Patent Grant
11498819
Certain aerial work platforms, known as scissor lifts, include a frame assembly that supports a platform. The platform is coupled to the frame assembly using a system of linked supports arranged in a crossed pattern, forming a scissor assembly. As the supports rotate relative to one another, the scissor assembly extends or retracts, raising or lowering the platform relative to the frame. Accordingly, the platform moves primarily or entirely vertically relative to the frame assembly. Scissor lifts are commonly used where scaffolding or a ladder might be used, as they provide a relatively large platform from which to work that can be quickly and easily adjusted to a broad range of heights. Scissor lifts are commonly used for painting, construction projects, accessing high shelves, changing lights, and maintaining equipment located above the ground.
One embodiment relates to a lift device including a base, a platform configured to support an operator, and a scissor assembly coupling the base to the platform. The scissor assembly includes an actuator configured to extend and retract the scissor assembly to move the platform between a fully raised position and a fully lowered position, a first scissor arm pivotally coupled to a second scissor arm, and a prop pivotally coupled to the first scissor arm such that the prop rotates about a lateral axis. The prop is configured to selectively engage an engagement surface defined by at least one of the second scissor arm and a protrusion coupled to the second scissor arm, thereby preventing the platform from reaching the fully lowered position.
Another embodiment relates to a lift device including a base, a platform configured to support an operator, and a scissor assembly coupling the base to the platform. The scissor assembly includes an actuator configured to extend and retract the scissor assembly to move the platform between a fully raised position and a fully lowered position, a first scissor arm pivotally coupled to a second scissor arm about a middle axis that extends laterally, a first rod coupled to the first scissor arm and aligned with a first lateral axis, a second rod coupled to the second scissor arm and aligned with a second lateral axis, and a prop pivotally coupled to the first rod such that the prop rotates about the first lateral axis. The prop is configured to selectively engage the second rod to limit downward movement of the platform. A straight line is defined between the first lateral axis and the second lateral axis, and a center of gravity of the prop is offset from the straight line when the prop engages the second rod.
Still another embodiment relates to a lift device including a base, a platform configured to support an operator, and a scissor assembly coupling the base to the platform. The scissor assembly includes an actuator configured to extend and retract the scissor assembly to move the platform between a fully raised position and a fully lowered position, a first scissor arm pivotally coupled to a second scissor arm about a middle axis, a third scissor arm pivotally coupled to a lower end of the of the first scissor arm about a first end axis, a fourth scissor arm pivotally coupled to an upper end of the second scissor arm about a second end axis, a first rod coupled to the first scissor arm and extending along the first end axis, a second rod coupled to the second scissor arm and extending along the second end axis, and a prop pivotally coupled to the first rod such that the prop rotates about the first end axis. The prop is configured to selectively engage the second rod, thereby preventing the platform from reaching the fully lowered position. The second rod is positioned above the first rod such that the prop extends upward from the first rod when the prop engages the second rod.
The invention is capable of other embodiments and of being carried out in various ways. Alternative exemplary embodiments relate to other features and combinations of features as may be recited herein.
The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:
Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.
According to an exemplary embodiment, a scissor lift includes a base, a platform configured to support at least one operator, and a lift assembly coupled to the base and the platform and configured to raise and lower the platform relative to the base. The lift assembly includes a series of scissor layers arranged on top of one another. Each scissor layer includes a pair of inner scissor arms pivotally coupled to a pair of outer scissor arms. The inner scissor arms of each scissor layer are pivotally coupled to the outer scissor arms of the adjacent scissor layers with a stowed position rod. The bottom scissor layer is coupled to the base, and the top scissor layer is coupled to the platform. One or more actuators rotate the scissor arms relative to one another such that the overall length of the scissor assembly changes, raising and lowering the platform.
