Patent Grant
12180051
The present invention relates to cargo handling equipment. More particularly, the present invention relates to carton clamps for use primarily with lift trucks.
Material handling vehicles such as lift trucks are used to pick up and deliver loads between stations. A typical lift truck 10 has a mast 12, which supports a load-lifting carriage 14 that can be raised along the mast 12 (see
Instead of forks 20, a lift truck 10 may have a load clamp assembly 32 coupled to its mast 12 (See
Load clamps, also known as carton clamps, are well known, but existing designs are designed primarily for lifting a single carton. Typically, they approach a load with the clamp arms 34 spread wider than the load, maneuver so that the load is between the clamp arms 34 and then close the clamp arms 34 until they grasp the load. Then the load can be lifted and moved. However, the standard carton clamp design makes it problematic for the clamps to grasp two separate items or two separate stacks of items such as stacks of cartons, bales, or tires. If the items in the two stacks are not rectangular objects, clamping force is not likely to be transmitted from one stack to the other without inducing torque and rotation in one or more of the load objects, potentially twisting the objects off the stack.
The present invention will be described by way of representative embodiments, illustrated in the accompanying drawings in which like references denote similar elements, and in which:
Before beginning a detailed description of the subject invention, mention of the following is in order. When appropriate, like reference materials and characters are used to designate identical, corresponding, or similar components in different figures.
In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application and business related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.
Use of directional terms such as “upper,” “lower,” “above,” “below”, “in front of,” “behind,” etc. are intended to describe the positions and/or orientations of various components of the invention relative to one another as shown in the various Figures and are not intended to impose limitations on any position and/or orientation of any embodiment of the invention relative to any reference point external to the reference. Herein, “left” and “right” are from the perspective of an operator of a lift truck. Herein, “lateral” refers to directions to the left or the right and “longitudinal” refers to a direction perpendicular to the lateral direction and to a plane defined by the fork frame.
Those skilled in the art will recognize that numerous modifications and changes may be made to the various embodiments without departing from the scope of the claimed invention. It will, of course, be understood that modifications of the invention, in its various aspects, will be apparent to those skilled in the art, some being apparent only after study, others being matters of routine mechanical, chemical and electronic design. No single feature, function, or property of the first embodiment is essential. Other embodiments are possible, their specific designs depending upon the particular application. As such, the scope of the invention should not be limited by the particular embodiments herein described but should be defined only by the appended claims and equivalents thereof.
In some alternative embodiments, the third clamp actuator 238 is a telescoping actuator with three concentric cylinders that share the same axis. In some alternative embodiments, an inner cylinder nests slidingly within a middle cylinder, which nests slidingly withing an outer cylinder. The outer cylinder is fixed to the frame 202 and has a base hydraulic line connection. A piston with a rod are slidingly positioned within the inner cylinder and the rod is connected to the third clamp arm 270. A rod hydraulic line is connected to the inner cylinder on the rod side of the piston. In some alternative embodiments, the middle cylinder is omitted and the inner cylinder nests slidingly within the outer cylinder. In some alternative embodiments, the rod is omitted, the piston is fixed in the middle cylinder at an end farthest from the third clamp arm 270 and inner cylinder is directly coupled to the third clamp arm 270.
In some alternative embodiments, the third clamp actuator is an electrical telescoping actuator.
In the first embodiment single-double load clamp 200, the side shift function is provided by a separate side-shift actuator (not shown in first embodiment 200, but similar to the side-shift actuator 386 in the second embodiment 300—see
Each of the guide channels (204, 206, 208, 210, 212, 214) has a guide channel cavity, open at the ends. Each of the guide channels (204, 206, 208, 210, 212, 214) has a guide slot 240 on the front, opening to the guide channel cavity. In some embodiments, each of the guide channels (204, 206, 208, 210, 212, 214) has a channel bearing, positioned inside the guide channel cavity, and shaped to conform thereto, and with its own interior cavity that is similarly shaped, but slightly smaller. Each channel bearing is detachably coupled to its respective guide channel (204, 206, 208, 210, 212, 214). In the first embodiment 200, each channel bearing is detachably coupled to its respective guide channel (204, 206, 208, 210, 212, 214) with a removable fastener scheme such as cap screws and nuts, but in other embodiments, other fastening schemes may be used. The channel bearings comprise suitable bearing material that provides low friction and are softer than the components with which they have sliding contact in order to preferentially wear. Since the channel bearings are removable, they can be easily replaced when worn down.
