METHOD AND SYSTEM FOR A LOW HEIGHT LIFT DEVICE

A scissors lift vehicle includes a chassis, a first pair of wheels disposed at one end of the chassis and a second pair of steering wheels disposed at an opposite end of the chassis. The wheels include a circular profile having a radius R. The scissors lift vehicle includes a track having an upper surface and a lower surface extending aft at a height less than R above the travel surface. A pivot connection is coupled to the aft plate at a height less than R above the travel surface. A scissors stack assembly includes a plurality of paired scissors linkages. Each scissors linkage of a first pair of scissors linkages is coupled to a respective pivot connection. Each scissors linkage of a second pair of scissors linkages includes a truck coupled to a distal end. The truck is configured to engage the upper surface of the track.

BACKGROUND

This description relates to lift devices, and, more particularly, to an adjustable height man lift and methods of assembling adjustable height man lifts.

Scissors lifts are a type of platform that can usually only be moved in a vertical direction. The lift mechanism is often mounted to a self-propelled carriage or chassis having wheels for moving the platform between work areas. The mechanism to achieve the vertical lift is a plurality of linked, folding supports oriented in a crisscross or “X” pattern. The pattern is also known as a pantograph. The upward motion is achieved by the application of a force to a set of parallel linkages, elongating the crossing pattern, and propelling the work platform vertically. Because scissors lift devices evolved from a device that included a scissors lift assembly mounted on a pulled carriage that was not self-propelled, current scissor lift designs still have the scissors lift assembly mounted on top of a carriage. In self-propelled models, many of the propelling features are mounted under the scissors lift assembly. A hydraulic system, electrical system including batteries, and a control system are also typically mounted on the carriage below the scissors lift assembly. Additionally, axles, steering and transmission components are also mounted on the carriage under the scissors lift assembly. Accordingly, because of the equipment located under the scissors lift assembly on the carriage, the height of the work platform that carries a user to the work area is greatly elevated above the floor surface. To gain access to the work platform of known scissors lift assemblies, the user must climb onto the platform, usually using several ladder steps attached to the carriage and/or platform, and usually carrying tools, equipment, and/or repair parts. Such access is laborious for the user. Moreover, mounting the scissors lift assembly on top of the carriage increases the height of the scissors lift vehicle when the scissors lift assembly is fully retracted. The increased height limits areas that the scissors lift vehicle can access.

BRIEF DESCRIPTION OF THE DISCLOSURE

In one aspect, a scissors lift vehicle includes a chassis formed of a pair of parallelly-oriented channels. Each channel includes a first forward end and a second aft end. The first forward ends of each of channel are coupled together using a forward plate extending orthogonally between the first forward ends. The second aft ends of each of the channels are coupled together using an aft plate extending orthogonally between the second aft ends and parallel to the forward plate. The scissors lift vehicle also includes a first pair of wheels disposed at one end of the chassis and a second pair of steering wheels disposed at an opposite end of the chassis. The wheels are configured to roll along a travel surface and include a circular profile having a radius R. Each wheel of each pair of wheels is spaced apart laterally with respect to the other wheel of the pair. The pairs of wheels are spaced apart longitudinally from the other pair of wheels. The scissors lift vehicle includes a track including an upper surface, a lower surface and a thickness extending therebetween, the track extending aft at a height less than R above the travel surface from the forward plate parallel to the pair of channels and a pivot connection coupled to the aft plate at a height less than R above the travel surface. A scissors stack assembly includes a plurality of paired scissors linkages extendable from a retracted position to an extended position. Each scissors linkage of a first pair of scissors linkages of the plurality of paired scissors linkages is pivotally coupled to a respective pivot connection. Each scissors linkage of a second pair of scissors linkages of the plurality of paired scissors linkages includes a truck coupled to a distal end of each scissors linkage of the second pair of scissors linkages. The truck is configured to engage the upper surface of the track.

