Patent Description:
Typical pallet trucks support one, two in-line, or three in-line standard size pallets. Typically, pallet trucks include lifting load forks that are welded at their rear end or heel end to a frame and/or battery box. The front end of the forks typically includes support rollers. A hydraulic system operates a lifting mechanism that moves the support rollers, and lifts the battery box and the forks together with goods, such as pallets loaded thereon. The support rollers are typically coupled to the lift mechanism, for example with a linkage that transmits the force from a hydraulic lifting cylinder to the support rollers. A valve arrangement is provided to relieve the hydraulic pressure in the lifting cylinder, thus lowering and placing the load on the floor. Steer wheels are located behind the battery box. A steering mechanism, such as a tiller, also may be provided to steer the steer wheels relative to the battery box and forks.

The prior art document <CIT> discloses a lift truck with two modular lockable forks comprising the features of the preamble of claim <NUM>. The forks comprise an upright portion which can be hooked into hocks of the vehicle for the attachment of the forks.

The prior art documents <CIT> and <CIT> disclose industrial pallet trucks with two forks that can be hydraulically lowered and raised with respect to a base support portion of the truck.

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the invention is defined by the appended claims.

Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments; however, the order of description should not be construed to imply that these operations are order dependent.

The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed embodiments.

The terms "coupled" and "connected," along with their derivatives, may be used. Rather, in particular embodiments, "connected" may be used to indicate that two or more elements are in direct physical or electrical contact with each other. "Coupled" may mean that two or more elements are in direct physical or electrical contact. However, "coupled" may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.

The description may use the terms "embodiment" or "embodiments," which may each refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," and the like, as used with respect to embodiments, are synonymous.

<FIG> illustrates a front right isometric view of a prior art battery box and fork assembly <NUM> showing a pair of forks <NUM> welded to the battery box <NUM>. As is typical with conventional pallet trucks, the forks <NUM> are permanently welded to the battery box <NUM> and to a torsion tube <NUM>. Thus, the forks <NUM>, battery box <NUM>, and torsion tube <NUM> are permanently connected together, that is, they cannot be separated without some form of destructive separation technique such as grinding out the welds or cutting one component free from the others. While this configuration results in a strong joint between each individual fork <NUM>, the battery box <NUM>, and the torsion tube <NUM>, such strength is achieved at the expense of both versatility in configuration and economy of packing and shipping.

One challenge faced by pallet truck manufacturers is that customers often need varying fork configurations such as forks with variable spreads, lengths, tips, and widths. Because forks are typically welded to the battery box, changing fork parameters requires costly and time-consuming retooling to modify the battery box and fork design to produce a pallet truck conforming to individual customer specifications. In some situations, such redesigns can add up to six weeks lead-time.

To overcome the aforementioned problems and others, the inventors have developed a modular fork and battery box system where the forks are locked to the battery box and may be unlocked to accommodate customer preference. In addition, this modular system allows for more efficient use of container space during shipping when compared against forks welded to a battery box. For example, the battery box and forks may be created at one plant, and shipped to another plant for final assembly into a pallet truck. When the forks <NUM> are welded to the battery box <NUM> and a torsion tube <NUM>, as is typically done, the battery box and fork assembly <NUM> is bulky and does not pack efficiently into a shipping container. In contrast, a modular battery box and fork assembly with lockable forks, such as described and claimed herein, may be more efficiently packed into a shipping container because the forks do not need to be locked to the battery box prior to shipping. Such modular systems also provide for aftermarket modification of the fork configuration, and replacement of a damaged fork, without replacing the battery box or damaging the battery box by cutting into or otherwise altering the battery box to remove a fork welded to the battery box. These and other features provide a competitive advantage and differentiator in an exceedingly crowded market.

Turning to <FIG>, a battery box and fork assembly <NUM> includes a battery box <NUM> and two lockable forks <NUM>. Locking a fork to a battery box, torsion member, or both, means that such fork can also be unlocked from the battery box, torsion member, or both. The battery box <NUM> is sized to fit a battery or battery array. When used in conjunction with a pallet truck, pallet jack, or other suitable forklift, the entire battery box and fork assembly <NUM> may be raised and lowered as a single unit, for example via a hydraulic cylinder.

