The present invention relates generally to ladders and accessories for same, and more particularly to a ladder leveling apparatus employing motorized electric actuators to selectively extend the bottom end of one side rail of a ladder relative to the other to ensure a level orientation of the ladder when used on sloped uneven surfaces.
Various ladder leveling apparatuses have been proposed in the prior art for the purpose of establishing a safe, level ladder position when used on sloped or uneven surfaces. Examples of such apparatuses are found in U.S. Pat. Nos. 2,971,602, 4,673,061, 5,044,468, 5,816,364, 7,774,950, 8,011,473, 8,360,204, and U.S. Pat. No. 9,322,215; U.S. Patent Application Publications 2008/0078616 and 2014/0083799; Canadian Patent Application CA2825179; and International PCT Publication WO2014/083221.
However, there remains room for improvement, and Applicant has developed a unique ladder levelling solution with advantages and beneficial features not heretofore seen.
According to one aspect of the invention there is provided a ladder leveling apparatus for a ladder comprising a pair of side rails and a series of rungs spanning between said side rails at spaced intervals therealong, said leveling mechanism comprising:
at least one electric linear actuator comprising a respective electric motor operable in opposing directions to drive extension and retraction of an output shaft of said electric linear actuator to which a respective ground engagement foot is attached at a distal end of said output shaft, said at least one electric linear actuator being attached or attachable to a respective side rail of the ladder in a position placing the respective ground engagement foot proximate a lower end of the respective side rail when the respective output shaft is in a retracted position, such that extension of the output shaft from said retraced position displaces the ground-engaging foot downwardly past the lower end of the respective side rail;
at least one battery unit mounted or mountable to said ladder and connected or connectable to said at least one electric linear actuator to control extension and collapse thereof; and
a control system operable to control extension and retraction of the at least one linear actuators.
In some embodiments, the control system comprises at least one wired or wireless control respectively mounted or mountable to said respective side rail of the ladder and connected or connectable in a control circuit with said at least one battery unit and said at least one electric linear actuator to control extension and retraction thereof.
In some embodiments, the control system comprises at least one momentary rocker switch with a neutral off position, and two momentary on positions corresponding to extension and retraction of the electric linear actuators.
In some embodiments, said at least one control is mounted to the respective side rail of the ladder at an exterior side thereof opposite the rungs.
In some embodiments, said at least one control is mounted to the respective side rail of the ladder at a location nearer to the bottom end of the side rail than to an opposing top end thereof.
In some embodiments, said at least one control is mounted to the respective side rail of the ladder at a location within six feet of the bottom end thereof.
In some embodiments, said at least one battery unit is mounted to a respective rung of the ladder.
In the instance of a rung-mounted battery unit, said battery unit may comprise support straps for closure around a respective rung of the ladder to mount said at least one battery unit to said respective rung in a position therebeneath.
In the instance of a rung-mounted battery unit, said battery unit may be mounted to said respective rung in a position residing beneath said respective rung and leaving a topside thereof unobstructed for stepping access thereto by a user.
In the instance of a rung-mounted battery unit, control circuit wiring from said at least one battery unit to said at least one electric linear actuator may extend from said battery unit along the respective rung to the respective side rail of said at least one electric linear actuator.
In such instance, said control circuit wiring may run upwardly along an inner side of said respective rail from said respective rung.
In some embodiments, said at least one electric linear actuator is coupled to the respective side rail of the ladder at an exterior side thereof by at least one U-bolt embracing around a housing of said electric linear actuator.
In one embodiment, the at least one electric linear actuator comprises a pair of electric linear actuators that are respectively coupled to the side rails of the ladder at exterior sides thereof opposite the rungs, and are coupled together by a threaded rod passing internally through a hollow rung of the ladder.
In other embodiments, one or more quick-attach mechanisms are associated with the at least one electric linear actuator and operable for releaseable attachment thereof to the respective side rail of the ladder.
In such embodiments, said one or more quick-attachment mechanisms preferably comprise a rung-insert removably insertable into a hollow interior of a respective rung of the ladder.