In another aspect, a method of assembling a scissors lift vehicle includes providing a chassis having an opening formed between a pair of parallelly oriented side channels and coupling a first pair of wheels to one end of the chassis and a second pair of steering wheels to an opposite end of the chassis. The wheels are configured to roll along a travel surface and each wheel includes a circular profile having a radius R. The method also includes coupling a pivot connection the end of the chassis at a height less than R above the travel surface and coupling a track, having an upper surface, a lower surface and a thickness extending therebetween, to the opposite end of the chassis. The track extends aft at a height less than R above the travel surface. The method further includes coupling a scissors stack assembly to the chassis within the opening. The scissors stack assembly including a plurality of paired scissors linkages, each scissors linkage of a first pair of scissors linkages of the plurality of paired scissors linkages, pivotally coupled to a respective pivot connection, each scissors linkage of a second pair of scissors linkages of the plurality of paired scissors linkages including a truck coupled to a distal end of each scissors linkage of the second pair of scissors linkages. The truck configured to engage the upper surface of the track.

In yet another aspect, a scissors lift vehicle includes a chassis, a first pair of wheels disposed at one end of the chassis and a second pair of steering wheels disposed at an opposite end of the chassis. The wheels are configured to roll along a travel surface and each wheel has a circular profile having a radius R. A track includes an upper surface, a lower surface and a thickness extending therebetween. The track extends longitudinally from one end of the chassis within an opening of the chassis at a height less than R above the travel surface. A pivot connection is coupled to the opposite end of the chassis at a height less than R above the travel surface. The scissors lift vehicle also includes a scissors stack assembly positioned within the opening and including a plurality of paired scissors linkages. Each scissors linkage of a first pair of scissors linkages of the plurality of paired scissors linkages is pivotally coupled to a respective pivot connection. Each scissors linkage of a second pair of scissors linkages of the plurality of paired scissors linkages includes a truck coupled to a distal end of each scissors linkage of the second pair of scissors linkages. The truck is configured to engage the upper surface of the track.

DETAILED DESCRIPTION OF THE DISCLOSURE

The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to embodiments of a scissors lift vehicle and a method of assembling a scissors lift vehicle.

In the example embodiment, the scissors lift vehicle includes a chassis including a pair of parallelly oriented structural members or channels. Each channel includes a first forward end and a second aft end. The first forward ends of each of the channels are coupled together using a forward plate extending orthogonally between the first forward ends. The second aft ends of each of the channels are coupled together using an aft plate extending orthogonally between the second aft ends and parallel to the forward plate.

The scissors lift vehicle also includes a first pair of wheels positioned at one end of the chassis and a second pair of steering wheels positioned at an opposite end of the chassis. In some embodiments, at least one of the second pair of steering wheels are drive wheels configured to propel the scissors lift vehicle using a propulsion motor. The propulsion motor includes at least one of an electric motor and a hydraulic motor. The wheels are configured to roll along a travel surface and include a circular profile having a radius R. In various embodiments, the first pair of wheels includes follower wheels. Each wheel of each pair of wheels are spaced apart laterally with respect to the other wheel of the pair. The pairs of wheels are spaced apart longitudinally from the other pair of wheels.

The scissors lift vehicle further includes a track including an upper surface, a lower surface and a thickness extending therebetween. The track extends aft at a height less than R above the travel surface from the forward plate parallel to the pair of channels. A pivot connection is coupled to the aft plate at a height less than R above the travel surface.

The scissors lift vehicle also includes a scissors stack assembly including a plurality of paired scissors linkages extendable from a retracted position to an extended position. Each scissors linkage of a first pair of scissors linkages of the plurality of paired scissors linkages is pivotally coupled to a respective pivot connection. Each scissors linkage of a second pair of scissors linkages of the plurality of paired scissors linkages includes a truck coupled to a distal end of each scissors linkage of the second pair of scissors linkages. The truck is configured to engage the upper surface of the track.

