Title:
Adjustable platform for a stepladder
Kind Code:
A1


Abstract:
An adjustable platform for a stepladder can be raised by simply lifting the platform manually, and the platform automatically stays there after being released. For safety, strength and stability, the platform is supported by two extendable rods. Even though there are two rods and two clamps for holding them, a single worker can still release and lower the platform at a controlled rate of descent. To do this, the clamps are of a particular design and are strategically positioned relative to the rods.



Inventors:
Vergote, Leo H. (Nixa, MO, US)
Application Number:
11/206876
Publication Date:
02/22/2007
Filing Date:
08/18/2005
Primary Class:
International Classes:
E04G3/00
View Patent Images:
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Primary Examiner:
CHAVCHAVADZE, COLLEEN MARGARET
Attorney, Agent or Firm:
ROBERT J. HARTER (LA CROSSE, WI, US)
Claims:
1. A tool for a stepladder with an uppermost step, comprising: a clamp assembly mountable to the stepladder and being manually selectively movable to a hold-position and a release-position; a pair of substantially parallel rods coupled to the clamp assembly in sliding relationship therewith; and a platform supported by the pair of substantially parallel rods and being manually selectively movable to a raised position and a lowered position such that: a. when the clamp assembly is in the hold-position, the clamp assembly permits the platform to be manually raised from the lowered position to the raised position but inhibits the platform from descending from the raised position to the lowered position; and b. when the clamp assembly is in the release-position, the clamp assembly permits the platform to be manually selectively raised and lowered.

2. The tool of claim 1, further comprising a spring coupled to the clamp assembly, wherein the spring urges the clamp assembly to the hold-position.

3. The tool of claim 1, further comprising a series of discrete gripping points disposed on the pair of substantially parallel rods, wherein the clamp assembly is strategically situated to engage the series of discrete gripping points to selectively hold the platform at a plurality of elevations.

4. The tool of claim 1, wherein the platform comprises a plastic base with a raised outer rim and a wooden top overlaying the plastic base, wherein the raised outer rim helps align the wooden top to the plastic base.

5. The tool of claim 1, further comprising a stop member coupled to at least one of the clamp assembly, the platform and the pair of substantially parallel rods, wherein the stop member ensures at least a minimum hand clearance exists between the platform and the uppermost step to avoid creating a hand-pinching hazard therebetween.

6. A tool for a stepladder with an uppermost step, the tool can be used by a user having a right-hand and a left-hand, the tool comprising: a RH sleeve mountable to the stepladder; a RH rod disposed in sliding relationship within the RH sleeve; a RH gripper coupled to the RH sleeve and being movable between a RH hold-position and a RH release-position such that RH gripper in the RH hold-position engages the RH rod so that the RH rod can move more freely upward than downward, and the RH gripper in the RH release-position permits the RH rod to move freely upward and downward; a RH lever coupled to the RH gripper and being movable relative to the RH sleeve between a RH lock-position and a RH unlock-position, wherein the RH gripper moves to the RH hold-position in response to the RH lever moving in a RH lock direction to the RH lock-position, and the RH gripper moves to the RH release-position in response to the RH lever moving in a RH unlock direction to the RH unlock-position; a RH spring coupled to the RH sleeve and the RH lever to urge the RH lever to the RH lock-position; a LH sleeve mountable to the stepladder; a LH rod disposed in sliding relationship within the LH sleeve; a LH gripper coupled to the LH sleeve and being movable between a LH hold-position and a LH release-position such that LH gripper in the LH hold-position engages the LH rod so that the LH rod can move more freely upward than downward, and the LH gripper in the LH release-position permits the LH rod to move freely upward and downward; a LH lever coupled to the LH gripper and being movable relative to the LH sleeve between a LH lock-position and a LH unlock-position, wherein the LH gripper moves to the LH hold-position in response to the LH lever moving in a LH lock direction to the LH lock-position, and the LH gripper moves to the LH release-position in response to the LH lever moving in a LH unlock direction to the LH unlock-position; a LH spring coupled to the LH sleeve and the LH lever to urge the LH lever to the LH lock-position; and a platform extending between and supported by the RH rod and the LH rod such that the platform moves vertically therewith, and wherein the RH unlock direction is at least one of a) downward, and b) toward the RH rod, and the LH unlock direction is at least one of a) downward, and b) toward the LH rod, so that the user can lower the platform by using the right-hand to both grip the RH rod and move the RH lever to the RH unlock-position and use the left-hand to both grip the LH rod and move the LH lever to the LH unlock-position, and the user can raise the platform, the RH rod and the LH rod by simply lifting the platform even while the RH lever is at the RH lock position and the LH lever is at the LH lock position.

