the reservoir 31, the principal switching valve 58 will be switched under the pressure in the second pressure receiving portion 64 to assume its second position E, thus establishing a fluid communication between the first port 59 and the fourth port 62 and a fluid communication between the second port 60 and the third port 61. This will cause a pressure fluid to be supplied into the second chamber 50 of the cylinder portion 52 and will, with a pressure difference arising from a difference in area between the first chamber 49 and the second chamber 50, act to displace the piston 14 leftwards.

If the piston 14 is displaced to reach a leftward stroke end position, the servo valve 53 will assume its first position B, thus establishing a fluid communication between the pump port 54 and the principal port 55 while blocking a fluid communication between the tank port 56 and the subsidiary port 57. This will cause the pressure fluid to be delivered into the first pressure receiving portion 63 of the principal switching valve 58 to switch the latter to assume its second position D and will, for a reason as mentioned above, act to displace the piston 14 rightwards.

It can be seen that the repetition of the foregoing actions will cause the piston 14 to be reciprocated.

An explanation will next be given with respect to the operation of altering the speed of reciprocation and the force of movement of the piston 14.

Assuming now that the switching valve 70 lies at the drain position F, blocking a fluid communication between the second chamber 50 and the subsidiary chamber 51 and causing the subsidiary chamber 51 to communicate with the reservoir 31, the chamber pressure receiving area required to displace the piston 14 leftwards can be seen to be equal to the pressure receiving area (A1-A2) of the second chamber 50, where A1 represents the cross sectional area of the larger diameter section 45 and A2 represents the cross sectional area of the intermediate diameter rod section 47.

If the pressure receiving portion 71 of the switching valve 70 is supplied with a pressure fluid, the switched valve 70 will be switched to assume its position of communication G to establish a fluid communication between the second chamber 50 and the subsidiary chamber 51, the chamber pressure receiving area required to displace the piston 14 leftwards will be the sum of the second chamber (50) pressure receiving area (A1-A2) and the subsidiary chamber (51) pressure receiving area (A2-A3) where A3 is the cross sectional area of the smaller diameter rod section 48.

In this manner, it can be seen that with the switching valve 70 being set to assume its drain position F the chamber pressure receiving area required to displace the piston 14 leftwards will be reduced. Noting that this serves to accelerate the speed of reciprocation of the piston 14, it will be appreciated that the vibration generating unit so far described and proposed herein is highly suitable, desirable and excellent for use as a drive source for a breaker chisel.

It can also be seen that with the switching valve 70 being held to assume its position of communication G the chamber pressure receiving area required to displace the piston rightwards will be increased. Noting that this serves to increase the force of displacement of the piston 14, it will also be appreciated that the same vibration generating unit herein embodied is here again highly suitable, desirable and excellent for use as a drive source for a ramming tool.

It should be noted at this point that the body part 13 of the vibration generating unit 12 described hereinabove is formed with a tool insertion bore 72 continuously with the cylinder bore 43, as shown in Fig. 3. The tool insertion bore 72 is adapted to accommodate either the breaker chisel 15 or the ramming tool 16, that is inserted therein. Then, a pin 73 is passed through a longitudinally elongated recess formed axially of the breaker chisel 15 or the ramming tool 16 to hold them interchangeably so that they when accepted may be capable of being reciprocated with a predetermined vibratory stroke amplitude.

Referring to Fig. 3, it should also be noted that a cap 74 is shown as detachably fitted in the tool insertion bore 73 and as retained by the pin 73 and as having a hook 75 suspended therefrom. This being the case, it is seen that if neither a breaking operation or a ramming operation is to be carried out, the cap 74 can be attached to the body portion 13 to fit in the tool insertion bore 73 so as to preclude introduction of a foreign matter. Then, the cap 74 can also be used to perform a suspending operation with the hook 75 attached thereto.

Next, the operation of the first embodiment of the invention described above will be described.

Breaking Work

The breaker chisel 15 is fastened to the body part 13 of the vibration generating unit 12 and the selector switch 37 is set at the breaking position g.

The pedal 34 is depressed to operate the service valve controlling hydraulic pilot valve 33, thereby permitting a pressure fluid to be delivered into the service valve controlling pilot circuit 35. This will cause the pressure fluid to be delivered to the pressure receiving portion 22a of the service valve 22 which will then be set to assume its supply position, permitting a pressure fluid discharged from the hydraulic pump 18 to be supplied into the body position 13 of the vibration generating unit 12. The piston 14 will then be reciprocated to periodically impact the breaker chisel 15 for initiating a breaking work.

