Patent Publication Number: US-2021186782-A1

Title: Platform lift with enhanced occupant sensing, platform lifting and locking

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This present nonprovisional application is related to and claims benefit of and priority from U.S. Provisional Patent Application Ser. No. 62/838,567 filed on Apr. 25, 2019, the entire contents of which are hereby incorporated by reference thereto. 
    
    
     TECHNICAL FIELD 
     The subject matter relates to platform lifts. It further relates to wheelchair lifts that are configured to lift a wheelchair from a ground level position to a floor level position in a vehicle and inversely. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are incorporated in and constitute part of the specification and illustrate various embodiments. In the drawings: 
         FIG. 1  illustrates a perspective view of a lift with the lift platform being in a stowed position; 
         FIG. 2  illustrates a perspective view of the lift with the lift platform being in a floor level position; 
         FIG. 3  illustrates a partial perspective view of the lift with the lift platform in the floor level loading position and a bridgeplate being disposed in a bridging position; 
         FIG. 4  illustrates a perspective view of the lift with the lift platform being in a ground level position; 
         FIG. 5  illustrates a partial perspective view of the lift, particularly showing lift platform lifting and lowering mechanism with the bridgeplate being disposed in a bridging position; 
         FIG. 5A  illustrates a partial perspective view of the lift, particularly showing lift platform and bridgeplate being disposed in the stowed position; 
         FIG. 6  illustrates an exemplary control circuit employed within the lift of  FIGS. 1-5A ; 
         FIG. 7  illustrates a partial perspective view of the lift of  FIGS. 1-5A , particularly showing a hydraulic system; 
         FIG. 8  illustrates a partial perspective view of the hydraulic system showing encapsulated, decouplable power interface; 
         FIG. 9  illustrates a partial perspective view of the lift with the lift platform in the intermediate floor level position, particularly showing an exemplary lift platform movement control device that includes detection plume volumes from acoustic sensor arrays; 
         FIG. 10  illustrates a partial perspective view of the lift with the acoustic sensor arrays being illustrated in exploded view; 
         FIG. 11  illustrates a partial perspective view of a switch and potentiometer assembly employed within the lift of  FIGS. 1-5A ; 
         FIG. 12  illustrates an exploded view of the switch and potentiometer assembly of  FIG. 11 ; 
         FIG. 13  illustrates a partial elevation view of the lift showing bridgeplate locking device with the bridgeplate being disposed in a bridging position; 
         FIG. 14  illustrates a partial elevation view of the lift showing bridgeplate locking device with the bridgeplate being disposed in a barrier position; 
         FIG. 15  illustrates a partial perspective view of the lift showing bridgeplate locking device with a cable routing; 
         FIG. 16  illustrates a partial perspective view of the lift showing bridgeplate locking device with a cable routing and over tension assembly; 
         FIG. 17  illustrates a perspective view of the lift with a stow lock assembly shown in a locked position; 
         FIG. 18  illustrates a partial elevation view of the lift, particularly showing a stow lock actuator in the stow lock assembly; 
         FIG. 19  illustrates a partial perspective view of the control enclosure close-up showing a locking arm of the stow lock assembly in a locked position; 
         FIG. 20  illustrates a partial perspective view of the control enclosure, particularly illustrating locking arms in the stow lock assembly; 
         FIG. 21  illustrates an exploded view of the stow lock assembly in a relationship to the control enclosure, partially illustrated; 
         FIG. 22  illustrates a cross-section view of a light assembly along lines XXII-XXII of  FIG. 4 ; 
         FIG. 23  illustrates an exploded view of the light assembly; 
         FIG. 24  illustrates a partial perspective view of the lift with a replaceable ground support structure; 
         FIG. 25  illustrates a perspective view of a lift with a single lift platform being disposed in a deployed position; 
         FIG. 26  illustrates a perspective view of a lift with a split lift platform being disposed in a deployed position and with a single bridgeplate being disposed in a barrier position; 
         FIG. 27  illustrates a perspective view of a lift with a split lift platform being disposed in a deployed position and with a split bridgeplate being disposed in a barrier position; 
         FIG. 28  illustrates a perspective view of the lift of FIG. with a split bridgeplate in a stowed position, biased adjacent the control assembly; and 
         FIG. 29  illustrates a perspective view of a lift with a single arm carrying a one-piece lift platform, shown in the deployed position. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Prior to proceeding to the more detailed description of the present disclosure, it should be noted that, for the sake of clarity and understanding, identical components which have identical functions have been identified with identical reference numerals throughout the several views illustrated in the drawing figures. 
