HAND TRUCK

Abstract

A hand truck (10) comprises a frame (12), a platform (14) for carrying a load, an axle (26), two wheels (16) mounted on the axle (26), axle guide members (42), and biasing means (30). The axle (26) is moveable along the axle guide members (42) to move the axle (26) relative to the platform (14). The biasing means (30) compresses to resist tilting of the hand truck (10).

Claims

1. A hand truck, comprising: a frame; a platform for carrying a load; an axle; at least one wheel mounted on the axle; axle guide means; and biasing means, wherein at least a portion of the axle is moveable along the axle guide means to move the axle relative to the platform, and wherein the biasing means is configured to be compressed by tilting the frame towards a surface on which the hand truck is disposed to bias the axle away from the platform.

2. The hand truck of claim 1, wherein the biasing means is further configured to become incompressible responsive to tilting of the hand truck, thereby providing a hard stop.

3. The hand truck of claim 1, wherein the axle guide means defines a channel in which at least a portion of the axle is slideable.

4. The hand truck of claim 3, wherein the axle is journaled in an axle sleeve and at least a portion of the axle sleeve is slideable in the channel.

5. The hand truck of claim 1, wherein the biasing means is attachable to the axle and at least one of: i. the frame; ii. the platform; and iii. the axle guide means.

6. The hand truck of claim 1, wherein the biasing means is arranged inside the axle guide means.

7. The hand truck of claim 1, wherein the biasing means comprises at least one spring.

8. The hand truck of claim 7, further comprising tensioning means for adjusting the tension of said at least one spring.

9. The hand truck of claim 8, wherein said tensioning means comprises at least one screw.

10. The hand truck of claim 1, wherein the biasing means is releasably attachable.

11. The hand truck of claim 1, further comprising at least one protrusion, located on the platform, wherein the protrusion is arranged to grip a portion of a load in use.

12. The hand truck of claim 1, wherein the platform is releasably attachable to the frame.

13. (canceled)

14. The hand truck assembly of claim 19, wherein the platform is releasably attachable to the frame.

15. The hand truck of claim 2, wherein the axle guide means defines a channel in which at least a portion of the axle is slideable.

16. The hand truck of claim 2, wherein the biasing means is attachable to the axle and at least one of: i. the frame; ii. the platform; and iii. the axle guide means.

17. The hand truck of claim 2, wherein the biasing means is arranged inside the axle guide means.

18. The hand truck of claim 2, wherein the biasing means comprises at least one spring, and wherein the hand truck further comprises tensioning means for adjusting the tension of said at least one spring.

19. A hand truck assembly, comprising: a hand truck, including a frame, a platform for carrying a load, an axle, at least one wheel mounted on the axle, axle guide means, and biasing means, wherein at least a portion of the axle is moveable along the axle guide means to move the axle relative to the platform, and wherein the biasing means is configured to be compressed by tilting the frame towards a surface on which the hand truck is disposed to bias the axle away from the platform; and at least one rigid rod, attachable to the axle and at least one of: i. the frame; ii. the platform; and iii. the axle guide means.

20. The hand truck assembly of claim 19, wherein the biasing means is further configured to become incompressible responsive to tilting of the hand truck, thereby providing a hard stop.

21. The hand truck assembly of claim 19, wherein the biasing means comprises at least one spring, and wherein the hand truck further includes tensioning means for adjusting the tension of said at least one spring.

Description

[0042] Embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:

[0043] FIG. 1 shows a side view of a hand truck of a first embodiment of the present invention in an upright position;

[0044] FIG. 2 shows a close-up perspective view of the hand truck of FIG. 1 in the upright position;

[0045] FIG. 3 shows a side view of the hand truck of FIG. 1 in a tilted position;

[0046] FIG. 4 shows a close-up perspective view of the hand truck of FIG. 1 in the tilted position;

[0047] FIG. 5 shows a perspective view of a second embodiment of the present invention;

[0048] FIG. 6 shows a perspective view of a third embodiment of the present invention;

[0049] FIG. 7 shows a perspective view of a fourth embodiment of the present invention; and

[0050] FIG. 8 shows a perspective view of a fifth embodiment of the present invention.

