Patent Description:
<CIT> discloses a hand truck including a frame, a telescopic handle pivotally connected with the frame, and a joint structure assembled between the frame and the handle. The frame is disposed with a collapsible wheel unit adjustable in position, and the handle and the frame can be bent and extended to a proper length and then fixed in position so that a user can push the hand truck with convenience. Further, the hand truck can be shaped alternately into a two-wheel vertical truck or a four-wheel platform hand truck.

According to the present disclosure, a collapsible load carrier includes a rolling base and a base pusher mounted on the rolling base for movement relative to the rolling base, the load carrier comprising wheels that can be collapsed to assume a compact storage mode and that can be reconfigured in the field by a user to function in two operating modes, e.g. front-and-rear- wheel cart mode and <NUM>-wheel hand-truck mode.

The invention relates to a collapsible load carrier according to claim <NUM> and a method for operating a load carrier according to claim <NUM>.

The collapsible load carrier comprises among others a first wheel-bias spring which is coupled to the left wheel-support rail and to a first wheel support including a first rail receiver, a first fork, and a first cam block.

In an illustrative embodiment a second wheel-bias spring is coupled to the right wheel-support rail and to a second wheel support including a second rail receiver, a second fork, and a second cam block.

Further, among others, the first wheel-bias spring is arranged to extend around a portion of the left wheel-support rail and to engage the first wheel support to bias the first wheel support, along with the left front wheel, toward the folded storage position.

In an illustrative embodiment the second wheel-bias spring is arranged to extend around a portion of the right wheel-support rail and to the second wheel support to bias the second wheel support, along with the right front wheel, toward the folded storage position.

In an illustrative embodiment a spreader plate engages the cam blocks during the movement of a front linkage relative to the rolling base that accompanies a change of the load carrier from the flat storage mode to the front-and-rear-wheel mode.

In an illustrative embodiment the spreader plate is moved toward the left and right front wheels to engage cam sections of the cam blocks and ride thereon in camming relation to move the companion front wheel unit from the folded storage position to the unfolded rolling position and thus spread the left and right front wheel units (<NUM>, <NUM>) apart.

In an illustrative embodiment a first cam block includes, in sequence, a first root section, a first cam section, and a first lock section and a second cam block includes, in sequence, a second root section, a second cam section, and a second lock section, wherein a spreader plate of a wheel spreader engages or lies adjacent to the root sections when the load carrier is in the flat storage mode.

In an illustrative embodiment the spreader plate of the wheel spreader engages the lock sections (e.g., channels) formed in a hook included in the cam block to retain the left and right front wheel units in their unfolded rolling positions.

In an illustrative embodiment a wheel support of right front wheel unit is a monolithic component formed to include a rail receiver, a fork, a cam block, and a hook, wherein the rail receiver is coupled to right rail, wherein the fork is coupled to rail receiver and is configured to support right front wheel for rotation relative to wheel support, wherein the cam block is coupled to fork and interacts with spreader plate of wheel spreader of load- carrier mode changer when right front wheel is moved from the folded storage position to the unfolded rolling position, wherein the hook extends from cam block and is configured to receive base pusher when base pusher is in the stored position so that base pusher is held in place relative to rolling base.

In an illustrative embodiment a wheel support of left front wheel unit is a monolithic component formed to include a rail receiver, a fork, a cam block, and a hook, wherein the rail receiver is coupled to left rail, wherein the fork is coupled to rail receiver and is configured to support left front wheel for rotation relative to wheel support, wherein the cam block is coupled to fork and interacts with spreader plate (74P) of wheel spreader (<NUM>) of front linkage (<NUM>) of load-carrier mode changer (<NUM>) when left front wheel (<NUM>) is moved from the folded storage position to the unfolded rolling position, wherein the hook (<NUM>) extends from cam block (<NUM>) and is configured to receive base pusher (<NUM>) when base pusher (<NUM>) is in the stored position so that base pusher (<NUM>) is held in place relative to rolling base (<NUM>).

In an illustrative embodiment the rolling base includes a load-support frame, a left front wheel unit including a left front wheel, and a right front wheel unit including a right front wheel, wherein the load- support frame includes a left wheel-support rail, a right wheel-support rail, and a toe-plate shelf mounted on forward ends of rails for pivotable movement about a shelf pivot axis between an inactive flat position used in the flat storage mode and the front-and-rear-wheel cart mode of load carrier and an active extended position used in the <NUM>-wheel hand-truck mode of load carri er.

In an illustrative embodiment the load carrier includes spring means for normally and yieldably pivoting each left and right front wheel unit about its pivot axis to assume the folded storage position in which the left and right front wheels in the front wheel units disengage a ground underlying the rolling base and the left front wheel in the left front wheel unit is arranged to extend toward the right front wheel in the right front wheel unit.

In an illustrative embodiment the spring means includes a left torsion spring coupled to the left wheel-support rail and the left front wheel unit and a right torsion spring coupled to the right wheel-support rail and the right-front wheel unit.

In an illustrative embodiment the rolling base includes a load-support frame and a toe-plate shelf coupled to the load-support frame near a second end of the load-support frame for movement about a shelf pivot axis, wherein the toe-plate shelf moves about the shelf pivot axis from an inactive flattened position to an active extended position.

In an illustrative embodiment the left front wheel unit is coupled to the left wheel-support rail of the load-support frame and the right front wheel unit is coupled to right wheel-support rail of the load-support frame, wherein the left front wheel unit includes the left front wheel and couples the left front wheel to the left wheel-support rail of the load-support frame for movement about a left wheel axis, wherein the right front wheel unit includes the right front wheel and couples the right front wheel to the right wheel-support rail of the load-support frame for movement about a right wheel axis, wherein the left and right front wheels move about wheel axes from the folded storage positions to the unfolded rolling positions, wherein the movement of the left and right front wheels is independent of movement of the toe-plate shelf.

According to the present disclosure, a collapsible load carrier includes a rolling base and a base pusher mounted on the rolling base for movement relative to the rolling base, wherein the collapsible load carrier further includes a load-carrier mode changer coupled to the rolling base and to the base pusher, wherein the load-carrier mode changer is configured to provide means for converting the load carrier either to a flat storage mode, a front-and-rear-wheel cart mode, or a <NUM>-wheel hand-truck mode at the option of a user without tools.

In an illustrative embodiment the rolling base includes two front wheels and the base pusher includes two rear wheels.

In an illustrative embodiment all four wheels are disengaged from ground underlying the rolling base when the load carrier is in the flat storage mode, and/or wherein all four wheels are arranged to engage and roll on ground underlying the rolling base when the load carrier is configured in the field by a user to assume a front-and-rear wheel cart mode, and/or wherein only the two front wheels are arranged to engage and roll on the ground underlying the rolling base when the load carrier is configured in the field by the user to assume a <NUM>-wheel hand-truck mode.

In an illustrative embodiment the mode changer also includes a rear linkage coupled to the pivotable base pusher, wherein the rear linkage includes slider links and pusher links, wherein the slider links are coupled to slider to pivot relative to slider, and wherein pusher links are pivotably coupled to both a corresponding slider link and base pusher to pivot relative to both the corresponding slider link and the base pusher.

In an illustrative embodiment the load carrier includes a pusher rotator having a forward lock and an aft lock.

In an illustrative embodiment the pusher rotator provides means for blocking or allowing movement of the pusher links between a FIRST POSITION to establish the front-and-rear-wheel cart mode of the load carrier, and a SECOND POSITION to establish the <NUM>-wheel hand-truck mode of the load carrier.