     The following detailed description is merely exemplary in nature and is not intended to limit the described examples or the application and uses of the described examples. As may be used herein, the words “example”, “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “example”, “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present disclosure are provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the coupled drawings, and described in the following specification, are simply examples of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the examples disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     References in the specification to “one embodiment”, “an embodiment”, “an exemplary embodiment”, “another embodiment”, “a presently preferred embodiment”, “an alternative embodiment”, “one variation”, “a variation” and similar phrases mean that a particular feature, structure, or characteristic described in connection with the embodiment or variation, is included in at least an embodiment or variation of the disclosure. The phrase “in an embodiment”, “in one variation” or similar phrases, as may be used in various places in the specification, are not necessarily meant to refer to the same embodiment or the same variation. 
     For purposes of description herein, the directional and/or relationary terms such as “upper”, “top”, “lower”, “bottom”, “left”, “right”, “rear”, “back”, “front”, “apex”, “vertical”, “horizontal”, “lateral”, “exterior”, “interior” and derivatives thereof are relative to each other and are dependent on the specific orientation of an applicable element or article, and are used accordingly to aid in the description of the various embodiments and are not necessarily intended to be construed as limiting. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented. “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer,” or “section” discussed below could be termed a second element, component, region, layer, or section without departing from the teachings herein. 
     The term “couple” or “coupled”, when used in this specification and appended claims, refers to an indirect or direct physical connection between the identified elements, components, or objects. Often the manner of the coupling will be related specifically to the manner in which the two coupled elements interact. 
     The term “directly coupled” or “coupled directly,” when used in this specification and appended claims, refers to a physical connection between identified elements, components, or objects, in which no other element, component, or object resides between those identified as being directly coupled. 
     The terms “removable”, “removably coupled”, “removably disposed,” “readily removable”, “readily detachable”, “detachably coupled”, “separable,” “separably coupled,” and similar terms, as used in this specification and appended claims, refer to structures that can be uncoupled, detached, uninstalled, or removed from an adjoining structure with relative ease (i.e., non-destructively, and without a complicated or time-consuming process), and that can also be readily reinstalled, recoupled, or coupled to the previously adjoining structure. 
     Moreover, the ordinary and customary meaning of term “substantially” includes “reasonably close to: nearly, almost, about”, connoting a term of approximation. See In re Frye, Appeal No. 2009-006013, 94 USPQ2d 1072, 1077, 2010 WL 889747 (B.P.A.I. 2010). The term “substantially” is used in this document to accommodate minor variations that may be appropriate, for example due to a manufacturing process. 
     For example, the term “substantially horizontally” as used herein when referring to elements or features of the conveyor(s) should be understood to mean that such elements or features are positioned with respect to a vertical line extending there above at an angle of 90°, except for manufacturing tolerances. The angle can be in the range of from about 89° to about 91°, in the range of from about 88° to about 92°, in the range of from about 87° to about 93°, or in the range of from about 85° to about 95°. In other words, the term “substantially horizontally” should be also understood to mean that, if deviating from absolutely horizontal, the conveyor is operable to convey material completely or partially between ends of the conveyor. 
     The term “generally horizontal(ly)” or “generally vertical(ly)” should be also understood to mean respectively horizontally or vertically disposed element or surface but the term does not exclude the possibility of orienting such feature or surface at a small angle relative to respectively absolute horizontal or vertical plane. 
     As may be used herein, the terms “adapted” and “configured” mean that the element, component, or other subject matter is designed and/or intended to perform a given function. Thus, the use of the terms “adapted” and “configured” should not be construed to mean that a given element, component, or other subject matter is simply “capable of” performing a given function but that the element, component, and/or other subject matter is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the function. It is also within the scope of the present disclosure that elements, components, and/or other recited subject matter that is recited as being adapted to perform a particular function may additionally or alternatively be described as being configured to perform that function, and vice versa. Similarly, subject matter that is recited as being configured to perform a particular function may additionally or alternatively be described as being operative to perform that function. 
     Anywhere the term “comprising” is used, embodiments and components “consisting essentially of” and “consisting of” are expressly disclosed and described herein.” 