When maintaining certain parts of a scissor lift, it is desirable to maintain the lift assembly in a partially extended position (e.g., corresponding to a partially raised position of the platform) to facilitate access to certain parts of the scissor lift (e.g., an actuator positioned between the inner scissor arms, etc.). Such maintenance procedures may cause the actuators to release some or all of the force that they exert to hold the lift assembly in the partially extended position. By way of example, the maintenance procedure may call for part of a hydraulic circuit powering the actuator to be drained of hydraulic fluid. Accordingly, it is desirable to have a secondary system for holding the lift assembly in the partially extended position without requiring a continuous force from the actuators.
The lift assembly further includes a prop pivotally coupled to one of the scissor arms. The prop defines a recess that is configured to receive a protrusion extending from one of the scissor arms positioned above the prop. Along an edge of the recess, the prop defines a first engagement surface that engages a second engagement surface of the protrusion that is received by the recess. When the first engagement surface and the second engagement surface engage one another, the prop spaces the scissor arms apart from one another, preventing the lift assembly from reaching a fully retracted position and thereby preventing the platform from reaching a fully lowered position. The prop is selectively repositionable between a stowed position and a deployed position. In the stowed position, the prop is rotated downward and away from the second engagement surface. In the deployed position, the prop is rotated upward and toward the second engagement surface such that the first engagement surface will engage the second engagement surface when the platform is moved downward. A loaded position is located between the stowed position and the deployed position. The geometry of the recess is configured (e.g., tapered) such that the prop automatically moves to the loaded position when the platform is fully supported by the prop.
The lift assembly further includes a stop having a first stop surface and a second stop surface. The stop is fixedly coupled to one of the outer scissor arms. The prop engages the first stop surface when in the deployed position, and the prop engages the second stop surface when in the stowed position. Accordingly, the stop limits the position of the prop to between the stowed position and the deployed position. The center of gravity of the prop is positioned longitudinally inward of the axis of rotation of the prop when the prop is in the stowed position and longitudinally outward of an axis of rotation of the prop when the prop is in the deployed position. Accordingly, the force of gravity acting on the center of gravity biases the prop to stay in the stowed position when in the stowed position and biases the prop to stay in the deployed position when in the deployed position. This permits a user to simply raise the prop prior to performing maintenance, and the weight of the prop acting against the stop holds the prop in place until the first and second engagement surfaces contact one another.
According to the exemplary embodiment shown in
Referring again to
The lift device 10 is supported by a plurality of tractive assemblies 40, each including a tractive element (e.g., a tire, a track, etc.), that are rotatably coupled to the frame assembly 12. The tractive assemblies 40 may be powered or unpowered. As shown in
Referring to
A series of guards or railings, shown as guard rails 62, extend upwards from the deck 60. The guard rails 62 extend around an outer perimeter of the deck 60, partially or fully enclosing a supported area on the top surface of the deck 60 that is configured to support operators and/or equipment. The guard rails 62 provide a stable support for the operators to hold and facilitate containing the operators and equipment within the supported area. The guard rails 62 define one or more openings 64 through which the operators can access the deck 60. The opening 64 may be a space between two guard rails 62 along the perimeter of the deck 60, such that the guard rails 62 do not extend over the opening 64. Alternatively, the opening 64 may be defined in a guard rail 62 such that the guard rail 62 extends across the top of the opening 64. In some embodiments, the platform 16 includes a door that selectively extends across the opening 64 to prevent movement through the opening 64. The door may rotate (e.g., about a vertical axis, about a horizontal axis, etc.) or translate between a closed position and an open position. In the closed position, the door prevents movement through the opening 64. In the open position, the door does not prevent movement through the opening 64.