[0051] 10: hand truck [0052] 12: frame [0053] 14: platform [0054] 16: wheels [0055] 18: handle [0056] 20: struts [0057] 22: U-shaped portions [0058] 24: aperture [0059] 26: axle [0060] 28: axle sleeve [0061] 30: springs [0062] 32: first ends of springs [0063] 34: face of axle sleeve [0064] 36: second ends of springs [0065] 38: end plates [0066] 40: inside surfaces of U-shaped portions [0067] 42: axle guide means [0068] 44: axle guide members [0069] 46: inner surfaces of axle guide members [0070] 48: outer surfaces of the axle sleeve [0071] 50: cover plates [0072] 52: channels [0073] 54: protrusion [0074] 56: spring tensioning screw

[0075] Referring to FIGS. 1 to 4, a hand truck 10 according to a first embodiment of the present invention is shown. FIGS. 1 and 2 show the hand truck 10 in an upright position, in which the hand truck 10 is ready to receive a load, while FIGS. 3 and 4 show the hand truck 10 in a tilted position, in which the hand truck is either ready to be moved or is in the process of being moved by a user.

[0076] The hand truck 10 is shown having a frame 12, a platform 14 for receiving and carrying a load at an end of the frame 12, and two wheels 16 rotatable about axle 26.

[0077] The frame 12 has a handle 18 at an end of the frame 12 distant from the platform 14, a number of laterally-arranged struts 20 for providing support to a load, and two U-shaped portions 22 extending outwardly from the frame 12 on a side of the frame 12 opposite the platform 14. In an embodiment, the U-shaped portions 22 are mirror-images of one another. The U-shaped portions 22 are shown each having an aperture 24 for passage of an axle 26. The apertures are shown having an elongate shape.

[0078] The hand truck 10 is shown having two wheels 16 arranged on an axle 26. The axle 26 is shown journaled through an axle sleeve 28 of square cross-section. Axle sleeves of other cross-section shapes are possible, and cross-section shapes having one or more flat faces for engagement with the one or more springs or other biasing means present a greater surface area for more stable engagement. The axle 26 is shown passing through the elongate apertures 24 of the respective U-shaped portions 22 of the frame 12.

[0079] Biasing means in the form of two springs 30 are shown located at opposite ends of the axle sleeve 28. Springs 30 are formed from metal. First ends 32 of the two springs 30 are attached to a face 34 of the axle sleeve 28. Second ends 36 of the two springs 30 are attached to respective end plates 38 which are fixed to, and protrude inwardly from, the corresponding U-shaped portions 22. The biasing means 30 is configured to be compressed by tilting the frame 12 towards a surface on which the hand truck is disposed, such as the ground, to bias the axle 26 away from the platform 14.

[0080] It should be understood that biasing means other than coil springs could be used. For example, gas springs or rubber rods would also provide similar advantages to compressible metal springs.

[0081] Fixed to an inside surface 40 of each U-shaped portion 22 is an axle guide means 42 comprising two axle guide members 44 arranged either side of the axle sleeve 28 to define respective channels 52 such that the inner surfaces 46 of the axle guide members 44 are proximal to respective outer surfaces 48 of the axle sleeve 28. The axle guide members 44 are arranged on each respective U-shaped portion 22 so as to guide the axle sleeve 28 to move along the axle guide members 44 so that the axle sleeve 28 slides along the channels 52. The springs 30 are shown positioned between each respective pair of axle guide members 44 within respective channels 52, where the end plates 38 to which the springs 30 are attached are shown located adjacent respective ends of the pairs of axle guide members 44.

[0082] Referring to FIGS. 2 and 4, cover plates 50 are shown located adjacent respective pairs of axle guide members 44, slidably received in grooves thereof and adjacent the axle sleeve 28 so as to enclose the respective springs 30. As illustrated by a comparison of FIGS. 2 and 4, the cover plates 50 are arranged to be fixed relative to the axle sleeve 28 and to be moveable relative to the axle guide members 44.

[0083] Referring to FIGS. 2, 4 and 5 a spring tensioning means in the form of spring tensioning screw 56 is provided for each spring 30. The spring tensioning screw 56 can be rotated to adjust the tension of springs 30. If the springs are tensioned to their fullest extent so that they are unable to compress any further, the hand truck effectively becomes a standard hand truck. In this condition, the platform 14 is lifted to its fullest extent from the ground which is useful for moving along bumpy ground.

