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 connected at their rear end or heel end to a chassis or battery box. The front end of each fork typically includes one or more support rollers, commonly called load wheels. A hydraulic system, which is located in proximity to the chassis or battery box, operates a lifting mechanism that moves the load wheels and lifts the chassis or battery box and the forks together with goods, such as pallets loaded thereon. The load wheels are typically coupled to the lift mechanism by a mechanical linkage that transmits force from a hydraulic lifting cylinder to the load wheels. 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 chassis and forks.

Current material-handling trucks have a low success rate of entering or exiting an empty or lightly-loaded (<NUM> or less) closed-bottom pallet. More often than not, the front load wheel jams against the bottom board, causing the pallet to be pushed along the ground rather than having the forks enter the pallet as intended. Such pushing the pallet along the ground is undesirable because the horizontal surface on which the pallet sits can be damaged and/or the bottom board of the pallet can be damaged, reducing its useful life. The success rate appears to depend on several factors such as driver skill, pallet weight, pallet condition, friction between ground and pallet, etc. Also, failure to enter the pallet prevents the pallet from being retrieved. Moreover, failure to exit an empty pallet results in the pallet being trapped on the forks, rendering the truck useless until the pallet is removed. <CIT> shows a forked material-handling vehicle having a caterpillar-like arrangement at each fork with endless chain running over multiple wheels to prevent the wheels from contacting the ground. One wheel may be motorized, or a non-motorized short chain drive can be arranged at the tip of the forks. <CIT> shows a one-piece running gear having two wheels and an endless kinematic running link around the wheels to kinematically connect them and to prevent the wheels from contacting the ground. <CIT> discloses a roller load support for mounting on a load carrying vehicle such as a lift truck and has an elongate frame with a forwardly tapering vertical thickness and an upper surface for insertion beneath the underside of a load. Different longitudinally spaced pluralities of transverse upper rollers are movably upwardly to protrude through the frame's upper surface to engage the underside of the load during the insertion process. During the insertion process, the upper rollers are pushed upward by corresponding different pluralities of transverse lower rollers which rotatably engage the floor or other surface beneath the frame and frictionally counterrotate the upper rollers.

A forked pallet truck according to the invention is claimed in claim <NUM>. A method for employing a fork of a forked pallet truck according to the invention is claimed in claim <NUM>.

This overview is provided to introduce a selection of concepts in a simplified form that are further described in greater detail below. This overview is not intended to identify key or essential inventive concepts of the claimed subject matter, nor is it intended for limiting the scope of the claimed subject matter. Some example embodiments are set forth below:.

According to the invention, a forked pallet truck having a chassis, an elongate fork and a load wheel assembly, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, and wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end, wherein the load wheel assembly comprises a non-motorized forward load wheel configured to directly roll on a floor, a non-motorized rear load wheel configured to directly roll on a floor, and a non-motorized torque-coupling assembly connected between the forward load wheel and the rear load wheel ,for coupling torque between the forward load wheel and the rear load wheel and wherein the forked pallet truck has a load wheel extension mechanism for extending the load wheel assembly away from the fork.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a forward load wheel, a rear load wheel, and a torque-coupling assembly connected between the forward load wheel and the rear load wheel, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, and wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end.

In an embodiment, a method for moving a fork of a forked material-handling vehicle across a surface employs a forked material-handling vehicle having a chassis, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, wherein the fork has a forward wheel and a rear wheel, wherein the forward wheel is nearer than the rear wheel to the distal end, and wherein the rear wheel is nearer than the forward wheel to the proximal end. The method comprises rolling the forward wheel on the floor as the fork moves forward in the distal direction; rolling the rear wheel on the surface as the fork moves forward in the distal direction; and in response to the forward wheel hitting an obstacle on the surface that hinders turning of the forward wheel, transferring torque from the rear wheel to the forward wheel to thereby enable the forward wheel to roll over the obstacle.

In an embodiment, an elongate body of a fork of a forked material-handling vehicle with a chassis comprises a body proximal end and a body distal end, wherein the body proximal end is suitable for direct or indirect support by, or attachment to, the chassis; a load wheel assembly operatively connected to the elongate body, wherein the load wheel assembly is directly or indirectly connected to the elongate body closer to the body distal end than to the body proximal end, wherein the load wheel assembly includes a forward load wheel and a rear load wheel; and a torque-coupling assembly adapted to couple torque between the forward load wheel and the rear load wheel.

In an embodiment, a fork for a forked material-handling vehicle comprises a discrete elongate body; a load wheel module, including a load wheel assembly having a forward load wheel, a rear load wheel, and a torque-coupling assembly connected between the forward load wheel and the rear load wheel; and a fork tip.

In an embodiment, a fork assembly for a forked material-handling vehicle with a chassis comprises a pair of elongate bodies, each elongate body comprising: a body proximal end and a body distal end, wherein the body proximal end is suitable for direct or indirect support by, or attachment to, the chassis; a load wheel assembly operatively connected to the elongate body, wherein the load wheel assembly is directly or indirectly connected to the elongate body closer to the body distal end than to the body proximal end, wherein the load wheel assembly includes a forward load wheel and a rear load wheel; and a torque-coupling assembly adapted to couple torque between the forward load wheel and the rear load wheel.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a non-motorized forward load wheel; a non-motorized rear load wheel; and a non-motorized torque-coupling assembly connected between the forward load wheel and the rear load wheel, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, and wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a forward load wheel having a forward load wheel surface; a rear load wheel having a rear load wheel surface; and a torque-coupling assembly connected between the forward load wheel and the rear load wheel, wherein the torque-coupling assembly includes a coupling wheel (or idler wheel) having a coupling wheel surface, and wherein the coupling wheel surface has direct contact with the forward load wheel surface and the rear load wheel surface, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, and wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a forward load wheel having a forward rotation axle having a forward first end and a forward second end; a rear load wheel having a rear rotation axle having a rear first end and a rear second end; a first wheel carrier having a forward connection point and a rear connection point, wherein the forward first end of the forward first rotation axle is rotatably connected to the forward connection point of the first wheel carrier, and wherein the rear first end of the rear rotation axle is rotatably connected to the rear connection point of the first wheel carrier wherein the first wheel carrier is configured to pivotably connect to the fork; a second wheel carrier having a forward connection point and a rear connection point, wherein the forward second end of the forward rotation axle is rotatably connected to the forward connection point of the second wheel carrier, and wherein the rear second end of the rear rotation axle is rotatably connected to the rear connection point of the second wheel carrier, wherein the second wheel carrier is configured to pivotably connect to the fork; and a torque-coupling assembly connected between the forward load wheel and the rear load wheel, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a forward load wheel; a rear load wheel; a torque-coupling assembly connected between the forward load wheel and the rear load wheel, wherein the torque-coupling assembly includes a force-applying coupling assembly configured to elastically couple torque between the forward load wheel and the rear load wheel, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, and wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end.

According to the invention, a method for employing a fork of a forked material-handling vehicle to engage a closed pallet including a bottom slat resting on a floor and a top slat for supporting a load is defined in claim <NUM>. The method utilizes a forked pallet truck with a chassis, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork being attached directly or indirectly to the chassis, wherein the fork having a forward load wheel and a rear load wheel, the forward load wheel being nearer than the rear load wheel to the distal end, and wherein the rear load wheel being nearer than the forward load wheel to the proximal end and wherein the forked pallet truck has a load wheel extension mechanism for extending the load wheel assembly away from the truck. The method comprises rolling the forward load wheel directly on the floor as the fork moves forward in the distal direction; rolling the rear load wheel directly on the floor as the fork moves forward in the distal direction; and in response to the forward load wheel hitting the slat that hinders turning of the forward load wheel, employing torque coupled from the rear load wheel to the forward load wheel to thereby enable the forward load wheel to roll over the bottom slat and beneath the top slat.

In an embodiment, a fork assembly for a forked material-handling vehicle comprises a discrete elongate body; a discrete load wheel module, including a load wheel assembly having a forward load wheel, a rear load wheel, and a torque-coupling assembly connected between the forward load wheel and the rear load wheel; a first interlocking mechanism detachably connecting the elongate body to the load wheel module; a discrete fork tip; and a second interlocking mechanism detachably connecting the load wheel module to the fork tip.

In an embodiment, a load wheel module for a fork assembly for a forked material-handling truck comprises a frame; a load wheel assembly operatively connected to the frame, the load wheel assembly having a forward load wheel, a rear load wheel, and a torque-coupling assembly connected between the forward load wheel and the rear load wheel; and a hydraulic actuator contained within the frame and operatively connected to the load wheel assembly to lower the load wheel hydraulically.

In an embodiment, a pallet truck comprises a steer wheel; a chassis operatively connected to the steer wheel; and substantially parallel first and second forks operatively connected to and extending from the chassis and configured to hold a load for conveyance by the pallet truck as the pallet truck moves, wherein the first fork comprises a first elongate body, a first load wheel assembly, and a first fork tip, wherein the second fork comprises a second elongate body, a second load wheel assembly, and a second fork tip, wherein the first load wheel assembly comprises a first forward load wheel, a first rear load wheel, and a first torque-coupling assembly connected between the first forward load wheel and the first rear load wheel, and wherein the second load wheel assembly comprises a second forward load wheel, a second rear load wheel, and a second torque-coupling assembly connected between the second forward load wheel and the second rear load wheel.

