JP2014148411A - Switching device for movable range of rotary shaft for control of hydraulic pump and external loader for cargo work with the switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching device which switches a rotation range of a manual handle for controlling an opening amount of an oil pressure change valve and holds it in an optimal range in order to control an operation speed of a hydraulic pump.SOLUTION: A two-stage switching device for a movable range of a rotary shaft 5 for control of a hydraulic pump 21 comprises: the rotary shaft 5 for rotating an oil pressure change valve 22 of the hydraulic pump 21; a base plate 2 for holding the rotary shaft 5 in a rotatable manner; a C-shaped annular outer stopper 4 provided on the base plate 2; a C-shaped annular inner stopper 3 integrated with the rotary shaft 5 along the outer stopper 4; a manual handle 6 in an upper end of the rotary shaft 5; a plunger holding plate 7a additionally provided in a side portion of the base plate 2; a manual spring-type plunger 7 installed in the plunger holding plate 7a; a spring-return operation pin 7g, for the plunger 7, which can be inserted into and pulled out of a notched portion of the inner stopper 3 and a notched portion of the outer stopper 4.

Description

  The present invention relates to a switching device for switching the rotation movable range of a manual hydraulic pressure change valve for changing the pressure of a hydraulic pump used for a hydraulic lifter of a loader for cargo handling, in particular, a stopper for a rotation angle range of a handle for rotating the hydraulic pressure change valve. The present invention relates to a switching device that regulates the hydraulic pressure change valve to prevent excessive change and allows the change angle to be switched in two stages so as to regulate the lowering speed according to the load state of a hydraulic lifter or the like. It is related with the loader for cargo handling which provided.

  Traditionally, when loading or unloading various materials such as parts and products for industrial products from storage shelves or cargo handling shelves, or loading them on storage shelves or cargo handling shelves, these loads are moved to the front of the storage shelves. Then, pick up and unload the cargo from the required height, or lift and store the material on the storage shelf, or approach the location of the material storage shelf, receive the material on the storage shelf, drop it down, or other place There are various loaders for loading and unloading that have a hydraulic lifter as a device that moves to the required height position of goods and transfers them to a necessary height position.

  In a loader having such a hydraulic lifter, in a hydraulic lifter on which a heavy load of several hundred kg to 1000 kg is loaded, the loaded heavy load is loaded when being lowered from a high position to a low position. When a load of several hundred kg to 1000 kg is applied to the lifter fork, the fork is rapidly lowered. When the fork gets down to a low position as described above, it suddenly stops at the low position, the load swings with inertia, and the movement is transmitted to the load as an impact. As a result, the cargo may bounce on the fork and become extremely dangerous. Conversely, when a heavy load is loaded on a fork, when the loaded heavy load is lifted from a low position to a high position, it slowly rises due to the weight of the fork load, so the fork is fully lifted and stopped. Even so, it is safe because the load does not swing due to inertia. Therefore, it is necessary to take measures to prevent these dangers when descending, but on the other hand, when there is no load on the fork, there is no danger of falling from the fork even when descending, It is desirable to lower the fork as quickly as possible for efficiency.

  Therefore, for safety when loading and lowering the load of the hydraulic lifter fork, the operating lever of the hydraulic pressure change valve that controls the hydraulic pressure of the hydraulic pump that operates the fork is tilted by experience. is there. Therefore, these hydraulic lifters shall have an up / down switching lever in addition to the operating lever of the hydraulic pressure change valve of the hydraulic pump, and when the fork is raised, the switching lever is switched to the up side. It can be raised by operating the lever, but when the fork is lowered, the fork is gradually lowered by switching the switching lever to the lower side. To stop the descent, move the switch lever to the up side to stop. An apparatus has been proposed in which the operation lever is disabled during the lowering (see, for example, Patent Document 1). The switching lever of Patent Document 1 has a handle at its upper end, and the operation is switched by turning the handle left and right. When the handle is turned counterclockwise, the fork starts to descend, and when the handle is fully rotated counterclockwise, the descending speed becomes maximum and descends to the bottom in a few seconds. However, the device of Patent Document 1 is a mechanism for operating the hydraulic pump safely because the amount of rotation of the handle is determined depending on the intuition and experience of the operator, and is easily different for each operator. It was not a hydraulic switching device.