The first (left) clamp arm 266 (see
The second (right) clamp arm 268 (see
The third (center) clamp arm 270 (see
In some alternative embodiments, guide channels 204, 206, 208, 210, 212, 214 may be arranged differently than in the first embodiment single-double load clamp 200, with the necessary adjustments made to the components of the clamp arms 266, 268, 270. For example, in some embodiments, the first guide channel 204 is the middle of the upper guide channels, the second guide channel 206 is the lower of the upper guide channels, and the third guide channel 208 is the upper of the upper guide channels. Likewise, the fourth guide channel 210 is the middle of the lower guide channels, the fifth guide channel 212 is the lower of the lower guide channels, and the sixth guide channel 214 is the upper of the lower guide channels. The first sliding beam 272 is still slidingly inserted into first guide channel 204, the second sliding beam 274 into the fourth guide channel 210, the third sliding beam 276 into third guide channel 208, the fourth sliding beam 278 into the sixth guide channel 214, the fifth sliding beam 280 into the second guide channel 206 and the sixth sliding beam 282 into the fifth guide channel 212. The coupling of the first sliding beam 272 and second sliding beam 274 with the first (left) clamp plate 260, the coupling of the third sliding beam 276 and fourth sliding beam 278 with the second (right) clamp plate 262, and the coupling of the fifth sliding beam 280 and the sixth sliding beam 282 with the third (center) clamp plate 264 are all shifted to preserve alignment between the first (left) clamp plate 260, the second (right) clamp plate 262 and the third (center) clamp plate 264.
In some alternative embodiments, the first clamp arm 266 is on the right (when viewed from the driver's perspective) with its first sliding beam 272 and its second sliding beam 274 extending inwardly from the first (left) clamp plate 260 towards the left with the necessary adjustments made to the components of the clamp arms 266, 268, 270. The second clamp arm 268 is on the left (when viewed from the driver's perspective) with its third sliding beam 276 and the fourth sliding beam 278 extending inwardly from the second (right) clamp plate 262 towards the right. The third (center) clamp arm 270 remains in the center but its sliding beams 280, 282 extend to the right from the rear of the third (center) clamp plate 264 (when viewed from the driver's perspective).
In some alternative embodiments, the third (center) clamp arm 270 is fixed to the frame 202 and remains stationary during clamping operations. In some of such embodiments, the bearings inside the second guide channel 206 and the fifth guide channel 212 maybe omitted. In some such embodiments, the second guide channel 206 and the fifth guide channel 212 are themselves omitted.
In the first embodiment single-double load clamp 200, the first, second, and third clamp arms (266, 268, 270) do not have clamp pads coupled to an inside surface of their clamp plates (260, 262, 264). However, in other embodiments one or more of the first, second, and third clamp arms (266, 268, 270) may have one or more clamp pads attached made of rubber or some other suitable resilient material.
The frame 302 is configured to be coupled to a carriage 14 of a lift truck 10. In the second embodiment single-double load clamp 300, the first clamp arm 366 is on the left (viewed from the driver's perspective) and the second clamp arm 368 is on the right. The second embodiment single-double load clamp 300 has a first clamp actuator 334 attached to the frame 302 and to the first (left) clamp arm 366. The second embodiment single-double load clamp 300 has second clamp actuator 336 attached to the frame 302 and to the second (right) clamp arm 368. The second embodiment single-double load clamp 300 is configured for the first clamp actuator 334 and second clamp actuator 336 to respectively pull the first clamp arm 366 and the second clamp arm 368 toward each other or push them away from each other. The single-double load clamp 300 has a third clamp actuator 338 attached to the frame 302 and to the third (center) clamp arm 370. In the second embodiment 300, the third clamp actuator 338 is a telescoping actuator with a center actuator 342 attached to an upper actuator 344 and a lower actuator 346. The base sides of each of the center actuator 342, the upper actuator 344, and the lower actuator 346 are all hydraulically connected and the rod sides of each of the center actuator 342, the upper actuator 344, and the lower actuator 346 are all hydraulically connected. The center actuator 342 is attached to the frame 302 via an actuator bracket 332. The upper actuator 344 and the lower actuator 346 are attached to the third clamp arm 370, each with their own actuator bracket 332. In alternative embodiments, the center actuator 342 is attached to the third clamp arm 370 via an actuator bracket 332 and the upper actuator 344 and the lower actuator 346 are attached to the frame 302, each with their own actuator bracket 332. The third clamp actuator 338 is configured for telescoping action in which each of the three actuators 342, 344, 346 of the third clamp actuator 338 have a rod that extends and retracts in synchronization with the other two rods. The telescoping action allows the third clamp arm 370 to move twice as far as each of three rods moves, allowing for the third clamp actuator 338 to be half the length as a single cylinder actuator would be for the same rod stroke.