[0084] Alternatively, if spring tensioning screw 56 is rotated such that the spring is at its least compressed condition, this provides a large amount of cushioning when moving a load. If a user wishes to move a load up and down stairs, depending on the weight of the load, the spring tensioning screw 56 can be rotated to provide a required level of cushioning for a weight of load that assists in moving up and down stairs. For example, for a light load, it has been found that a small amount of tensioning is useful. On the other hand, for a heavy load, a large amount of spring tensioning can be chosen by rotation of the spring tensioning screw 56. A large amount of pre-tensioning in the spring also makes it more difficult to tilt the hand truck.

[0085] While this embodiment of the present invention is shown and described as having two springs, it is to be understood that further embodiments having one spring, or more than two springs, or no spring, are possible.

[0086] Referring to FIG. 5, a second embodiment of the present invention is shown in the form of a hand truck 10 having a frame 12 and a platform 14. The platform has a protrusion 54 protruding upwardly from the platform 14 for gripping a portion of a gas canister when the gas canister is loaded onto and transported by the hand truck 10.

[0087] Referring to FIGS. 6 to 8, third, fourth, and fifth respective embodiments of the present invention are shown. Each of these embodiments is in the form of a hand truck 10 having a frame 12 and platform 14, wherein each platform 14 is releasably attachable to the frame 12, and is otherwise substantially identical to the first embodiment. However, it is to be understood that the second embodiment may also have a releasably attachable platform.

[0088] In use, a load is placed on the platform 14 while the hand truck 10 is in the upright position. A user, wanting to transport the load, pulls the handle 18 of the hand truck 10 so as to rotate the hand truck 10 from the upright position to a tilted position at an angle suited to the user. As the hand truck 10 is tilted by the application of a moment by a user, the axle 26 moves along the axle guide members 44 toward the frame 12 whilst compressing springs 30, and therefore toward the load. This causes the fulcrum of the rotation to be moved toward the frame 12, and therefore toward the load. As a result of moving the fulcrum closer to the load, the moment required to lift the load during rotation is reduced for a given load, thereby reducing the magnitude of force a user is required to provide in order to tilt the hand truck 10 from the upright to the tilted position.

[0089] In the tilted position as shown in FIGS. 3 and 4, the spring travel in the axle guide means 42 can be chosen to be sufficient such that the hand truck can come to rest in a tilted position without being held by the user in which the hand truck is supported on the ground by the edges of U-shaped portions 22. This provides the advantage that the hand truck can be left in a condition ready for removal. When a load has been moved to a required location, a user pushing handle 18 upwardly is assisted by the restoring force of the springs 30 moving from their compressed to uncompressed conditions.

[0090] Springs of different strengths can be used to tailor the biasing force resisting relative motion of the axle sleeve 28 and the load. For example, no spring may be used, thereby minimising the moment required to tilt a given load and enabling a greater tilt angle for transport by a shorter or less strong user, or a stiff spring may be used, to enable a stronger or taller user to transport the load at a lesser tilt angle.

[0091] Furthermore, springs of different strengths and shapes may be selected to tailor at what combination of load and tilting angle the hard stop of the spring is reached. The springs further serve as suspension when transporting the hand truck over bumpy ground or up or down stairs, increasing the comfort and safety of the user. Furthermore, one or more rigid rods, such as metal bars, of appropriate dimensions can be placed between the axle sleeve 28 and one or more of the end plates 38 to prevent relative motion of the axle sleeve 28 and the load.

[0092] During a demonstration comparing two examples of the present invention, wherein the first of the two examples had two rigid rods placed along the axle guide members 44 to prevent relative motion of the axle sleeve 28 and the load and the second of the two examples replaced the rigid rods with springs 30, it was found that the force required to lift a given load and tilt the hand truck 10 to a given angle was reduced from 20 Newtons in the case of the first examples to 8 Newtons in the case of the second.

[0093] It will be appreciated by those skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departing from the scope of the invention as defined by the appended claims. For example, the wheels of the hand truck can be mounted on farther apart from one another on the axle to increase the stability of the hand truck.