In an illustrative embodiment the pusher rotator includes a handle, a crossbar, the forward lock, and the aft lock. In an illustrative embodiment the handle and the crossbar extend between and interconnect the slider links.

In an illustrative embodiment the forward lock is coupled to the slider along a side of the slider facing the base pusher. In an illustrative embodiment the aft lock is coupled to the slider along another side of the slider facing toe-plate shelf.

In an illustrative embodiment the forward lock is configured to engage handle when pusher links are in the FIRST POSITION, and wherein the aft lock (<NUM>) is configured to engage handle when pusher links are and/or shifter linkage is in the SECOND POSITION.

In an illustrative embodiment each lock includes a corresponding wall and a corresponding blocker. In an illustrative embodiment the handle is received between a wall and a blocker when handle is engaged by a lock. In an illustrative embodiment the blockers are configured to pivot relative to the slider to block or allow movement of the handle and, in turn, movement of pusher links.

In an illustrative embodiment the blockers are biased toward blocking movement of the handle and pusher links by a bias spring.

According to the present disclosure a collapsible load carrier may comprise.

In an illustrative embodiment the base pusher is also movable about the base-pusher pivot axis from the stored position in the first direction past the upright cart position to reach a two-wheel hand truck position to lie in generally coplanar relation to the top of the load-support frame of the rolling base to define an included angle of about <NUM>° therebetween to establish a <NUM>-wheel hand-truck mode of the load carrier in which the rolling base is supported for rolling movement only on the front wheels upon movement of the rolling base and the base pusher as a unit to disengage any rear wheel in the base pusher from the ground underlying the rolling base.

In an illustrative embodiment the load-carrier mode changer means includes a front linkage coupled to the left and right front wheel units and mounted for sliding movement on the load-support frame of the rolling base and a rear linkage coupled to the base pusher and mounted for movement relative to the front linkage between a first position on the front linkage associated with the flat storage mode and the front-and-rear-wheel cart mode of the load carrier and a second position located on the front linkage between the first position and the front wheel units and associated with the <NUM>-wheel hand-truck mode of the load carrier and the base pusher is configured to pivot about the base-pusher pivot axis in the first direction from the upright cart position to the <NUM>-wheel hand-truck position while the front linkage remains in a stationary position on the load-support frame of the rolling base during movement of the rear linkage relative to the front linkage from the first position to the second position to establish the <NUM>-wheel hand truck mode of the load carrier.

In an illustrative embodiment the front linkage includes a slidable spreader driver mounted for sliding movement on the load-support frame and a wheel spreader coupled to the slidable spreader driver and arranged to engage a cam provided on each of the left and right front wheel units to move the left and right front wheel units against motion-resisting forces applied to the left and right front wheel units by the spring from the folded storage positions to the unfolded rolling positions in response to movement of the base pusher about the base-pusher pivot axis in the first direction to move, in unison, the rear linkage, the slidable spreader driver, and the wheel spreader as a unit toward the front wheels so that the left and right front wheel units are spread apart to cause the front wheels in the left and right front wheel units to rotate about a common axis and on ground underlying the rolling base.

In an illustrative embodiment the rear linkage includes a pusher rotator mounted for movement on the slidable spreader driver of the front linkage between the first and second positions and a push rod coupled to the pusher rotator and to the base pusher to cooperate with the pusher rotator while the pusher rotator remains in the first position to convert pivoting motion of the base pusher about the base-pusher pivot axis into sliding motion of the slidable spreader driver on the load-support frame in a direction toward the front wheels to urge the wheel spreader into camming engagement with the left and right front wheel units to move those wheel units from their folded storage positions to their unfolded rolling positions.

In an illustrative embodiment the load-carrier mode changer means includes a slidable spreader driver mounted for sliding movement on the load-support frame and a wheel spreader coupled to the spreader driver and arranged to engage a cam provided on each of the left and front wheel units and wherein the left and right front wheel units move from the folded storage positions to the unfolded rolling positions during camming engagement with the wheel spreader in response to sliding motion of the slidable spreader driver on the load-support frame toward the front wheels to cause the wheel spreader to move away from the base-pusher pivot axis.

In an illustrative embodiment the wheel spreader includes a proximal portion mounted on the load-support frame for pivotable movement about a spreader-pivot axis and a free portion arranged to pivot about the spreader-pivot axis and engage the cam provided on each of the left and right front wheel units.

In an illustrative embodiment the wheel spreader includes a spreader plate mounted for pivotable movement on the rolling base and a wheel link pivotably coupled to each of the spreader plate and the slidable spreader driver to convert sliding motion of the slidable spreader driver into pivoting motion of spreader plate and wherein the pivoting spreader plate applies a pivot-inducing force to cams included in the left and right front wheel units to pivot the left and right front wheel units from the folded storage positions to the unfolded rolling positions in response to pivoting movement of the base pusher in the first direction about the base-pusher pivot axis to change the load carrier from the flat storage mode to the front-and-rear-wheel cart mode.

In an illustrative embodiment the load-carrier mode changer includes a front linkage coupled to the left and right front wheel units and a rear linkage coupled to the base pusher and mounted for movement on the front linkage between a first position associated with the flat storage mode and the front-and-rear-wheel cart mode of the load carrier and a second position associated with a <NUM>-wheel hand-truck mode of the load carrier, the front and rear linkages cooperate to provide means for pivoting the left and right front wheel units from the folded storage positions to the unfolded rolling positions only when the rear linkage occupies the first position on the front linkage, and the base pusher is arranged to pivot about the base-pusher pivot axis through a second pivot angle in a direction away from the front wheel units to move relative to the load-support frame of the rolling base from the upright cart position to a laidback hand-truck position to establish a <NUM>-wheel hand-truck mode of the load carrier in response to movement of the rear linkage relative to the front linkage from the first position to the second position.

In an illustrative embodiment the front linkage includes a slidable spreader driver mounted for sliding movement on the load-support frame and a wheel spreader coupled to the slidable spreader driver and arranged to lie in camming engagement with the left and right front wheel units and the rear linkage includes a pusher rotator mounted for movement on the slidable spreader driver between the first and second positions and a push rod coupled to the pusher rotator and to the base pusher.

In an illustrative embodiment the load-support frame and the base pusher cooperate to define therebetween an included angle of about <NUM>° upon movement of the base pusher to the upright cart position and the load-support frame and the base pusher cooperate to define therebetween an included angle of about <NUM>° upon movement of the base pusher to the laidback hand-truck position.

In an illustrative embodiment each of the first and second pivot angles is about <NUM>°.

According to the present disclosure the collapsible load carrier may comprise
a rolling base including a load-support frame, a left front wheel unit mounted for pivotable movement on the load-support frame about a left pivot axis between a folded storage position and an unfolded rolling position, a right front wheel unit mounted for pivotable movement on the load-support frame about a right pivot axis between a folded storage position associated with a flat storage mode of the load carrier in which front wheels in the front wheel units disengage ground underlying the rolling base and a front wheel in the left front wheel unit is arranged to extend toward a front wheel in the right front wheel unit and an unfolded rolling position associated with a front-and-rear-wheel cart mode of the load carrier in which the front wheels in the front wheel units are arranged to engage and roll on ground underlying the rolling base and rotate about a common axis of rotation, and a spring yieldably pivoting each front wheel unit about its pivot axis normally to assume the folded storage position,.