JP 2005-112612 A

  As described above, in a loader for loading and unloading that is a hydraulic lifter, a fork of a manual hydraulic lifter is inserted into a pallet on which a heavy object is placed, for example, for loading and unloading a load, from a high position to a low position. If the fork of a manual hydraulic lifter is moved rapidly and stopped suddenly when it is lowered, there is a risk that the load will vibrate due to the weight of the load placed on the fork and fall from the pallet. .

  Therefore, the problem to be solved by the present invention is to switch the rotation range of the manual handle that controls the opening amount of the hydraulic pressure change valve of the hydraulic pump to the optimum range in order to control the hydraulic pump operating speed according to the operating status. A manual switching device is provided. Furthermore, this manual switching device is applied to a movable mechanism of a hydraulic pump that moves up and down a fork of a hydraulic lifter that is an external loader for cargo handling, and an external loader for cargo handling having a hydraulic lifter that can operate efficiently and safely. Is to provide. In particular, in an external loader having a hydraulic lifter fork, a moving mechanism of a hydraulic pump for vertically moving the fork is used to load a heavy article of several hundred kg to 1000 kg, and when the loaded fork is lowered, it is slowly lowered and stopped. By controlling in this way, the shock at the time of stopping is eliminated, and the risk of dropping a heavy load from the fork is prevented. On the other hand, when the fork drops the unloaded fork after loading and unloading the load, it is controlled to drop and stop rapidly, or when the unloaded fork is raised, the fork rises rapidly. By controlling so that the fork stops, the fork operation time is shortened to increase efficiency. For this purpose, an external loader for cargo handling comprising a hydraulic lifter obtained by applying the above-described manual switching device to a movable mechanism of a hydraulic pump for vertically moving a fork is provided.

  Means of the present invention for solving the above problem is an attachment device attached to a hydraulic pressure change valve of a hydraulic pump in the first means. This attachment device includes a handle shaft for rotation of the operation of the hydraulic pressure change valve, a base plate that is rotatably inserted through the handle shaft, a C-shaped annular outer stopper provided on the base plate, A C-shaped annular inner stopper integrated with the handle shaft along the side wall surface of the stopper, a manual handle at the upper end of the handle shaft, a plunger holding plate attached to the side of the base plate, It consists of a manual spring type plunger installed on this plunger holding plate, an annular notch on the inner stopper, and an operating pin for a spring return type plunger that can be inserted and removed from the notch on the outer stopper. It is a switching device for a movable range of a rotary shaft for controlling a hydraulic pump, characterized by comprising an attachment device.

  In the second means, the C-shaped inner stopper integrated with the handle shaft for rotation of the hydraulic pressure change valve can be rotated by a manual handle integrally provided at the upper end of the rotary shaft of the hydraulic pressure change valve. The C-shaped annular outer stopper provided on the base plate is integrally formed with the base plate by adjusting the rotation angle around the rotation axis by a screw inserted into an annular adjusting screw hole formed in the center of the C-shaped ring. This is a device that is fixed, and is a device for switching the movable range of the rotary shaft for controlling the hydraulic pump of the first means.

  In the third means, the spring return type actuating pin of the plunger can be inserted and withdrawn from the side part into the notch part of the C-shaped annular inner stopper and the notch part of the C-shaped annular outer stopper. By rotating the handle, it is inserted into the notch of the C-shaped inner stopper arranged in front of the operating pin and is brought into contact with the counterclockwise tip of the C-shaped inner stopper. By restricting the rotation angle of the inner stopper clockwise, and pulling it out from the notch of the C-shaped inner stopper, the tip of the C-shaped inner stopper is further counteracted than the front of the manual plunger actuating pin. Rotate clockwise to abut the rear end face of the outer stopper's clockwise notch to restrict counterclockwise rotation by the handle of the inner stopper An apparatus characterized Being, which is a switching device for a rotary movement range of the hydraulic modulating valve of the hydraulic pump of the first means or the second means.