Each of the guide channels (304, 306, 308, 310, 312, 314) has a guide channel cavity, open at the ends. Each of the guide channels (304, 306, 308, 310, 312, 314) has a guide slot 340 on the front, opening to the guide channel cavity. In some embodiments, each of the guide channels (304, 306, 308, 310, 312, 314) has a channel bearing, positioned inside the guide channel cavity, and shaped to conform thereto, and with its own interior cavity that is similarly shaped, but slightly smaller. Each channel bearing is detachably coupled to its respective guide channel (304, 306, 308, 310, 312, 314). In the second embodiment 300, each channel bearing is detachably coupled to its respective guide channel (304, 306, 308, 310, 312, 314) with a removable fastener scheme such as cap screws and nuts, but in other embodiments, other fastening schemes may be used. The channel bearings comprise suitable bearing material that provides low friction and are softer than the components with which they have sliding contact in order to preferentially wear. Since the channel bearings are removable, they can be easily replaced when worn down.
The first (left) clamp arm 366 (see
The second (right) clamp arm 368 (see
The third (center) clamp arm 370 (see
The third clamp plate 364 has a minimal thickness, only enough to prevent shearing within each of the loads when inserted between two loads to be clamped (e.g., two stacks of cartons). The thickness of the third clamp plate 364 may not be sufficient to transmit the force required to clamp and carry a load only on one side of the third clamp plate 364 but not the other, at least not without damaging the third clamp plate 364. Hence, the second embodiment single-double load clamp 300 should not be used to clamp a single load in the double load mode—i.e., with a load between the third (center) clamp plate 364 and one of the flanking clamp plates 360, 362, but no load between the third (center) clamp plate 364 and the other of the flanking clamp plates 360, 362. In the second embodiment single-double load clamp 300, the third clamp plate 364 is everywhere thinner than the first clamp plate 360 or the second clamp plate 362. In some alternative embodiments, the third clamp plate 364 is on average thinner than the first clamp plate 360 or the second clamp plate 362. In some alternative embodiments, the third clamp plate 364 is everywhere no more than half the thickness of the first clamp plate 360 or the second clamp plate 362. In some alternative embodiments, the third clamp plate 364 is on average no more than half the thickness of the first clamp plate 360 or the second clamp plate 362.
In the second embodiment 300, the third clamp plate 364 is at least half an inch thick in most places, no more than 1 inch, preferably 9/16 of an inch. The third clamp plate 364 has a taper or bevel on the leading edge.
In the second embodiment single-double load clamp 300, the first (left) clamp arm 366 and second (right) clamp arm 368 and the third clamp arm 370 each have a clamp pad 350 coupled to an inside surface of their respective clamp plates 360, 362, 364. In the second embodiment 300, the clamp pad 350 is a rubber sheet with horizontal groves, but in other embodiments may be some other suitable material. In some other embodiments one or more of the clamp arms 366, 368, 370 do not have a clamp pad 350. In some other embodiments, the third (center) clamp arm 370 has sprayed on rubber coating.