The forks <NUM> may be considered as a right and left fork, respectively, depending on what side of the battery box <NUM> they are locked to. In the illustrated embodiment, the right and left fork are identical such that one could be swapped for the other. Each fork <NUM> includes several portions. The fully assembled fork <NUM> includes an optional heel portion <NUM>, a central body portion <NUM>, and a toe portion <NUM>. For convenience and modularity, the heel portion <NUM>, the body portion <NUM>, and the toe portion <NUM> may be identical for both the left and right side of the battery box <NUM>. Using identical components for both the left and the rights forks <NUM> increases the modularity of the system over a system in which the left and right forks are made with distinct, non-interchangeable components. However, distinct, non-interchangeable components may be used to create left and right forks in certain embodiments. The heel portion <NUM> and the toe portion <NUM> are connected to the central body portion <NUM>, for example, by welding or other suitable attachment. With respect to the fork <NUM>, the heel end is the end closest to the battery box <NUM>, and may include an optional heel portion <NUM>. The heel end of the fork <NUM> is configured to be locked to the battery box <NUM> and torsion member <NUM> as described below. The toe end is the opposite end furthest from the battery box <NUM> that initially engages a pallet when picking up a load.

<FIG> illustrates a close up of the heel portion <NUM> of the fork shown in <FIG>. The heel portion may be cast metal, or machined from a solid metal billet, as a solid unitary body or single portion. However, even as a casting, several surface features of the heel portion <NUM> are optionally machined to create smooth surfaces. For example, a smooth surface may comprise a surface finished to an average surface roughness of <NUM> or less. Such machining is optionally performed before assembling the fork <NUM> using the heel portion <NUM>, the body portion <NUM>, and the toe portion <NUM>. The heel portion <NUM> includes several features to facilitate securely locking the fork <NUM> to the battery box <NUM> and the torsion member <NUM> such that flex at the joint in inhibited, or minimized. The heel portion <NUM> includes a locking component, such as one or more bores <NUM>, that engage a locking component, such as bores <NUM> in the base plate <NUM> of the battery box <NUM> (<FIG>). Bores <NUM> may be blind bores or may pass completely through the upper surface <NUM> of the heel portion <NUM>, and bores <NUM> may be smooth or threaded, depending on the type of fastener used with bores <NUM>.

As shown in <FIG>, the bores <NUM> are disposed on an optional raised boss <NUM> that is optionally machined to have a smooth surface to facilitate, or maximize, contact between the raised boss <NUM> and the bottom of the battery box base plate <NUM>. Including a smooth surface on the upper portion of the raised boss <NUM> may enhance distribution of the forces exerted on the raised boss <NUM> when a load is applied to a fork <NUM>, for example during a lifting or traveling operation. In one embodiment, the bores <NUM> are blind and are sized and threaded to accommodate fasteners, such as bolts <NUM> (<FIG>), having sufficient strength to maintain a tight joint between the base plate <NUM> of the battery box <NUM> and the boss <NUM> of the heel portion <NUM>. For example, bolts of class <NUM> and/or class <NUM> having a nominal diameter of about <NUM> may be used. Such bolts <NUM> may be tightened to a torque setting of <NUM> newton meters to facilitate creating a tight joint. In various embodiments, the heel portion <NUM> may include four bores <NUM> at the approximate corners of the boss <NUM>. The placement of the bores <NUM> at the corners of the boss <NUM> may provide a fastener pattern that gives strength to the j oint.

As shown in <FIG>, the heel portion <NUM> also includes a locking component, such as bores <NUM>, on both sides <NUM> of the heel portion <NUM>. Sides <NUM> with their locking components are configured such that the locking components on the sides <NUM> are substantially orthogonal to the locking components on the upper surface <NUM>. As with the bores <NUM>, bores <NUM> may be blind bores or may pass completely through the side <NUM> of the heel portion <NUM>, and bores <NUM> may be smooth or threaded, depending on the type of fastener used with bores <NUM>. In some embodiments, when the battery box <NUM> and fork <NUM> are assembled, only a single side <NUM> of the heel portion <NUM> is locked to the torsion member <NUM>. In other embodiments, the battery box <NUM> may contain additional surfaces that couple with both sides <NUM> of the heel portion <NUM> and both sides <NUM> of the heel portion <NUM> may be locked to the torsion member <NUM>, battery box <NUM>, or both. In various embodiments, bolts of class <NUM> and/or class <NUM> having a nominal diameter of about <NUM> are used, and the bores <NUM> are sized and threaded appropriately. Even if the other set of bores <NUM> (those on the opposite side <NUM> of the heel portion <NUM>) are not used, they are included so that a fork <NUM> may be used either as a right or left fork in the assembled pallet truck. As with the boss <NUM>, the sides <NUM> of the heel portion <NUM> are optionally machined smooth, to facilitate creating a tight joint to the torsion member <NUM> (see <FIG>). The smooth surface may enhance surface area contact to form a tight fit of the forks <NUM> to the torsion member <NUM>, and may inhibit flex that might otherwise lead to bolt fatigue and failure.