Each truck optionally includes an inner support plate, an outer support plate, and a roller assembly extending therebetween. A linkage connection is configured to couple to the distal end of a respective scissors linkage of the second pair of scissors linkages. A track keeper includes a body extending from at least one of the inner support plate and the outer support plate to face to face proximity to the lower surface.

Optionally, the scissors lift vehicle also includes a third pair of scissors linkages joined by a lower hydraulic cylinder coupling member extending between the third pair of scissors linkages and a fourth pair of scissors linkages joined by an upper hydraulic cylinder coupling member extending between the fourth pair of scissors linkages. The scissors stack assembly further includes a hydraulic cylinder operatively coupled between the lower hydraulic cylinder coupling member and the upper hydraulic cylinder coupling member. In various embodiments, the third pair of scissors linkages and the fourth pair of scissors linkages are parallel with respect to each other.

The following description refers to the accompanying drawings, in which, in the absence of a contrary representation, the same numbers in different drawings represent similar elements.

FIG. 1is a side elevation view of a scissors lift vehicle100in accordance with an example embodiment of the present disclosure. In the example embodiment, scissors lift vehicle100includes a carriage102that includes a plurality of independently steerable wheels104, each configured to engage a travel surface106during operation of scissors lift vehicle100. Travel surface106could be an asphalt surface in an outdoor application of scissors lift vehicle100or may be concrete, wood, carpet, tile, or other surface in an indoor application of scissors lift vehicle100. Wheels104are configured to rotate about an axis of rotation108and may be powered by a dedicated motor (not shown) coupled directly to each wheel104. Wheels include a circular profile having a radius R and are spaced apart from each other along an underside of carriage102. Typically, one wheel104is positioned at or near each corner110of rectangularly-shaped carriage102. In various embodiments, wheels104are spaced as far as possible to improve the stability of scissors lift vehicle100, especially when a scissors stack assembly112is extended. In various embodiments, more than four wheels104, one at each corner110may be used. Additionally, carriage102may not be rectangularly-shaped, but may have other shapes, where additional wheels104could be used. Wheels104may be spaced apart in a fore/aft direction114and in a right/left or lateral direction (i.e., into or out of the page). Wheels104may be spaced from each other unequal distances apart, for example, a track of the fore wheels may be wider or narrower than the track of the aft wheels.

A base116is coupled to or formed with carriage102between wheels104spaced apart in the right/left direction and is positioned vertically such that base116lies within a profile of wheels104. For example, if wheels104are twelve inches in diameter, base116is positioned vertically less than twelve inches above the lowest extent of wheels104, which, in most cases, would be the equivalent of being less than twelve inches above travel surface106. Accordingly, in some embodiments, base116may be located less than 2R above travel surface106during operation of scissors lift vehicle100and in other embodiments base116may be located less than R above travel surface106during operation of scissors lift vehicle100.

In the example embodiment, scissors stack assembly112includes a plurality of scissors linkages118pivotally coupled together and extendable from a retracted position (shown inFIG. 1), where the scissors linkages are approximately horizontally configured to an extended position (not shown inFIG. 1), where the scissors linkages are approximately orthogonally configured with respect to each other. Scissors stack assembly112is pivotally coupled to base116through a first pair of scissors linkages120and122(122is hidden behind120inFIG. 1) and is slidably coupled to base116through a second pair of scissors linkages,124and126(126is hidden behind124inFIG. 1). Base116includes a slot128configured to receive a pin130. Base116and first pair of scissors linkages120and122are coupled in a pivotal joint (not shown inFIG. 1). Base116and second pair of scissors linkages124and126are coupled in a slidable joint132using slot128and pin130. Pivotal joint132and the slidable joint are located between wheels104spaced apart in the right/left direction and within a profile of wheels104.