     For purposes here, the conjunction “or” is to be construed inclusively (e.g., “a dog or a cat” would be interpreted as “a dog, or a cat, or both”; e.g., “a dog, a cat, or a mouse” would be interpreted as “a dog, or a cat, or a mouse, or any two, or all three”), unless: (i) it is explicitly stated otherwise, e.g., by use of “either . . . or,” “only one of,” or similar language; or (ii) two or more of the listed alternatives are mutually exclusive within the particular context, in which case “or” would encompass only those combinations involving non-mutually-exclusive alternatives. For purposes here, the words “comprising,” “including,” “having,” and variants thereof, wherever they appear, shall be construed as open-ended terminology, with the same meaning as if the phrase “at least” were appended after each instance thereof. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
     The particular embodiments of the present disclosure generally provide platform lifts that are designed to carry occupants with limited mobility, including those who rely on wheelchairs, scooters, canes and other mobility aids, so that they can move into and out of motor vehicle. 
     The particular embodiments of the present disclosure generally provide device and method directed to platform lifts for vans, busses, trains and the like vehicles. Lift can be also referred to as wheelchair loading and unloading apparatus or a lift assembly. The wheelchair can be occupied by a person or can be without the person. 
     In particular embodiments, the lift incorporates a mobile platform for receiving a wheelchair or an occupant with limited mobility who does not use wheelchair, a parallelogram mechanism to carry the platform, a base to mount the parallelogram mechanism, a hydraulic system for actuating the platform through the parallelogram mechanism, and roll stop and a mechanism to pivot the roll stop between two terminal positions, a bridgeplate and a control unit to accomplish different motion patterns. 
     In an embodiment, the lift incorporates a threshold safety warning system, for example such as an acoustic sensor array, to detect the presence of occupants and to enable interlocks and warning systems for enhanced operational safety. A combination of an electronic control, platform position sensor and acoustic sensor array monitors the bridgeplate and threshold areas providing both a visual and/or audible alert to passengers approaching an open threshold area from inside the vehicle and an interlock to prevent the lift platform from descending from vehicle floor level when the areas are occupied. 
     In an embodiment, the lift comprises a decouplable power interface with enhanced protection against high power short circuits, resulting in enhanced safety. 
     In an embodiment, the lift comprises an LED light assembly affixed to the top of the platform side barriers. The modular construction of the light assembly facilitates the lighting of the platform surface and/or the provision flashing side lights to warn on-coming traffic that the lift is in operation. 
     In an embodiment, the lift incorporates a replaceable ground contact that protects the lower extremities of the vertical arms from the damage associated with repeated contact with the ground. 
     In an embodiment, a lift comprises a combination bridging and lockable inner barrier plate which is operated by a cable. 
     In an embodiment, the lift comprises a platform storage locking device integrated into the control enclosure such that it can be pre-assembled apart from the main structure of the unit and such that the same bill of material can be assembled to enable the lock to be used on either side of the lift. The control enclosure incorporates a controller and hydraulic components. The controller can be any one of a micro-processor based, a programmable logic controller, a relay logic and any combinations thereof. The controller can comprise on or more printed circuit boards (PCBs). 
     Now in a reference to  FIGS. 1-5A , therein is illustrated a lift  10  that can be configured to meet Federal Motor Vehicle Safety Standard (FMVSS)  403 . FMVSS  403  affects both privately owned automotive vehicles, such as family vans and minivans, as well as automotive vehicles designed for commercial uses, such as school and public buses. Further, FMVSS  403  is applicable specifically to the equipment that raises and lowers the wheelchair. The installation of  403  compliant equipment is controlled by FMVSS  404 . 
     In particular embodiments, the lift  10  comprises a base  20 , a parallelogram mechanism  30  mounted on the base  20 , a lift platform  70  that is carried by the parallelogram mechanism  30 , a control assembly  200  for actuating the lift platform  70  through the parallelogram mechanism  30 , a platform folding and unfolding mechanism, including an elbow assembly  40 , an occupant retention device that can incorporate any one of a belt  124 , a bridgeplate  130 , and a roll stop  136  pivotally coupled to the lift platform  70 , a lift platform movement control device, and an electrical control circuit  159  to accomplish different motion patterns and annunciations. 