In an embodiment, the load wheel assembly further comprises a non-motorized lead-entry roller positioned forward from the non-motorized forward load wheel. The lead-entry roller may be in the form of a paddle wheel having multiple paddles or may have other features on its surface, such ridges, bumps, a tire, or other surface texture to enable it to grip and climb over an obstacle, such as a base board, on the floor, rather than push it horizontally. The load wheel assembly further comprises a non-motorized torque-coupling assembly connected between the non-motorized lead-entry roller and one or more of the forward load wheel and the rear load wheel. Examples of suitable torque-coupling assemblies include one or more chains or belts, such as toothed belts, and gears.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a non-motorized forward load wheel; a non-motorized rear load wheel; and a non-motorized lead-entry roller positioned forward from the non-motorized forward load wheel.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle with a chassis comprises a forward load wheel; a rear load wheel, wherein the fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end; and a torque-coupling means connected between the forward load wheel and the rear load wheel to couple torque between the forward load wheel and the rear load wheel, wherein the torque-coupling means comprises a force-applying coupling means configured to elastically couple torque between the forward load wheel and the rear load wheel.

In an embodiment, a load wheel assembly for an elongate fork of a forked material-handling vehicle having a chassis comprises a non-motorized forward load wheel; a non-motorized rear load wheel, wherein fork has a proximal end and a distal end, wherein the proximal end of the fork is configured for direct or indirect attachment to the chassis, and wherein the load wheel assembly is configured for connection to the fork closer to the distal end than to the proximal end; and a non-motorized means for coupling torque between the forward load wheel and the rear load wheel.

In an embodiment, the torque-coupling assembly comprises a torque-coupling means for coupling torque between the forward load wheel and the rear load wheel.

In an embodiment, the torque-coupling assembly comprises an idler wheel.

In an embodiment, the idler wheel comprises a tire.

In an embodiment, the idler wheel comprises a solid core.

In an embodiment, the idler wheel comprises a pneumatic core.

In an embodiment, the torque-coupling assembly comprises a polymer.

In an embodiment, the tire comprises a polymer.

In an embodiment, the idler wheel comprises polyurethane.

In an embodiment, the tire comprises polyurethane.

In an embodiment, the forward load wheel has a forward load wheel surface, wherein the rear load wheel has a rear load wheel surface, and wherein at least one of the forward load wheel surface and the rear load wheel surface comprises a non-smooth texture.

In an embodiment, the torque-coupling assembly includes an idler wheel having an idler wheel surface that has direct contact with the forward load wheel surface and the rear load wheel surface.

In an embodiment, the forward load wheel comprises a non-motorized forward load wheel, the rear load wheel comprises a non-motorized rear load wheel, and the torque-coupling assembly comprises a non-motorized torque-coupling assembly.

In an embodiment, the forward load wheel is non-motorized, the rear load wheel is non-motorized, and the torque-coupling is a non-motorized.

In an embodiment, the forward load wheel has a forward axle having a forward first end and a forward second end, and the rear wheel has a rear axle having a rear first end and a rear second end, wherein a first wheel carrier has a forward connection point and a rear connection point, wherein the forward first end of the forward first axle is rotatably connected to the forward connection point of the first wheel carrier, and wherein the rear first end of the rear axle is rotatably connected to the rear connection point of the first wheel carrier, wherein a second wheel carrier has a forward connection point and a rear connection point, wherein the forward second end of the forward axle is rotatably connected to the forward connection point of the second wheel carrier, and wherein the rear second end of the rear rotation axle is rotatably connected to the rear connection point of the second wheel carrier.

In an embodiment, the first wheel carrier is configured to pivotably connect directly or indirectly to the fork of the forked material-handling vehicle, and/or wherein the second wheel carrier is configured to pivotably connect directly or indirectly to the fork of the forked material-handling vehicle.

In an embodiment, the torque-coupling assembly comprises an idler wheel having grooves, tread voids, or surface features.

In an embodiment, the torque-coupling assembly comprises a metallic idler wheel.

In an embodiment, the torque-coupling assembly is positioned above the forward load wheel and the rear load wheel.

In an embodiment, the forward load wheel has a forward wheel radius, the rear load wheel has a rear wheel radius, the idler wheel has an idler wheel diameter, and the idler wheel diameter is smaller than or equal to the forward wheel radius and the rear wheel radius.

In an embodiment, the forward load wheel has a forward wheel height above the ground, the rear load wheel has a rear wheel height above the ground, the idler wheel has an idler wheel height above the ground, and the idler wheel height is shorter than or equal to the forward wheel height and the rear wheel height.

In an embodiment, the forward load wheel has a forward wheel height above the ground, the rear load wheel has a rear wheel height above the ground, the idler wheel has an idler wheel height above the ground, and the idler wheel height is within <NUM>% of the forward wheel height and/or the rear wheel height.

In an embodiment, the torque-coupling assembly comprises a force-applying coupling assembly (or a force-applying coupler) configured to couple torque between the forward load wheel and the rear load wheel.

In an embodiment, the torque-coupling assembly comprises a force-applying coupling means configured to couple torque between the forward load wheel and the rear load wheel.

In an embodiment, the torque-coupling assembly comprises a resilient force-applying coupling assembly (or a resilient force-applying coupler) configured to elastically couple torque between the forward load wheel and the rear load wheel.

In an embodiment, the torque-coupling assembly comprises a resilient force-applying coupling means configured to elastically couple torque between the forward load wheel and the rear load wheel.

In an embodiment, the force-applying coupling assembly is configured to continuously elastically couple torque between the forward load wheel and the rear load wheel.

In an embodiment, the force-applying coupling assembly comprises a torsion spring.

In an embodiment, the force-applying coupling assembly comprises a tension spring.

In an embodiment, the force-applying coupling assembly comprises one or more leaf springs.

In an embodiment, the force-applying coupling assembly comprises one or more spring plates.

In an embodiment, the force-applying coupling assembly comprises a tension plate.

In an embodiment, force-applying coupling assembly comprises a spring-loaded clip.

In an embodiment, the forward load wheel has a forward axle assembly, the rear wheel has a rear axle assembly, the idler wheel has an idler axle, the torque-coupling assembly is indirectly connected to the idler axle, and the torque-coupling assembly at least partly directly or indirectly surrounds the forward axle assembly or the rear axle assembly.

In an embodiment, the forward load wheel has a forward axle assembly, the rear wheel has a rear axle assembly, the idler wheel has an idler axle, the force-applying coupling assembly comprises a torsion spring directly or indirectly connected to the idler axle, and the torsion spring at least partly directly or indirectly surrounds the forward axle assembly or the rear axle assembly.

In an embodiment, the force-applying coupling assembly is connected directly or indirectly to the first wheel carrier or the second wheel carrier.

In an embodiment, the torsion spring is connected directly or indirectly to the first wheel carrier or the second wheel carrier.

In an embodiment, the first wheel carrier and/or the second wheel carrier has a forward pocket and a rear pocket positioned higher than the respective forward load wheel and the rear load wheel, and the torque-coupling assembly extends from the forward pocket to the rear pocket and arcs over at least a portion of the idler axle forcing (or tensioning) the idler axle toward the forward load wheel and the rear load wheel.

In an embodiment, the first wheel carrier and/or the second wheel carrier has a forward pocket and a rear pocket positioned higher than the respective forward load wheel and the rear load wheel, and the force-applying coupling assembly extends from the forward pocket to the rear pocket and arcs over at least a portion of the idler axle forcing (or tensioning) the idler axle toward the forward load wheel and the rear load wheel.

In an embodiment, the idler axle comprises an idler slot, and a portion of the force-applying coupling assembly passes through the idler slot.

In an embodiment, the idler axle comprises an idler slot, and one or more of the leaf springs pass through the idler slot.

In an embodiment, force-applying coupling assembly comprises fastener slots adapted to receive a fastener that secures the force-applying coupling assembly to the wheel carrier.

In an embodiment, one or more of the leaf springs include a fastener slot, and wherein a fastener is positioned through the fastener slot to secures the leaf spring to the wheel carrier.

In an embodiment, the force-applying coupling assembly comprises multiple compression springs.

In an embodiment, the torque-coupling assembly comprises a tension plate that covers at least a portion of the idler axle and is pressed toward to the first wheel carrier or the second wheel carrier.

In an embodiment, the force-applying coupling assembly comprises a tension plate that covers at least a portion of the idler axle and is pressed toward to the first wheel carrier or the second wheel carrier.

In an embodiment, the tension plate has a flat level portion over the idler axle.

In an embodiment, the force-applying coupling assembly comprises one or more compression springs to press the tension plate toward the first wheel carrier or the second wheel carrier.

In an embodiment, the spring-loaded clip is attached to one or both of forward and rear portions of the first wheel carrier or the second wheel carrier.

In an embodiment, the force-applying coupling assembly is attached to both forward and rear portions of the first wheel carrier or the second wheel carrier.

In an embodiment, the force-applying coupling assembly is bolted to both forward and rear portions of the first wheel carrier or the second wheel carrier.