FIG. 2is a front elevation view of scissors lift vehicle100in accordance with the example embodiment of the present disclosure. In the example embodiment, scissors lift vehicle100includes base116positioned below axis108such that base is less than R distance above travel surface106. Such a position permits scissors stack assembly112to be positioned lower in relation to travel surface106than other known scissors lift vehicles. Accordingly, a deck202is mounted to scissors stack assembly112at a relatively lower height204above travel surface106. Height204is configured to conform to a standard step height of a user for entry onto deck202directly from travel surface106without intermediate stepping surfaces, such as, steps, stairs, or pegs. In the example embodiment, a standard step height of about 20.0 inches is contemplated based on ANSI/SIA A92.6-2006. Other step heights may be selected based on local custom or other regulations. A width206of carriage102is configured to fit within an interior door frame of, for example, but, not limited to, an office, a home, or a commercial building.

FIG. 3is a side elevation view of a portion of scissors lift vehicle100illustrating scissors stack assembly112including a plurality of scissors linkages118pivotally coupled together.FIG. 4is another side elevation view of scissors lift vehicle100. Scissors lift vehicle100includes a chassis300including a pair of parallelly oriented structural members or channels302. Each channel302includes a first forward end304and a second aft end306. First forward ends304of each of channels302are coupled together using a forward plate308extending orthogonally between first forward ends304. Second aft ends306of each of channels302are coupled together using an aft plate310extending orthogonally between second aft ends306and parallel to forward plate308.

Scissors lift vehicle100also includes a first pair of wheels312positioned at one end314of chassis300and a second pair of steering wheels316positioned at an opposite end318of chassis300. In some embodiments, at least one of second pair of steering wheels316are drive wheels configured to propel scissors lift vehicle using a propulsion motor320. Propulsion motor320includes at least one of an electric motor and a hydraulic motor. Wheels312,316are configured to roll along travel surface106and include a circular profile324having a radius R. In various embodiments, first pair of wheels312are embodied as follower wheels that may be supported by separate axles325(shown inFIG. 8). Each wheel of each pair of wheels312,316is spaced apart laterally with respect to the other wheel312,316of the pair. The pairs of wheels312,316are spaced apart longitudinally from the other pair of wheels312,316.

Scissors lift vehicle100further includes a track324including an upper surface326, a lower surface328, and a thickness330extending therebetween. Track324extends aft at a height331less than R above travel surface106from forward plate308parallel to pair of channels302. A pivot connection332is coupled to aft plate310at a height less than R above travel surface106.

Scissors lift vehicle100also includes scissors stack assembly112including a plurality of paired scissors linkages118extendable from a retracted position to an extended position. Each scissors linkage334,336of a first pair of scissors linkages338of plurality of paired scissors linkages118is pivotally coupled to a respective pivot connection332. Each scissors linkage340,342of a second pair of scissors linkages344of plurality of paired scissors linkages118includes a truck346coupled to a distal end348of each scissors linkage340,342of second pair of scissors linkages344. Truck346is configured to engage upper surface326of track324.

Optionally, scissors lift vehicle100also includes a third pair of scissors linkages350(In the example embodiment, first pair338and third pair350are the same pair, but this does not need to be the case) joined by a lower hydraulic cylinder coupling member352extending between third pair of scissors linkages350and a fourth pair of scissors linkages352joined by an upper hydraulic cylinder coupling member354extending between fourth pair of scissors linkages352. Scissors stack assembly112further includes a hydraulic cylinder assembly356operatively coupled between lower hydraulic cylinder coupling member352and upper hydraulic cylinder coupling member354. In various embodiments, third pair of scissors linkages350and fourth pair of scissors linkages352are parallel with respect to each other.

FIG. 5is a side view of truck346.FIG. 6is a forward view looking aft of truck346. Each truck346optionally includes an inner support plate502, an outer support plate504, and a roller assembly506extending therebetween. A linkage connection508is configured to couple to distal end348of a respective scissors linkage of second pair of scissors linkages. A track keeper510includes a body512extending from at least one of inner support plate502and outer support plate504to face to face proximity to lower surface528.

FIG. 7is a plan view of a forward section of chassis300.FIG. 8is a perspective view of the forward section of chassis300(shown inFIG. 7). Between channels302an opening700is formed to permit positioning scissors stack assembly112within chassis300. Track326extends aft from forward plate308or other support member configured to support track326. Truck346rolls on track326to permit translation of distal end348in a longitudinal direction702.