In an illustrative embodiment the front linkage includes a slidable spreader driver mounted for sliding movement on the load-support frame and a wheel spreader coupled to the slidable spreader driver to lie between the slidable spreader driver and the front wheels and arranged to lie in camming engagement with the front wheel units.

In an illustrative embodiment the rear linkage is mounted for movement on the front linkage between a first position associated with the flat storage mode and the front-and-rear-wheel cart mode of the load carrier and a second position associated with the <NUM>-wheel hand-truck mode of the load carrier, the front and rear linkages cooperate to provide means for pivoting the left and right front wheel units from the folded storage positions to the unfolded rolling positions only when the rear linkage occupies the first position on the front linkage, and the base pusher is arranged to pivot about the base-pusher pivot axis in the first direction to move relative to the load-support frame of the rolling base from the upright cart position to a laidback hand-truck position to establish a <NUM>-wheel hand-truck mode of the load carrier n response to movement of the rear linkage relative to the front linkage from the first position to the second position.

In an illustrative embodiment the rear linkage includes a pusher rotator mounted for movement on the front linkage between the first and second positions and a push rod pivotably coupled to each of the pusher rotator and the base pusher.

In an illustrative embodiment the pusher rotator is mounted on the front linkage for pivotable movement about a rotator pivot axis between the first and second positions.

In a illustrative embodiment the front linkage includes a slidable spreader driver mounted for sliding movement on the load-support frame and a wheel spreader coupled to the slidable spreader driver and arranged to lie in camming engagement with the left and right front wheel units and the rear linkage includes a pusher rotator mounted for movement on the slidable spreader driver between the first and second positions and a push rod coupled to the pusher rotator and to the base pusher.

According to the present disclosure, a collapsible load carrier includes a rolling base and a base pusher mounted on the rolling base for movement relative to the rolling base. In illustrative embodiments, the collapsible load carrier further includes a load-carrier mode changer coupled to the rolling base and to the base pusher. The mode changer is configured to pivot left and right front wheel units of the rolling base relative to companion wheel-support rails of the rolling base from a folded storage position to an unfolded rolling position.

In illustrative embodiments, the rolling base comprises a load-support frame including left and right wheel-support rails and the base pusher is mounted on the rails for pivotable movement relative to the load-support frame about a base-pusher pivot axis. The rolling base also includes a left front wheel unit mounted on the left wheel-support rail for pivotable movement between a folded storage position and an unfolded rolling position and a right front wheel unit mounted on the right wheel-support rail for pivotable movement between a folded storage position and an unfolded rolling position. The mode changer is coupled at a rear end to the pivotable base pusher and at a front end to the pivotable left and right front wheel units.

In illustrative embodiments, the load-carrier mode changer is coupled to the rolling base and to the base pusher and configured to provide means for converting the load carrier either to a flat storage mode, a front-and-rear-wheel cart mode, or a <NUM>-wheel hand-truck mode at the option of a user without tools. The mode changer includes a front linkage coupled to the front wheel units and arranged to slide on the wheel-support rails of the load-support frame. The mode changer also includes a rear linkage coupled to the pivotable base pusher and to the front linkage in either a FIRST POSITION or a SECOND POSITION selected by the user. It is within the scope of the present disclosure to use a single rear wheel so that three wheels engage and roll on ground underlying the rolling base in an alternative front-and-rear-wheel cart mode of the load carrier.

In illustrative embodiments, the rolling base includes two front wheels and the base pusher includes two rear wheels. All four wheels are disengaged from ground underlying the rolling base when the load carrier is in the flat storage mode. All four wheels are arranged to engage and roll on ground underlying the rolling base when the load carrier is configured in the field by a user to assume a front-and-rear wheel cart mode. In contrast, only the two front wheels are arranged to engage and roll on the ground underlying the rolling base when the load carrier is configured in the field by the user to assume a <NUM>-wheel hand-truck mode.

In illustrative embodiments, the base pusher can be pivoted by a user about the base-pusher pivot axis through a <NUM>° angle to move relative to the rolling base from a stored position on top of the load-support frame of the rolling base to change the load carrier from a flat storage mode to a <NUM>-wheel hand-truck mode. First the base pusher is pivoted in a rearward first direction through about a <NUM>° angle to assume an upright cart position to place the rear wheel(s) on the ground while the rear linkage is in the FIRST POSITION on the front linkage to cause the front and rear linkages to move together as a unit to pivot the left and right front wheel units to the unfolded rolling positions and to place the front wheels on the ground along with the rear wheel(s) to establish the front-and-rear-wheel cart mode of the load carrier. Then the base pusher is pivoted in the same direction through another <NUM>° angle to disengage the rear wheel(s) from the ground during movement of the rear linkage to the SECOND POSITION on the front linkage to place the base pusher in line with the top of the load-support frame of the rolling base to assume a laidback hand-truck position to establish the <NUM>-wheel hand-truck mode of the load carrier. Thus, the load carrier can be converted in the field by a user without tools using the load-carrier mode changer to assume either a flat storage mode, a front-and-rear-wheel cart mode, or a <NUM>-wheel hand-truck mode.

Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived.

A load carrier <NUM> in accordance with the present disclosure includes a rolling base <NUM>, a pivotable base pusher <NUM>, and a load-carrier mode changer <NUM> as shown in <FIG>. Load-carrier mode changer <NUM> can be operated in the field without tools by a user in a manner suggested diagrammatically in <FIG> and illustratively in <FIG> and <FIG> to convert load carrier <NUM> from the flat storage mode shown in <FIG>, <FIG>, and <FIG> to a front-and-rear-wheel cart mode shown in <FIG>, <FIG>, and <FIG>, and to a <NUM>-wheel hand-truck mode shown in <FIG>, <FIG>, and <FIG>.

Rolling base <NUM> includes a load-support frame <NUM>, a left front wheel unit <NUM> including a left front wheel <NUM>, and a right front wheel unit <NUM> including a right front wheel <NUM> as shown, for example, in <FIG> and <FIG>. Load-support frame <NUM> includes a left wheel-support rail <NUM>, a right wheel-support rail <NUM>, and a toe-plate shelf <NUM> mounted on forward ends of rails <NUM>, <NUM> for pivotable movement about a shelf pivot axis 24A between an inactive flat position shown in <FIG> used in the flat storage mode and the front-and-rear-wheel cart mode of load carrier <NUM> and an active extended position shown in <FIG> and used in the <NUM>-wheel hand-truck mode of load carrier <NUM>. Once left front wheel unit <NUM> is mounted on left rail <NUM>, left front wheel unit <NUM> is pivotable about a left pivot axis 36A aligned with left rail <NUM> as suggested in <FIG>. Once right front wheel unit <NUM> is mounted on right rail <NUM>, right front wheel unit <NUM> is pivotable about a right pivot axis 38A aligned with right rail <NUM> as suggested in <FIG>. Load-support frame <NUM> also includes a left end cap <NUM> to be mounted on a forward end of left rail <NUM> after left front wheel unit <NUM> is mounted on left rail <NUM> and a right end cap <NUM> to be mounted on a forward end of right rail <NUM> after right front wheel unit <NUM> is mounted on right rail <NUM>.

Base pusher <NUM> includes a push handle <NUM> and an outrigger wheel unit <NUM> configured to be coupled to push handle <NUM> to move therewith as suggested, for example, in <FIG> and <FIG>. Push handle <NUM> includes a left leg <NUM>, a right leg 55R, and a U-shaped handgrip <NUM> interconnecting upper ends of legs <NUM>, 55R as suggested in <FIG>. Outrigger wheel unit <NUM> includes a left caster <NUM> including a left rear wheel 61R, a right caster <NUM> including a right rear wheel 62R, and a caster-support rail <NUM> coupled to lower ends of left and right legs <NUM>, 55R of base pusher <NUM> and to each caster <NUM>, <NUM>.