  The fourth means includes a left and right underframe that has a fixed caster at the lower end of the front end and protrudes left and right, a rear end connecting frame that connects the left and right rear ends of the left and right underframe, and a left and right underframe A carriage unit comprising a rear projecting frame having a free caster at the lower part projecting rearward of the rear part, left and right columnar masts standing on the rear ends of the left and right platform frames of the carriage part, and the front of the left and right columnar masts A hydraulic lifter consisting of a fork abutment that supports the left and right forks protruding in the up and down direction and a hydraulic pump that supports the fork abutment and moves up and down, and is arranged on a hydraulic pressure change valve. An external loader comprising a switching device for a movable rotation range of a control handle shaft, which is an external loader composed of a hydraulic lifter.

  Regarding the external loader composed of a hydraulic lifter to which the switching device of the present invention that can control the release of the pressurized hydraulic pressure is applied, there is no particular limitation on the power and system for driving the pump that pressurizes the hydraulic pressure. . Thus, for example, not only a mechanism that pressurizes a hydraulic pump by moving a manual lever up and down, but even in a case where the hydraulic pressure of the pump is increased by power such as a motor drive, In this case, the switching device of the present invention can be applied as appropriate. Therefore, in the description of the mode for carrying out the invention below, a mechanism provided with a hydraulic lifter that manually pressurizes will be described as an example. However, other pressurizing means can be applied to the hydraulic lifter. It does not deny sex.

  Since the first means of the present invention is a switching device that can switch the rotation amount of the rotary shaft of the hydraulic pressure change valve stepwise in the means for controlling the hydraulic pressure change amount of the hydraulic pressure change valve of the hydraulic means of the hydraulic pump. When there is a load on the hydraulic means, excessive hydraulic pressure due to excessive rotation of the rotating shaft of the switching device for controlling the hydraulic pressure change amount of the hydraulic pressure change valve can make the hydraulic pump operating speed higher than expected and dangerous. Can be prevented. Furthermore, when there is no addition to the hydraulic means of the hydraulic pump, it is assumed that the movable speed of the hydraulic means is accelerated by rotation of the rotating shaft of the switching device for controlling the hydraulic pressure change amount of the hydraulic pressure change valve. At any time, the hydraulic means can be moved efficiently and at an appropriate speed as planned in advance, and safety and efficiency can be improved.

  The second means of the present invention is a notch integrated with the rotating shaft of the switching device in order to make it possible to switch the rotational amount of the rotating shaft of the switching device for controlling the hydraulic pressure change amount of the hydraulic pressure change valve stepwise. A C-ring inner stopper having a portion and a C-shaped outer stopper having a surrounding notch, and being disposed on a base plate that holds these, the safety and efficiency of the first means Can be raised more accurately.

  According to the third means of the present invention, the operating pin of the spring return type plunger can be inserted / removed between the cutout portion of the C-shaped annular inner stopper and the cutout portion of the C-shaped annular outer stopper. By regulating the amount of rotation of the handle integrated with the stopper, the safety and efficiency of the first means or the second means can be further improved.

  Furthermore, the fourth means is an external loader composed of a hydraulic lifter having a switching device for the rotation movable range of the hydraulic pressure change valve of the hydraulic pump of any one of the first to third means, When the load is placed on the fork and lowered, the fork can be moved and stopped slowly, so that the vibration when stopped can prevent the load from falling from the fork, while loading the load on the fork. When there is no load, the fork can be moved up and down quickly, so an external loader consisting of a hydraulic lifter can be operated safely and efficiently.