In such instance, said at least one electric linear actuator may comprise a pair of electric linear actuators that are respectively coupled to the side rails of the ladder and each have a respective quick attach mechanism with a respective rung insert, in which case a length of each rung-insert may be less than half a rung-width of said ladder to enable insertion of the rung-inserts of the quick-attach mechanisms into a same rung from opposing ends thereof.
Preferably, said rung-insert is selectively expandable and collapsible in a radial direction to enable attachment of the at least one electric linear actuator to the respective rung by insertion of the rung-insert into said respective rung, and radial expansion of said rung-insert once inside said respective rung to frictionally engage with internal wall surfaces of said respective rung.
In some embodiments, the at least one control is respectively connected to the at least one linear actuator by a flexible cord or wireless connection allowing selective mounting of the control at a user selectable position along the respective side rail.
In some embodiments, said at least one electric linear actuator comprises a pair of electric linear actuators that are respectively coupled to the side rails of the ladder and said at least one battery unit comprises a pair of batteries respectively attached to, our housed together with, the pair of electric linear actuators, whereby mounting of said pair electric linear actuators to the side rails of the ladder also mounts the batteries to said rails of the ladder.
In some embodiments, the control system comprises a remote control operable to send control signals to the first and second linear actuators for wireless control thereof at a distance from the ladder.
Preferred embodiments of the invention will now be described in conjunction with the accompanying drawings in which:
In the drawings like characters of reference indicate corresponding parts in the different figures.
The levelling apparatus is primarily made up of two extension/retraction units 24 respectively attached to the side rails 14 of the ladder, a battery unit 26 mounted to the lowermost rung 16a of the ladder, and a pair of controls 28 respectively mounted to the side rails 14 at locations higher up the ladder from the rail-mounted extension/retraction units 24 and rung-mounted battery unit 26.
Each extension/retraction unit features an electrically powered linear actuator 28 with an elongated housing 30 and an extendable/retractable output shaft 32. The output shaft 32 reaches outward from the cylindrical housing 30 at a lower end thereof that resides in close proximity to the bottom end 14a of the respective side rail 14 of the ladder. In the illustrated embodiment, the ladder features two pivotal feet 27 respectively coupled to the side rails 14 in a manner pivotal relative thereto about a shared horizontal axis parallel to the rungs 16, as is common in the art. The lower end of the output shaft 32 of each linear actuator 28 has a secondary ground engagement foot 34 coupled thereto by a respective pivot pin 36, whereby the secondary ground engagement foot 34 is likewise pivotable about a horizontal axis parallel to the rung direction of the ladder. Each linear actuator 28 is of a known commercially available type, which features an electric motor 38 operable to rotatably drive a screw mechanism located inside the cylindrical housing 30 on a longitudinal axis thereof, while an internally threaded portion of the output shaft 32 is threaded on the screw mechanism. Driven rotation of the screw mechanism in opposing directions by the motor 38 drives longitudinal displacement of the output shaft 32 back and forth along the longitudinal axis of the housing 30. These actuators include limit switches that automatically terminate operation of the motor once the output shaft has reached a predetermined travel limit in either direction.
In a fully retracted position of the output shaft 32, shown in
Each linear actuator is clamped against the outer side of the respective side rail, i.e. the side of the side rail facing away from the rungs of the ladder. For such purposes, by a pair of U-bolts 40 embrace around the cylindrical housing 30 of the actuator 28 near the top and bottom ends thereof, and are fastened through drilled holes in the respective side rail 14 of the ladder. In addition to this, further mounting of each extension/retraction unit to the ladder is achieved by a threaded rod 42 that passes through the second lowest rung 16b of the ladder so that the two ends of the threaded rod 42 reach through respective brackets 44 fixed atop the upper ends of the two linear actuators 28. A pair of nuts or threaded caps 46 are tightened onto the ends of the threaded rod 42. The U-bolts and the nuts or caps 46 on the threaded rod 42 thus clamp the two extension/retraction units 24 against their respective side rails of the ladder, while the threaded rod 42 passing through the respective rung 16b of the ladder prevents either of the extension/retraction units from sliding down the respective side rail. This combination of clamping the units 24 to the side rails and hanging them from the respective rung 16b ensures secure attachment to the ladder.