Mode changer <NUM> includes a front linkage <NUM> and a rear linkage <NUM> as suggested in <FIG> and <FIG>. Front linkage <NUM> includes a spreader driver <NUM> and a wheel spreader <NUM> including a pivotable spreader plate 74P and wheel links <NUM>, <NUM> interposed between and coupled to pivotable spreader plate 74P and spreader driver <NUM> as suggested in <FIG> and <FIG>. Front linkage <NUM> also includes a spreader-driver retainer <NUM> that is configured to block or allow sliding movement of spreader driver <NUM> along rails <NUM>, <NUM> of load-support frame <NUM> at the option of a user. Rear linkage <NUM> includes a pivotable pusher rotator <NUM> and a push rod 86P including pusher links <NUM>, <NUM> pivotably coupled at one end to pivotable pusher rotator <NUM> and at opposite ends to pivotable base pusher <NUM> at the lower ends of left and right legs <NUM>, 55R of push handle <NUM> below the caster-support rail <NUM> as suggested in <FIG>. Pusher rotator <NUM> includes a movable handgrip <NUM> comprising pivot links <NUM>, <NUM> and a crossbar <NUM> interconnecting pivot links <NUM>, <NUM> and a handgrip-motion blocker <NUM> associated with crossbar <NUM> as suggested in <FIG> and <FIG>.

In illustrative embodiments, the mode changer <NUM> is operable in the field by a user without tools to convert load carrier <NUM> easily from its flat storage mode to a front-and-rear-wheel cart mode or an upright <NUM>-wheel hand-truck mode. In the flat storage mode, front wheels <NUM>, <NUM> are aligned to cause their treads to face toward one another and their axes of rotation to lie in spaced-apart parallel relation to one another. In the other modes, front wheels <NUM>, <NUM> are aligned to cause their treads to engage and roll on ground <NUM> underlying rolling base <NUM> and to cause front wheels <NUM>, <NUM> to rotate about a common axis of rotation.

Left front wheel unit <NUM> includes a cam block <NUM> arranged to lie alongside wheel <NUM> and engage a portion of spreader plate 74P of wheel spreader <NUM> of front linkage <NUM> of mode changer <NUM> during pivoting motion of base pusher <NUM> about base-pusher pivot axis <NUM> to change the mode of load carrier <NUM> from the flat storage mode to the front-and-rear-wheel cart mode as suggested diagrammatically in <FIG> and illustratively in <FIG>. Similarly, right-front wheel unit <NUM> includes a cam block <NUM> near right wheel <NUM>. Cam block <NUM> includes, in sequence, a ROOT section <NUM>, a CAM section <NUM>, and a LOCK section <NUM> and cam block <NUM> includes, in sequence, a ROOT section <NUM>, a CAM section <NUM>, and a LOCK section <NUM>. Spreader plate 74P of wheel spreader <NUM> engages or lies adjacent to ROOT sections <NUM>, <NUM> when load carrier <NUM> is in the flat storage mode as suggested in <FIG>. Spreader plate 74P engages CAM sections <NUM>, <NUM> during the movement of front linkage <NUM> relative to rolling base <NUM> that accompanies a change of load carrier <NUM> from the flat storage mode to the front-and-rear-wheel mode as suggested in <FIG> and <FIG> and <FIG>. In this circumstance, spreader plate 74P is moved toward front wheels <NUM>, <NUM> to engage CAM sections <NUM>, <NUM> and ride thereon in camming relation to move the companion front wheel unit <NUM> or <NUM> from the folded storage position to the unfolded rolling position and thus spread the front wheel units <NUM>, <NUM> apart. Lastly, spreader plate 74P of wheel spreader <NUM> engages LOCK sections <NUM>, <NUM> (e.g., channels) formed in a hook (<NUM> or <NUM>) included in cam block (<NUM> or <NUM>) as suggested diagrammatically in <FIG> and <FIG> and illustratively in <FIG> to retain the front wheel units <NUM>, <NUM> in their unfolded rolling positions.

Sliding movement of the load-carrier mode changer <NUM> on the left and right rails <NUM>, <NUM> of the rolling base <NUM> to cause the front wheel units <NUM>, <NUM> to pivot from the folded storage positions to the unfolded rolling positions in response to pivoting movement of the base pusher <NUM> from the stored position to the upright cart position is shown diagrammatically in <FIG>. Movement of the pivotable pusher rotator <NUM> included in the rear linkage <NUM> of the load-carrier mode changer <NUM> from the FIRST POSITION shown in <FIG> to the SECOND POSITION shown in <FIG> causes the base pusher <NUM> to pivot from the upright cart position suggested in <FIG> to the laidback hand-truck position suggested in <FIG>.

As suggested in a diagrammatic view of the load carrier <NUM> provided in <FIG>, load carrier <NUM> is retained in the compact flat storage mode of <FIG>. Front linkage <NUM> of the load-carrier mode changer <NUM> includes a slidable spreader driver <NUM> coupled to the base pusher <NUM> via the rear linkage <NUM> and mounted for sliding movement on the rails <NUM>, <NUM> included in the rolling base <NUM> and a wheel spreader <NUM> arranged to interconnect the slidable spreader driver <NUM> and the pivotable left and right front wheel units <NUM>, <NUM>. Spreader plate 74P of wheel spreader <NUM> is arranged to engage a ROOT section of each front wheel unit <NUM>, <NUM>. Pivotable base-pusher rotator <NUM> included in the rear linkage <NUM> of the load-carrier mode changer <NUM> is coupled to the base pusher <NUM> and mounted for pivoting movement on the slidable spreader driver <NUM> and arranged to lie in a FIRST POSITION on the slidable spreader driver <NUM>.

<FIG> is a diagrammatic view similar to <FIG> showing that the left and right front wheel units <NUM>, <NUM> have pivoted toward one another in directions <NUM>, <NUM> through an angle of about <NUM>° owing to engagement of spreader plate 74P of wheel spreader <NUM> with the CAM section of each front wheel unit <NUM>, <NUM> in response to pivoting movement of the base pusher <NUM> away from the rolling base <NUM> about the base-pusher pivot axis 14A to cause sliding movement of the slidable spreader driver <NUM> on the left and right rails <NUM>, <NUM> of the rolling base <NUM> in a direction toward the front wheel units <NUM>, <NUM> and movement of spreader plate 74P of wheel spreader <NUM> on the CAM section of each front wheel unit <NUM>, <NUM>.

<FIG> is a diagrammatic view showing that the front wheel units <NUM>, <NUM> have been pivoted further on the rails <NUM>, <NUM> to assume the unfolded rolling positions in response to pivoting movement of the base pusher <NUM> to assume the upright cart position and suggesting that spreader plate 74P of wheel spreader <NUM> has been moved along the CAM section of each front wheel unit <NUM>, <NUM> to engage the LOCK section of each front wheel unit <NUM>, <NUM> to retain the front wheel units <NUM>, <NUM> in the unfolded rolling positions.

<FIG> is a diagrammatic view showing that the base pusher <NUM> has been pivoted in a rearward direction about the base-pusher pivot axis 14A relative to the rolling base <NUM> to assume a laidback hand-truck position in response to pivoting movement of the pivotable base-pusher rotator <NUM> on the slidable spreader driver <NUM> from the FIRST POSITION in a direction away from the base-pusher pivot axis 14A and toward the front wheels <NUM>, <NUM> to arrive at a SECOND POSITION.