The single-double load clamp hydraulic system 400 includes a first clamp actuator 434, a second clamp actuator 436, and a third clamp actuator 438 and is configured to provide power and control for them. The actuators (434, 436, and 438) of the single-double load clamp hydraulic system 400 may be the actuators (234, 236, and 238) as described for the first embodiment single-double load clamp 200, or they may be the actuators (334, 336, and 338) as described for the second embodiment single-double load clamp 300, or they may have some differences. In particular, the third clamp actuator 438 may not be a three-cylinder telescoping actuator as are the third clamp actuator 238 in the first embodiment single-double load clamp 200 and the third clamp actuator 338 in the second embodiment single-double load clamp 300, but may be some other suitable actuator such as a single cylinder actuator. The single-double load clamp hydraulic system 400 has a first actuator rod line 444 connected to a rod side of the first clamp actuator 434, a first actuator base line 446 connected to the base side of the first clamp actuator 434, a second actuator rod line 440 connected to a rod side of the second clamp actuator 436, a second actuator base line 442 connected to a base side of the second clamp actuator 436, a third actuator rod line 448 connected to a rod side of the third clamp actuator 438, and a third actuator base line 450 connected to a base side of the third clamp actuator 438.
The single-double load clamp hydraulic system 400 has a clamp open line 406 and a clamp close line 408 that are configured for connecting respectively to a hydraulic feed line and a hydraulic return line from the lift truck 10. A directional control valve on the truck controls flow to and from the clamp open line 406 and clamp close line 408. In a first (open) position the directional control valve ports pressurized hydraulic fluid to the clamp open line 406 and ports the clamp close line 408 to a low-pressure return or sump. In a second (close) position the directional control valve ports pressurized hydraulic fluid to the clamp close line 408 and ports the clamp open line 406 to the low-pressure return. In a third (neutral) position the directional control valve blocks all flow to and from the clamp open line 406 and the clamp close line 408.
The single-double load clamp hydraulic system 400 includes a first check valve 422, a second check valve 424, and a third check valve 426. The first check valve 422 connects the clamp open line 406 to the third actuator base line 450 and allows flow from the third actuator base line 450 to the clamp open line 406, but blocks reverse flow. The second check valve 424 connects the clamp open line 406 to the third actuator rod line 448 and allows flow from the third actuator rod line 448 to the clamp open line 406, but blocks reverse flow. The third check valve 426 connects the clamp close line 408 to a flow divider 420 that connects to the first actuator rod line 444 and the second actuator rod line 440. The flow divider 420 has flow restriction elements to facilitate an even division of flow. The third check valve 426 is a pilot operated check valve with a fifth pilot line 460 that connects a pilot port of the third check valve 426 to the clamp open line 406. The third check valve 426 is configured for allowing hydraulic fluid to flow from the clamp close line 408 to the flow divider 420 but blocks reverse flow unless the pressure in the fifth pilot line 460 exceeds a fractional threshold. The fractional threshold for the third check valve 426 is one third of the pressure on the checked side of the third check valve 426 (the side connected to flow divider 420). However, in other embodiments the fractional threshold for the third check valve 426 may be anywhere from one sixth to unity.
The single-double load clamp hydraulic system 400 includes a first control valve 410, a second control valve 412, a third control valve 414, and a fourth control valve 416. The first control valve 410 is a three-port two-position solenoid operated valve that in a first position allows flow in either direction between a first port connected to the clamp open line 406 and a second port connected to the third actuator base line 450. In a second position, the first control valve 410 allows flow in either direction between the first port connected to the clamp open line 406 and a third port connected to the third actuator rod line 448.
The second control valve 412 is a two-port two-position pilot operated valve that in a first position blocks flow in either direction between a first port connected to the clamp close line 408 and a second port connected to the third actuator rod line 448. In a second position, the second control valve 412 allows flow in either direction between the first port connected to the clamp close line 408 and the second port connected to the third actuator rod line 448. A first pilot line 452 connects the clamp close line 408 to a first pilot port on the second control valve 412. A fourth check valve 428 in the first pilot line 452 allows flow from the clamp close line 408 to the first pilot port on the second control valve 412, but blocks flow in the reverse direction. The first pilot line 452 further connects the first pilot port on the second control valve 412 to a second pilot line 454 via a first flow reducer 430. The second pilot line 454 connects to a second pilot port on the second control valve 412 and connects to the third actuator base line 450. The second control valve 412 is configured for moving to the first position when pressure in first pilot line 452 exceeds pressure in the second pilot line 454 by a first threshold and configured for moving to the second position when pressure in the second pilot line 454 exceeds pressure in the first pilot line 452 by a second threshold. For the second control valve 412, the first and second thresholds are 400 PSI (pounds per square inch), but in other embodiments can be anywhere in the range of 100 to 600 PSI.