<FIG> illustrates a top view of an example battery box and fork assembly <NUM>, showing a pair of forks <NUM> locked to the battery box <NUM> via bolts <NUM>. As shown in <FIG>, the bottom of the battery box <NUM> includes a base plate <NUM> that extends the length and width of the bottom of the battery box <NUM>. Cutouts <NUM> in the base plate <NUM> may be included to permit passage of linkage components (not illustrated for clarity) that move the load wheels (not illustrated) located at the toe ends <NUM> of the forks <NUM>. The base plate <NUM> may be a separate plate that is welded or otherwise suitably attached to the battery box <NUM>, or the base plate <NUM> may be formed as part of the battery box <NUM>.

The battery box <NUM> optionally includes spacer bars <NUM>. Spacer bars <NUM> may be coupled to the base plate <NUM> via welds <NUM>, or otherwise suitably attached to the base plate <NUM>. Spacer bars <NUM> may serve two purposes. One purpose is to elevate the bottom of a battery or battery array above the surface of the base plate <NUM> to provide additional clearance for passage of linkage components that move the load wheels located at the toe ends <NUM> of the forks <NUM>. Another purpose may be to provide additional torsional resistance when differential loading is applied to one of the forks <NUM>. For example, spacer bars <NUM> may be welded to the base plate <NUM> such that the spacer bards are aligned with the sides <NUM> and <NUM> of a torsion member <NUM> coupled to the battery box <NUM>. By aligning the spacer bars <NUM> with the sides <NUM> and <NUM> of the torsion member <NUM>, a larger section modulus may be created (compared to not aligning the spacer bars <NUM> with the sides <NUM> and <NUM> of the torsion member <NUM>) that resists twisting of the base plate <NUM> when a differential load is applied to the forks <NUM>.

With reference to <FIG> and <FIG>, a top surface <NUM>/<NUM> of each heel portion <NUM> is configured to be locked to the base plate <NUM> by including a locking component, for example, a set of bores <NUM>. Likewise, the base plate <NUM> is configured to be locked to each heel portion <NUM> by including a locking component, for example, first and second sets of bores <NUM>. The locking components of the base plate <NUM> may be considered to engage the locking components of the heel portions <NUM> when the underside of the base plate contacts the top surface <NUM>/<NUM> of each heel portion <NUM>, and each of the bores <NUM> aligns with a corresponding bore <NUM> in the base plate <NUM>.

Fasteners are included to lock the locking components together. For example, bolts <NUM> pass through eight smooth bores <NUM> in the base plate <NUM> and into the threaded, blind bores <NUM> in the boss <NUM> of the heel portion <NUM> of each fork <NUM>. The bolts <NUM> are tightened, for example, to a torque setting of <NUM> newton meters, to lock each fork <NUM> to the base plate <NUM>. In some embodiments, bores in the top surface of the heel portion may pass through the entire heel portion and may be smooth. Fasteners such as rivets or bolts with corresponding nuts may be used to lock such a fork heel portion to a battery box. In other embodiments, a heel portion may not be included and the locking component, such as one or more threaded or smooth bores, may be formed directly in the fork body. In addition to bolts and rivets, other suitable fasteners may be used to lock forks to a battery box, where such fasteners are constructed such that they are removable without damaging the battery box, torsion member, or fork.

With reference to <FIG> and <FIG>, side surfaces <NUM> of each heel portion <NUM> are configured to be locked to the torsion member <NUM> by including a locking component, for example, a set of bores <NUM>. Likewise, the torsion member <NUM> is configured to be locked to each heel portion <NUM> by including a locking component, for example, a first side <NUM> containing bores <NUM> and a second side <NUM> containing bores <NUM>. The locking components of the torsion member <NUM> may be considered to engage the locking components of the heel portions <NUM> when the first side <NUM> of the torsion member <NUM> contacts a side <NUM> of a heel portion <NUM>, the second side <NUM> of the torsion member <NUM> contacts a side <NUM> of a heel portion <NUM>, and each of the bores <NUM> aligns with a corresponding bore <NUM>. Optionally, the sides <NUM> of the heel portions <NUM> may be machined to include a smooth surface. Torsion member <NUM> side plates <NUM> and <NUM> may be made from sheet or plate steel, or may also optionally be machined to include a smooth surface.