The access assembly 20 is coupled to a side of the frame assembly 12. As shown in
The lift assembly 14 is configured to extend and retract, raising and lowering the platform 16 relative to the frame assembly 12. The lift assembly 14 is selectively repositionable between a fully retracted position and a fully extended position. The fully retracted position corresponds to a fully lowered position of the platform 16. The fully lowered position may be used by an operator when entering or exiting the platform 16 (e.g., using the access assembly 20) or when transporting the lift device 10. The fully extended position corresponds to a fully raised position of the platform 16. The fully raised position and any positions between the fully raised position and the fully lowered position may be used by the operator when accessing an elevated area (e.g., to perform construction work, to visually inspect an elevated object, etc.).
Referring to
Each of the scissor layers includes a pair of first scissor arms or scissor members (e.g., tubular members, solid members, etc.), shown as inner arms, and a pair of second scissor arms or scissor members (e.g., tubular members, solid members, etc.), shown as outer arms. Each inner arm is coupled (e.g., fixedly) to the other inner arm within that scissor layer. Each outer arm is coupled (e.g., fixedly) to the other outer arm within that scissor layer. The inner arms of each scissor layer are pivotally coupled (e.g., by one or more pins or rods) to the corresponding outer arms of that scissor layer near the centers of both the inner arms and the outer arms. Accordingly, the inner arms of each layer pivot relative to the outer arms of that scissor layer about a lateral axis. Specifically, the bottom scissor layer 100 includes inner arms 110 and outer arms 112 that pivot relative to one another about a lateral axis, shown as middle axis 114. The middle scissor layer 102 includes inner arms 120 and outer arms 122 that pivot relative to one another about a lateral axis, shown as middle axis 124. The middle scissor layer 104 includes inner arms 130 and outer arms 132 that pivot relative to one another about a lateral axis, shown as middle axis 134. The top scissor layer 106 includes inner arms 140 and outer arms 142 that pivot relative to one another about a lateral axis, shown as middle axis 144.
The scissor layers are stacked atop one another to form the lift assembly 14. Each pair of inner arms and each pair of outer arms has a top end and a bottom end. The ends of the inner arms and the outer arms are pivotally coupled (e.g., by one or more pins or rods) to the adjacent ends of the inner or outer arms of the adjacent scissor layers. Each set of inner arms is directly pivotally coupled to one or more sets of outer arms. This facilitates spacing each pair of inner arms a first distance apart from one another and spacing each pair of outer arms a second distance apart from one another, where the second distance is greater than the first distance. This facilitates ensuring that the fully lowered position is as low as possible, increasing the accessibility of the platform 16 and making the lift device 10 more compact.
The upper ends of the outer arms 112 are pivotally coupled to the lower ends of the inner arms 120 such that they rotate relative to one another about a lateral axis, shown as end axis 150. The upper ends of the inner arms 110 are pivotally coupled to the lower ends of the outer arms 122 such that they rotate relative to one another about another end axis 150. The upper ends of the outer arms 122 are pivotally coupled to the lower ends of the inner arms 130 such that they rotate relative to one another about a lateral axis, shown as end axis 152. The upper ends of the inner arms 120 are pivotally coupled to the lower ends of the outer arms 132 such that they rotate relative to one another about another end axis 152. The upper ends of the outer arms 132 are pivotally coupled to the lower ends of the inner arms 140 such that they rotate relative to one another about a lateral axis, shown as end axis 154. The upper ends of the inner arms 130 are pivotally coupled to the lower ends of the outer arms 142 such that they rotate relative to one another about another end axis 154.
Referring to
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Referring to
An actuator (e.g., a hydraulic cylinder, a pneumatic cylinder, a motor-driven leadscrew, etc.), shown as lift actuator 240, is configured to extend and retract the lift assembly 14. As shown in
Referring to
The arm inspection prop 300 includes a pair of panels, shown as side plates 302. The side plates 302 are laterally offset from one another. In some embodiments, the side plates 302 are substantially identical. The side plates 302 are coupled to one another by a series of structural members, shown as cross members 304. The cross members 304 extend laterally between the side plates 302 and are coupled (e.g., fastened, welded, etc.) to the side plates 302. As shown, the arm inspection prop 300 includes three cross members 304. In other embodiments, the arm inspection prop 300 includes more or fewer cross members 304. The cross members 304 maintain the spacing between the side plates 302 and prevent the side plates 302 from twisting relative to one another. An interface, shown as handle 306, is coupled to one of the cross members 304. The handle 306 is configured to facilitate manipulation (e.g., rotation) of the arm inspection prop 300 by an operator. Together, the side plates 302, the cross members 304, and the handle 306 form a main body of the prop 300. In some embodiments, all of the components of the main body are fixedly coupled to one another.