     The base  20  comprises a baseplate  21 . The baseplate  21  is affixed, for example by fasteners, to a vehicle floor surface (not shown). The base  20  also comprises two towers. Each tower comprises a pair of supports  26  and  27 . Each support  26  and  27  upstands, in a vertical direction, on the baseplate  21 . Each support  26  and  27  is rigidly attached to the top surface  21 A of the baseplate  21 . The support  26  is illustrated as an inner support and the support  27  is illustrated as an outer support. The distance between inner supports  26  defines an operable width of the lift  10 , that is sufficient to pass the wheelchair (not shown) therethrough. The baseplate  21  also defines a threshold area  28 . 
     The base  20  can also comprise two optional uprights  22  upstanding, in a spaced apart relationship with each other, on a respective end of the baseplate  21 . Each upright  22  can be terminated with a mounting plate  24 . During use, the upright  22  with the mounting plate  24  can be used to fasten the lift  10  to a vehicle structure, for example such as a door post (not shown) so as to not rely solely onto the floor structure of the vehicle. When the uprights  22  are provided, each tower is generally disposed adjacent a respective upright  22 . 
     The parallelogram mechanism  30  comprises at least a four-bar linkage mechanism with upper arms  32 , lower arms  34 , vertically disposed arms  38 , and a cylinder  36 . Each of the upper arms  32 , lower arms  34 , and vertically disposed arms  38  can be provided with a U-shaped cross-section in a plane normal to a length of each arm. One end of the upper arm  32  is pivotally coupled to each pair of supports  26  and  27  at a pivot  32 A. In an example, the pivot  32 A can comprise a shaft being rigidly secured to the supports  26  and  27  and at least an aperture in the arm  32 . In an example, the pivot  32 A can comprise a shaft being rigidly secured to the arm  32  and an aperture in each of the supports  26  and  27 . In an example, the pivot  32 A can comprise a tubular member disposed within U-shaped arm  32  or the shaft can be enlarged within the U-shaped arm  32 . The pivot  32 A can also comprise a bearing. The other end of the arm  32  is pivotally coupled to each arm  38  at a pivot  32 B. The pivot  32 B can be constructed identically to the pivot  32 A. One end of the arm  34  is pivotally coupled, at one end thereof, to each pair of supports  26  and  27  at a pivot  34 A. The pivot  34 A can be constructed identically to the pivot  32 A. The other end of the arm  34  is pivotally coupled to each vertically disposed arm  38  at a pivot  34 B. The pivot  34 B can be constructed identically to the pivot  32 A. The cylinder  36  is pivotally mounted at a stationary end thereof to the arm  34  at a pivot  34 A and is pivotally mounted at a movable end thereof to the pivot  32 B. The cylinder  36  that can be pneumatically or hydraulically operated. The cylinder  36  is of a telescopic single-action type and converts pneumatic or hydraulic pressure into the platform lifting and folding force. The vertically disposed arms  38  are also pivotally connected, at their lower ends to the lift platform  70  at pivots  38 A. The pivot  38 A can be constructed identically to the pivot  32 A. 
     The platform folding and unfolding mechanism is represented by the elbow assembly  40 . The lift  10  comprises two elbow assemblies  40 , one at a respective side of the lift platform  70 . In a particular reference to  FIG. 5 , each elbow assembly  40  comprises a substantially vertical elbow link  42 , a substantially horizontal elbow link  44 , a spring  46  and a roller  48 . One end of the vertical elbow link  42  is pivotally connected to one end of the horizontal elbow link  44  at a pivot  42 A. A longitudinally opposite end of the vertical elbow link  42  is pivotally connected to a rear end of the platform  70  at a pivot  42 B. The other end of the horizontal elbow link  44  is pivotally connected to the vertical arm  38  at a pivot  44 A. The spring  46  is connected to each of the vertical elbow link  42  and the horizontal elbow link  44 . The roller  48  is mounted for a rotational movement about the pivot  42 A. During operation, the peripheral edge surface of the roller  48  contacts the lower parallel arm  34 , as is best shown in  FIG. 5 , when the lift platform  70  moves between the stowed position and floor level position. The roller  48  improves motion by reducing friction, although the roller  48  can be replaced by a stationary member with a smooth service (not shown). During operation, the motions of the lift platform  70  are well controlled and especially prevent the lift platform  70  from free falling or free deploying movement during the lift&#39;s swing-up and swing-down motions. When the lift platform  70  is away from its floor level position to the ground level position of  FIGS. 2 and 4 , the roller  48  is disengaged with the underneath sides of the lower arm  34 . As the lift platform  70  is lifted up from its floor level position towards its stowed position, the roller  48  comes into a contact with the lower arm  34  which pushes down the vertical elbow link  42 , and the inner lift platform section  74  is raised through the pivot connection. This action facilitates folding of the lift platform  70 . Additional features of the platform folding and unfolding mechanism are disclosed in U.S. Pat. No. 9,149,397 B2 issued to Gallingani et al. which is incorporated in it&#39;s entirety herewithin. The detail description of such additional features of the platform folding and unfolding mechanism are omitted herewithin for the sake of brevity. Accordingly, the lift platform  70  is to be understood as including such platform folding and unfolding mechanism. 