The third control valve 414 is a two-port two-position pilot operated valve that in a first position blocks flow in either direction between a first port connected to the clamp close line 408 and a second port connected to the third actuator base line 450. In a second position, the third control valve 414 allows flow in either direction between the first port connected to the clamp close line 408 and the second port connected to the third actuator base line 450. A third pilot line 456 connects the first pilot line 452 to a first pilot port on the third control valve 414. The third pilot line 456 further connects the first pilot port on the third control valve 414 to a fourth pilot line 458 via a second flow reducer 432. The fourth pilot line 458 connects to a second pilot port on the third control valve 414 and connects to the third actuator rod line 448. The third control valve 414 is configured for moving to the first position when pressure in third pilot line 456 exceeds pressure in the fourth pilot line 458 by a first threshold and configured for moving to the second position when pressure in the fourth pilot line 458 exceeds pressure in the third pilot line 456 by a second threshold. For the third control valve 414, the first and second thresholds are 400 PSI (pounds per square inch), but in other embodiments can be anywhere in the range of 100 to 600 PSI.
The fourth control valve 416 is a two-port two-position pilot operated relief valve that in a first (normal) position blocks all flow through the fourth control valve 416. In a second position, the fourth control valve 416 allows flow through the fourth control valve 416 between the first actuator rod line 444 and the second actuator rod line 440. The fourth control valve (416)) is configured to be in the first position unless a differential pressure between the second actuator rod line 440 and the first actuator rod line 444 exceeds a first threshold. The threshold for the fourth control valve 416 is 1500 PSI (pounds per square inch), but in other embodiments can be anywhere in the range of 500 to 2500 PSI.
In some embodiments, the first control valve 410, the second control valve 412, and the third control valve 414, the fourth control valve 416 all share the same manifold.
In single load mode, one of the outer arms and the central arm act in tandem for gripping a single load. Starting with a single-double load clamp in a fully closed single load mode (see
The lift truck operator then places the directional control valve in a first (open) position, porting pressurized fluid to the clamp open line 406 and connecting the clamp close line 408 to a low pressure sump. Hydraulic fluid flows from the clamp open line 406 to the base side of the first clamp actuator 434 via the first actuator base line 446, causing the first clamp actuator 434 to extend and the first clamp arm 366 to move in an outward direction. Hydraulic fluid flows from the clamp open line 406 through the first control valve 410 to the base side of the third clamp actuator 438 via the third actuator base line 450 causing the third clamp actuator 438 to extend and the third clamp arm 370 to move in an outward direction towards the second clamp arm 368.
Hydraulic fluid pressure in the clamp open line 406 opens the third check valve 426, allowing hydraulic fluid to leave the rod side of the second clamp actuator 436 through the second actuator rod line 440, the flow divider 420, the third check valve 426 and out the clamp close line 408 to the low pressure sump. Hydraulic pressure from the clamp open line 406 is transmitted into the second pilot line 454 via the third actuator base line 450 which causes the second control valve 412 to shift to its second position. This allows hydraulic fluid to flow from the rod side of the third clamp actuator 438 via the third actuator rod line 448, flow through the second control valve 412, and out the clamp close line 408 to the low pressure sump. The rod side of the first clamp actuator 434 has a path for hydraulic fluid to drain out through the first actuator rod line 444, the flow divider 420, the third check valve 426 and out through the clamp close line 408 to sump. The base side of the second clamp actuator 436 has a path for hydraulic fluid to drain out through the second actuator base line 442, through the third actuator rod line 448, through the second control valve 412, and out the clamp close line 408 to the low pressure sump.
Neither side of the second clamp actuator 436 is pressurized, so it will neither extend nor retract on its own. The third clamp actuator 438 will at some point extend the third clamp arm 370 far enough to contact the second clamp arm 368. The third clamp actuator 438 will then push both the third clamp arm 370 and the second clamp arm 368 further outward with hydraulic fluid flowing out from the rod side the second clamp actuator 436 to the low pressure sump and hydraulic fluid flowing into the base side of the second clamp actuator 436 from the third actuator rod line 448. The nested second and third clamp arms (368, 370) continues to move laterally outward until the third clamp actuator 438 reaches maximum extension. The first clamp arm 366 continues to move laterally outward until the first clamp actuator 434 reaches maximum extension. At this point the single-double load clamp is in a fully open single load configuration (see
The lift truck operator can return the directional control valve to the third (neutral) position when the single-double load clamp is in a fully open configuration or at any point in-between fully closed and fully open. Pressure is then lost in the clamp open line 406 and the path from the clamp close line 408 to the sump is cut off. With pressure lost in the second pilot line 454, the second control valve 412 returns to its first position, blocking flow from the third actuator rod line 448 and the second actuator base line 442. With pressure lost in the fifth pilot line 460, the third check valve 426 returns to its check position blocking flow from the second actuator rod line 440 and the first actuator rod line 444. With these paths blocked, the actuators (434, 436, 438) and the clamp arms (366, 368, 370) are effectively held in their current positions.
