The present application relates to lift trucks, and in particular to a carriage for lift truck attachments that includes a side-shifting mechanism and provides for the lift truck attachments to be tilted about an axis extending in the direction of side-shifting mechanism movement.
It is desirable for a lift truck attachment such as forklift forks to be able to tilt, thereby lowering or raising the tips of the forks. In some lift trucks tilting can be accomplished by tilting the mast on which a carriage for attachments is mounted. In other lift trucks, a mast is mounted on the truck at a fixed angle, usually so that the mast is vertical when the truck is on a level surface.
On such a lift truck, attachments such as forklift forks may be mounted on a carriage arranged to move vertically along the mast. The carriage typically includes an inner frame that is movable along the mast and an outer frame, carried by the inner frame, on which attachments such as forks may be mounted. The carriage may include a side-shifter mechanism for moving the attachments laterally with respect to the mast of the lift truck. Since the mast cannot be tilted with respect to the lift truck, the carriage must include a mechanism for tilting the attachments with respect to the mast.
A side-shifter mechanism typically includes at least one hydraulic cylinder-and-piston assembly arranged to move lift truck attachments laterally in either direction through a limited distance with respect to the mast on which the carriage is mounted.
In some previously known lift trucks including side-shifters incorporating hydraulic cylinders, an attachment-carrying outer frame portion of the carriage, able to be moved by the side-shifter, is supported on a laterally-extending upper support member that is part of the inner frame. The upper support member may be the top member of an inner frame portion of the carriage, extending between a pair of generally vertically extending side members of the inner frame. In some cases, the upper support member may be located immediately above the side-shifter cylinder-and-piston assembly. Such a laterally-extending upper support member has a cylindrical upper surface, and the outer frame portion of the carriage, moved by the side-shifter, includes bearings that can slide laterally along and pivot about the cylindrical surface of the laterally-extending upper support member as the forks or other attachments mounted on the outer frame are tilted.
The just-described arrangement requires regular cleaning and lubrication of the upper support member and bearings of the outer frame. It may also require special attachment of the side-shifter cylinder-and-piston assembly to the outer frame, to allow the outer frame to tilt with respect to the inner frame.
In other lift trucks with side-shifting and tilting capabilities the outer frame of the carriage may be mounted on a support shaft extending laterally between the side members of the inner frame. This sort of arrangement also requires bearings that allow rotational and translational movement of the outer frame relative to such a support shaft.
It is therefore desired to have a carriage for attachments for a lift truck with a vertical mast, in which both side-shifting and tilting of the carriage and attachments can be accomplished, and in which bearings accommodating side-shifting and tilting do not require routine maintenance.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.
Referring now to the drawings that form a part of the disclosure herein, a lift truck 20 shown in
The carriage 24 is shown in
The carriage 24 includes a pair of frames, an outer frame 34 and an inner frame 36 that supports the outer frame as will be explained in greater detail presently. The stub axles 30 are mounted on respective ones of a pair of generally vertical side members 38 of the inner frame 36. The side members 38 are spaced apart from each other laterally of the carriage 24 by a distance limited by the space available between a pair of side members of a mast 22 with which the carriage 24 is associated, as will be understood from
A pair of outwardly facing C-shaped mounting receptacles 44, aligned horizontally with each other, are defined near upper ends of the side members 38, facing outwardly, toward the outer frame 34. A side-shifter cylinder-and-piston assembly 50, described in greater detail below, is held in the receptacles 44 and extends laterally between the side members 38. The cylinder portions of the side-shifter cylinder-and-piston assembly 50 are securely fastened, as by the cylinder portions being welded to each of the side members 38, thus interconnecting the side members 38. The cylinder portions of the side-shifter cylinder-and-piston assembly 50 are thus integrated in the inner frame 36 as a second rigid transverse structural member of the inner frame 36.
The outer frame 34 includes a pair of upright side members 52 and 54 that are interconnected with each other by a horizontal, upper attachment mounting bar 26 that extends between and is securely fastened, as by being welded, to each of the side members 52 and 54 at the top of the outer frame 34. A transversely-extending bottom attachment mounting member 58 interconnects the lower ends of side members 52 and 54, to which it is also securely attached, as by being welded. The bottom attachment mounting member 58 has a depth 60 that helps to give the outer frame 34 sufficient rigidity. For example, the depth 60 may be about 125 mm.