     The lift platform  70  is configured to receive the occupant. The occupant can be seated in a wheelchair or a mobility scooter (not shown) or standing. The standing occupant may or may not use a mobility aid, for example such as a cane (not shown). In a further reference to  FIGS. 2 and 4 , the lift platform  70  is illustrated as being comprised by a first lift platform section  74  and a second lift platform section  100 . The first lift platform section  74  is being illustrated as an inner lift platform section and the second lift platform section  100  is being illustrated as an outer lift platform section. The first lift platform section  74  has one end  76  thereof being configured to pivotally mount to each vertically disposed arm  38  at the pivot  38 A and, subsequently to the base  20 , for a rotation between a vertical position and a horizontal position. The end  76  defines a rear of the first lift platform section  74  and the rear of the lift platform  70 . The first lift platform section  74  also has an opposite end  78 . The first lift platform section  74  also has a first surface  80  that becomes a top surface when the lift platform  70  is unfolded in a deployed position and a second surface  82  that is spaced apart from the first surface  80  to define a thickness of the first lift platform section  74 . The first surface  80  is being illustrated as a top surface of the platform  70 . This top surface receives thereon an occupant, either with or without a wheelchair (not shown). The first lift platform section  74  can be configured as a hollow frame member comprising the above described ends  76  and  78  and a pair of sides  84  and  86 . The sides  84  and  86  are illustrated as extending outwardly from the top surface  80  to provide side safety rails during use of the lift  10 . However, it is also contemplated that the sides  84  and  86  can be generally flush with the top surface  80 . One or more optional reinforcing members  88  can be rigidly secured to either ends  76  and  78 , as is illustrated, or alternatively to the sides  84  and  86  to increase rigidity and/or stiffness of the first lift platform section  74  and essentially prevent it from sagging or twisting during use. The quantity and configuration of the reinforcing members  88  will generally depend on any one of a width of the lift platform  70 , a length of the lift platform  70  in the deployed position, occupant weight with and without wheelchair. The first surface  80  can be provided as an illustrated meshed member secured to the ends  76 ,  78  and/or sides  84 ,  86 . Alternatively, the first surface  80  can be provided as a solid member. The opposite surface  82  can be open. Furthermore, as illustrated in various figures, the sides  84 ,  86  can extend outwardly from the ends  76 ,  78 , thus defining a U-shaped configuration of the first lift platform section  74 , best illustrated in  FIGS. 2-3 . 
     The second lift platform section  100  has a pair of ends  102  and  104 , a first surface  106  that becomes a top surface when the lift platform  70  is unfolded and a second surface  108  that is spaced apart from the first surface  106  to define a thickness of the second lift platform section  100 . The second end  104  is configured to contact the ground surface when the lift platform  70  is unfolded in the deployed position and is configured to move into a vertical position during movement of the lift platform  70 . The second lift platform section  100  can be also configured as a hollow frame member comprising the above described ends  102  and  104  and a pair of sides  110  and  112 . The sides  110  and  112  are illustrated as extending outwardly from the first surface  106  to provide side safety rails during use of the lift platform  70 . However, it is also contemplated that the sides  110  and  112  can be generally flush with the first surface  106 . One or more optional reinforcing members  114  can be rigidly secured to either ends  102  and  104 , as is illustrated or alternatively to sides  110  and  112  to increase rigidity and/or stiffness of the second lift platform section  100  and essentially prevent it from sagging or twisting during use. The quantity and configuration of the reinforcing members  114  will generally depend on any one of a width of the lift platform  70 , a length of the lift platform  70  in the deployed position, occupant weight with and without wheelchair. The first surface  106  can be provided as an illustrated meshed member secured to the ends  102 ,  104  and/or sides  110 ,  112 . Alternatively, the first surface  106  can be provided as a solid member. The opposite surface  108  can be open. Furthermore, as illustrated in various figures, the sides  110 ,  112  can extend outwardly from the ends  102 ,  104 , thus defining a U-shaped configuration of the second lift platform section  100 , best illustrated in  FIGS. 2 and 4 . Since the second end  104  can be configured to contact the ground surface when the lift platform  70  is unfolded in the deployed position, such second end  104  can be made large relative to the first end  102  to provide a solid stepping on surface. 