In illustrative embodiments, rolling base <NUM> comprises a load-support frame <NUM> including left and right front-wheel support rails <NUM>, <NUM> arranged to lie in spaced-apart parallel relation to one another, a left front wheel unit <NUM> mounted on the left front-wheel support rail <NUM> for pivotable movement about a left pivot axis 36A, and a right front wheel unit <NUM> mounted on the right front-wheel support rail <NUM> for pivotable movement about a right pivot axis 30A that is arranged to lie in spaced-apart parallel relation to the left pivot axis 36A as suggested in <FIG>, <FIG>, and <FIG>. Each of the left and right front wheel units <NUM>, <NUM> may pivot about its pivot axis 36A or 38A between a folded storage position shown in <FIG> and an unfolded rolling position shown in <FIG>. In the folded storage positions, none of the front wheels <NUM>, <NUM> in the left and right front wheel units <NUM>, <NUM> are arranged to engage and roll on ground <NUM> underlying the rolling base <NUM> as suggested in <FIG> and <FIG>. However, in the unfolded rolling positions, the front wheels <NUM>, <NUM> are arranged to engage and roll on the ground <NUM> underlying the rolling base <NUM> as suggested in <FIG>.

Load carrier <NUM> also includes spring means <NUM>, <NUM> for normally and yieldably pivoting each front wheel unit <NUM>, <NUM> about its pivot axis 36A or 38A to assume the folded storage position in which front wheels <NUM>, <NUM> in the front wheel units <NUM>, <NUM> disengage ground <NUM> underlying the rolling base <NUM> and the front wheel <NUM> in the left front wheel unit <NUM> is arranged to extend toward the front wheel <NUM> in the right front wheel unit <NUM> as suggested in <FIG> and <FIG>. The spring means <NUM>, <NUM> illustratively includes a left torsion spring <NUM> coupled to the left rail <NUM> and the left front wheel unit <NUM> and a right torsion spring <NUM> coupled to the right rail <NUM> and the right-front wheel unit <NUM>.

Base pusher <NUM> is formed to include left and right rear wheels 61R, 62R in an illustrative embodiment as suggested in <FIG>, <FIG>, and <FIG>. It is within the scope of this disclosure to include only one rear wheel in base pusher <NUM>.

Base pusher <NUM> is mounted on the left and right front-wheel support rails <NUM>, <NUM> of the rolling base <NUM> for pivotable movement about a base-pusher pivot axis 14A in a first direction from a stored position arranged to lie alongside the left and right front-wheel support rails <NUM>, <NUM> on top of the rolling base <NUM> in a flat storage mode of the load carrier <NUM> (see <FIG>) first through about a <NUM>° angle away from the left and right front-wheel support rails <NUM>, <NUM> to reach an upright cart position to establish a front-and-rear-wheel cart mode of load carrier <NUM> (see <FIG>) in which the two rear wheels 61R, 62R of the base pusher <NUM> along with two front wheels <NUM>, <NUM> in the left and right front wheel units <NUM>, <NUM> roll on ground <NUM> underlying the load carrier <NUM>. Then the base pusher <NUM> can be pivoted about the base-pusher pivot axis 14A in the same direction through about another <NUM>° angle to reach a laidback hand-truck position in which only the two front wheels <NUM>, <NUM> in the left and right front wheel units <NUM>, <NUM> roll on ground <NUM> underlying load carrier <NUM> to establish a <NUM>-wheel hand-truck mode of the load carrier <NUM> (see <FIG>).

Load carrier <NUM> includes a load-carrier mode changer <NUM> coupled to the rolling base <NUM> and to the base pusher <NUM> as suggested in <FIG>, <FIG>, and <FIG>. The load-carrier mode changer <NUM> is configured to provide means for pivoting the spring-biased left and right front wheel units <NUM>, <NUM> about their pivot axes 36A or 38A to move relative to the left and right front-wheel support rails <NUM>, <NUM> from the folded storage positions shown in <FIG>, <FIG> to assume unfolded rolling positions shown in <FIG>, <FIG> in which the front wheels <NUM>, <NUM> included in the left and right front wheel units <NUM>, <NUM> are arranged to engage and roll on ground <NUM> underlying the rolling base <NUM> and rotate about a common axis of rotation in response to pivoting movement of the base pusher <NUM> relative to the rolling base <NUM> about the base-pusher pivot axis 14A by a user in the field and cooperate with the rear wheels 61R, 62R included in the base pusher <NUM> to establish the front-and-rear-wheel cart mode of the load carrier <NUM>.

Load-carrier mode changer <NUM> includes a front linkage <NUM> coupled to the pivotable left and right front wheel units <NUM>, <NUM> and a rear linkage <NUM> coupled to the pivotable base pusher <NUM> as suggested in <FIG>, <FIG>, <FIG>, and <FIG>. The rear linkage <NUM> is always joined to the front linkage <NUM> to cooperate therewith to cause the pivotable left and right front wheel units <NUM>, <NUM> to pivot against biasing forces provided by the spring means <NUM>, <NUM> from the folded storage positions to the unfolded rolling positions in response to pivoting movement of the base pusher <NUM> about the base-pusher pivot axis 14A in a direction away from the front wheel units <NUM>, <NUM>.

In illustrative embodiments, the front linkage <NUM> includes a slidable spreader driver <NUM> mounted for sliding movement on the front-wheel support rails <NUM>, <NUM> of the rolling base <NUM> and a wheel spreader <NUM> coupled to the spreader driver <NUM> and to the left and right front wheel units <NUM>, <NUM> as suggested diagrammatically in <FIG> and illustratively in <FIG>, <FIG>. The rear linkage <NUM> includes a pivotable pusher rotator <NUM> mounted for movement on the spreader driver <NUM> between a FIRST POSITION and SECOND POSITION and a push rod 86P comprising pusher links <NUM>, <NUM> coupled to the pivotable pusher rotator <NUM> and to the pivotable base pusher <NUM>. Normally, the pivotable pusher rotator <NUM> is retained in the FIRST POSITION on the spreader driver <NUM> to cause the front wheel units <NUM>, <NUM> to pivot on the rails <NUM>, <NUM> from their folded storage positions to their unfolded rolling positions in response to pivoting of the base pusher <NUM> about the base-pusher pivot axis <NUM> in a direction away from the front wheel units <NUM>, <NUM> so as to convert the load carrier <NUM> from the flat storage mode to the front-and-rear-wheel cart mode. At the option of a user, the load carrier <NUM> is converted from the front-and-rear-wheel cart mode to the <NUM>-wheel hand-truck mode by moving the pivotable pusher rotator <NUM> on the spreader driver <NUM> from the FIRST POSITION to the SECOND POSITION to move the push rod 86P relative to the rolling base <NUM> to pivot the base pusher <NUM> about the base-pusher pivot axis 14A through an angle of about <NUM>° from the upright cart position to the laidback hand-truck position.