The battery unit 26 features at least one battery B, for example a single 12V battery, which may be rechargeable, and a pair of straps 48 fastened to either the battery itself or to an enclosure 50 in which the battery is contained. The straps are slung over and tied around the lowermost rung 16a of the ladder in order to secure the battery to the lowest rung 16a in a position suspended therebeneath. By attaching the battery unit to a rung of the ladder, the added weight of the battery B can be centered between the two side rails 14 of the ladder to maintain a balanced weight distribution of the overall assembly. This balanced weight is likewise maintained by use of two identical extension/retention mechanisms mounted in the same positions on the two side rails. Mounting the battery unit beneath the rung keeps the topside of the rung 16a open for unobstructed step access by the ladder user. Support of the battery on the lowest rung also keeps it from interfering with insertion and withdrawal of the climber's feet between the inter-rung spaces further up the ladder, and also helps contribute to a lower center of gravity for the overall assembly, thus improving the stability of same.
Each control 28 is operable over a respective one of the two linear actuators 28, and is mounted on the same side rail of the ladder as said respective actuator at a spaced distance further upward on the ladder. The control 28 is preferably placed at a height along the side rail 14 that is conveniently reachable by an average user when standing at ground level in front of the ladder, whereby adjustment of the ladder using the leveling apparatus is easily achievable before climbing onto the ladder. This way, the stability of the ladder is achieved before the user exerts any body weight on the ladder rungs, thus optimizing user safety. In preferred embodiments, the controls 28 are within six feet of the lower ends of the side rails, and may be located nearer to the lower ends of the side rails than to the top ends thereof, or at least closer to the bottom ends of the main section side rails than to the top ends of the extension section sides rails in the scenario of an extended extension ladder. In select embodiments, the controls are within five feet, or even four feet, of the lower ends 14a of the side rails 14 to ensure convenient comfortable access from ground level for users of varying height.
Each control 28 in the illustrated embodiment is a momentary rocker switch wired or wirelessly connected in a control circuit between the battery and the respective linear actuator thereof. The switch has a neutral ‘off’ position disconnecting the battery from the actuator. The rocker is placed in an upright orientation, where depression of its upper surface rocks the switch into a momentary “retraction on” position, which applies the correct polarity to the linear actuator to drive retraction thereof and raising of the secondary foot 34. On the other hand, depression of the switch's lower surface rocks the switch into a momentary “extension on” position, which applies the correct polarity to the linear actuator to drive extension thereof and lowering of the secondary foot 34.
By use of a momentary switch, safety is improved by not requiring a separate user input to turn off the actuator, as mere release of the switch will return the switch to its neutral “off” position, and thereby terminate any movement of the respective actuator. As shown, the upper surface 28a of the switch is preferably labelled with an “up” arrow, denoting the upward actuator retraction caused by depression thereof, while the lower surface 28b of the switch is preferably labelled with a “down” arrow, denoting the downward actuator extension caused by depression thereof. Additional text-based labelling of the switch may also be included, but at minimum, inclusion of arrow-based or other symbolic labelling is preferred to provide universally understood meaning regardless of the user's language or literacy.
The control circuitry includes wiring 52 spanning from the battery unit 26 along the lowermost rung 16 toward either side rail, and then up the inner side of each side rail to the respective linear actuator 28 and switch control 28 mounted externally thereon. Routing of the wiring up the inner side of the rail 14 reduces the likelihood of it catching on a user's hand or other object during transport or use of the ladder. Alternatively the mounted switch control 28 may operate wirelessly to reduce the amount of wiring required on the inner rail 14.