In an embodiment, the force-applying coupling assembly fits around both forward and rear ends of the first wheel carrier or the second wheel carrier.

In an embodiment, the torque-coupling assembly is controllably disengageable.

In an embodiment, the load wheel assembly is adapted for use in a fork assembly that comprises an elongate body; a load wheel module, which includes the load wheel assembly; and a fork tip.

In an embodiment, the load wheel assembly is adapted for use in a fork assembly that comprises a discrete elongate body; a discrete load wheel module, which includes the load wheel assembly; a first interlocking mechanism detachably connecting the elongate body to the load wheel module; a discrete fork tip; and a second interlocking mechanism detachably connecting the load wheel module to the fork tip.

In an embodiment, the load wheel assembly is adapted for use in a load wheel module that comprises a frame, wherein the load wheel assembly is operatively connected to the frame, and wherein a hydraulic actuator contained within the frame and operatively connected to the load wheel assembly to lower the load wheel hydraulically.

In an embodiment, the torque-coupling assembly comprises an upper idler wheel positioned above the forward and rear load wheels, a lower idler wheel positioned beneath the forward and rear load wheels, and a force-applying coupling assembly that directly or indirectly connects the upper idler wheel and the lower idler wheel and forces (or tensions) them toward each other.

In an embodiment, the idler wheel comprises or is attached to a gear wheel.

In an embodiment, at least one of the forward load wheel and the rear load wheel has grooves.

In an embodiment, the torque-coupling assembly comprises a belt.

In an embodiment, the torque-coupling assembly comprises one or more gears.

In an embodiment, the torque-coupling assembly comprises a track that forms a loop around the forward load wheel and the rear load wheel.

In an embodiment, the torque-coupling assembly comprises an idler wheel having an idler wheel surface, the idler wheel surface has direct contact with the forward load wheel surface and the rear load wheel surface, and the torque-coupling assembly comprises a force-applying coupling assembly configured to elastically urge the idler wheel into contact with the forward load wheel and the rear load wheel.

In an embodiment, the load wheel assembly is adapted for use in a pallet truck that comprises first and second fork assemblies, wherein each fork assembly includes a load wheel assembly and further comprises an elongate body with a body proximal end and a body distal end, wherein the body proximal end is suitable for direct or indirect attachment to a chassis; and a torque transfer assembly adapted to transfer torque between the forward and rear load wheels.

Additional aspects and advantages will be apparent from the following detailed description of example embodiments, which proceeds with reference to the accompanying drawings.

Example embodiments are described below with reference to the accompanying drawings. Unless otherwise expressly stated, the sizes, positions, etc., of components, features, elements, etc., as well as any distances therebetween, in the drawings are not necessarily to scale, and may be disproportionate and/or exaggerated for clarity.

Thus, the same or similar numbers may be described with reference to other drawings even if they are neither mentioned nor described in the corresponding drawing. Also, even elements that are not denoted by reference numbers may be described with reference to other drawings. Additionally, the drawings may include non-essential elements that are included only for the sake of thoroughness. These non-essential elements may be removed entirely or left only in outline form if drawing changes are desired to create greater clarity.

<FIG> is an orthogonal view of an example of a closed-bottom pallet (also called a closed pallet) <NUM> that is commonly used in the UK, USA, and Australia. The closed pallet <NUM> has one or more base boards <NUM> that contact a supporting surface <NUM>, such as the floor. The base boards <NUM> provide the foundation for spacers <NUM> that support one or more upper planks <NUM> that support a load.

<FIG> is a top schematic view of a prior pallet truck <NUM>, which is an example of a forked material-handling vehicle. Pallet trucks <NUM>, such as pedestrian pallet trucks (PPT) or rider pallet trucks (RPT), are often employed to handle pallets that are on the ground or on another horizontal surface, for example, when loading or unloading from a transport vehicle, such as a truck or shipping container. Pallet trucks <NUM> typically include a chassis <NUM> that supports or is attached to a battery box <NUM>. The chassis <NUM> or the battery box <NUM> is connected to a pair of forks <NUM>, each fork <NUM> having an elongate body <NUM>, a forward load wheel <NUM>, a rear load wheel <NUM>, and a tip <NUM>. The forward load wheel <NUM> and the rear load wheel <NUM> can be collectively referred to as load wheels <NUM>.

<FIG> is an isometric view of a load wheel unit <NUM> of a prior art pallet truck <NUM>. <FIG> are a series of side elevation views showing a progression of a fork <NUM> approaching a closed-bottom pallet <NUM> in a forward direction <NUM>, encountering the base board <NUM> of the closed-bottom pallet <NUM>, negotiating the base board <NUM> of the closed-bottom pallet <NUM>, and deploying a load wheel extension mechanism to lift the closed-bottom pallet <NUM> off of a supporting surface <NUM>. With reference to <FIG> and <FIG>, when engaging or disengaging closed pallets <NUM>, the forward load wheel <NUM> and the rear load wheel <NUM> of the pallet truck <NUM> cross over the top of the base boards <NUM> of the closed pallet <NUM> to enter and exit pallet pockets <NUM>. When a closed pallet <NUM> is empty, or has a light-weight palletized load (commonly meaning bearing a load of <NUM> or less), the forward load wheel <NUM> of the pallet truck <NUM> may lock upon contact with the closed pallet <NUM> and stop rotation instead of riding over the base boards <NUM> and into the pallet pockets <NUM> of the closed pallet <NUM>. However, the rear load wheel <NUM> may continue to rotate so that the closed pallet <NUM> may be shunted or pushed horizontally across the surface <NUM>. Similarly, the rear load wheel <NUM> may lock while the forward load wheel continues to roll during attempts to exit the pallet pockets <NUM>. Such shunting is undesirable because it can damage the base board <NUM> and/or the surface <NUM> on which the closed pallet <NUM> sits and may move the pallet <NUM> to an undesired location. Also, failure to enter the pallet <NUM> prevents the pallet <NUM> from being retrieved, and failure to exit an empty pallet <NUM> renders the truck <NUM> useless with a pallet <NUM> trapped on the forks <NUM> until the pallet <NUM> is removed.

One approach that increases the success ratio of pallet engagement and disengagement involves offsetting the forward load wheels <NUM> of the different forks <NUM> along a longitudinal axis <NUM> of the pallet truck <NUM>. <FIG> is a top schematic view of a pallet truck 40a having offset forward load wheels <NUM>. This approach permits the forward load wheels <NUM> on the different forks <NUM> to encounter base boards <NUM> sequentially, rather than simultaneously as would happen with a straight-in approach using non-offset forward load wheels <NUM>. Such sequential engagement between the forward load wheels <NUM> exerts less horizontal force on the base boards <NUM> compared to both forward load wheels <NUM> encountering the base board <NUM> simultaneously. This approach is disclosed in detail in <CIT>, entitled "Offset Load Rollers for a Pallet Truck". In one example, the tips <NUM> of the two forks <NUM> may be offset and the forward load wheels <NUM> may be about the same distances from distal tip ends <NUM> of the tips <NUM>. In another example, the forks <NUM> may have the same length (or different lengths) and the forward load wheels <NUM> may have different distances from the from distal tip ends <NUM> of the tips <NUM>. Despite these improvements, attempts at entry into, or exit from, pallet pockets <NUM> of closed pallets <NUM> that are empty, or have a light-weight palletized load, are only about <NUM>% successful.

This disclosure teaches additional or alternative means to increase the entry and exit potential with respect to pallet pockets <NUM> of closed pallets <NUM> that are empty or have a light-weight palletized load. For example, torque between the rear load wheel <NUM> and the forward load wheel <NUM> can be coupled so that if either of the rear load wheel <NUM> or the forward load wheel <NUM> meet resistance at a base board <NUM>, then rotation of the other of the load wheels <NUM> will increase the ability of the inhibited load wheel <NUM> to move over the base board <NUM>. In particular, if the forward load wheel <NUM> meets resistance when encountering the base board <NUM> while attempting to enter a pocket <NUM>, then the continuous rotation of the rear load wheel <NUM> if a forward direction (caused by friction against the ground due to movement of the pallet truck <NUM>) will cause rotation of the forward load wheel <NUM> if the torque is coupled between the load wheels <NUM>. Similarly, if the rear load wheel <NUM> meets resistance when encountering a base board <NUM> while attempting to exit a pocket <NUM>, then the continuous rotation of the forward load wheel <NUM> (in a reverse direction) will cause rotation of the rear load wheel <NUM> if the torque is coupled between the load wheels <NUM>.

<FIG> is a top plan view of a load wheel assembly <NUM> employing an embodiment of a torque-coupling assembly <NUM>, and <FIG> is a side elevation view of the load wheel assembly <NUM> of <FIG> with one of two wheel carrier struts <NUM> and a portion of a wheel-carrier bracket <NUM> removed for clarity. A torque coupler or torque-coupling assembly <NUM> can be implemented in many ways. One will appreciate that a torque-coupling assembly <NUM> can be implemented as any torque coupler known in the art, as well as any of the torque-coupling means for coupling torque described herein.