At this point of time, the pressure switch 36 will issue a pressure signal whereas no ramming command or signal will be provided from the selector switch 37, thus holding the timer relay 38 inoperative. This means that the floating switching valve 39 will be held at its drain position h. Since no pressure fluid is then supplied to the floating pilot circuit 41, the switching valve 70 shown in Fig. 2 will remain set to assume its drain position F, thus accelerating the speed of reciprocation of the piston 14 to enhance the effect of the desired breaking work.

Also during this breaking work, manipulating the lever 32a of the boom valve controlling hydraulic pilot valve 32 will cause the boom cylinder assembly 7 to perform its elongating and retracting operations, thus causing the boom member 6 to be vertically swung.

Ramming Work

The ramming tool 16 is fastened to the body part 13 of the vibration generating unit 12 and the selector switch 37 is set at the breaking position f.

If the pedal 34 is depressed in this state, as in the case of a breaking work, the service valve 22 will be set to take its supply position and the piston 14 in the vibration generating unit 12 will then commence reciprocating. Since the piston causes the ramming tool 16 to be vibrated, a desired ramming work will be initiated.

At this point of time, a pressure signal from the pressure switch 36 and a ramming command from the selector switch 37 will enter the timer relay 38. The timer relay 38 will a predetermined time interval thereafter energize the solenoid 40 of the floating switching valve 39 to set the latter to assume its supply position i.

This will cause the float valve 29 to be supplied with a pressure fluid at its pressure receiving portion 30 and to be thereby set to assume its drain position b. Since a fluid communication is then established of both its elongating chamber and retracting chamber 7a and 7b with the reservoir 31, the boom cylinder assembly 7 will then be brought into a state in which it undergoes elongating and retracting operations freely with an external force, i. e., a floating state.

If the boom cylinder assembly 7 is established in a floating state, the boom member 6 comes capable of being vertically swung up and down with an external force, meaning that a desired ramming work can thereby be carried out with an enhanced efficiency.

It should also be noted that with the floating pilot circuit 41 being supplied with a pressure fluid, the switching valve 71 shown in Fig. 2 will be set to assume its supply position G. Since this allows the piston 14 to be displaced with an increased force as described previously, the result here is a markedly enhanced ramming effect.

An explanation will next be given with respect to a second embodiment of the present invention.

As shown in Fig. 4, a floating switch 80 is provided as attached to the lever 32a of the boom member controlling hydraulic pilot valve 32. There is also provided a shuttle valve 81 that is designed to detect a higher of pressures that act on the first and second

pressure receiving portions

19a and 19b of the boom valve 19. A pressure switch 82 is provided at the outlet side of the shuttle valve 81.

Here, an ON signal from the float switch 80 and a pressure signal from the pressure switch are designed to enter the timer relay 38, which is operative to energize the solenoid 40 of the floating switching valve 39 in the presence of both an ON signal of the float switch 80 and a ramming command from the selector switch 37 which are received and yet in the absence of a pressure signal entered from the pressure switch 82.

Under such an arrangement, it should be seen that if the boom valve 19 is operated by manipulating the lever 32a of the boom member controlling hydraulic pilot valve 32 in the course of a ramming work, a pressure signal is inputted from the pressure switch 82, then the timer relay 38 will no longer energize the solenoid 40. Since the floating switching valve 39 is then set to assume its drain position h, the float valve 29 will assume its position of communication a.

It follows, therefore, that where a ramming work is in progress with the boom cylinder assembly 7 in a floating state, manipulating the boom member controlling hydraulic pilot valve 32 in an attempt to cause the boom cylinder assembly 7 to undergo elongating and retracting operations will remove the floating state in which it has been held, thus enabling the boom cylinder assembly 7 to restore those operations and the boom member 6 to restore its ability to swing vertically, but thereafter if those operations are suspended by an operator the boom cylinder assembly 7 will then automatically restore the floating state.

It should be noted at this point in the interest completeness that the embodiment described may be modified to the extent, say, to omit the floating switch 80 and to allow the timer relay 38 to energize the solenoid 40 for the floating switching valve 39 only when a ramming command from the selector switch 37 is inputted but a pressure signal from the pressure switch 82 is not inputted. It can be readily appreciated that with such a modification as well, the same effects as mentioned above will be obtainable.

It should however be noted here for the sake of clarity that the presence of the float switch 80 is believed to be far more desirable in the interest of safety. For: turning the lever 32a of the boom member controlling hydraulic pilot valve 32 into its neutral position during a ramming work will no way render the boom cylinder assembly 7 into a floating state unless the float switch 80 is turned ON.

An explanation will finally be given with respect to a third embodiment of the present invention.