The arm inspection prop 300 further includes a pair of brackets (e.g., repositionable members, retaining members, repositionable members, secondary members, etc.), shown as retaining members 308. The retaining members 308 are each removably coupled (e.g., fastened, etc.) to one of the side plates 302 such that they are selectively repositionable relative to the side plates 302. An aperture, shown as retaining aperture 310, is defined between each side plate 302 and the corresponding retaining member 308. The retaining apertures 310 are aligned with one another along a lateral axis. The retaining apertures 310 each have a substantially circular cross section that is slightly larger than the diameter of the rod 210. The rod 210 is received within the retaining apertures 310, pivotally coupling the arm inspection prop 300 to the inner arms 120 and the outer arms 132. The arm inspection prop 300 rotates about a lateral axis centered along the rod 210. In the embodiment shown in
Referring to
The width W1 of the stop 330 is less than the lateral distance between the retaining members 308, facilitating placement of the stop 330 between the retaining members 308. The stop 330 limits lateral movement of the arm inspection prop 300. By way of example, if a lateral force were to be applied to the arm inspection prop 300 with the arm inspection prop 300 in the position shown in
The width W2 of the stop 330 is greater than the lateral distance between the side plates 302 such that the stop 330 engages the arm inspection prop 300 to limit rotation of the arm inspection prop 300 about the end axis 152. Specifically, the stop 330 defines a first engagement surface, shown as first stop surface 332, and a second engagement surface, shown as second stop surface 334. The first stop surface 332 and the second stop surface 334 are defined on opposite sides of the stop 330. In some embodiments, the first stop surface 332 and the second stop surface 334 are substantially parallel to one another. The first stop surface 332 is configured to engage a set of third engagement surfaces, shown as first prop surfaces 336, defined by the arm inspection prop 300 to limit rotation of the arm inspection prop 300 in a first direction. The second stop surface 334 is configured to engage a set of fourth engagement surfaces, shown as second prop surfaces 338, defined by the arm inspection prop 300 to limit rotation of the arm inspection prop 300 in a second direction opposite the first direction. Each side plate 302 defines one of the first prop surfaces 336 and one of the second prop surfaces 338. The contour of the first stop surface 332 matches the contour of the first prop surfaces 336. Similarly, the contour of the second stop surface 334 matches the contour of the second prop surfaces 338. By way of example, in the embodiment shown in
In alternative embodiment, the stop 330 is an assembly including multiple separate bodies. In such an embodiment, a first body of the stop 330 may define the first stop surface 332 and a second body of the stop 330 may define the second stop surface 334. Additionally, the first stop surface 332 and/or the second stop surface 334 may be defined across multiple separate bodies. Accordingly, as used herein, the term “stop” may include a single body or multiple bodies.
Referring to
Referring to
The arm inspection prop 300 has a center of gravity, shown as CG. The position of the CG is described herein with reference to a longitudinal axis X and a vertical axis Y defined with respect to the frame assembly 12. A distance X is defined along the longitudinal axis X between the CG and the end axis 152, and a distance Y is defined along the vertical axis Y between the CG and the end axis 152. Gravity exerts a downward force on the CG, causing an effective moment M about the end axis 152. When the CG is positioned longitudinally inward of the end axis 152 (e.g., toward the center of the lift device 10, corresponding to a negative distance X), the effective moment M biases the arm inspection prop 300 toward the stowed position. When the CG is positioned longitudinally outward of the end axis 152 (e.g., away from the center of the lift device 10, corresponding to a positive distance X), the effective moment M biases the arm inspection prop 300 toward the deployed position.