(A) is a typical top view of the switching apparatus of the rotation movable range of the hydraulic pressure change valve of a hydraulic pump, (b) is a typical elevation view shown in the partial cross section seen from the side of the switching apparatus of (a). . It is a figure which shows the state which controlled the rotation angle of the inner side stopper by insertion of the operating pin of the plunger of the switching apparatus of (a) of FIG. It is a figure which shows the state which the restriction | limiting of the rotation angle of the inner side stopper by cancellation | release of the operating pin of the plunger of the switching device of Fig.1 (a) was cancelled | released, and the inner side stopper rotated and contacted the outer side stopper. The side view of the external loader which applied the switching device of the rotation movable range of the hydraulic pressure change valve of the hydraulic pump of the present invention to the hydraulic pump of the hydraulic lifter is shown. It is a rear view of the external loader of FIG. It is a top view of the external loader of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. First, the two-stage switching device 1 of the rotary shaft 5 according to the first to third aspects of the present invention will be described. This two-stage switching device is a device in a hydraulic pressure change valve of a hydraulic pump. For example, FIG. 6 is a switching device that switches in steps the opening amount of the hydraulic pressure change valve 22 of the hydraulic pump 21 in the hydraulic mechanism of the hydraulic lifter 24 that is the external loader 10 indicated by 6. That is, it is a switching device that switches the rotation range of the hydraulic pressure change valve 22 of the hydraulic pump 21 in stages. By the way, when a load of several hundred kilograms is placed on the left and right forks 18 of the hydraulic lifter 24 and lowered, the forks 18 try to descend rapidly due to the weight of the load. On the other hand, when the fork 18 is lowered with no load, no weight is applied. By the way, in order to control the rotation range of the hydraulic pressure change valve 22 of the hydraulic pump 21, the hydraulic pressure change valve handle 22a is manually operated while observing the movement of the fork 17. Normally in such a device, for example, when descending with a load of several hundred kilograms loaded on the fork, the descending speed is slowed for safety, and when there is no load on the fork, it is not dangerous, so the descending speed is The moving efficiency of the fork is increased as quickly as possible. For this purpose, a rotating shaft 5 having a manual huddle 6 is provided in addition to the hydraulic pressure change valve 22 of the hydraulic pump 21, and the rotating shaft of the hydraulic pressure change valve 22 is provided. 5 is rotating. However, since the rotating shaft 5 is manually operated, it is not easy to control a fine rotating operation, and experience is required.

  Accordingly, the present invention can rotate the manual handle 6 for operation added to the hydraulic pressure change valve 22 of the hydraulic pump 21 safely and easily by switching the operation without requiring such experience. The switching device is a two-stage switching device 1 shown in FIG. As shown in FIGS. 1A and 1B, the two-stage switching device 1 has an outer stopper 4 having a C-shaped annular shape mounted on a base plate 2, and an annular periphery of the outer stopper 4. The adjustment screw 4b is finely adjusted by screw tightening to the adjustment screw long hole 4c having a short opening at two locations facing each other. A rotation shaft 5 having a hydraulic pressure change valve (not shown) is rotatably inserted at the center of the lower end of the C-shaped outer stopper 4. Further, a C-shaped inner stopper 3 is rotatably inserted along the inner peripheral side wall surface of the C-shaped outer stopper 4, and this inner stopper 3 is attached to the rotary shaft 5 of the hydraulic pressure change valve by a welding portion 5 a. It is integrated. Furthermore, the C-shaped annular inner stopper 3 may be formed from a two-layered C-shaped annular plate. In this case, as shown in FIG. The adjustment screw 3b can be screwed into the adjustment screw long hole 3c having a short opening at two locations, and can be finely adjusted and fixed integrally with the lower C-shaped annular plate. In the above, the imaginary line indicated by the two-point difference line outside the notch 8 in the inner region and the outer side of the C-shaped outer stopper 4 from the imaginary line indicated by the two-point difference line inside the C-shaped inner stopper 3 and the inner 2 The notch 9 in the area between the phantom lines indicated by the dotted lines is assumed to be present in the same direction and directed toward the side of the rectangular base plate 2. Further, in order to rotate the C-shaped inner stopper 3, as shown in FIG. 1A, the manual handle 6 is fixed to the upper end of the rotating shaft 5 so as not to be loosened by the mounting nut 5 b. On the other hand, the base plate 2 is integrally fixed to one end of a device requiring the two-stage switching device 1 by an appropriate means.