The control circuit may include a wireless receiver R, for example contained within the same enclosure 50 as the battery B. The receiver is configured to receive remote control signals from a wireless remote control 54 capable of providing the same “on extension” and “on retraction” signals as the ladder's on-board controls 28. The remote control may likewise use two momentary rocker switches each having up and down arrows, and respectively labelled or logically positioned according to which switch controls which actuator. The illustrated example uses an “L” label at the left switch of the remote to designate that it controls the actuator on the left side of the ladder, and an “R” label at the right switch of the remote to designate that it controls the actuator on the right side of the ladder. Similar labelling may be provided on the ladder or the extension/retraction units to explicitly label to the two sides of the ladder in a distinctive manner from one another. While the illustrated embodiment employs both on-board controls 28 and a wireless remote control 54, one or the other may optionally be omitted, through the inclusion of on-board controls provides a redundant backup in the event of a lost remote control, or a depleted remote control battery. While the illustrated embodiment features a dedicated remote control, in other embodiments the remote control may be a programmable or general purpose device with a suitable transmitter/transceiver, for example a smart phone with a Bluetooth transceiver or other short-range transceiver compatible with a matching receiver/transceiver type of the ladder levelling apparatus.
The control circuitry may optionally include a tilt sensor and cooperating circuitry operable to extend an appropriate one of the linear actuators according to the detected direction of ladder tilt, and to proportionally extend the actuator by the appropriate amount to overcome the degree of tilt detected. In such embodiments with self-levelling control circuitry, the manual on-board control 28 and wireless remote control 54 may be omitted.
The first illustrated embodiment is based on a prototype of the invention retrofitted onto a conventional off-the-shelf extension ladder. It will be appreciated that more integral incorporation of the levelling apparatus into the ladder construction during factory assembly may involve several modifications from the illustrated embodiment, for example including internal mounting of components of the extension/retraction units into hollow side rails of the ladder, routing of control circuit wiring internally through the side rails and/or rungs, and incorporation of the battery and control circuit componentry into the side rails and/or rungs, etc.
Whereas the fastening of the extension/retraction units to the ladder in the manner taught by the first illustrated embodiment requires multiple steps to install or remove each such unit from the ladder, thus representing a generally permanent or semi-permanent installation not intended for removal by the end user, the second illustrated embodiment shown in
Instead of having a separate battery unit 26 shared by the two extension/retraction units 24, the embodiment of
With reference to the partially cross-sectioned view of
With reference to
Although
With two radially expanding/dilating rung inserts holding each extension/retraction unit 24′ against lateral withdrawal from the side of the ladder, and cooperating together to prevent any pivoting of the unit about one of the rung axes, a third rung insert may not be required. However,
In their relaxed states, the radial distance of each metal band from the skewer rod axis is comparable or even slightly larger than the inner radius of the hollow ladder rung, but because of their flexible nature allows insertion and withdrawal of the rung insert to and from the ladder rung when the cam lever is opened to its release position. Closing the cam lever to its over-center tightening position increases the radial extent of each band 78 to a value significantly exceeding the inner radius of the rung. Closing of the cam lever with the rung insert inside the hollow rung thus expands the metal bands 78 into increased frictional engagement against the inner wall surfaces of the hollow rung, thereby securing the rung insert and the attached remainder of the extension/retraction unit in place on the ladder.
The controls 28′ of the
One half of the scissor linkage features a first link 84a pivotally pinned to the internally threaded member 88 at one end, and reaching toward the housing 30′. The opposing end of the first link 84a is pivotally pinned to one end of a second link 84b, which continues to reach along the threaded rod 60′ further toward the inner side of the housing 30′. The opposing end of the second link 84b nearest the housing is pivotally pinned to a non-threaded sleeve or collar member 90 closing around the threaded rod 60′. The non-threaded member 90 has a smooth-walled inner bore of greater diameter than the threaded rod 60 so that relative rotation and axial displacement can occur between the threaded rod 60′ and the non-threaded member 90.