The lower part of the outer frame 34 may be relatively narrow with a width small enough to fit between a pair of outriggers of the lift truck, as may be seen in
Piston rods 70 and 72 extend laterally and coaxially from opposite ends of the side-shifter cylinder-and-piston assembly 50. An outer end 74 of the piston rod 70 is securely fastened to the upper portion of the side member 52, as by being screwed tightly into a threaded bore defined in the side member 52, with a shoulder 75 of the piston rod 70 abutting the side member 52 solidly to establish a rigid relationship. An outer end 76 of the piston rod 72 is similarly fastened to the upper portion of the opposite side member 54 of the outer frame 34.
The piston rods 70 and 72 are fitted movably within respective cylinders 120 and 122 of the side-shifter cylinder-and-piston assembly 50 and attach the outer frame 34 to the inner frame 36 yet allow the outer frame 34 to be shifted sideward or tilted with respect to the inner frame 36. Thus, the inner frame 36 supports the outer frame 34, and loads carried by the carriage 24 are transmitted from the outer frame 34 to the inner frame 36 through the piston rods 70 and 72 and the cylinders 120 and 122 of the side-shifter cylinder-and-piston assembly 50.
Extension of one of the piston rods 70 and 72 and retraction of the other within the side-shifter cylinder-and-piston assembly 50 effects lateral movement, or side-shifting, of the outer frame 34 with respect to the inner frame 36, as indicated by the arrow 78, and as shown by the broken-line depiction of the outer frame 34 in
The carriage 24 also provides for an attachment such as the forklift forks 28 to tilt with respect to the mast 22 about a central axis 80 of the side-shifter cylinder-and-piston assembly 50, with the piston rods 70 and 72 rotating accordingly in the cylinders 120 and 122 of the side-shifter cylinder-and-piston assembly 50 through an angle about the central axis 80. In order to effect tilting, a cylinder block 84 is carried between the side members 38 of the inner frame 36. A pair of supports 86 are mounted on the side members 38 and define a transverse axis 88 about which the cylinder block 84 is able to pivot to remain oriented directly toward the inner face 90 of the bottom attachment mounting member 58.
The cylinder block 84 defines a pair of cylinders 92 in which respective pistons 94 are disposed and can move toward the outer frame 34. A piston rod 96 extends from each piston 94 through a respective cylinder head 98 including an appropriate piston rod seal. Fittings 100 are provided on the cylinder block 84 to admit hydraulic fluid pressure to move the pistons 94 in either direction in the respective cylinder 92. A tilt pusher bar 102 extends along the outer side of the cylinder block 84, the side facing toward the inner face 90 of the bottom attachment mounting member 58. A pair of guide pins 104 extend from the pusher bar 102 into corresponding bores 106 in the cylinder block, to keep the pusher bar 102 aligned parallel with the cylinder block as the pusher bar is moved by the tilt piston rods 96. Each piston rod 96 extends into a respective bore 108 provided as a receptacle in the pusher bar 102, and a suitable pin 110 fits through aligned bores 112 in the pusher bar 102 and through the piston rods 96, locking the piston rods 96 into the pusher bar 102, so that movement of the pistons 94 in their cylinders 92 moves the pusher bar 102 toward or away from the cylinder block 84.
A pair of contact pads 114 of low-friction material, for example, a durable polymer such as nylon, are mounted on an outer face of the pusher bar 102 in position to rest against the inner face 90 of the transversely extending bottom attachment mounting bar 58 as shown best in
Referring to
As shown in
As the outer frame 34 is tilted about the side-shifter cylinder central axis 80 the pistons 70 and 72 rotate within the bore of the side-shifter cylinder assembly 50.
As shown in
At the inner end of the piston rod 70 or 72 a circumferential groove 128 holds a bearing 130 providing lateral support for the base, or inner end, of the piston rod 70. External oil passage grooves (not shown) in the bearing 130 allow passage of some hydraulic fluid between the bearing 130 and the cylinder wall surface 131 to lubricate the piston rod 70. The bearing 130 is retained by a disk-like retainer 132 kept in place in the base of the piston rod 70 by a suitable fastener such as a screw 134 threaded into the base of the piston rod, once the bearing 130 has been installed over the end of the piston rod, as shown in
As shown in enlarged view in
The resulting arrangement, as has been described, allows the outer frame 34 to be tilted as required about the central axis 80 of the side-shifter cylinder assembly 50. This arrangement eliminates the need for routine lubrication of the side-shifter arrangement, while also minimizing the height of the carriage 24, making the carriage capable of being extended, together with any attachments, into a minimum height space between adjacent shelves.
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
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United States Patent and Trademark Office; International Search Report and Written Opinion for Int'l App. No. PCT/US2019/012734; dated Apr. 15, 2019; 6 pages. |
Number | Date | Country | |
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20190241417 A1 | Aug 2019 | US |