With reference to <FIG>, the load wheel assembly <NUM> may include one or more wheel-carrier brackets <NUM> that operatively connect one or more of the load wheels <NUM> to the fork <NUM>. The wheel-carrier bracket <NUM> may include one or more fork attachment pivot holes <NUM> or 88a that can be used to attach the wheel-carrier bracket <NUM> to the fork <NUM>. The fork attachment pivot holes <NUM> may be positioned toward a proximal end of the wheel-carrier bracket <NUM> on separate bracket arms <NUM> connected by a bracket cross bar <NUM>. The wheel-carrier struts <NUM> may extend forward from the bracket cross bar <NUM> on separate sides of the load wheels <NUM>. In some embodiments, each wheel-carrier strut <NUM> may include an axle mount hole <NUM> (or other mounting means) adapted to receive a carrier axle <NUM> (with or without bushings <NUM>, see <FIG>) of a wheel carrier <NUM> to facilitate rotatable connection between the wheel-carrier struts <NUM> and the wheel carriers <NUM>. The wheel carriers <NUM> are also connected to a forward axle <NUM> and a rear axle <NUM> to permit rotation of the respective forward load wheel <NUM> and the rear load wheel <NUM>. For purposes of discussion, the wheel carrier <NUM>, the forward load wheel <NUM>, the rear load wheel <NUM>, the forward axle <NUM>, the rear axle <NUM>, and the torque-coupling assembly <NUM> can be grouped together as a load wheel unit <NUM>.

Forks <NUM> tend to have a limited height dimension that is typically shorter than a spacer height <NUM> of the closed-bottom pallet <NUM> so that the forks <NUM> and their respective load wheel assemblies <NUM> can easily fit between the base boards <NUM> and the upper planks <NUM>. The spacer height <NUM> may be slightly shorter than a pallet gap height <NUM> between the base boards <NUM> and the upper planks <NUM>. Accordingly, the forward load wheel <NUM> has a forward wheel radius <NUM> that may be less than half the spacer height <NUM> or less than half the pallet gap height <NUM>. Similarly, the rear load wheel <NUM> has a rear wheel radius <NUM> that may be less than half the spacer height <NUM> or less than half the pallet gap height <NUM>. Additionally, the forward load wheel <NUM> has a forward wheel height <NUM> above the supporting surface <NUM> that may be shorter than the spacer height <NUM> or the pallet gap height <NUM>. Similarly, the rear load wheel <NUM> has a rear wheel height <NUM> above the supporting surface <NUM> that may be shorter than the spacer height <NUM> or the pallet gap height <NUM>.

One will appreciate that the operative connection of the load wheels <NUM> to the fork can be implemented in a variety of alternative ways. For example, <FIG> show one embodiment for connecting the load wheels <NUM> to the fork and are described later.

Neither the forward load wheel <NUM> nor the rear load wheel <NUM> is connected directly or indirectly to a motor, i.e., the load wheels <NUM> are non-motorized or unmotorized. More specifically, there is no mechanical linkage from a drive motor that causes rotation of the load wheels <NUM>. Moreover, rotation of the load wheels <NUM> is caused by movement of the pallet truck <NUM> and contact of at least the forward load wheel <NUM> or the rear load wheel <NUM> with the supporting surface <NUM>.

The torque-coupling assembly <NUM> shown in <FIG> employs an idler wheel <NUM> (also called a coupling wheel) that may rotate about an idler axle <NUM> and that has an idler wheel surface <NUM> (also called a coupling wheel surface) that directly contacts both the forward load wheel <NUM> and the rear load wheel <NUM>. The idler wheel <NUM> may utilize a tire that can have a pneumatic or a solid core, such as used in any conventional tire. The surface <NUM> of the idler wheel <NUM> and/or the core of the idler wheel <NUM> can be made from the same or different materials. In some embodiments, the surface <NUM> and/or the core of the idler wheel <NUM> can be made from a polymer, such as polyurethane. In other embodiments, the surface <NUM> and/or the core of the idler wheel <NUM> can be made from a metal, such as aluminum or steel. In some embodiments, the surface <NUM> of the idler wheel <NUM> may employ a non-smooth texture.

The idler wheel <NUM> may have a small idler wheel diameter <NUM> so as to provide some clearance with an upper wall interior surface of the fork <NUM>. In particular, the idler wheel diameter <NUM> may be shorter than or equal to the forward wheel radius <NUM> and/or the rear wheel radius <NUM>. Moreover, the idler wheel <NUM> has an idler wheel height <NUM> above the supporting surface <NUM> that may be higher than or equal to the forward wheel height <NUM> or the rear wheel height <NUM>, or the idler wheel height <NUM> may be shorter than or equal to the forward wheel height <NUM> or the rear wheel height <NUM>. In some embodiments, the idler wheel height <NUM> may be within <NUM>% of the forward wheel height <NUM> or the rear wheel height <NUM>.

The amount of torque transferred by the torque-coupling assembly <NUM> is highly variable depending on materials used, surface finishes, and contamination from the environment. A suitable range for torque transfer may be from about <NUM> to <NUM> Newton meters (Nm) or may be from about <NUM> to <NUM> Newton meters (Nm). Generally, the amount of torque transferred by the torque-coupling assembly <NUM> is greater than or equal to <NUM>. One will appreciate, however, that the amount torque transferred may be less than <NUM>. One will also appreciate that the amount torque transferred may be greater than <NUM>.

This torque-coupling assembly <NUM> also employs one or more or force-applying coupling assemblies or force-applying couplers <NUM>. A force-applying coupler or force-applying coupling assembly <NUM> can be implemented in many ways. One will appreciate that a force-applying coupling assembly <NUM> can be implemented as any force-applying coupling assembly known in the art, as well as any of the force-applying coupling means for coupling force described herein. In many embodiments, such as any of the force-applying coupling assemblies <NUM> (with or without an additional letter designation), the force-applying coupling assembly <NUM> may fall into the subcategory of a resilient force-applying coupling assembly (or resilient force-applying coupler).

The force-applying coupler <NUM> shown in <FIG> also constitutes a resilient force-applying coupler <NUM>, employing a torsion spring <NUM>. The torsion spring <NUM> can have a single loop <NUM> or can have a helical component. The torsion spring <NUM> may include an idler arm <NUM> that is directly or indirectly connected to the idler wheel <NUM> such as to the idler axle <NUM>. The torsion spring <NUM> may also include a carrier arm <NUM> that is directly or indirectly connected to the wheel carrier <NUM>, such to its carrier axle <NUM>. In some embodiments, the idler arms <NUM> may have auxiliary projections <NUM> that insert into the idler axle <NUM> of the idler wheel <NUM> or that function as the axle <NUM> of the idler wheel <NUM>. In some embodiments, the idler arms <NUM> may slide through an axle slot <NUM> in an idler axle 120b of an idler wheel 116b as shown in <FIG>. The slot <NUM> may prevent rotation of the idler axle <NUM> in embodiments in which the idler wheel <NUM> constitutes a roller with bearings over the idler axle <NUM>.

In the embodiment shown in <FIG>, the loop <NUM> of the torsion spring <NUM> is positioned around the rear axle <NUM> and the idler arm <NUM> crosses carrier arm <NUM> to provide force (such as tension) to hold the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. One will appreciate however that the loop <NUM> of the torsion spring <NUM> could be positioned about the forward axle <NUM> instead of the rear axle <NUM>. Or, the loops of two torsion springs <NUM> could be positioned about both the forward axle <NUM> and the rear axle <NUM> to provide additional force (and/or a backup coupling) if desired. If torsion springs <NUM> are positioned on both sides (left and right) of the load wheels <NUM> and <NUM>, then the loops <NUM> of both torsion springs <NUM> may be positioned about the same axle. In some embodiments, however, the loops <NUM> may be positioned about different axles. One will also appreciate that the force-applying coupling assembly <NUM>, and more specifically the loops <NUM> of the torsion springs <NUM>, can alternatively be positioned outside the wheel carrier <NUM>, i.e. between the wheel carrier <NUM> and the strut <NUM>, on an extension of the forward axle <NUM> or the rear axle <NUM>. Such an axle extension could include a larger diameter rim to prevent the loop <NUM> from coming off the axle extension.

One advantage of employing a force-applying coupler <NUM> is that it can be adapted to apply enough force to couple the torque between the forward load wheel <NUM> and the rear load wheel <NUM> (e.g., ensure that there is sufficient friction between the forward load wheel <NUM> and the rear load wheel <NUM>), and at the same time not create unnecessary drag on the movement of the forward load wheel <NUM> and the rear load wheel <NUM>. Suitable force provided by the cumulative force-applying couplers <NUM> acting on the forward load wheel <NUM> and the rear load wheel <NUM> may be in the range of about <NUM> to <NUM> Newtons, or the force may be in the range of about <NUM> to <NUM> Newtons. Generally, the cumulative coupling force may be greater than or equal to about <NUM> Newtons. One will appreciate that the cumulative coupling force may be less than <NUM> Newtons. One will also appreciate that the cumulative coupling force may be greater than <NUM> Newtons. Additionally, one will appreciate that this cumulative force can be divided by the total number of springs in the total number of force-applying couplers <NUM> that are employed in any given torque-coupling assembly <NUM> to determine a desirable amount of force per force-applying coupler <NUM>.