Starting with the single-double load clamp in a fully open single load mode (see
Hydraulic fluid leaves the base side of the first clamp actuator 434 through the first actuator base line 446, through the clamp open line 406 and then to the lift truck sump. Hydraulic fluid leaves the base side of the second clamp actuator 436 through the second actuator base line 442, through the third actuator rod line 448, through the second check valve 424 to the clamp open line 406 and then to the lift truck sump.
The second clamp arm 368 pushes the third clamp arm 370 inward, with hydraulic fluid leaving the base side of the third clamp actuator 438 through the third actuator base line 450, the first control valve 410, then to the clamp open line 406 and then to the lift truck sump. Hydraulic fluid fills the rod side of the third clamp actuator 438 from the base side of the second clamp actuator 436 through the second actuator base line 442 and the third actuator rod line 448. Eventually the first clamp actuator 434 and second clamp actuator 436 cannot retract any further. At this point the single-double load clamp is in a fully closed single load configuration (see
The lift truck operator can return the directional control valve to the third (neutral) position when the single-double load clamp is in a fully closed configuration or at any point in-between fully open and fully closed. Pressure is then lost in the clamp close line 408 and the path from the clamp open line 406 to the sump is cut off. With these paths blocked, the actuators (434, 436, 438) and the clamp arms (366, 368, 370) are effectively held in their current positions.
Starting with a single-double load clamp in a fully closed single load mode (see
The lift truck operator then places the directional control valve in a first (open) position, porting pressurized fluid to the clamp open line 406 and connecting the clamp close line 408 to a low pressure sump. Hydraulic fluid flows from the clamp open line 406 to the first actuator base line 446 and from the clamp open line 406 through the first control valve 410 to the third actuator rod line 448 and then to the second actuator base line 442. This causes the first clamp actuator 434 and the second clamp actuator 436 to extend, moving the first clamp arm 366 and the second clamp arm 368 outwards and causes the third clamp actuator 438 tor retract, moving the third clamp arm 370 towards the center of the frame 302.
Hydraulic fluid pressure in the clamp open line 406 opens the third check valve 426. This allows hydraulic fluid to leave the rod side of the first clamp actuator 434 through the first actuator rod line 444, the flow divider 420, the third check valve 426 and out the clamp close line 408 to the low pressure sump, and further allows hydraulic fluid to leave the rod side of the second clamp actuator 436 through the second actuator rod line 440, the flow divider 420, the third check valve 426 and out the clamp close line 408 to the low pressure sump. Hydraulic pressure from the clamp open line 406 is transmitted via the third actuator rod line 448 into the fourth pilot line 458 which causes the third control valve 414 to shift to its second position. This allows hydraulic fluid to flow from the base side of the third clamp actuator 438 via the third actuator base line 450, flow through the second control valve 412, and out the clamp close line 408 to the low pressure sump.
The third clamp actuator 438 will eventually fully retract the third clamp arm 370 to the center of the frame 302. The first clamp actuator 434 and the second clamp actuator 436 will eventually fully extend the first clamp arm 366 and the second clamp arm 368. At this point the single-double load clamp is in a fully open double load configuration (see
The lift truck operator can return the directional control valve to the third (neutral) position when the single-double load clamp is in a fully open configuration or at any point in-between fully closed and fully open. Pressure is then lost in the clamp open line 406 and the path from the clamp close line 408 to the sump is cut off. With pressure lost in the 460, the third check valve 426 returns to its check position blocking flow from the second actuator rod line 440 and the first actuator rod line 444. With these paths blocked, the actuators (434, 436, 438) and the clamp arms (366, 368, 370) are effectively held in their current positions.
