Abstract
A hand truck includes a base plate assembly that can rotate between an extended position and a retracted position. The base plate assembly includes a base plate and upright extending base plate brackets. At least one of the base plate brackets comes into contact at least indirectly with the frame when the base plate assembly is rotated to the extended position. A biased lock and release member is mounted at least indirectly to the frame. The lock and release member is arranged to rotate to an open position against its bias when pressed upon by the base plate bracket. The base plate bracket is secured when the lock and release member returns to its closed position. If the lock and release member is pressed to the open position, the base plate bracket is released and the base plate assembly may be rotated to the retracted position.
Claims
1. A hand truck comprising: a hand truck frame and a base plate assembly that is rotatably mounted to the hand truck frame such that it can rotate between a first, extended position and a second, retracted position, the base plate assembly including a base plate and at least two upright extending base plate brackets, at least one of the base plate brackets arranged for coming into arresting contact with the hand truck frame when the base plate assembly is rotated to the first extended position, a biased lock and release member that is mounted at least indirectly to the hand truck frame, the lock and release member being arranged to rotate to an open position against its bias when pressed upon by the at least one base plate bracket, thereby allowing the base plate bracket to be received and then secured when the lock and release member returns to its closed position and such that when the lock and release member is manually pressed to the open position, the base plate bracket is released thereby allowing the base plate assembly to be rotated to the second, retracted position.
2. A retractable base plate mechanism for a hand truck having a frame and a base plate that is rotatably mounted to the frame, the base plate mechanisms comprising: a trap and release arrangement that is able to receive and trap a base plate member that is fixed to the base plate when the base plate is rotated from a retracted position to an operating extended position, the trap and release arrangement including a biased member that is able to move against its bias when pressed upon by the base plate member to allow passage of the base plate member to a base plate member stopping position as the base plate reaches the extended position, the base plate member stopping position being defined by a stop feature that is fixed relative to the hand truck frame, the biased member the capture and release arrangement also being able to move in response to its bias and return to a trapping position, thereby trapping the base plate member between the biased member and the fixed stop feature of the hand truck frame.
3. The retractable base plate mechanism of claim 2, wherein, the biased member of the trap and release arrangement also presents at least one feature that may be pressed upon by an operator so as to release the trapping of the base plate member thereby allowing the base plate to be rotated to from the extended operating position to the retracted position.
4. The retractable base plate mechanism of claim 3, wherein, the biased member of the trap and release arrangement is rotatably mounted at least indirectly to the frame and is biased to rotate toward a position that is suitable for trapping the base plate member.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a first perspective view of a hand truck that includes one embodiment of a retractable base plate lock and release mechanism.
[0010] FIG. 2 is an enlarged perspective view of the one embodiment of the retractable base plate mechanism taken from view indication 2 in FIG. 1.
[0011] FIG. 3 is a second perspective view of the hand truck showing the one embodiment of the retractable base plate lock and release mechanism.
[0012] FIG. 4 is an enlarged perspective view of the one embodiment of the retractable base plate mechanism taken from view indication 4 in FIG. 3.
[0013] FIG. 5 is a side view of the hand truck showing the one embodiment of the retractable base plate lock and release mechanism.
[0014] FIG. 6 is an enlarged side view of the one embodiment of the retractable base plate mechanism taken from view indication 6 in FIG. 5.
[0015] FIG. 7 is a first enlarged side view of the one embodiment of the retractable base plate mechanism showing the base plate assembly in the first extended position and showing the lock and release mechanism in the first closed, securing position.
[0016] FIG. 8 is a second enlarged side view of the one embodiment of the retractable base plate mechanism showing the base plate assembly in an intermediate position that is rotated away from the first extended position and showing the lock and release mechanism in a second open releasing position.
[0017] FIG. 9 is a third enlarged side view of the one embodiment of the retractable base plate mechanism showing the base plate assembly in a retracted position and showing the lock and release mechanism in the first closed position.