7. The tool of claim 6, further comprising a series of discrete gripping points disposed along the RH and LH rods, wherein the RH and LH grippers engage the series of discrete gripping points to selectively hold the platform at a plurality of elevations.

8. The tool of claim 6, wherein the platform comprises a plastic base with a raised outer rim and a wooden top overlaying the plastic base, wherein the raised outer rim helps align the wooden top to the plastic base.

9. The tool of claim 6, wherein the RH and LH unlock directions are downward.

10. The tool of claim 6, wherein the RH gripper and the RH lever are an integral extension of each other, whereby the RH gripper and the RH lever comprise a unitary piece.

11. The tool of claim 6, wherein the RH and LH rods are situated between the RH and LH levers.

12. The tool of claim 6, further comprising a stop member coupled to at least one of the clamp assembly, the platform and the pair of substantially parallel rods, wherein the stop member ensures at least a minimum hand clearance exists between the platform and the uppermost step to avoid creating a hand-pinching hazard therebetween.

13. A method of using a tool that includes a platform supported by a RH rod and a LH rod, which in turn are coupled to a stepladder by way of a RH clamp assembly and a LH clamp, wherein the RH and LH clamp assemblies can be manually manipulated between a hold-position and a release-position, the method comprising: manually lifting the platform from a lowered position to a raised position while the RH and LH clamp assemblies are in the hold-position; manually releasing the platform; upon manually releasing the platform, automatically holding the platform at the raised position by virtue of the RH and LH clamp assemblies being at the hold-position; and manually gripping at least one of the RH rod and the LH rod while simultaneously moving the RH and LH clamp assemblies to the release-position so that the platform controllably descends back down to the lowered position.

14. The method of claim 14, wherein the step of automatically holding the platform at the raised position involves having the RH and LH clamp assemblies engage one of a plurality of discrete gripping points that are at a substantially fixed position relative to the platform.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention generally pertains to stepladders and more specifically to an extendable tool for such a ladder.

2. Description of Related Art

There are a variety of lift platforms that can be attached to a stepladder. A drawback of many of them is that the user needs to use one hand to raise the platform and another one to lock it in place. This may be fine when the platform is lightweight and unloaded; however, a heavier platform or one carrying a load may be difficult to lift with just one hand. Moreover, if the platform needs to be raised to a significant height, the user may need to stretch in an awkward manner between the platform and the locking mechanism.

U.S. Pat. No. 3,208,555 discloses a hoisting attachment for a ladder where a user operates a crank to raise and lower the platform. With a hoist, a user could conceivably raise the platform by simply turning the crank and not bother with stretching between the platform and the crank. If the user, however, does not manually hold the platform or steady the load as it rises, there is a risk that the load may accidentally slip off the platform, which could damage the load or injure the user.

Consequently, a need exists for a ladder-mounted lift platform that overcomes the drawbacks of current lift platforms.

SUMMARY OF THE INVENTION

An object of some embodiments of the invention is to provide a ladder-mounted platform where the platform can be readily raised by simply pushing the platform up, and the platform automatically stays at the elevated position without having to manually actuate a locking mechanism.

Another object of some embodiments is to support the platform with two extendable rods for stability and strength, and position each rod sufficiently close to a locking mechanism so that each hand of the user can simultaneously release the locking mechanism and grip one of the rods so that the platform can be lowered in a controlled manner.

Another object of the invention is to enable a user to simultaneously stand upon a lower step of a stepladder (thereby adding stability to the ladder), using one hand to grasp the side of the ladder (thereby stabilizing the user), and using the other hand to simultaneously 1) raise the platform 2) steady the load on the platform, and 3) lock the platform at the desired elevation.