Load carrier <NUM> is convertible by a user in the field without tools to assume a flat storage mode, a cart mode, and a <NUM>-wheel hand-truck mode as shown in <FIG>. In the flat storage mode shown in <FIG>, a pair of front wheels <NUM>, <NUM> included in a rolling base <NUM> are in a folded storage position and a base pusher <NUM> is in a stored position extending along a load-support frame <NUM> of the rolling base <NUM> so that load carrier <NUM> is generally flattened for storage. In the cart mode shown in <FIG>, front wheels <NUM>, <NUM> are moved to an unfolded rolling position and base pusher <NUM> is moved to an upright cart position extending generally perpendicular to load-support frame <NUM> of rolling base <NUM> so that load carrier <NUM> provides a <NUM>-wheeled hand truck for transporting goods. In the <NUM>-wheel hand-truck mode shown in <FIG>, front wheels <NUM>, <NUM> remain in the unfolded rolling position and base pusher <NUM> is moved to a laidback hand-truck position extending generally parallel to frame <NUM> of rolling base <NUM> so that load carrier <NUM> provides a two-wheeled stand-up dolly for transporting goods.

In the illustrative embodiment, load carrier <NUM> includes a mode changer <NUM> coupled to rolling base <NUM> and to base pusher <NUM> as shown in <FIG>. Mode changer <NUM> provides front-wheel mover means for pivoting front wheels <NUM>, <NUM> from the folded storage position to the unfolded rolling position in response to movement of base pusher <NUM> from the stored position to the upright cart position as shown in <FIG>, <FIG>. Mode changer <NUM> provides pusher-retainer means for holding base pusher <NUM> in either the upright cart position or in the laidback hand-truck position relative to load-support frame <NUM> as shown in <FIG> and <FIG>.

Load carrier <NUM> illustratively includes rolling base <NUM>, base pusher <NUM> coupled to rolling base <NUM>, and load-carrier mode changer <NUM> as shown, for example, in <FIG>. Rolling base <NUM> is adapted for supporting goods to be transported by load carrier <NUM>. Base pusher <NUM> is coupled to load-support frame <NUM> included in rolling base <NUM> near a first end <NUM> of load-support frame <NUM> for movement relative to rolling base <NUM> about a base-pusher pivot axis 14A and is adapted to provide a grip for a user during use of load carrier <NUM>. Load-carrier mode changer <NUM> is coupled to rolling base <NUM> and to base pusher <NUM> and facilitates reconfiguration of load carrier <NUM> between modes by moving front wheels <NUM>, <NUM> included in rolling base <NUM> and by holding base pusher <NUM> in predetermined positions relative to rolling base <NUM>.

Rolling base <NUM> includes a load-support frame <NUM> and a toe-plate shelf <NUM> coupled to load-support frame <NUM> near second end <NUM> of load-support frame <NUM> for movement about a shelf pivot axis 24A. Toe-plate shelf <NUM> moves about shelf pivot axis 24A from an inactive flattened position, shown in <FIG>, to an active extended position shown in <FIG>.

Load-support frame <NUM> includes a left rail <NUM>, a right rail <NUM> spaced apart from and arranged to extend parallel to left rail <NUM>, a left end cap <NUM> sized to receive and to be coupled to left rail <NUM>, and a right end cap <NUM> sized to receive and to be coupled to right rail <NUM> as shown in <FIG> and <FIG>. Left front wheel <NUM> is coupled to left rail <NUM> for movement about left wheel axis 36A which extends along left rail <NUM>. Right front wheel <NUM> is coupled to right rail <NUM> for movement about right wheel axis 38A which extends along right rail <NUM> so that right wheel axis 38A is spaced apart from and arranged to extend parallel to left wheel axis 36A. Toe-plate shelf <NUM> is coupled to left and right end caps <NUM>, <NUM> of load-support frame <NUM> for movement about shelf pivot axis 24A.

Left front wheel unit <NUM> is coupled to left rail <NUM> of load-support frame <NUM> and a right front wheel unit <NUM> is coupled to right rail <NUM> of load-support frame <NUM> as shown in <FIG>. Left front wheel unit <NUM> includes left front wheel <NUM> and couples left front wheel <NUM> to left rail <NUM> of load-support frame <NUM> for movement about left wheel axis 36A. Right front wheel unit <NUM> includes right front wheel <NUM> and couples right front wheel <NUM> to right rail <NUM> of load-support frame <NUM> for movement about right wheel axis 38A. Front wheels <NUM>, <NUM> move about wheel axes 36A, 38A from the folded storage positions, shown in <FIG>, to the unfolded rolling positions shown in <FIG>. Movement of front wheels <NUM>, <NUM> is independent of movement of toe-plate shelf <NUM>.

In the folded storage positions, front wheels <NUM>, <NUM> are arranged to extend inwardly toward one another to cause load carrier <NUM> to be flattened as shown in <FIG> and <FIG>. More specifically, left front wheel <NUM> is arranged to extend from left rail <NUM> toward right front wheel <NUM> and right rail <NUM> of load-support frame <NUM> when in the folded storage position. Correspondingly, right front wheel <NUM> is arranged to extend from right rail <NUM> toward left front wheel <NUM> and left rail <NUM> of load-support frame <NUM> when in the folded storage position.

In the unfolded rolling position, front wheels <NUM>, <NUM> are arranged to extend downwardly to engage a floor <NUM> underlying load carrier <NUM> as shown in <FIG>, <FIG>, and <FIG>. More specifically, left front wheel <NUM> and right front wheel <NUM> are arranged to extend in the same downward direction away from load-support frame <NUM> when in the unfolded rolling position.

Left front wheel unit <NUM> includes a brace bracket <NUM> coupled left rail <NUM>, a wheel support <NUM> coupled to left rail <NUM> for movement about left wheel axis 36A, and a left front wheel <NUM> coupled to wheel support <NUM> as suggested in <FIG>. A wheel-bias spring <NUM> is coupled to left rail <NUM> and to wheel support <NUM>. Wheel support <NUM> includes a rail receiver <NUM>, a fork <NUM>, and a cam block <NUM> as shown in <FIG> and <FIG>. Wheel-bias spring <NUM> is arranged to extend around a portion of left rail <NUM> and to engage brace bracket <NUM> and wheel support <NUM> to bias wheel support <NUM>, along with left front wheel <NUM>, toward the folded storage position as shown in <FIG>, <FIG>.

Wheel support <NUM> of left front wheel unit <NUM> is illustratively a monolithic component formed to include a rail receiver <NUM>, a fork <NUM>, a cam block <NUM>, and a hook <NUM> as shown in <FIG> and <FIG>. Rail receiver <NUM> is coupled to left rail <NUM>. Fork <NUM> is coupled to rail receiver <NUM> and is configured to support left front wheel <NUM> for rotation relative to wheel support <NUM>. Cam block <NUM> is coupled to fork <NUM> and interacts with spreader plate 74P of wheel spreader <NUM> of front linkage <NUM> of load-carrier mode changer <NUM> when left front wheel <NUM> is moved from the folded storage position to the unfolded rolling position. Hook <NUM> extends from cam block <NUM> and is configured to receive base pusher <NUM> when base pusher <NUM> is in the stored position as shown in <FIG> and <FIG> so that base pusher <NUM> is held in place relative to rolling base <NUM>.

Right front wheel unit <NUM> is similar to left front wheel unit <NUM> and includes a brace bracket <NUM> coupled right rail <NUM>, a wheel support <NUM> coupled to right rail <NUM> for movement about right wheel axis 38A, and a right front wheel <NUM> coupled to wheel support <NUM>. A wheel-bias spring <NUM> is coupled to right rail <NUM> and to wheel support <NUM>. Wheel-bias spring <NUM> is arranged to extend around a portion of right rail <NUM> and to engage brace bracket <NUM> and wheel support <NUM> to bias wheel support <NUM>, along with right front wheel <NUM>, toward the folded storage position as shown in <FIG>, <FIG>.