A second half of the scissor linkage similarly features a third link 84c with one end pivotally pinned to the internally threaded member 88, and a fourth link 84d with one end pivotally pinned to the third link and the other end pivotally pinned to the non-threaded member 90. The pivot pins of the linkage all lie parallel to one another, and perpendicular to the longitudinal axis of the threaded rod 60′. A first grip pad 92 is coupled to the linkage at the pivot point 93a between the first and second links, and a second grip pad 94 is likewise coupled to the linkage at the pivot point 93b between the third and fourth links. Each grip pad faces outwardly away from the linkage, i.e. radially outward from the threaded rod 60′.
To use this scissor-based quick-attach rung insert, scissor linkage of the rung insert is inserted into a hollow ladder rung in the radially collapsed state of
If removal of the unit is desired, rotation of the crank 86 in the opposite direction will displace the internally threaded member 88 in the reverse direction along the threaded rod 60′ toward the free end 60a thereof. This radially collapses the scissor linkage, thereby withdrawing the grip pads 92, 94 from their frictional engagement against the inner surface of the ladder rung, thus allowing withdrawal of the rung insert and removal of the overall unit from the ladder.
During this process, a cam-action of the lever 58′ acting against a washer 99 at the outer side of the bushing 98 draws the threaded rod 60′ further through the housing 30′ toward the outer side thereof, thus pulling the threaded member 88 at the distal end of the linkage 84 toward the proximal end of the linkage at which the non-threaded member 90 is abutted against the inner side of the housing. This action thereby performs an additional degree of axial contraction, and thus radial expansion, of the scissor linkage 84, thereby further tightening the grip pads 92, 94 against the rung's inner surface. In summary, this first-time installation involves an initial tightening stage performed by rotational driving of the threaded rod 60′ by rotation of the cam lever 58′ about the rod axis, followed by a subsequent further tightening stage performed by pivotally closing the cam lever 58′ about a camming axis perpendicular to the rod axis.
To later remove the unit from the ladder, movement of the cam-lever 58′ about the camming axis back into its open/release position of
Tightening of the U-bolt 40 through a pair of corresponding installer-drilled fastener holes 104 in the side rail of the ladder secures the housing 30″ against the outer side of the ladder's side rail. Once again, this bolt-on solution can be used on any ladder regardless of whether it has hollow open ended rungs or solid/closed-end rungs.
In summary, the disclosed embodiments each provide a means of leveling a ladder on an uneven surface by using an electrically powered motorized mechanism that is either built into a ladder or added to the rails of an existing ladder in order to effect and maintain a level orientation. The actuator has a foot that is at the same level as, or retracted slightly upwardly from, the feet of the existing ladder. In the case where there is an uneven surface and one side rail of the ladder is lower than the other, the actuator on the low side may be extended in order to achieve a level ladder position. The actuators are battery powered and a momentary switch, either on the ladder or on a remote control, or both, is used to selectively provide power of the appropriate polarity to the appropriate actuator such as to cause it to go up or down, as the case may be. This provides a simple and quick way to level a ladder over and over again with very little effort on the part of the operator.
Since the battery is not required to maintain the feet positions of the actuators, the power requirements are minimal and the battery could be made smaller and likely easily hidden inside the rung(s) of the ladder. When needed, the ladder leveling operation is performed by a motorized mechanism powered by a battery or other power source, but otherwise the ladder operates as normal. The motor and battery unit can be built into the ladder during manufacturing or added as an add-on to one or more sides of the ladder. The disclosed add-on units are attached to a ladder using a quick connect method utilizing the hollow rungs of the ladder, or by a bolted or other attachment to the rails that does not limit use to hollow-rung ladders. The adjustments to the effective rail length of the ladder can be done easily with the touch of a button as opposed to having to crank, or pull-down, or release a pin, or otherwise perform two-handed adjustment of a ladder's side rail. The leveling can be performed remotely from the ladder if need be via suitable remote control, whether wired or wireless. The battery or power source is not required to maintain the ladder leveler's feet positions, as power is only required to change them. As outlined above, tilt detection and control circuitry that could be easily added to the powered ladder such that the ladder would automatically level itself. The forgoing embodiments thus provide a simple and quick method of leveling a ladder over and over again with very little effort on the part of the operator.
Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.