Another object of the invention is to install a platform just above an uppermost step a stepladder so that the platform creates an obstruction that deters a user from stepping upon that uppermost step.

Another object of some embodiments is to support a raisable platform using square or rectangular tubes (as opposed to round ones) to ensure that grippers solidly engage discrete points on a facet of the tube.

Another object of some embodiments is to provide the platform or ladder-mounted tool with a stop member that ensures at least minimum hand clearance between the platform and the top step of the ladder to avoid creating a hand-pinching hazard therebetween.

Another object of some embodiments is to provide the ladder tool with clamp assembly that includes a spring for urging the clamp to a hold-position so that the clamp assembly automatically holds the platform at a raised position upon simply releasing the platform and clamp assembly.

Another object of some embodiments is to support the platform with two extendable rods that include an evenly distributed series of gripping points so that the clamp assembly can selectively engage the points to solidly hold the platform at a series of discrete elevations.

Another object of some embodiments is to provide a plastic platform with a raised outer rim to help contain a wooden top, wherein the wooden top can be readily replaced, cut, drilled, nailed into, or otherwise modified to meet the needs of the user.

Another object of some embodiments is to support the platform with two extendable rods and use a rod-locking mechanism with a lever that can unlock the rod-locking mechanism by pushing the lever down or towards an adjacent rod so that the user can readily and simultaneously grip a rod and move the lever to its unlock position with one hand.

Another object of some embodiments is to provide a ladder-mountable lift platform with a clamping mechanism that includes a rod-gripper and an actuating lever that extend integrally from each other to comprise a unitary piece, which can reduce product cost and increase reliability.

Another object of some embodiments is to place the platform-supporting rods between the locking levers so that a user can readily grip the rods and actuate the levers at the same time.

One or more of these and/or other objects of the invention are provided by a tool or method that enables a user to raise a ladder-mounted platform and automatically lock it into position by simply releasing the platform

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front view of a stepladder with a platform tool being manually raised.

FIG. 2 is a front view of the stepladder of FIG. 1 but showing the platform held at a raised position.

FIG. 3 is a front view of the stepladder of FIG. 1 but showing the platform being lowered.

FIG. 4 is a left side view of an upper portion of the stepladder of FIG. 1.

FIG. 5 is a cross-sectional front view of a RH side of the platform tool with the clamp assembly in a hold-position.

FIG. 6 is a cross-sectional view similar to FIG. 5 but showing the platform being lifted while the clamp assembly is in a hold-position.

FIG. 7 is a cross-sectional view similar to FIGS. 5 and 6 but showing the clamp assembly in a release-position that allows the platform to be freely raised or lowered.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-7 shows a tool 10 that can be attached to an uppermost step 12, which is above a second highest step 14, of a self-supporting stepladder 16. The term, “stepladder” refers to a self-standing generally triangular structure with a series of steps. Tool 10 includes a work platform 18 supported by two substantially parallel rods 20 (a RH rod 22 and a LH rod 24) that can be manually raised and lowered. Platform 18 can be used for holding tools, light fixtures, planks, boards, conduit, pipes, drywall, paint cans, a vise or clamp, and other parts. Tool 10 also includes a clamp assembly 26 that works in conjunction with rods 20 in such a way as to make it easy and safe to raise and lower platform 18. Clamp assembly 26 is movable between a hold-position (FIGS. 1, 2, and 4-6) and a release-position (FIGS. 3 and 7).

FIG. 1 shows a user 28 manually lifting platform 18 from a lowered position (FIG. 5) to a raised position (FIG. 2). While user 28 is lifting platform 18, clamp assembly 26 (which comprises a RH clamp assembly 30 and a LH clamp assembly 32) is in the hold-position. Even with clamp assembly 26 in the hold-position, platform 18 can be readily raised without significant resistance.

FIG. 2 shows that upon manually releasing platform 18, the platform generally stays at its raised position (or settles to a discrete point slightly below that) and does so automatically because clamp assembly 26 is in its hold-position even while platform 18 is rising. The term, “automatically” means that a clamp does not have to be manually manipulated in order for the platform to be held in place.