  On the side of the base plate 2 of the notch 8 of the C-shaped annular inner stopper 3 and the notch 9 of the C-shaped annular outer stopper 4 of the two-stage switching device 1, that is, on the left side of FIG. As shown in FIG. 1 (b), a plunger holding plate 7a having a plunger 7 attached by an attachment frame 7c is integrally attached to the lower surface of the base plate 2 by a welding portion 7b. This plunger 7 has a gripping part 7d and an operating pin 7g provided on the tip side thereof. Although not shown, a large-diameter hole opened in the outer part of the spring mechanism part 7e is provided inside the spring mechanism part 7e. A gap for inserting the spring formed between the shaft of the operating pin 7g inserted into the large-diameter hole is provided with a constant length, and this gap having a certain length corresponds to the length of the gap. A spring is inserted, and the operating pin 7g is received in an elastic shape. That is, in this state, as shown in FIG. 1, the tip of the operating pin 7g is elastically brought into contact with the left annular wall surface by the spring at the position of the inner notch 8 of the C-shaped inner stopper 3. ing. In the state of FIG. 1, the abutting position of the tip of the operating pin 7g with the inner notch 8 of the inner stopper 3 is more clockwise than the position of the abutting end surface 3a of the inner stopper 3 at the counterclockwise tip. Therefore, in this abutting state, the hydraulic pump is set to the lowest level at the lower end of the rotary shaft 5 of the manual handle 6 with the hydraulic release amount of the hydraulic change valve of the hydraulic pump (not shown) as the first stage small release amount. It is supposed to run at a slow speed. When stopping the operation of the hydraulic pump, it can be stopped by turning the handle 6 clockwise, and since it is an operation of the hydraulic pump that was originally operating slowly, the handle 6 is rotated clockwise to rapidly rotate the hydraulic pump. Even if the operation of the pump is stopped, the operation of the hydraulic pump can be stopped safely without the vibration of the device operated by the hydraulic pump.

  1, the C-shaped annular inner stopper 3 is further rotated counterclockwise as shown in FIG. 1, and the C-shaped annular inner stopper 3 is notched. The side of the distal end of the actuating pin 7g of the manual plunger 7 inserted in the region of the portion 8 is brought into contact with the abutting end surface 3a of the distal end of the C-shaped inner stopper 3 in the rotational direction. When the rotation angle is fixed, the hydraulic pressure change amount by the hydraulic pressure change valve of the hydraulic pump is set to a slow speed, and the hydraulic pump is operated in a stable and constant slow state. Also in this case, when stopping the operation of the hydraulic pump, it can be stopped by turning the handle 6 clockwise, and since the operation of the hydraulic pump that was originally operating slowly, the handle 6 is rotated rapidly in the clockwise direction. Even if the operation of the hydraulic pump is stopped in this way, it is safe to stop the operation of the hydraulic pump without the vibration of the device operated by the hydraulic pump.

  By the way, in the mechanism operated by the hydraulic pump, in the no-load state, as already described, it is safe to operate rapidly. Therefore, when there is no load on the hydraulic pump mechanism, as shown in FIG. 3, the tip of the operating pin 7g of the plunger 7 is against the elastic force of the spring inside the plunger 7 in the left side of the figure. When the manual handle 6 is further rotated counterclockwise by pulling it out toward the outer peripheral surface of the C-shaped inner stopper 3, the contact end surface 3 of the C-shaped inner stopper 3 is outside the C-shaped outer ring. The abutting end surface 4 of the stopper 4 is abutted to maximize the amount of change of the hydraulic pump, and the hydraulic pump is operated at the fastest speed. In addition, in this case, since the device operated by the hydraulic pump is unloaded, even if the operation of the hydraulic pump is rapidly stopped by rapidly rotating the handle 6 clockwise, it may drop or vibrate. Since there is no cargo to carry, there is nothing dangerous and safe.

  Next, the above-described two-stage switching device 1 of the present application is the hydraulic lifter 24 in the cargo handling work that has been performed with feeling and experience by an external loader for cargo handling that is a commercially available hydraulic lifter for cargo handling work. An example applied to the loader 10 will be described below with reference to FIGS.

  4 is a side view of an external loader 10 for cargo handling that is a hydraulic lifter 24 to which the two-stage switching device 1 of the present application is applied, FIG. 5 is a rear view thereof, and FIG. 6 is a plan view thereof.