One will also appreciate that the force coupling (or resilient force coupling) of the idler wheel <NUM> to the load wheels <NUM> can be implemented in a variety of other ways. For example, <FIG> is a top plan view of a load wheel assembly 82a employing an alternative embodiment of a torque-coupling assembly 80a, and <FIG> is a side elevation view of the load wheel assembly 82a of <FIG> with one of the wheel-carrier struts <NUM> and a portion of the wheel-carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80a may employ an alternative force-applying coupler (or resilient force applying coupler) 122a that includes an alternative to the torsion spring <NUM> in the form of a spring plate or leaf spring 124a. The leaf spring 124a may include spring end tabs <NUM> that extend from a central curved portion <NUM> of the leaf spring 124a. The leaf spring 124a may be connected to optional bosses or ridges <NUM> of an alternative wheel carrier 96a by any suitable attachment means such as carrier bolts (or screws) <NUM>. The idler wheel <NUM> may have a smaller idler wheel height <NUM> adapted to accommodate a downward curve of the leaf spring 124a that can provide force against the idler axle <NUM> so that the leaf spring 124a urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. <FIG> shows a side elevation view of a leaf spring 124a of <FIG> in one example of a relaxed shape when the leaf spring 124a is not yet deployed over the idler axle <NUM> and connected to the wheel carrier <NUM>.

<FIG> is a top plan view of a load wheel assembly 82b employing another alternative embodiment of a torque-coupling assembly 80b, <FIG> is a side elevation view of the load wheel assembly 82b of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity, and <FIG> is a side elevation view of an idler wheel 116b of the torque-coupling assembly 80b. The alternative torque-coupling assembly 80b may employ an alternative force-applying coupler (or resilient force-applying coupler) 122b that includes an alternative spring 124b in the form of an inverted leaf spring or spring plate. The spring 124b may be held by spring brackets <NUM> that form pockets <NUM> on an alternative wheel carrier 96b at a position above or near the forward axle <NUM> and the rear axle <NUM>, or the spring 124b may be connected to the wheel carrier 96b by any suitable attachment means such as carrier bolts (or screws).

The spring 124b may slide through an axle slot <NUM> in an idler axle 120b of the idler wheel 116b torque-coupling assembly 80b as shown in <FIG>, to provide force against the idler axle 120b so that the leaf spring urges the idler wheel 116b against the forward load wheel <NUM> and the rear load wheel <NUM>. As previously noted, the slot <NUM> may prevent rotation of the idler axle 120b in embodiments in which the idler wheel 116b constitutes a roller with bearings over the idler axle 120b. Alternatively, the spring 124b may be positioned (not shown) above the idler axle 120b to provide downward force against the idler axle 120b so that the leaf spring urges the idler wheel 116b against the forward load wheel <NUM> and the rear load wheel <NUM>. The idler wheel 116b may have an idler wheel height 118b adapted to accommodate the curve of the leaf spring (or the curve of the leaf spring may be adapted to idler wheel height 118b) to provide force against the idler axle 120b so that the leaf spring urges the idler wheel 116b against the forward load wheel <NUM> and the rear load wheel <NUM>. Although not shown, bolts <NUM>, screws, pins, or other fasteners can be employed to secure the spring 124b to the spring brackets <NUM> from above the spring brackets <NUM> into holes or slots toward the ends of the springs 124b.

<FIG> is a top plan view of a load wheel assembly 82c employing another alternative embodiment of a torque-coupling assembly 80c, and <FIG> is a side elevation view of the load wheel assembly 82c of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80c may employ an alternative force-applying coupler (or resilient force-applying coupler) 122c that includes a spring clip 124c generally in the form of a "U"-shaped clip, having a lower segment <NUM>, a bend <NUM>, and an upper segment <NUM>. The lower segment <NUM> of the spring clip 124c may be a wire or a strip. The lower segment <NUM> of the spring clip 124c may be connected to a hole (not shown) on the top <NUM> of the wheel carrier 96c at a position above or near the forward axle <NUM> and the rear axle <NUM> by any suitable attachment means such as one or more carrier bolts <NUM> (or screws).

The upper segment <NUM> of the spring clip 124c may constitute a pre-loaded spring that is positioned (as shown in <FIG>) above the idler axle <NUM> to provide downward force against the idler axle <NUM> so that the spring clip 124c urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. Alternatively, the upper segment <NUM> may slide through an axle slot (not shown, but such as in <FIG>) in an idler axle <NUM> of the idler wheel <NUM> of the torque-coupling assembly 80c to provide force against the idler axle <NUM> so that the spring clip 124c urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. As noted previously, such a slot <NUM> may prevent rotation of the idler axle <NUM> in embodiments in which the idler wheel <NUM> constitutes a roller with bearings over the idler axle <NUM>.

The idler wheel <NUM> may have an idler wheel height 118c adapted to accommodate the curve and upper segment of the spring clip 124c (or the curve of the spring clip 124c may be adapted to idler wheel height 118c) to provide force against the idler axle <NUM> so that the spring clip 124c urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. One will appreciate that the bolt <NUM> may be positioned closer to either the forward axle <NUM> or the rear axle <NUM> with the bend <NUM> positioned closer to the opposite axle. When the spring clips 124c are positioned at both sides of the idler wheel <NUM>, the bends <NUM> can be facing the same direction or different directions. <FIG> shows a side elevation view of the spring clip 124c of <FIG> in one example of a relaxed shape when the spring clip 124c is not yet deployed about the ends <NUM> and <NUM> of the wheel carrier <NUM>.

<FIG> is a top plan view of a load wheel assembly 82d employing another alternative embodiment of a torque-coupling assembly 80d, and <FIG> is a side elevation view of the load wheel assembly 82d of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80d may employ an alternative force-applying coupler (or resilient force-applying coupler) 122d that includes a tension clip 124d generally in the form of a "frog"-shaped clip, having a rounded upper back segment <NUM>, two upper thigh segments <NUM>, and a knee bend <NUM>, two lower leg segments <NUM>, and two foot segments <NUM>.

The rounded upper back segment <NUM> of the tension clip 124d may be positioned (as shown in <FIG>) above the idler axle <NUM> to provide downward tension against the idler axle <NUM> so that the tension clip 124d urges the idler wheel 116c against the forward load wheel <NUM> and the rear load wheel <NUM>. Alternatively, the rounded upper back segment <NUM> may slide through an axle slot (not shown, but such as shown in <FIG>) in an idler axle <NUM> of the idler wheel <NUM> of the torque-coupling assembly 80d to provide tension against the idler axle <NUM> so that the tension clip 124d urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. As noted previously, such a slot <NUM> may prevent rotation of the idler axle <NUM> in embodiments in which the idler wheel <NUM> constitutes a roller with bearings over the idler axle <NUM>. The upper back segment may be flat instead of rounded and may have a length that is longer than the diameter of the idler axle <NUM> to allow some float of the idler wheel <NUM> in connection with its contact to the forward load wheel <NUM> and the rear load wheel <NUM>.

The upper back segment <NUM> may adjoin an upper thigh segment <NUM> on each side that each reach an outward knee bend <NUM> that may be above and near the forward end <NUM> and the rear end <NUM> of the wheel carrier <NUM>. From the knee bends <NUM>, lower leg segments <NUM> project toward the wheel carrier <NUM> and are attached to foot segments <NUM> that at least partly wrap around and tensionally engage the ends <NUM> and <NUM>. The tension clip 124d can be slipped onto the wheel carrier <NUM> without any additional fastener; however, the foot segments <NUM> or other parts of the tension clip 124d could be connected to the wheel carrier <NUM> by bolts or other fasteners. <FIG> shows a side elevation view of the tension clip 124d of <FIG> in one example of a relaxed shape when the tension clip 124d is not yet deployed about the ends <NUM> and <NUM> of the wheel carrier <NUM>.

<FIG> is a top plan view of a load wheel assembly 82e employing another alternative embodiment of a torque-coupling assembly 80e, and <FIG> is a side elevation view of the load wheel assembly 82e of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80e may employ an alternative force-applying coupler (or resilient force-applying coupler) 122e that includes a tension plate <NUM>, compression springs <NUM> and shoulder bolts <NUM>. The tension plate <NUM> may have a straight upper back segment <NUM> between two bends <NUM> for vertical strut segments <NUM>, which may terminate in plate tabs <NUM> that may be parallel (as shown) or angled (not shown) with respect to the top of an alternative wheel carrier 96e. The shoulder bolts <NUM> may extend through slots or holes (not shown) in the plate tabs <NUM> and be connected by a threaded portion (not shown) to threaded holes (not shown) in a surface at the top <NUM> of the wheel carrier 96e. The compression springs <NUM> may be positioned around shanks of the shoulder bolts <NUM> between bolt heads <NUM> and the plate tabs <NUM> to press the plate tabs toward the top <NUM> of the wheel carrier 96e. The pressure of the compression springs <NUM> against the plate tabs <NUM> causes the tension plate <NUM> against the idler axle <NUM>, which causes the idler wheel <NUM> to press against the forward load wheel <NUM> and the rear load wheel <NUM>. One or more of the length of the shoulder bolts <NUM>, the strength of the compression springs <NUM>, the diameter <NUM> of the idler wheel <NUM>, and the diameter of the idler axle <NUM> can be adjusted to determine the idler wheel height 118e.