The location of the CG may be varied by adjusting one or more parameters of the arm inspection prop 300. By way of example, the shapes of the side plates 202 may be varied. As shown in
As shown in
As shown in
As shown in
As shown in
As the lift assembly 14 extends, the inner arms 120 and the stop 330 rotate. This changes the orientation of the arm inspection prop 300 relative to the direction of gravity in the stored and deployed positions. If the lift assembly 14 is extended above a threshold height, shown in
As shown in
The arm inspection prop 300 provides a variety of additional benefits. The arm inspection prop 300 permits an operator to hold the platform 16 and lift assembly 14 in place without the use of additional tools or devices that would have to be retrieved prior to use. Because the arm inspection prop 300 is coupled to the rod 210, the arm inspection prop 300 cannot be inverted and used in an undesirable orientation. Because the arm inspection prop 300 is centered laterally, the arm inspection prop 300 does not induce any undesirable moment loading that would be associated with supporting only side of the lift assembly 14.
Although the rod 210 and the rod 220 are shown herein as being positioned along the end axis 152 and the end axis 154, the rod 210 and the rod 220 may alternatively be coupled to any of the other adjacent lateral axes that are discussed herein. By way of example, the rod 210 and the rod 220 may be positioned along: the end axis 160 and the end axis 150; the end axis 170 and the end axis 150; the end axis 150 and the end axis 152; the end axis 154 and the end axis 180; or the end axis 154 and the end axis 190, respectively. The arm inspection prop 300 may be moved along with the rod 210 and the rod 220. When positioning the arm inspection prop 300, the accessibility of the arm inspection prop 300 to the operator may be taken into account. Additionally, when the arm inspection prop 300 is moved to a lower scissor layer, the arm inspection prop 300 may be configured to support larger forces, as the arm inspection prop 300 will be required to support the weight of additional scissor layers as well.
In further alternative embodiments, the rod 210 and/or the rod 220 are not positioned along any of the end axes. Rather, the rod 210 and/or the rod 220 may be offset relative to all of the end axes. In such embodiments, the arm inspection prop 300 may rotate about an axis that is not one of the end axes described herein. Additionally, in such embodiments, the recess surface 342 may be configured to engage an outer surface 344 of a component that is not aligned with one of the end axes.
In other embodiments, different parts of the lift assembly 14 are translationally fixed relative to the frame assembly 12 and/or the platform 16. By way of example, the end axis 160 may be free to translate relative to the frame assembly 12, and the end axis 170 may be fixed relative to the frame assembly 12. By way of another example, the end axis 180 may be free to translate relative to the platform 16, and the end axis 190 may be fixed relative to the platform 16.
As utilized herein, the terms “approximately,” “about,” “substantially,” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.
It should be noted that the terms “exemplary” and “example” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).
The terms “coupled,” “connected,” and the like, as used herein, mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent, etc.) or moveable (e.g., removable, releasable, etc.). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.
References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below,” “between,” etc.) are merely used to describe the orientation of various elements in the figures. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, Z, X and Y, X and Z, Y and Z, or X, Y, and Z (i.e., any combination of X, Y, and Z). Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to each be present, unless otherwise indicated.
It is important to note that the construction and arrangement of the systems as shown in the exemplary embodiments is illustrative only. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements. It should be noted that the elements and/or assemblies of the components described herein may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Accordingly, all such modifications are intended to be included within the scope of the present inventions. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the preferred and other exemplary embodiments without departing from scope of the present disclosure or from the spirit of the appended claims.
This application claims the benefit of U.S. Provisional Application No. 62/819,209, filed Mar. 15, 2019, which is incorporated herein by reference in its entirety.
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