  As shown in FIGS. 4 to 6, the external loader 10 including the hydraulic lifter 24 includes a carriage unit 11 projecting forward at the bottom, left and right columnar masts 17 rising from the carriage unit 11, and columnar masts 17. It consists of left and right forks 18 that protrude horizontally forward. The carriage unit 11 has a fixed caster 15 that cannot rotate at the lower part of the front end of the left and right frame 12. The rear ends of the left and right underframes 12 serve as rear end connecting underframes 13 that connect the respective underframes 12 to the left and right. Further, there are left and right rear projecting frames 14 at the rear of the rear end connecting base frame 1, respectively, and lower casters 16 that can be rotated are respectively provided below the left and right rear projecting frames 14. The universal caster 16 has a conventional foot stopper 20 for fixing the rotation. The left and right columnar masts 17 are provided with fork abutments 19 that support the left and right forks 18.

  The fork support 19 is connected to a chain via a lower hydraulic pump 21 which is a conventional fork lifting mechanism as a hydraulic lifter 24 and an upper pulley. The hydraulic pump 21 has a hydraulic pressure change valve 22 at a lower portion thereof. The hydraulic pressure change valve 22 is provided with a handle shaft 22b that is tilted and operated up and down to control the hydraulic pressure of the hydraulic pump 21. A hydraulic pressure change valve handle 22a is provided at the upper end of the shaft 22b. By the way, every time the hydraulic pressure change valve 22 is tilted up and down, the hydraulic pressure is increased by the hydraulic pump 21 and the fork support 19 connected to the chain is raised. On the other hand, when no load is loaded on the fork 18, a quick-lift foot pedal 22 c is provided at the lower part on the rear side of the hydraulic lifter 24 in order to rapidly raise the fork support 19. By stepping on the quick-lifting foot pedal 22c with a leg, the fork support 19 can be rapidly raised at twice the normal speed. The hydraulic pressure change valve handle 22a and the quick lifting foot pedal 22c can be moved only when the fork 18 is raised. The fork 18 is positioned at the upper position shown in FIG. 4, positioned at the lower position drawn by a two-dot chain line, or positioned at the lowermost position, or sometimes positioned at the uppermost position. However, when raising, it is carried out by the hydraulic pressure change valve handle 22a and the quick-lift foot pedal 22c. The fork 18 is lowered by manually rotating the manual handle 6 of the rotary shaft 5 in the conventional hydraulic lifter device. However, in the present invention, the fork 18 of the hydraulic lifter 24 is lowered by the two-stage switching device 1 described above, and will be further described below.

  Further, as shown in the rear view of FIG. 5, the hydraulic pressure change valve 22 is provided with a rotating shaft 5. In the conventional apparatus, the manual handle 6 at the upper end of the rotary shaft 5 is rotated. In the present invention, the two-stage switching device 1 described above is provided below the manual handle 6 of the rotating shaft 5. That is, the two-stage switching device 1 is attached and fixed to the reinforcing connecting frame of the left and right columnar masts 17 of the hydraulic lifter 24. The two-stage switching device 1 is used when the fork 18 is lowered. Furthermore, the external loader 10 that is the hydraulic lifter 24 shown in this embodiment is provided with a lifter operation handle 23 that protrudes from the rear ends of the left and right columnar masts 17 in order to move the load forward and backward. The operator holds the lifter operation handle 23 and moves the hydraulic lifter 24 back and forth from the back of the hydraulic lifter 24.