In an alternative embodiment, the upper back segment <NUM> may slide through an axle slot (not shown, but such as shown in <FIG>) in an idler axle <NUM> of the idler wheel <NUM> of the torque-coupling assembly 80e to provide tension against the idler axle <NUM> so that the force-applying coupler 122e urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. As noted previously, such a slot <NUM> may prevent rotation of the idler axle <NUM> in embodiments in which the idler wheel <NUM> constitutes a roller with bearings over the idler axle <NUM>.

<FIG> is a top plan view of a load wheel assembly 82f employing another alternative embodiment of a torque-coupling assembly 80f, and <FIG> is a side elevation view of the load wheel assembly 82f of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80f employs both top and bottom idler wheels <NUM> that may be identical or different. Differences might include one or more of idler wheel diameter <NUM>, idler axle diameter, and idler wheel surface textures, and idler wheel compositions, etc. One will appreciate that the torque-coupling assembly 80f is adapted so that the bottom of the bottom idler wheel <NUM> is at or above the bottom of the forward load wheel <NUM> and the rear load wheel <NUM>. In many embodiments, the idler wheel diameter <NUM> and/or the spacing between the forward load wheel <NUM> and the rear load wheel <NUM> can be adjusted to determine the height of the bottom of the bottom idler wheel <NUM> from the supporting surface <NUM>. The spacing might be partly controlled by the strength of an alternative force-applying coupler (or resilient force-applying coupler) 122f.

The alternative force-applying coupler 122f of the alternative torque-coupling assembly 8of may employ a tension spring 124f that tensions both the top and bottom idler wheels <NUM> against the upper surfaces <NUM> and lower surfaces <NUM> of the load wheels <NUM> and <NUM>. The tension spring 124f may include axle loops <NUM> that partly or completely circle the idler axles <NUM> of the top and bottom idler wheels <NUM>. The tension spring 124f also includes a spring section <NUM> that connects the axle loops <NUM> to tension the idler axles <NUM> of the top and bottom idler wheels <NUM> toward each other. This tension urges the top and bottom idler wheels <NUM> to contact the respective upper surfaces <NUM> and lower surfaces <NUM> of the load wheels <NUM> and <NUM> and couple the torque of the forward load wheel <NUM> and the rear load wheel <NUM>. One or more of the strength of the spring section <NUM>, the diameter <NUM> of the idler wheel <NUM>, and the diameter of the idler axle <NUM> can be adjusted to determine the relative elevation of the idler wheel surfaces with respect to the surfaces of the forward load wheel <NUM> and the rear load wheel <NUM>.

<FIG> is a top plan view of a load wheel assembly <NUM> employing another alternative embodiment of a torque-coupling assembly <NUM>, and <FIG> is a side elevation view of the load wheel assembly <NUM> of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly <NUM> may employs a pair of top and bottom idler wheels assemblies <NUM> that may be identical or different. Differences might include one or more of idler wheel width, idler wheel diameter <NUM>, idler axle diameter, and idler wheel surface textures, etc..

Each idler wheel assembly <NUM> includes multiple idler wheels 116a, such as two idler wheels 116a, connected by a central axle block <NUM>. A top idler wheel assembly <NUM> of the alternative torque-coupling assembly <NUM> might include idler wheels 116a1 and 116a<NUM> having respective idler axles 120a<NUM> and 120a<NUM> that are connected by a central axle block <NUM>, and a bottom idler wheel assembly <NUM><NUM> of the alternative torque-coupling assembly <NUM> might include a first bottom idler wheel (not shown) and a second bottom idler wheel 116b<NUM> having a respective first bottom idler axle (not shown) and a second bottom axle 120a<NUM> that are connected by a central axle block <NUM><NUM>.

An alternative force-applying coupler (or resilient force-applying coupler) <NUM> of the alternative torque-coupling assembly <NUM> may employ a tension bolt <NUM> with top and bottom compressions springs <NUM><NUM> and <NUM><NUM> (collectively compression springs <NUM>). The tension bolt <NUM> extends between the forward load wheel <NUM> and the rear load wheel <NUM> and through the central axle blocks <NUM><NUM> and <NUM><NUM>. The compression springs <NUM> may be positioned around the shank of the tension bolt <NUM> between bolt heads <NUM><NUM> and <NUM><NUM> and the respective proximal surfaces of the central axle blocks <NUM><NUM> and <NUM><NUM> to press them toward each other.

The pressure of the compression springs <NUM> against the central axle blocks <NUM><NUM> urges the idler axles 120a<NUM> and 120b<NUM> toward each other (and idler axle 120a<NUM> toward the other bottom idler axle (not shown)), which causes the idler wheel 116a<NUM> (and idler wheel 116a<NUM>) to press against the upper surfaces <NUM> of the forward load wheel <NUM> and the rear load wheel <NUM> and causes the idler wheel 116b<NUM> (and the other lower idler wheel (not shown)) to press against the lower surfaces <NUM> of the forward load wheel <NUM> and the rear load wheel <NUM>, thereby coupling the torque of the forward load wheel <NUM> and the rear load wheel <NUM>. One or more of the strength of the compression springs <NUM>, the diameter <NUM> of the idler wheels <NUM>, and the diameter of the idler axles <NUM> can be adjusted to determine the relative elevation of the top and bottom idler wheel surfaces with respect to the respective top and bottom surfaces of the forward load wheel <NUM> and the rear load wheel <NUM>. One will appreciate that the torque-coupling assembly <NUM> can be adapted so that the bottom of the bottom idler wheel 116a<NUM> is at or above the bottom of the forward load wheel <NUM> and the rear load wheel <NUM>.

<FIG> is a top plan view of a load wheel assembly <NUM> employing another alternative embodiment of a torque-coupling assembly <NUM> with alternative force-applying coupler (or resilient force-applying coupler) <NUM> positioned outside the wheel carrier <NUM>, and <FIG> is a side elevation view of the load wheel assembly <NUM> of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. <FIG> is a top plan view of a load wheel assembly <NUM> employing alternative embodiment of a torque-coupling assembly <NUM> with a force-applying coupler positioned inside the wheel carrier <NUM>, and <FIG> is a side elevation view of the load wheel assembly <NUM> of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly <NUM> employs top and bottom idler wheels <NUM> that may be identical or different. Differences might include one or more of idler wheel diameter <NUM>, idler axle diameter, and idler wheel surface textures, etc..

The alternative force-applying coupler <NUM> may employ a torsion spring <NUM> that forces both the top and bottom idler wheels <NUM> against the upper surfaces <NUM> and lower surfaces <NUM> of the load wheels <NUM> and <NUM>. The torsion spring <NUM> may include one or more axle loops <NUM> (a single loop or a helical component) that circle the one of the forward axle <NUM> of the forward load wheel <NUM> or the rear axle <NUM> of the rear load wheel <NUM>.

In the embodiment shown in <FIG>, the load wheel axle <NUM> or <NUM> or an extension of it, about which the torsion spring <NUM> is deployed, may extend out further beyond the wheel carrier <NUM> to provide greater support for the loop <NUM> of the torsion spring <NUM>. Such elongated load wheel axle <NUM> or <NUM> may extend to, or almost to, the wheel carrier <NUM> to prevent the torsion spring <NUM> from sliding off the load wheel axle <NUM> or <NUM>. In the embodiment shown in <FIG>, the torsion spring <NUM> is positioned between the wheel carrier <NUM> and the load wheel <NUM> (or <NUM>) so the loop <NUM> of the torsion spring <NUM> cannot slide off of the load wheel axle <NUM> (or <NUM>).

The torsion spring <NUM> may include two idler arms <NUM> that cross each other and are directly or indirectly connected to the separate idler wheels <NUM>, such as to axles (not shown) of the idler wheels <NUM>. Alternatively, the idler arms <NUM> may have auxiliary projections <NUM> that insert into the axles of the idler wheels <NUM> or that function as the axles of the idler wheels <NUM>. In an alternative embodiment, the idler arms <NUM> may slide through an axle slot (not shown, but such as shown in <FIG>) in an idler axle (not shown, but such as shown in <FIG>) of the idler wheel <NUM> of the torque-coupling assembly <NUM> to provide force against the idler axle so that the force-applying coupler <NUM> urges the idler wheel <NUM> against the forward load wheel <NUM> and the rear load wheel <NUM>. As noted previously, such a slot <NUM> may prevent rotation of the idler axle <NUM> in embodiments in which the idler wheel <NUM> constitutes a roller with bearings over the idler axle <NUM>.

Typically, the torque-coupling assembly <NUM> employs a torsion spring <NUM> on each side of the wheel carrier <NUM>. The torsion springs <NUM> can be employed around opposite sides of the same load wheel axle, or a first torsion spring <NUM> can be employed around the rear axle <NUM> one side of the wheel carrier <NUM> while a second torsion spring <NUM> can be employed around the forward axle <NUM> on the other side of the wheel carrier <NUM>. One will appreciate that torsion springs <NUM> can be deployed around both the forward and rear axles <NUM> and <NUM> on both sides of the wheel carrier <NUM>.