     The lift platform  70  also comprises a hinge  118  that is configured to operatively couple the end  78  of the first lift platform section  74  to the end  102  of the second lift platform section  100 . In an example, the hinge  118  can be a continuous hinge or can be provided in separate sections. In an example, a short hinge section can be mounted adjacent each side. In either example, the second lift platform section  100  is movable between a generally folded stowed position being disposed in a surface-to-surface facing arrangement with the first lift platform section  74 , as is best illustrated in  FIG. 1  and a deployed unfolded position being disposed in an end-to-end facing arrangement with the first lift platform section  74  and defining a planar lift platform surface during the operation of the lift platform  70 , as is illustrated for example in  FIGS. 2 and 4 . 
     During operation, the parallelogram mechanism  30  is configured to move the lift platform  70  between a (fully) stowed position of  FIG. 1  and a ground level (fully deployed) position of  FIG. 4 , through a floor level position of  FIGS. 2-3 . In the floor level position of  FIGS. 2-3 , the lift platform  70  may be aligned, in a vertical direction with a floor of the vehicle (not shown). In the ground level position of  FIG. 4 , at least a portion of the lift platform  70 , for example such as the second end  104 , is generally resting on the ground surface (not shown) or is positioned in a close proximity to the ground surface (not shown). It will be understood that in the floor level position, the lift  10  and, more particularly, the lift platform  70  transitions occupant(s) to/from the vehicle floor (not shown) and that in the ground level position the lift platform  70  transitions occupant(s) to/from ground surface. In this document, the ground surface can also comply a low-rise ground platform. Furthermore, the stowed position can be also referred to as a stored position of the lift platform  70 . 
     In a further reference to  FIGS. 1-5A , the lift  10  comprises left and right handrails  120  that move with respect to the extension and retraction of the hydraulic cylinders  36 . Each handrail  120  extends through an opening  38 B in each vertical arm  38  and comprises a mount  122  with a flange  122 A that is fastened to a respective horizontal elbow link  44 . 
       FIGS. 1-5A  also illustrate the occupant retention apparatus. 
     The occupant retention device can comprise the belt  124 . The belt  124 , restrains an occupant, standing on the lift platform  70 , from inadvertently falling of the lift platform  70 . Thus, the belt  124  can be also referred to as occupant restraint belt  124 . Generally, the belt  124  will be used in commercial/transit application benefiting from presence of an attendant. However, the belt  124  may not be required and/or present on lifts  10  installed in privately used vehicles. Each end of the belt  124  is attached to each handrail  120 . The ends of the belt  124  are connected by way of the releasable buckle  126 . The belt  124  can be electrically interlocked, by way of a restraint belt interlock switch  186  disposed within the buckle  126 , with the control system of the lift  10  so that the lift platform  70  would not move unless the occupant restraint belt  124  is securely fastened. 
     The occupant retention device can comprise the bridgeplate  130  that is mounted for a pivotal movement between two terminal positions. During operation, when the lift platform  70  is in the floor level position of  FIG. 2  and in one terminal position, the bridgeplate  130  is pivoted to bridge a gap between the second end  78  and the baseplate  21  and permit on-boarding onto the lift platform  70  or off-boarding from the lift platform  70  onto the vehicle floor. In other words, when the lift platform  70  is in the floor level position, the bridgeplate  130  is disposed generally horizontally, resting on the baseplate  21 . In this position, the wheelchair bound person or a person with a limited mobility can move from the interior compartment of the vehicle (not shown) onto the lift platform  70  or can move from the lift platform  70  into the interior compartment of the vehicle (not shown). In other words, the occupant of the lift platform  70  can on-board or off-board the lift platform  70 . Prior to a movement of the lift platform  70  from the floor level position of  FIGS. 2-3  toward the ground level position of  FIG. 4 , the bridgeplate  130  is pivoted into a generally vertical plane. Thus, in another terminal position, the bridgeplate  130  is disposed generally vertically to provide an internal roll stop of the lift  10 . Such internal roll stop can be also referred to as an inner barrier or a rear roll stop. As the lift platform  70  moves between the floor level position of  FIGS. 2-3  and the ground level position of  FIG. 4 , the bridgeplate  130  remains in the vertical position so as to prevent unintended movement of the wheelchair from the lift platform  70 . The mechanism to pivot and lock the bridgeplate  130  will be described later in this document. 