  Now, the hydraulic lifter 24 of the external loader 10 is brought close to the rack that stores and stores articles for loading on the pallet, and the pallet on which the necessary articles are placed is taken out from the upper shelf of the rack and lowered. The fork 18 of the hydraulic lifter 24 is raised to the upper position by tilting up and down movement of the hydraulic fluctuation valve handle, the fork 18 is inserted into the pallet and lifted slightly to retract the hydraulic lifter 24, and then the fork 18 is loaded. Lower the placed pallet. When lowering, in order to rotate the handle shaft 22b of the hydraulic pressure change valve 22 so as to release the hydraulic pressure of the hydraulic pump 21, in the conventional apparatus, the manual handle 6 of the rotary shaft 5 is manually operated. In contrast, in the present invention, the operating pin 7g of the spring return type plunger 7 of the attached two-stage switching device 1 is pushed forward, and as shown in FIG. After the counterclockwise contact end face 3a of the C-shaped annular inner stopper 3 is brought into contact with the side portion to fix the rotation of the rotary shaft 5, the descending speed of the fork 18 is set to a constant slow speed, for example, 1 minute The pallet on which the cargo is loaded is lowered as the descent speed of 1 meter per hour, and stops when it is lowered. The state in which the counterclockwise contact end surface 3a of the C-shaped inner stopper 3 is in contact with the side of the tip of the operating pin 7g is that the specification of the external loader is 400 kg at the maximum load amount, Even if the maximum load is 400 kilograms, for example, if the vertical movement stroke of the fork 18 of the hydraulic lifter 24 is 1.5 m, it will be omitted if the lift is lowered from the top to the bottom. Since it descends at a slow speed of 1 minute 30 seconds, it stops, so the load can be safely stopped without shaking the inertia.

  On the other hand, when the load is unloaded onto the top of the rack and the fork 18 is lowered with no load applied to the fork 18 of the hydraulic lifter 24, there is nothing that the tip of the operating pin 7g of the plunger 7 swings on the fork 18. The hydraulic pressure of the hydraulic pump 21 until the tip of the operating pin 7g of the spring return type plunger 7 of the attached two-stage switching device 1 comes into contact with the counterclockwise contact end surface 3a of the C-shaped inner stopper 3. If the change valve 22 does not operate, the fork 18 has no load and no load, so the fork 18 does not easily descend. Therefore, in such a case, the position of the counterclockwise contact end surface 3a of the C-shaped annular inner stopper 3 is repositioned by the adjusting screw 3b and the adjusting screw long hole 3c shown in FIG. , So that the rotation angle of the hydraulic pressure change valve 22 of the hydraulic pump is increased, that is, the angle of the side of the tip of the operating pin 7g to the position of the counterclockwise contact end surface 3a of the C-shaped inner stopper 3 is increased. Thus, the descending speed per minute of the fork 18 at no load is set to about 2 m. In accordance with this, as shown in FIG. 3, positioning is performed so that the side of the tip of the operating pin 7g contacts the contact end surface 4a which is the clockwise tip of the C-shaped annular outer stopper 4. To do. By doing so, the fork 18 of the unloaded hydraulic lifter 24 can be lowered and stopped at a lowering speed of about 2 m per minute as described above, and can be safely operated by the operator.

  As described above, the switching device for the rotationally movable range of the hydraulic pressure change valve of the hydraulic pump according to the first to third aspects of the present invention is an external device comprising the hydraulic lifter 24 as described in the fourth aspect. When applied to the hydraulic pressure change valve handle shaft 22b of the hydraulic pressure change valve 22 of the loader 10, according to the maximum load capacity of the specification of the hydraulic lifter 24, first, the counterclockwise contact of the C-shaped annular inner stopper 3 is applied. The position of the contact end surface 3a is positioned by the adjustment screw 3b and the adjustment screw elongated hole 3c shown in FIG. 1A, and the position of the contact end surface 4a in the clockwise direction of the C-shaped outer stopper 4 is also shown in FIG. By positioning with the adjusting screw 4b and the adjusting screw long hole 4c shown in 1 (a), it can be widely applied to the external loader 10 including the hydraulic lifter 24 having various maximum loading capacity specifications. That. In the case of no load, as described above, the positional relationship between the adjustment screw 3b of the C-shaped annular inner stopper 3 and the adjustment screw long hole 3c and the adjustment screw 4b of the C-shaped annular outer stopper 4 are adjusted as described above. By adjusting the positional relationship of the screw long holes 4c, it is possible to achieve an appropriate and safe operating speed of the fork 18, and the above-described screw tightening in the no-load state is a characteristic of the specification of the hydraulic lifter 24. If a mark is provided on the side of the adjustment screw long hole, the screw can be easily tightened in accordance with the mark.