The torsion springs <NUM> urge the top and bottom idler wheels <NUM> toward each other so that they contact the respective the upper surfaces <NUM> and lower surfaces <NUM> of the load wheels <NUM> and <NUM> and couple the torque of the forward load wheel <NUM> and the rear load wheel <NUM>. The strength of the torsion spring <NUM> and/or the diameter <NUM> of the idler wheel <NUM> can be adjusted to determine the relative elevation of the idler wheel surfaces with respect to the surfaces of the forward load wheel <NUM> and the rear load wheel <NUM>. One will appreciate that the torque-coupling assembly <NUM> can be adapted so that the bottom of the bottom idler wheel <NUM> is at or above the bottom of the forward load wheel <NUM> and the rear load wheel <NUM>.

<FIG> is a top plan view of a load wheel assembly 82i employing another alternative embodiment of a torque-coupling assembly 80i, and <FIG> is a side elevation view of the load wheel assembly 82i of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80i employs an idler gear wheel 116i connected through bearings <NUM> to the wheel carrier <NUM>. Alternatively, the torque-coupling assembly 80i employs idler gear wheels 116i connected through bearings <NUM> on opposite sides of the wheel carrier <NUM> and that may be identical or different. Differences might include the idler wheel gear diameter. Each idler gear wheel 116i interacts with one or more gears <NUM> that are fixed to the forward load wheel <NUM> and the rear load wheel <NUM> to transfer torque between them. Load wheel motion arrows <NUM> show the direction of rotation of the load wheels (and idler wheel motion arrow <NUM> shows the direction of motion of the idler gear wheel 116i) when the wheel carrier <NUM> moves backward. These arrows would be reversed when the wheel carrier <NUM> moves in the forward direction.

<FIG> is a top plan view of a load wheel assembly 82j employing another alternative embodiment of a torque-coupling assembly 80j, and <FIG> is a side elevation view of the load wheel assembly 82j of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly 80j employs a "raceway" <NUM> connected to the wheel carrier <NUM>. Alternatively, the torque-coupling assembly 80j employs raceways <NUM>, which may be identical or different, connected on opposite sides of the wheel carrier <NUM>. Each raceway <NUM> interacts with one or more gears 192j that may be fixed to the forward load wheel <NUM> and the rear load wheel <NUM> to transfer torque between them.

This embodiment is based on the recirculating ball concept (also known as worm and sector or recirculating ball and nut), such as commonly used in steering systems and ball screws. However, in this embodiment, no screw is involved. The ball bearings are simply used to form the torque transfer device using a formed gear to push the balls along a raceway to the driven gear. The pushing force provides the torque transfer.

<FIG> is a top plan view of a load wheel assembly <NUM> employing another alternative embodiment of a torque-coupling assembly <NUM>, and <FIG> is a side elevation view of the load wheel assembly <NUM> of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly <NUM> employs an idler wheel <NUM> that has an idler wheel axle <NUM> that is aligned with the carrier axle <NUM>. Moreover, the carrier axle <NUM> and the idler wheel axle <NUM> may be a single component. One or both of the forward load wheel <NUM> and the rear load wheel <NUM> can be a smaller size than in the other embodiments, or the forward load wheel <NUM> and the rear load wheel <NUM> can be spaced further apart than in other embodiments to accommodate the diameter <NUM> of the idler wheel <NUM>. The diameter <NUM> of the idler wheel <NUM> and the material of the idler wheel <NUM> can be adapted to couple torque between the forward load wheel <NUM> and the rear load wheel <NUM>. For example, the material of the idler wheel <NUM> may comprise an elastic material such as neoprene, polyurethane or Santoprene™ and may include longitudinal apertures <NUM> that facilitate the idler wheel <NUM> compressing when contacted by the surfaces of the load wheels <NUM>. The stiffness of the material for the idler wheel <NUM> and the size and shape of the apertures <NUM> may be designed to increase or decrease the amount of pressure exerted by the idler wheel <NUM> on the forward load wheel <NUM> and the rear load wheel <NUM>.

<FIG> is a top plan view of a load wheel assembly <NUM> employing another alternative embodiment of a torque-coupling assembly <NUM>, and <FIG> is a side elevation view of the load wheel assembly <NUM> of <FIG> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. The alternative torque-coupling assembly <NUM> employs one or more toothed belts <NUM> that may be on only one side of the wheel carrier <NUM> or on opposite sides of the wheel carrier <NUM>. Each toothed belt <NUM> interacts with one or more gears or pulleys <NUM> that may be fixed to the forward load wheel <NUM> and the rear load wheel <NUM> to transfer torque between them.

<FIG> is a top plan view of a load wheel assembly 82n that is similar to that shown in <FIG> but additionally comprising a lead-in roller <NUM> in the form of a paddle wheel having multiple paddles <NUM>. <FIG> is a first side elevation view of the load wheel assembly <NUM> with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity, and <FIG> is a second side elevation view of the load wheel assembly 82n with a wheel carrier strut <NUM> and a portion of a wheel carrier bracket <NUM> removed for clarity. <FIG> are views from opposite sides of the load wheel assembly 82n.

The lead-in roller <NUM> is shown in the form of a paddle wheel having paddles <NUM>; however, any type of wheel can be employed. By way of illustration and not limitation, the lead-in roller <NUM> may have, instead of paddles <NUM>, other features on its surface, such ridges, bumps, or other surface texture to enable it to grip and climb over an obstacle, such as a base board <NUM>, on the floor, rather than push it horizontally. As another example, the lead-in roller <NUM> may have a tacky outer surface, such as a rubber tire; alternatively, the entire lead-in roller may be made from a solid tacky material, such as rubber, a rubber-based compound, or a rubber-like material. The effective diameter of the lead-in roller <NUM> may be different from that of the load wheels <NUM>. For example, the effective diameter of the lead-in roller <NUM> may be less than or equal to that of the load wheels <NUM>, as the lead-in roller is preferably not load bearing like the load wheels <NUM>; instead, the lead-in roller <NUM> is preferably meant to climb over an obstacle, such as a base board <NUM>, on the floor but otherwise not contact a flat floor. To that end, the lead-in roller may have the same or different (larger or smaller) diameter as the load wheels <NUM> but positioned upward in a horizontally biased position relative to the load wheels <NUM>. That may be accomplished, for example, by having bent wheel carriers <NUM> (e.g., right end up in <FIG>, left end up in <FIG>), instead of the straight ones illustrated in <FIG>.

The lead-in roller <NUM> may be coupled to the torque of one or more of the load wheels <NUM> through a torque-coupling assembly 8on, which may employ, for example, a toothed belt <NUM> that interacts with a gear 192n connected to an axle <NUM> of the lead-in roller <NUM>, as shown in <FIG>. One will appreciate that the torque-coupling assembly <NUM> may be employed to couple the lead-in roller <NUM> with only the rear load wheel <NUM>, with only the forward load wheel <NUM>, or with both of the rear load wheel <NUM> and the forward load wheel <NUM>. One will further appreciate that the torque-coupling assembly 8on may be employed on only one side of the load wheel unit, as shown, or with both sides of the load wheel unit <NUM>.

One will also appreciate that torque coupling between the lead-in roller <NUM> and one or both of the load wheels <NUM> can be implemented in any manner, such as by any of the force applying couplers 122a-<NUM>. Other examples of mechanism to couple torque to the lead-in roller <NUM> include, for example, chain(s) and gears or untoothed belt(s). Similarly, the lead-in roller <NUM> may be utilized in conjunction with any other type of load wheel assembly, such as any of the load wheel assemblies <NUM>-<NUM>, or with load wheel assemblies that do not couple torque between their load wheels. Alternatively, the lead-in roller <NUM> may not be coupled to either of the load wheels <NUM>.

<FIG> illustrate respective top plan, right side elevation, bottom, and bottom right isometric views of an example of a modular fork assembly <NUM> that can be used as a fork <NUM> in a forked material-handling vehicle, such as a pallet truck <NUM>. With reference to <FIG>, each modular fork assembly <NUM> includes multiple components. A fully assembled modular fork assembly <NUM> includes an elongate body <NUM>, a load wheel module <NUM>, and a fork tip <NUM> (also referred to as a fork toe). A proximal or body-facing end <NUM> of the load wheel module <NUM> can be detachably connected to a distal end <NUM> (opposite the proximal end <NUM>) of the elongate body <NUM>, the distal end <NUM> being furthest from a battery box (not shown). And, the fork tip <NUM> can be detachably connected to a distal or fork tip-facing end <NUM> of the load wheel module <NUM>. The elongate body <NUM>, the load wheel module <NUM>, and the fork tip <NUM> may be randomly selected from an inventory of respective substantially identical elongate bodies <NUM>, load wheel modules <NUM>, and fork tips <NUM>.