Wheel support <NUM> of right front wheel unit <NUM> illustratively is a monolithic component formed to include a rail receiver <NUM>, a fork <NUM>, a cam block <NUM>, and a hook <NUM> as shown in <FIG> and <FIG>. Rail receiver <NUM> is coupled to right rail <NUM>. Fork <NUM> is coupled to rail receiver <NUM> and is configured to support right front wheel <NUM> for rotation relative to wheel support <NUM>. Cam block <NUM> is coupled to fork <NUM> and interacts with spreader plate 74P of wheel spreader <NUM> of load-carrier mode changer <NUM> when right front wheel <NUM> is moved from the folded storage position to the unfolded rolling position. Hook <NUM> extends from cam block <NUM> and is configured to receive base pusher <NUM> when base pusher <NUM> is in the collapsed storage position as shown in <FIG> and <FIG> so that base pusher <NUM> is held in place relative to rolling base <NUM>.

Base pusher <NUM> illustratively includes a push handle <NUM> and an outrigger wheel unit <NUM> as shown, for example, in <FIG>. Push handle <NUM> is coupled to load-support frame <NUM> of rolling base <NUM> for movement about base-pusher pivot axis 14A. Outrigger wheel unit <NUM> is coupled to push handle <NUM> for movement with push handle <NUM> about base-pusher pivot axis 14A and illustratively includes a left caster <NUM>, a right caster <NUM>, and a caster-support rail <NUM> arranged to interconnect left caster <NUM> and right caster <NUM>. Base pusher <NUM> pivots about base-pusher pivot axis 14A from the stored position, shown in <FIG>, to the upright cart position, shown in <FIG>, and to the laidback hand-truck position shown in <FIG>.

In the stored position shown in <FIG> and <FIG>, base pusher <NUM> is arranged to extend along load-support frame <NUM> of the rolling base <NUM> to cause load carrier <NUM> to be generally flattened for storage. More specifically, push handle <NUM> of base pusher <NUM> is arranged to extend over a portion of load-support frame <NUM> when base pusher <NUM> is in the stored position. Outrigger wheel unit <NUM> is arranged to lie generally outward of first end <NUM> of load-support frame <NUM> to cause left and right casters <NUM>, <NUM> to lie in a plane defined by load-support frame <NUM> when base pusher <NUM> is in the stored position as shown in <FIG>.

In the upright cart position shown in <FIG> and <FIG>, base pusher <NUM> is arranged to extend generally perpendicular to load-support frame <NUM> of rolling base <NUM> to cause load carrier <NUM> to provide a four-wheeled cart for transporting goods as shown in <FIG> and <FIG>. Push handle <NUM> is arranged to extend upwardly from load-support frame <NUM> away from an underlying floor <NUM> when base pusher <NUM> is in the upright cart position. Outrigger wheel unit <NUM> is arranged to extend downwardly from load-support frame <NUM> to cause left and right casters <NUM>, <NUM> to engage an underlying floor <NUM> when base pusher <NUM> is in the upright cart position.

In the laidback hand-truck position show in <FIG> and <FIG>, base pusher <NUM> is arranged to extend generally parallel to load-support frame <NUM> of rolling base <NUM> to cause load carrier <NUM> to provide a two-wheeled stand-up dolly for transporting goods as shown in <FIG> and <FIG>. Push handle <NUM> is arranged to extend generally parallel to and away from first end <NUM> of load-support frame <NUM> when base pusher <NUM> is in the laidback hand-truck position. Outrigger wheel unit <NUM> is arranged to extend generally parallel to and toward second end <NUM> of load-support frame <NUM> when base pusher <NUM> is in the laidback hand-truck position.

Load-carrier mode changer <NUM> illustratively includes a front linkage <NUM> and a rear linkage <NUM> as shown in <FIG> and <FIG>. Front linkage <NUM> is configured to move front wheels <NUM>, <NUM> from the folded storage position to the unfolded rolling position in response to movement of base pusher <NUM> from the stored position to the upright cart position as shown in <FIG>, <FIG>. Rear linkage <NUM> is configured to hold base pusher <NUM> in either the upright cart position or in the laidback hand-truck position relative to load-support frame <NUM> as shown in <FIG> and <FIG>.

Front linkage <NUM> illustratively includes a wheel spreader <NUM> comprising a spreader plate 74P and wheel links <NUM>, <NUM>, and a slidable spreader driver <NUM> as shown in <FIG> and <FIG>. Spreader plate 74P of wheel spreader <NUM> is configured to engage cam blocks <NUM>, <NUM> of left and right front wheel units <NUM>, <NUM> to push units <NUM>, <NUM> and front wheels <NUM>, <NUM> in those units <NUM>, <NUM> from the folded storage position to the unfolded rolling position as shown in <FIG>. Spreader plate 74P of wheel spreader <NUM> is received in LOCK (channel) sections <NUM>, <NUM> formed in hooks <NUM>, <NUM> attached to corresponding front wheels <NUM>, <NUM> when front wheels <NUM>, <NUM> are moved to the unfolded-rolling position to hold the front wheels <NUM>, <NUM> in the unfolded-rolling position and to brace the front wheels <NUM>, <NUM> during use of the load carrier <NUM>. Wheel links <NUM>, <NUM> are pivotably coupled to spreader plate 74P to pivot relative to spreader plate 74P and to slidable spreader driver <NUM> to pivot relative to slidable spreader driver <NUM>. Slidable spreader driver <NUM> is coupled to load-support frame <NUM> to slide along load-support frame <NUM>.

Rear linkage <NUM> includes a spreader-driver retainer <NUM>, pivotable pusher rotator <NUM>, and push rod 86P, as shown, for example, in <FIG> and <FIG>. Slidable spreader driver <NUM> is coupled to load-support frame <NUM> to slide relative to load-support frame <NUM> and to base pusher <NUM> through rear linkage <NUM>. Slidable spreader driver <NUM> facilitates movement of base pusher <NUM> from the stored position to the upright cart position as shown in <FIG>. Spreader-driver retainer <NUM> is configured to block or allow movement of slidable spreader driver <NUM> along load-support frame <NUM>. Rear linkage <NUM> is coupled to slidable spreader driver <NUM> and to base pusher <NUM> to interconnect slidable spreader driver <NUM> and base pusher <NUM>. Rear linkage <NUM> facilitates movement of base pusher <NUM> relative to slidable spreader driver <NUM> and load-support frame <NUM> from the upright cart position to the laidback hand-truck position as shown in <FIG>.

Spreader-driver retainer <NUM> illustratively includes a left spring pin <NUM>, a right spring pin <NUM>, and a pin release <NUM> as shown in <FIG> and <FIG>. Left spring pin <NUM> is coupled to left rail <NUM> of load-support frame <NUM> and right spring pin <NUM> is coupled to right rail <NUM> of load-support frame <NUM>. Left and right spring pins <NUM>, <NUM> extend into corresponding left and right pin receivers <NUM>, <NUM> formed in slidable spreader driver <NUM> when base pusher <NUM> is moved to the upright cart position from the stored position as shown in <FIG>, <FIG>. When spring pins <NUM>, <NUM> are received in pin receivers <NUM>, <NUM>, slidable spreader driver <NUM> is blocked from movement along load-support frame <NUM>. Pin release <NUM> is configured to push pins <NUM>, <NUM> out of pin receivers <NUM>, <NUM> when a user is ready to move base pusher <NUM> back from the upright cart position to the stored position.