Referring to Fig. 5, this embodiment makes an arrangement in which the boom valve 19 is assumed to take a float position x, and the boom member controlling hydraulic pilot valve 32 is provided with a detent mechanism. Here, the boom valve 19 is designed as capable of being switched to the float position x where the boom member controlling hydraulic pilot valve 32 is operated in a full stroke mode.

If such an arrangement is taken, it should be noted that where the lever 32a of the boom member controlling hydraulic pilot valve 32 is manipulated by a full stroke extent to supply a pressure fluid into the second pressure receiving portion 19b of the boom valve 19, the boom valve 19 will be switched to assume the floating position x and yet with the lever 32a held at the full stroke end, as it is and with the boom cylinder assembly 7 held in the floated position a ramming operation can be carried out effectively.

While the present invention has hereinbefore been set forth with respect to certain illustrative embodiments thereof, it will readily be appreciated by a person skilled in the art to be obvious that many alterations thereof, omissions therefrom and additions thereto can be made without departing from the essence and the scope of the present invention. Accordingly, it should be understood that the present invention is not limited to the specific embodiments thereof set out above, but includes all possible embodiments thereof that can be made within the scope with respect to the features specifically set forth in the appended claims and encompasses all the equivalents thereof.

Claims

A combined ramming and breaking work machine, comprising:

a boom means mounted on a vehicle body so as to be capable of being vertically swung and adapted to be driven by a boom cylinder means;

an arm means mounted to said boom means so as to be capable of being swung vertically and adapted to be driven by an arm cylinder means;

a fluid pressure driven vibration generating means operatively coupled to said arm means;

a breaker chisel and a ramming tool which are adapted to be interchangeably and each operatively coupled to said vibration generating means; and

a floating state switching means for rendering said boom cylinder means in a floating state, selectively where a ramming operation is being carried out.
A combined ramming and breaking work machine as set forth in claim 1 in which said floating state switching means comprises:

a first operation sensing means for detecting a condition representing said vibration generating means being in an operating state;

a selector switch means for selectively providing a breaking command and a ramming command;

a float valve means disposed in a circuit lying between said boom cylinder means and a boom valve means for delivering a pressure fluid thereto;

a floating switch valve means for controlling said float valve means to change its positions from one to another; and

a timer relay means operative, only when both a condition representing signal from said first operation sensing means and said ramming command from said selector switch means are inputted, for acting on said floating switch valve means to establish a floating position in said float valve means.
A combined ramming and breaking work machine as set forth in claim 2 in which said first operation sensing means comprises a pressure switch means responsive to a pressure in a pilot circuit means lying between a service valve means for delivering a pressure fluid to said vibration generating means and a hydraulic pilot valve means for controlling said service valve means.
A combined ramming and breaking work machine as set forth in claim 1 in which said floating state switching means comprises:

a selector switch means for selectively providing a breaking command and a ramming command;

a float valve means disposed in a circuit lying between said boom cylinder means and a boom valve means for delivering a pressure fluid thereto;

a floating switch valve means for controlling said float valve means to change its positions from one to another;

a second operation sensing means for detecting a condition representing said boom cylinder means being in an operating state and proving an output signal in response to said condition; and

a timer relay means selectively operative, only when said output signal from said second operation sensing means is not inputted and said ramming command from said selector switch means is inputted, for acting on said floating switch valve means to establish a floating position in said float valve means.
A combined ramming and breaking work machine as set forth in claim 4 in which said second operation sensing means comprises:

a shuttle valve means responsive to a higher of pressures of pressure fluids acting on a first pressure receiving portion and a second pressure receiving portion of said boom valve means from a fluid pressure operated pilot valve means that operates said boom valve means in a controlled manner; and

a pressure switch means responsive to a pressure of said shuttle valve means at its output side.
A combined ramming and breaking work machine as set forth in claim 5, further comprising a float switch means, said timer relay means being selectively operable, only when both an ON signal from said float switch means and said ramming command from said selector switch means are inputted and further an output signal from said pressure switch means is not inputted, for acting on said floating switch valve means to establish the floating position in said float valve means.
A combined ramming and breaking work machine as set forth in claim 1 in which said floating state switching means includes:

a boom valve means adapted to deliver a pressure fluid to said boom cylinder means and having a floating position; and

a fluid pressure operated pilot valve means for operating said boom valve means in a control manner, said pilot valve means having a detent mechanism and further adapted, when operated in a full stroke mode, to switch said boom valve means to take said floating position.
A combined ramming and breaking work machine as set forth in any one of claims 1 to 7 in which a body portion of said vibration generating means is formed with a bore adapted to accept a working tool, said bore having a cap adapted to be detachably fitted thereto, said cap having a hook appended thereto.