Fasteners are included to lock the locking components together. For example, bolts <NUM> pass through bores <NUM> in the first side <NUM> and the second side <NUM> of the torsion member <NUM> and into the threaded, blind bores <NUM> in the sides <NUM> of the heel portion <NUM> of each fork <NUM>. The bolts <NUM> are tightened, for example, to a torque setting of <NUM> newton meters to lock each fork <NUM> to the torsion member <NUM>. In some embodiments, bores in the side surfaces of the heel portions may pass through the entire heel portion and may be smooth. Fasteners such as rivets or bolts with corresponding nuts may be used to lock such a fork heel portion to a torsion member. In other embodiments, a heel portion may not be included and the locking component, such as one or more threaded or smooth bores, may be formed directly in the fork body. In addition to bolts and rivets, other suitable fasteners may be used to lock forks to a torsion member, where such fasteners are constructed such that they are removable without damaging the battery box, torsion member, or fork.

With reference to <FIG>, the torsion member <NUM> is formed from the first side <NUM>, second side <NUM>, a rear side <NUM> extending between the first side <NUM> and the second side <NUM>, and a front side <NUM> extending between the first side <NUM> and the second side <NUM>. The torsion member <NUM> is secured to the base plate <NUM>, for example, via welds <NUM>. In other embodiments, the torsion member <NUM> and the base plate <NUM> may be integrally formed together, for example, via casting or additive manufacturing.

With reference to <FIG>, Table <NUM> shows an example preload placed on bolts A-L when tightened to a torque value of <NUM> newton meters for bolts A, B, C, D, E, F, G, and H and to a torque value of <NUM> newton meters for bolts I, J, K, and L. Table <NUM> also shows an example percentage change of the preload when a simulated load of <NUM> (<NUM>,<NUM> lbs) is applied to the forks <NUM>. As shown by the small changes in the preload percentages in Table <NUM>, the load applied to the forks is fairly evenly distributed to the bolts within the bolt pattern shown in <FIG>.

In other embodiments, locking components other than bores may be used. For example, with reference to <FIG>, a battery box and fork assembly <NUM> includes forks <NUM> that are locked to the battery box <NUM>, torsion member <NUM>, and locking plates <NUM> via locking components that engage with an interference, or press, fit. Locking plates <NUM> may be considered as a base plate first and second locking component in certain embodiments.

Torsion member <NUM> includes a first side <NUM> and a second side <NUM> that each includes a locking component comprising one or more slots <NUM>. Likewise, each of the locking plates <NUM> includes a locking component comprising one or more slots <NUM>. The sides <NUM> of heel portions <NUM> include locking components that comprise one or more protrusions <NUM> that are sized and shaped to fit into the slots <NUM> and <NUM>.

To lock the forks <NUM> to the battery box <NUM>, to the torsion member <NUM>, and to the locking plates <NUM>, the protrusions <NUM> are aligned with the slots <NUM> and <NUM>. Each fork <NUM> is then moved in the direction of arrow IN such that the protrusions <NUM> engage the slots <NUM> and <NUM> with an interference, or press, fit. To unlock the forks <NUM> from the battery box <NUM>, the the torsion member <NUM>, and the locking plates <NUM> each fork <NUM> is moved in the direction of arrow OUT such that the protrusions <NUM> disengage from the slots <NUM> and <NUM>.

The location of the protrusions and slots described above may be reversed. Additionally, other suitable locking components, fasteners, or both, may be used. For example, the base plate <NUM> may include locking components that comprise one or more protrusions (not illustrated) and the heel portion <NUM> of forks <NUM> may include a locking component on an upper surface that comprises one or more slots (not illustrated) that are sized and shaped to receive the protrusions on the underside of the base plate <NUM> with an interference, or press, fit.

Claim 1:
A modular lockable fork (<NUM>) for a vehicle, comprising:
a heel end and a toe end,
characterized in that the heel end comprises:
(i) an upper surface (<NUM>) configured to be locked to a battery box (<NUM>) of the vehicle and including a first locking component (<NUM>) configured to engage a locking component of the battery box (<NUM>), and
(ii) a side surface (<NUM>, <NUM>) configured to be locked to a torsion member (<NUM>) coupled to the battery box (<NUM>) and including a second locking component (<NUM>) configured to engage a locking component of the torsion member (<NUM>).