Pin release <NUM> illustratively includes left and right pin pushers <NUM>, <NUM>, a button <NUM>, and a bias spring <NUM> as shown in <FIG>. Left and right pin pushers <NUM>, <NUM> are mounted to slidable spreader driver <NUM> to slide outwardly in response to a user pressing button <NUM> to cause pins <NUM>, <NUM> to be pushed out of pin receivers <NUM>, <NUM> formed in slidable spreader driver <NUM> as shown, for example in <FIG>. Button <NUM> is coupled to slidable spreader driver <NUM> for movement relative to slidable spreader driver <NUM> from a disengaged position allowing left and right pin pushers <NUM>, <NUM> to be moved inwardly by pins <NUM>, <NUM> to an engaged position pushing left and right pin pusher <NUM>, <NUM> outwardly. Bias spring <NUM> is arranged to lie between slidable spreader driver <NUM> and button <NUM> to bias button <NUM> to the disengaged position.

Rear linkage <NUM> includes slider links <NUM>, <NUM> and pusher links <NUM>, <NUM> as shown in <FIG> and <FIG>. Slider links <NUM>, <NUM> are coupled to slidable spreader driver <NUM> to pivot relative to slidable spreader driver <NUM>. Pusher links <NUM>, <NUM> are pivotably coupled to both a corresponding slider link <NUM>, <NUM> and base pusher <NUM> to pivot relative to both the corresponding slider link <NUM>, <NUM> and base pusher <NUM>. Pusher rotator <NUM> of rear linkage <NUM> moves between a FIRST POSITION when base pusher <NUM> is in the upright cart position and a SECOND POSITION when base pusher <NUM> is in the laidback hand-truck position. When the pusher rotator <NUM> is in the FIRST POSITION, slider links <NUM>, <NUM> extend from slidable spreader driver <NUM> toward the base pusher <NUM> as shown in <FIG>. When the pusher rotator <NUM> is in the SECOND POSITION, slider links <NUM>, <NUM> extend from slidable spreader driver <NUM> away from the base pusher <NUM> as shown in <FIG>.

To move load carrier <NUM> from flat-storage mode to cart-pusher mode, as shown in <FIG>, a user pivots base pusher <NUM> about base-pusher pivot axis 14A from the stored position to the upright cart position in a first direction as suggested by arrow <NUM> in <FIG>. In response to movement of base pusher <NUM>, slidable spreader driver <NUM> is moved along load-support frame <NUM> in a forward direction as suggested by arrow <NUM> until spreader-driver retainer <NUM> blocks further movement of slidable spreader driver <NUM> along load-support frame <NUM> as suggested in <FIG>. Also, in response to movement of base pusher <NUM>, front wheels <NUM>, <NUM> are moved about axes 36A, 38A as suggested by arrows <NUM>, <NUM> to move from the folded storage positions to the unfolded rolling positions as shown in <FIG>. The user may also move toe-plate shelf <NUM> to the active extended position from the inactive flat position if it is desired.

To move load carrier <NUM> from <NUM>-wheel cart mode to <NUM>-wheel hand-truck mode, as shown in <FIG>, a user moves the pusher rotator <NUM> from the FIRST POSITION to the SECOND POSITION as suggested by arrow <NUM> in <FIG> to cause base pusher <NUM> to pivot about base-pusher pivot axis 14A in the first direction from the upright cart position to the laidback hand-truck position as suggested by arrow <NUM> in <FIG>. The user may also move toe-plate shelf <NUM> to the active extended position from the inactive flat position if not already so moved.

To move load carrier <NUM> from <NUM>-wheel hand-truck mode to the <NUM>-wheel cart mode, a user moves pusher rotator <NUM> from the SECOND POSITION to the FIRST POSITION. This movement causes base pusher <NUM> to pivot about pusher axis 14A from the laidback hand-truck position to the upright cart position.

To move load carrier <NUM> from the <NUM>-wheel cart mode to the flat storage mode, a user first moves the toe-plate shelf <NUM> to the flat position if it was moved to the extended position previously. Next, the user presses button <NUM> of slider retainer <NUM> as suggested by arrow <NUM> in <FIG>. In response to the user pressing button <NUM>, pin pushers <NUM>, <NUM> are moved outward and push spring pins <NUM>, <NUM> out of slidable spreader driver <NUM> to free slidable spreader driver <NUM> to move along load-support frame <NUM>. The user then pivots base pusher <NUM> about base-pusher pivot axis 14A from the upright cart position to the stored position. As base pusher <NUM> moves from the upright cart position to the stored position, front-wheel mover <NUM> allows wheel-bias springs <NUM>, <NUM> to move front wheels <NUM>, <NUM> from the unfolded rolling positions to the folded storage positions.

Another illustrative load carrier <NUM> is shown in <FIG>. The load carrier <NUM> is substantially similar to the load carrier <NUM> shown in <FIG> and described herein. Accordingly, similar reference numbers in the <NUM>/<NUM> series indicate features that are common between the load carrier <NUM> and the load carrier <NUM>.

Unlike load carrier <NUM>, load carrier <NUM> includes a pusher rotator <NUM> having forward and aft locks <NUM>, <NUM> (rather than a single lock <NUM>). Pusher rotator <NUM> provides means for blocking or allowing movement of the links <NUM>, <NUM> between a first position, corresponding to the upright cart position of the base pusher <NUM>, and a second position, corresponding to the laidback hand-truck position of the base pusher <NUM>.

Pusher rotator <NUM> illustratively includes a handle <NUM>, a crossbar <NUM>, forward lock <NUM>, and aft lock <NUM> as shown in <FIG>. Handle <NUM> and crossbar <NUM> extend between and interconnect slider links <NUM>, <NUM>. Forward lock <NUM> is coupled to slidable spreader driver <NUM> along a side of slidable spreader driver <NUM> facing base pusher <NUM>. Aft lock <NUM> is coupled to slidable spreader driver <NUM> along another side of slidable spreader driver <NUM> facing toe-plate shelf <NUM>. Forward lock <NUM> is configured to engage handle <NUM> when links <NUM>, <NUM> are in a first position. Aft lock <NUM> is configured to engage handle <NUM> when shifter linkage <NUM> is in a second position.

Claim 1:
A collapsible load carrier (<NUM>) includes a rolling base (<NUM>) and a base pusher (<NUM>) mounted on the rolling base (<NUM>) for movement relative to the rolling base (<NUM>), the load carrier (<NUM>) comprising wheels that can be collapsed to assume a compact storage mode and that can be reconfigured in the field by a user to function in two operating modes, e.g. front-and-rear- wheel cart mode and <NUM>-wheel hand-truck mode,
wherein a left front wheel unit (<NUM>) includes a left brace bracket (<NUM>) coupled to left rail (<NUM>), a left wheel support (<NUM>) coupled to left rail (<NUM>) for movement about left wheel axis (36A), and a left front wheel (<NUM>) coupled to left wheel support (<NUM>), wherein a left wheel-bias spring (<NUM>) is coupled to the left wheel-support rail (<NUM>) and to a left wheel support (<NUM>) including a left rail receiver (<NUM>), a left fork (<NUM>), and a left cam block (<NUM>), wherein the left wheel-bias spring (<NUM>) is arranged to extend around a portion of the left wheel-support rail (<NUM>) and to engage the left brace bracket (<NUM>) and the left wheel support (<NUM>) to bias the left wheel support (<NUM>), along with the left front wheel (<NUM>), toward the folded storage position.