Second pair of steering wheels are rotated around a kingpin704for steerage using a steering linkage706that, in some embodiments, includes a leadscrew drive708. In various embodiments, leadscrew steering linkage706is powered by an actuator710that includes at least one of a hydraulic actuator and an electric actuator. Actuator710may be positioned proximate an end712of leadscrew drive708or along a length714of leadscrew drive708.

FIG. 9is a plan view of an aft section of chassis300.FIG. 10is another plan view of an aft section of chassis300. In the example embodiment, pivot connection332is coupled to aft plate310at a height less than R above travel surface106.

FIG. 11is a flow chart of a method1100of assembling a scissors lift vehicle. In the example embodiment, method1100includes providing1102a rectangular chassis having an opening formed between a pair of parallelly oriented side channels and coupling1104a first pair of wheels to one end of the chassis and a second pair of steering wheels to an opposite end of the chassis. The wheels are configured to roll along a travel surface and each wheel includes a circular profile having a radius R. In various embodiments, the travel surface may be a smooth surface such as, but not limited to an asphalt roadway or parking lot, or a paved surface such as, but not limited to a convention center floor. In some embodiments, the travel surface may be a rough surface including loose rock or gravel and unevenness. In the example embodiment, the first pair of wheels is embodied in a pair of follower wheels. The pair of steering wheels may also be drive wheels coupled to a propulsion motor configured to propel the scissors lift vehicle along the travel surface. The propulsion motor may be an electric motor or a hydraulic motor.

Method1100includes coupling1106a pivot connection the end of the chassis at a height less than R above the travel surface and coupling1108a track, having an upper surface, a lower surface, and a thickness extending therebetween, to the opposite end of the chassis. The track extends aft at a height less than R above the travel surface. Method1100includes coupling1110a scissors stack assembly to the chassis within the opening. The scissors stack assembly includes a plurality of paired scissors linkages. Each scissors linkage of a first pair of scissors linkages of the plurality of paired scissors linkages, pivotally coupled to a respective pivot connection, each scissors linkage of a second pair of scissors linkages of the plurality of paired scissors linkages including a truck coupled to a distal end of each scissors linkage of the second pair of scissors linkages, the truck configured to engage the upper surface of the track. The truck serves to permit longitudinal movement of the scissors linkage to permit extension and retraction of the scissors stack assembly. The truck includes rolling elements to effect the longitudinal translation of the scissors linkage and a keeper to maintain the position of the truck on the track. The truck may be formed by providing an inner support plate, an outer support plate, and a roller assembly extending therebetween, and coupling a linkage connection to the truck assembly. The linkage connection is configured to couple to a distal end of a respective scissors linkage of the second pair of scissors linkages. The truck is further formed by coupling a track keeper having a body extending from at least one of the inner support plate and the outer support plate into face-to-face proximity to the lower surface of the track.

Method1100may optionally include coupling a third pair of scissors linkages together using a lower hydraulic cylinder coupling member extending between the third pair of scissors linkages and coupling a fourth pair of scissors linkages using an upper hydraulic cylinder coupling member extending between the fourth pair of scissors linkages. The scissors stack assembly further includes a hydraulic cylinder operatively coupled between the lower hydraulic cylinder coupling member and the upper hydraulic cylinder coupling member. In various embodiments, the third pair of scissors linkages and the fourth pair of scissors linkages are parallel with respect to each other.

The above-described embodiments of a method and system of a scissors lift vehicle provide a cost-effective and reliable means of lifting workers to an elevated work site. More specifically, the methods and systems described herein facilitate a worker's ingress and egress to a work platform coupled to a scissors lift assembly portion of the scissors lift vehicle. In addition, the above-described methods and systems facilitate accessing narrow portals to work areas. As a result, the methods and systems described herein facilitate worker safety and work site access in a cost-effective and reliable manner.