  As described above, the switching device for the rotation movable range of the hydraulic pressure change valve of the hydraulic pump according to the first to third aspects of the present invention is not limited to the external loader 10 including the hydraulic lifter 24, and the hydraulic pump It can be used in a wide range of other hydraulic devices to which is applied.

1 Two-stage switching device 2 Base plate 3 Inner stopper (C-shaped annular)
3a Contact end face 3b Adjustment screw 3c Adjustment screw long hole 4 Outer stopper (C-shaped annular)
4a Contact end face 4b Adjustment screw 4c Adjustment screw long hole 5 Rotating shaft 5a Welded part 5b Nut 6 Manual handle 7 Plunger (spring turn type)
7a Plunger holding plate 7b Welding part 7c Mounting frame 7d Grip part 7e Spring mechanism part 7f Nut 7g Actuation pin 8 Inner notch (inside stopper)
9 Outer notch (outside stopper)
DESCRIPTION OF SYMBOLS 10 External loader 11 Carriage part 12 Left and right base frame 13 Rear end connection base frame 14 Left and right rear projecting frame 15 Fixed caster 16 Swivel caster 17 Columnar mast 18 Left and right fork 19 Fork stand 20 Foot stopper 21 Hydraulic pump 22 Hydraulic pressure Change valve 22a Hydraulic change valve handle 22b Handle shaft (hydraulic change valve handle)
22c Foot pedal for quick lifting 23 Lifter steering handle 24 Hydraulic lifter

Claims (4)

  In a hydraulic pressure change valve of a hydraulic pump, a handle shaft for rotating the hydraulic pressure change valve, a base plate that is rotatably inserted through the handle shaft, a C-shaped annular outer stopper provided on the base plate, A C-shaped inner stopper that is integrated with the handle shaft along the side wall surface of the outer stopper, a manual handle at the upper end of the handle shaft, and a plunger holding plate attached to the side of the base plate; , Consisting of a manual spring type plunger installed on this plunger holding plate, and an annular notch portion of the inner stopper and an operating pin of a spring return type plunger that can be inserted into and extracted from the notch portion of the outer stopper A device for switching a movable range of a rotary shaft for controlling a hydraulic pump.   The C-shaped inner stopper integrated with the handle shaft for rotation of the hydraulic pressure change valve can be rotated by a manual handle integrally provided at the upper end of the rotary shaft of the hydraulic pressure change valve, and is provided on the base plate. The C-shaped annular outer stopper is integrally fixed to the base plate by adjusting the rotation angle around the rotation axis with a screw inserted into an annularly shaped adjusting screw hole formed in the center of the C-shaped ring. The apparatus for switching a movable range of a rotary shaft for controlling a hydraulic pump according to claim 1.   The spring return type operating pin of the plunger can be inserted and withdrawn from the side of the notch of the C-shaped inner stopper and the notch of the outer stopper of the C-shape, and the operating pin by rotating the manual handle Is inserted into the notch of the C-shaped annular inner stopper arranged in front of the front and is brought into contact with the counterclockwise tip of the C-shaped annular inner stopper, so that the inner stopper can be rotated counterclockwise by the manual handle. In addition, the tip of the C-shaped inner stopper is further rotated counterclockwise from the front face of the operating pin of the manual plunger by pulling out the C-shaped inner stopper from the notch. The outer stopper is in contact with the rear end surface of the clockwise notch and regulates the counterclockwise rotation by the handle of the inner stopper, and Switching device of the rotational movement range of the hydraulic modulating valve of a hydraulic pump according to claim 1 or 2 that.   Left and right frame that has a fixed caster at the lower end of the front end and protrudes to the left and right, a rear end connection frame that connects the left and right rear ends of the left and right frame, and a rear extension of the rear of the left and right frame A carriage unit comprising a rear projecting frame having a free caster at the lower part, left and right columnar masts standing on the rear ends of the left and right platform frames of the carriage unit, and left and right forks projecting forward of the left and right columnar masts A hydraulic lifter consisting of a fork abutment that supports the fork abutment, a hydraulic pump that supports the fork abutment and moves up and down, and a movable rotation of a handle shaft for controlling the hydraulic pump disposed in the hydraulic pressure change valve An external loader comprising a hydraulic lifter, characterized by having a range switching device.

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