FIG. 3 shows how platform 18 can be lowered at a controlled rate of descent. With a right-hand 34, user 24 simultaneously grips RH rod 22 and pushes a RH lever 36 of RH clamp assembly 30 down to an unlock-position (RH unlock position), which moves RH clamp assembly 30 to its release position (RH release position, see also FIG. 7). Likewise, user 28 uses a left-hand 38, to simultaneously grip LH rod 24 and push a LH lever 40 of LH clamp assembly 32 down to an unlock-position (LH unlock position), which moves LH clamp assembly 32 to its release position (LH release position). Friction between the user's hands and rods 22 and 24 slow the decent of platform 18.

Although such operation can be achieved by various structural designs, details of one example of the invention are shown in FIGS. 4-7. The following description will be primarily with reference to the right-hand side of tool 10 (FIGS. 5-7), since the left-hand side (FIG. 4) has basically the same structure as the right side.

In this example of the invention, tool 10 comprises a base 42 that can be removably attached to uppermost step 12 by way of a fastener 44. A ring nut 46 fastens a RH sleeve 48 to base 42. A coupling 50 connects a tube 52 to RH sleeve 48, and a cap 54 can be fitted to the bottom end of sleeve 52. RH rod 22, in this example, is square tubing that slides within the generally cylinder pieces of sleeve 48, coupling 50 and tube 52. A bracket 56 connects an upper end of rod 22 to the underside of platform 18.

To hold RH rod 22 at various elevations, RH clamp assembly 30 includes a RH clamp housing 58, a RH gripper 60, a RH spring 62, and RH lever 36. RH lever 36 and RH gripper 60 can be integral extensions of each other, whereby RH lever 36 and RH gripper 60 comprise a unitary piece. A pin 64 allows RH lever 36 and RH gripper 60 to pivot relative to RH clamp housing 58. Spring 62 urges RH lever 36 in a RH lock direction (such as upward) to the RH lock-position and urges RH gripper 60 to a RH hold-position where RH gripper 60 engages RH rod 22 (FIGS. 5 and 6).

Manually pushing RH lever 36 in a RH unlock direction (such as downward) against the urging of RH spring 62 moves RH gripper 60 to the RH release position where RH gripper 60 disengages RH rod 22 as shown in FIG. 7.

To positively hold RH rod 22 at various discrete elevations, RH rod 22 includes a series of discrete gripping points 66 that can be solidly engaged by RH gripper 60. Gripping points 66 can be in the form of recesses or protrusions.

Cap 54 at the bottom of tube 52 provides a stop member that can limit the downward movement of tube 22, thereby ensuring that at least a minimum hand clearance exists between the underside of platform 18 and the top surface of uppermost step 12 to avoid creating a hand-pinching hazard therebetween. It should appreciated by those of ordinary skill in the art that a various other structures could provide a functionally equivalent stop member.

It should be noted that all of the named RH elements have an equivalent LH corresponding element. For instance, RH sleeve 48 corresponds to LH sleeve 48′, RH rod 22 corresponds to LH rod 24, RH gripper 60 corresponds to LH gripper 60′, the RH hold-position corresponds to the LH hold-position, the RH release-position corresponds to the LH release-position, the RH lock position corresponds to the LH lock position, the RH unlock-position corresponds to the LH unlock-position, the RH lock direction (e.g., upward) corresponds to the LH unlock direction (e.g., also upward), the RH unlock direction (e.g., downward) corresponds to the LH unlock direction (e.g., also downward), etc.

In some embodiments platform 18 comprises a plastic base 68 with a raised outer rim 72 and a wooden top 70 overlaying plastic base 68, wherein the raised outer rim 72 helps align wooden top 70 to plastic base 68. Wooden top 70 provides a convenient work surface that can be readily replaced, cut, drilled, nailed into, or otherwise modified to meet the needs of the user. Rim 72 is preferably less than 1.5-inches tall (inside vertical dimension) so that standard lumber having a 2-inch nominal thickness (1.5-inch actual thickness) can protrude above rim 72. Platform 18 can also be provided with various openings and cavities for holding an assortment of tools and parts.

Although the invention is described with reference to a preferred embodiment, it should be appreciated by those of ordinary skill in the art that various modifications are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the following claims.





 
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