DETAILED DESCRIPTION
[0018] Referring to the drawings, FIG. 1 shows an example of a multi-position hand truck 1 that includes a retractable base plate assembly 10. Hand truck 1, in this example, is a hand truck that includes a frame 5 and a handle assembly 7 as well as two main wheels 1W (one of which has been removed from FIGS. 1-9 for clarity of illustration) which are mounted to a main wheel axel 1A that, in turn, is supported by opposite spaced wheel brackets 5B. In this example, handle assembly 7 is able to be reconfigured rapidly for at least two configurations, namely, a first upright dolly configuration as shown in FIGS. 1, 3, and 5 and a second cart configuration (not shown) in which frame 5 is generally horizontal and handle assembly 7 is fully extended and rotated so that handle assembly 7 is perpendicular to the end of frame 5 opposite the main wheels 1W with a set of secondary wheels which are mounted to the lower end of handle assembly 7 supporting the end of frame 5 that is opposite main wheels 1W. An example of a multi-position handle arrangement for a hand truck is shown and described in U.S. Pat. No. 10,864,933 which is incorporated herein by reference.
[0019] One embodiment of a retractable and extendible hand truck base plate assembly 10 includes a base plate assembly 12 and a securing and releasing portion 30. Base plate assembly 12 includes a base plate 14 and two base plate brackets 16 that are fixed to base plate 14. Base plate brackets 16 are spaced apart and are oriented to extend normally from the upper surface of base plate 14. As can be best seen in FIGS. 2 and 6, in this example, base plate bracket 16 includes a relatively wide lower body portion 16B and a relatively slender upper finger portion 16F that extends away from body portion 16B in a direction that is generally normal to base plate 14. Securing and releasing portion 30 includes a frame bracket 32 and a securing and releasing member 34 which will be described in greater detail below.
[0020] Base plate assembly 12 is mounted to the lower end of frame 5 so that it is able to rotate with respect to frame 5 about axis A1 which is indicated in FIG. 2 between a first, extended position as shown in FIGS. 1-7 and a second retracted position as shown in FIG. 9. In this example, base plate brackets 16 are both mounted in a rotating fashion for rotation about a common transverse axis A1. Because base plate brackets 16 are fixed to base plate 14, all of base plate assembly 12 rotates with base plate brackets 16 between the extended and retracted positions shown in FIGS. 7 and 9 respectively.
[0021] As noted above and as is best shown in FIGS. 2 and 4, securing and releasing portion 30 includes a frame bracket 32 and lock and release member 34. At least one frame bracket 32 is fixed to at least one of the side members of truck frame 5 as is best shown in FIGS. 2, 4 and 6. Frame bracket 32 presents a flat surface 32A which faces toward lock and release member 34.
[0022] In this example, lock and release member 34 is rotatably mounted to main wheel axel 1A and, in this example, is mounted adjacent to wheel bracket 1B. As can be most easily seen in FIG. 4, lock and release member 34 presents a surface 34E which is arranged to come into contact with the upper edge of wheel bracket 1B. In this example, lock and release member 34 is biased by a spring (not shown) that connects between lock and release member 34 and wheel bracket 1B. The spring (not shown) biases lock and release member 34 in the clockwise direction when viewed from the perspective of FIGS. 5-9. Thus, lock and release member 34, if acted on primarily by the spring bias, will rotate clockwise (as viewed from the perspective of FIGS. 5-9) from the open position shown in FIG. 8 to the closed position shown in FIGS. 1-7 and 9 until surface 34E comes into contact with the upper edge of wheel bracket 1B. However, if sufficient manual pressure is applied to at least one of two tabs 34T1 or 34T2 which extend from the body of lock and release member 34, then lock and release member 34 may be rotated counter-clockwise against its spring bias from the closed position shown in FIGS. 1-7, and 9 and toward the open position shown in FIG. 8.