For convenience and modularity, the elongate body <NUM>, the load wheel module <NUM>, and the fork tip <NUM> may be identical for both the left and right modular fork assemblies <NUM> (e.g., the fork assemblies <NUM> that may be coupled to the left and right sides of a battery box). Using identical components for both the left and right fork assemblies <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-identical exchangeable components may be used to create different left and right modular fork assemblies <NUM>. For example, the elongate body <NUM> may be made in any desired length, detachably coupled to one of several different designs for the load wheel module <NUM>, which is in turn detachably coupled to a desired fork tip <NUM> to create a customizable modular fork assembly <NUM> to accommodate a wide range of customer preferences. Load wheels with torque-coupling assemblies may be used in conventional fork configurations or other suitable environments as well.

<FIG> illustrates a front right bottom isometric view of a load wheel module <NUM> with a load wheel assembly <NUM> in an undeployed position <NUM>; <FIG> illustrates a front right bottom isometric view of the load wheel module <NUM> with the load wheel assembly <NUM> in a deployed position <NUM>; and <FIG> illustrates a front right top isometric view of a wheel module substructure <NUM>. With reference to <FIG>, and <FIG>, the load wheel module <NUM> may include any of the load wheel assemblies <NUM> including their respective torque-coupling assemblies <NUM>. The load wheel module <NUM> also includes a frame <NUM> that houses the wheel module substructure <NUM>. The frame <NUM> includes a frame upper surface <NUM> and a frame lower surface <NUM>. The frame upper surface <NUM> may be configured to support and provide sliding contact to a load, and the frame lower surface <NUM> may be configured to provide one or more points of contact with components of the wheel module substructure <NUM>.

The frame <NUM> may have a body-facing end <NUM> and a fork tip-facing end <NUM> that may be substantially identical in shape or that may be different. For example, both of the body-facing end <NUM> and the fork tip-facing end <NUM> may be configured to include substantially identical interlocking mechanism components. In particular, the sheer-resistant features, such as protruding features (not shown) or the receiving features <NUM> may be identically positioned on both of the body-facing end <NUM> and the fork tip-facing end <NUM>. The wheel module <NUM> depicted in <FIG> includes receiving features <NUM> configured into its fork tip-facing end <NUM>. One will appreciate, however, that the body-facing end <NUM> and the fork tip-facing end <NUM> may have different types of sheer-resistant features in the same or different locations on each of the facing ends of the frame <NUM>.

The frame <NUM> may also include an aperture <NUM> in both of the body-facing end <NUM> and the fork tip-facing end <NUM> if symmetry is desired for manufacturing. However, in some embodiments, only the body-facing end <NUM> of the frame <NUM> may include the aperture <NUM> to provide passage for a hydraulic line (not shown) that conveys hydraulic power from a hydraulic power source (not shown) to a hydraulic actuator <NUM> in the load wheel module <NUM>. In other embodiments, the aperture <NUM> may provide passage for a mechanical link arm to facilitate lowering and raising a load wheel <NUM> via a suitable mechanical system coupled to the load wheel module <NUM>, where the mechanical link arm receives a motive force from a power source located in a forklift truck body.

The wheel module substructure <NUM> may include a hydraulic actuator assembly <NUM> and a load wheel assembly <NUM> that is operatively connected to the frame <NUM>. The load wheel assembly <NUM> includes a wheel carrier strut <NUM> (also called a wheel carrier frame) that is operatively connected to, and supports, the load wheel unit <NUM> that includes a wheel carrier <NUM> that supports the load wheels <NUM>. In one example, the wheel carrier strut <NUM> has a U-shaped distal portion that is pivotally connected to the wheel carrier <NUM> on both sides of the load wheels <NUM>.

The wheel module substructure <NUM> may be positioned within the frame <NUM> such that the hydraulic actuator assembly <NUM> is positioned closer to the body-facing end <NUM> of the load wheel module <NUM> and the load wheel assembly <NUM> is positioned closer to the fork tip-facing end <NUM> of the load wheel module <NUM>. In particular, the hydraulic actuator <NUM> may be positioned closer to the body-facing end <NUM> and the load wheels <NUM> may be positioned closer to the fork tip-facing end <NUM>.

The wheel carrier strut <NUM> is also operatively connected to the load wheel module frame <NUM> and to the hydraulic actuator assembly <NUM>. In one example, the operative connection to the frame <NUM> may be implemented by one or more pivot bars <NUM> that may be pivotally connected at a bar frame end <NUM> to the frame <NUM> and at a bar strut end <NUM> to the wheel carrier strut <NUM>. Part of a pivot mechanism <NUM> at the bar frame end <NUM> may be secured within a recess <NUM> in an exterior side surface <NUM> of the frame <NUM> so that the part of the pivot mechanism <NUM> will not catch when the modular fork assemblies <NUM> are slid into load structures that support the load. One will appreciate that other pivot mechanisms can additionally or alternatively be counter sunk into the components that they are pivoting. For example, although not depicted in this manner, part of the pivot mechanism <NUM> at the bar strut end <NUM> may be recessed into the pivot bar <NUM>.

An actuator-facing end <NUM> of the wheel carrier strut <NUM> may be operatively connected to the hydraulic actuator assembly <NUM> via a pivot mechanism <NUM> at a strut-facing end <NUM> of the hydraulic actuator assembly <NUM>. The pivot mechanism <NUM> may include a pivot <NUM> that extends through one or more strut teeth <NUM> at the actuator-facing end <NUM> of the wheel carrier strut <NUM> that are interweaved with one or more actuator assembly teeth <NUM> at the strut-facing end of the hydraulic actuator assembly <NUM>.

The hydraulic actuator assembly <NUM> may include a hydraulic line input connector (also called a cap-end port) (not shown) operative for connecting the hydraulic actuator <NUM> to a hydraulic line (not shown) that transmits hydraulic fluid from a hydraulic power source (not shown). The hydraulic line input connector may supply a hydraulic manifold <NUM> that distributes hydraulic power from the hydraulic line into multiple hydraulic barrels (also called hydraulic cylinders) <NUM> that each include a piston <NUM> (shown in broken lines in <FIG>) that is operatively connected to a piston rod <NUM>. In some embodiments, the hydraulic actuator <NUM> may include from one to ten pistons <NUM>. <FIG> shows an example of a hydraulic actuator <NUM> that includes four hydraulic barrels <NUM>, each of which includes a respective piston <NUM>.

The load wheel unit <NUM> may rest in an undeployed position <NUM> when the hydraulic actuator <NUM> is not actively pushing the piston rods <NUM> beyond a cylinder head <NUM> of the piston assembly. The load wheel unit <NUM> may be deployed into a deployed position <NUM> in response to a load wheel deployment signal that may be provided by an automated system or may be provided in response to a manually activated input, such as a switch or button. The load wheel deployment signal directly or indirectly causes hydraulic power to be propagated through a hydraulic line positioned within the elongate body <NUM> of the modular fork assembly <NUM>. The hydraulic power may be in the form of a hydraulic fluid under pressure.

The hydraulic line delivers the hydraulic power through the hydraulic line input connector to the hydraulic manifold <NUM> that distributes the hydraulic power to the hydraulic barrels <NUM> of the hydraulic actuator <NUM>. The hydraulic power pushes the pistons <NUM> of the hydraulic actuator <NUM> so that the piston rods <NUM> extend beyond the cylinder head <NUM> to push against the actuator-facing end <NUM> of the wheel carrier strut <NUM>, causing the pivot bar <NUM> to force the load wheel unit <NUM> to assume a predetermined deployed position <NUM> in which the load wheel unit <NUM> is vertically spaced apart from the load wheel module frame <NUM>. One will appreciate that the hydraulic line and hydraulic actuator assembly <NUM> can be replaced by a link rod that is actuated close to the proximal end <NUM> of the elongate body <NUM> and a mechanical system coupled to the load wheel module <NUM> and arranged to lower and raise the load wheels <NUM> in response to movement of the link rod. For example, a suitable mechanical system may be coupled to a load wheel module <NUM> with a link rod extending through an elongate body <NUM> of a fork assembly <NUM> to mechanically connect the mechanical system with a power source such that force from the power source is transmitted via the link rod to the mechanical system to lower and raise the load wheels <NUM>.

Modular fork assemblies <NUM> and load wheel modules are described in greater detail in <CIT>, entitled "Modular Fork Assembly for a Material-Handling Vehicle".

Claim 1:
A forked pallet truck (<NUM>) having a chassis (<NUM>), an elongate fork (<NUM>), and a load wheel assembly, wherein the fork (<NUM>) has a proximal end (<NUM>) and a distal end (<NUM>), wherein the proximal end (<NUM>) of the fork (<NUM>) is directly or indirectly attached to the chassis (<NUM>), and wherein the load wheel assembly (<NUM>) is connected to the fork (<NUM>) closer to the distal end (<NUM>) than to the proximal end (<NUM>), wherein the load wheel assembly (<NUM>) comprises:
a non-motorized forward load wheel (<NUM>) configured to directly roll on a floor (<NUM>);
a non-motorized rear load wheel (<NUM>) configured to directly roll on the floor (<NUM>); and
a non-motorized torque-coupling assembly (<NUM>) connected between the forward load wheel (<NUM>) and the rear load wheel (<NUM>) for coupling torque between the forward load wheel (<NUM>) and the rear load wheel (<NUM>),
characterized in that
the forked pallet truck (<NUM>) has a load wheel extension mechanism for extending the load wheel assembly (<NUM>) away from the fork (<NUM>).