Starting with the single-double load clamp in fully open double load mode (see
Hydraulic fluid leaves the base side of the first clamp actuator 434 through the first actuator base line 446, through the clamp open line 406 and then to the lift truck sump. Hydraulic fluid leaves the base side of the second clamp actuator 436 through the second actuator base line 442, through the third actuator rod line 448, through the second check valve 424 to the clamp open line 406 and then to the lift truck sump.
The second pilot line 454 and the fourth pilot line 458 are depressurized with paths to sump through the first check valve 422 and the second check valve 424 respectively, so the second control valve 412 and the third control valve 414 remain in their first positions. In these positions, they block pressurized hydraulic fluid from the clamp close line 408 from reaching the third clamp actuator 438, so no pressure reaches the third clamp actuator 438 to cause it to move. However, both sides of the third clamp actuator 438 have open paths to sump. The base side of the third clamp actuator 438 can drain hydraulic fluid through the third actuator base line 450, through the first check valve 422, through the clamp open line 406 to sump. The rod side of the third clamp actuator 438 can drain hydraulic fluid through the third actuator rod line 448, through the second check valve 424, through the clamp open line 406 to sump. Thus, the third clamp actuator 438 and the third clamp arm 370 are free to move and will not resist being moved by other forces. As the first clamp actuator 434 and the second clamp actuator 436 retract, either the first clamp arm 366 or the second clamp arm 368 will contact one of the loads first, depending on which load is wider—the first load between the first clamp arm 366 and the third clamp arm 370 or the second load between the second clamp arm 368 and the third clamp arm 370. If the first clamp arm 366 contacts the first load before the second clamp arm 368 contacts the second load, the first clamp arm 366 will push the first load into contact with third clamp arm 370 then push the first load and the third clamp arm 370 towards the second load and the second clamp arm 368. If the second clamp arm 368 contacts the second load before the first clamp arm 366 contacts the first load, the second clamp arm 368 will push the second load into contact with third clamp arm 370 then push the second load and the third clamp arm 370 towards the first load and the first clamp arm 366. If no loads are contacted, eventually the first clamp actuator 434 and second clamp actuator 436 cannot retract any further. At this point the single-double load clamp is in a fully closed double load configuration (see
The lift truck operator can return the directional control valve to the third (neutral) position when the single-double load clamp is in a fully closed configuration or at any point in-between fully open and fully closed. Pressure is then lost in the clamp close line 408 and the path from the clamp open line 406 to the sump is cut off. With these paths blocked, the actuators (434, 436, 438) and the clamp arms (366, 368, 370) are effectively held in their current positions.
In some alternative embodiments, the clamp actuators are electrical, controlled by an electronic controller. The electronic controller is configured for operating similarly to the first and second embodiments in one of two modes: Single load mode or double load mode. In single load mode a center clamp arm is nested against one outer clamp arm, creating a single clamping zone. In double load mode, the single-double load clamp is configured for gripping two loads-a first load between a first (outer) clamp arm and a third (central) clamp arm and a second load between a second (outer) clamp arm and the third (central) clamp arm. The third (central) actuator will not resist movement while closing in dual mode. This allows the third (central) arm to float to adapt to any load size and prevents unnecessary force on the third (central) actuator.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5707201 | Hamlik | Jan 1998 | A |
| 5807060 | Hamlik | Sep 1998 | A |
| 10207907 | Hamlik | Feb 2019 | B1 |
| 10589970 | Hamlik | Mar 2020 | B1 |
| 11220416 | Hamlik | Jan 2022 | B1 |
| 11370644 | Hamlik | Jun 2022 | B1 |
| 11608256 | Hamlik | Mar 2023 | B1 |
| 11878900 | Hamlik | Jan 2024 | B1 |
| 12006197 | Hamlik | Jun 2024 | B1 |
| 20160152455 | Hamlik | Jun 2016 | A1 |
| 20180155168 | Hamlik | Jun 2018 | A1 |
| 20190210851 | Hamlik | Jul 2019 | A1 |
| 20220063973 | Hamlik | Mar 2022 | A1 |
| 20230136144 | Hamlik | May 2023 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 63324149 | Mar 2022 | US | |
| 63236227 | Aug 2021 | US |