[0023] The operation of lock and release member 34 may be best understood by referring to FIGS. 7-9 while also consulting FIGS. 2, 4 and 6. FIGS. 2, 4, 6 and 7 show lock and release member 34 in the closed position and base plate assembly 12 in the extended position such that the upper finger portion 16F of base plate bracket 16 is captured between frame bracket 32 and lock and release member 34. FIGS. 7-9 show how the finger portion 16F of base plate bracket 16 may be released so that base plate assembly 12 may be rotated from the extended (operating) position shown in FIG. 7 to the retracted position shown in FIG. 9. The configuration shown in FIG. 8 may be initiated by applying manual pressure to either tab 34T1 or 34T2 to rotate lock and release member 34 counter-clockwise (from the perspective of FIGS. 7-9) against its spring bias so as to allow the finger portion 16F of base plate bracket 16 to pass under a curved lower surface 34C (See FIG. 6) of lock and release member 34 and then be further rotated to the retracted position shown in FIG. 9. Tab 34T1 is adapted to be accessible to the foot of an operator for applying pressure to tab 34T1 particularly when the hand truck is in an upright position. Tab 34T2 is adapted to be accessible to the hand or fingers of an operator who might reach though the truck frame to release the base plate assembly in order to fold up the base plate assembly and may be most accessible and useful when hand truck 1 is in a horizontal cart position.
[0024] When FIGS. 7-9 are viewed in reverse order, it is possible to understand how base plate assembly 12 may be rotated from the retracted position shown in FIG. 9 to the extended, operating position shown n FIG. 7. As base plate assembly 12 is rotated clockwise (as seen from the perspective of FIGS. 7-9) until the finger portion 16F of base plate bracket 16 comes into contact with curved lower surface 34C of lock and release member 34. The application of manual pressure by an operator on base plate assembly 12 causes finger portion 16F of base plate bracket 16 to press against lower surface 34C of lock and release member 34 causing lock and release member 34 to rotate counter-clock-wise (as viewed in FIG. 8) against its bias such that base plate bracket 16 and lock and release member 34 reach the relative positions shown in FIG. 8. The continued application of manual pressure to base plate assembly 12 causes finger portion 16F of base plate bracket 16 to pass under lock and release member 34 and come into contact with a surface 32S of frame bracket 32. When base plate bracket 16 comes into contact with frame bracket 32 (or at least in very close proximity) there is no longer any interference to hinder lock and release member 34 from rotating clockwise in response to its spring bias into the closed position shown in FIG. 7. Lock and release member 34 also presents a surface 34S which is generally parallel to surface 32S of frame bracket 32. Surfaces 32S and 34S as well as the features of the finger portion 16F of base plate bracket 16 are arranged so that finger portion 16F of base plate bracket 16 is captured between surfaces 34S and 32S until an operator applies manual force upon one of the protruding tabs (34T1 or 34T2) of lock and release member 34 to rotate lock and release member 34 to the open position shown in FIG. 8.
[0025] As can be understood from the above description, retractable base plate mechanism 10 provides an easy-to-use capture and release arrangement that is able to receive and capture a base plate member that is fixed to a hand truck base plate (or toe plate) merely by swinging the base plate from a retracted position to an operating extended position. The capture and release arrangement includes a biased lock and release member that is biased to move between an open position to a closed position, and which can be moved from the closed position to the open position either by manual pressure against its bias or if pressed upon by the base plate member if the base plate is being rotated from its retracted position to its extended operating position. If the base plate is in the extended operating position, the base plate member is able to be captured and held in place because, when the biased lock and release member moves into the closed position, the base plate member is constrained on one side by the biased lock and release member and on its opposite other side at least indirectly by a portion of the hand truck frame. The same mechanism also presents features that may be manually pressed upon by an operator so as to release the base plate member thereby allowing the base plate to be rotated from the extended operating position to the retracted position. Thus, it is possible for an operator to quickly extend and secure the base plate in an operating position or retract the base plate to a folded position with simple and intuitive actions.
[0026] It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof.