     When the lift platform  70  is stowed, a free edge  137  of the bridgeplate  130  rests on the surface of the baseplate  21 , as is best shown in  FIG. 5B . When the lift platform is moved from the floor level position of  FIGS. 2-3  into a stowed position of  FIG. 1 , the free edge  137  slides on the upper surface  21 A of the baseplate  21  toward the rear of the base  20 . When the lift platform  70  is fully stowed, such free edge  137  is allowed to move away and toward the upper surface  21 A as the vehicle (not shown) travels over uneven surfaces including without limitations railroad tracks, road surface cracks, bumps, potholes, and the like. Since both the bridgeplate  130  and the baseplate  21  are generally manufactured from metal, such movement of the free edge  137  is generally associated with a rattling sound. Such rattling sound can be an annoyance to vehicle occupants. The lift  10  can overcome such disadvantage of conventional lifts by employing a stop  60  at one or both inner supports  26 . Now in a reference to  FIG. 5A , the stop  60  is so mounted at a distance from the upper surface  21 A that a portion of the free edge  137  is disposed under a peripheral surface  62  of the stop  60 . In other words, it can be said that the portion of the free edge  137  is wedged under the stop  60  when the lift platform  70  is being in the stowed position. The peripheral surface  62  can be provided as a resiliently compressible material that would compress under contact with the portion of the free edge  137 . Thus, a method of operating the lift  10  or the method of stowing the lift platform  70  can also include a step of at least restricting if not completely eliminating a movement of the free edge  137  of the bridgeplate  130  away from and toward the upper surface  21 A of the baseplate  21 . 
     The stop  60  can be also provided as a roller and, more particularly, as an elastomeric roller. The elastomeric roller is Strategically positioned to capture and hold the outboard edge  137  of the bridgeplate  130  when the lift platform  70  is in the stowed position. By capturing the outboard edge  137  of the bridgeplate  130  when the lift platform  70  is stowed and the vehicle is moving, the significant source of rattling is at least reduced if not eliminated, resulting in a more comfortable driver and passenger experience. 
     The occupant retention device can comprise the roll stop  136 . The roll stop  136  also pivots, during operation, between two terminal positions. The mechanism that pivots the roll stop  136  is disposed under the lift platform  70  can be of a type as described in U.S. Pat. No. 4,534,450 or 6,086,314, both issued to Savaria, which are being incorporated by reference in their entirety herewithin. The detail description of such mechanism is omitted herewithin for the sake of brevity. Accordingly, the illustrated roll stop  136  is to be understood as including such mechanism. In one terminal position when the lift platform  70  is in the ground level position, the roll stop  136  is pivoted into a generally coplanar position with the lift platform  70  to allow one of loading onto the lift platform  70  from a ground level (and off-loading from the lift platform  70  onto the ground level. Prior to movement of the lift platform  70  between the ground level position of  FIG. 4  and the floor level position of  FIGS. 2-3 , the roll stop  136  is pivoted into another terminal position and is disposed in a plane being traverse to a plane of the lift platform  70 . The roll stop  136  remains in such another terminal position until the lift platform  70  is ready to be moved into a stowed position of  FIG. 1 . In such another terminal position, the roll stop  136  is disposed generally vertically and traverse to the plane of the lift platform  70  to prevent unintentional discharge from the lift platform  70  during movement of such lift platform  70  between ground level and floor level. The roll stop  136  can be also referred to as an outer barrier. 
     The occupant restraint belt  124  and the roll strop  136  do not have to be used in a combination with each other. The occupant restraint belt  124  is suitable for use on commercial/public DOT-compliant vehicles that require a presence of operator or attendant to aid occupants in wheelchair or occupants with limited mobility. The roll stop  136  is common on private vehicles that do not enjoy benefit of an external operator or attendant. Thus, although the lift  10  of  FIGS. 1-5A  has been illustrated as employing both the occupant restraint belt  124  and the roll stop  136 , only one device can be used. 
     Now in a reference to  FIG. 6 , the electrical control circuit  159  comprises an electric motor  172  that is coupled through a motor contactor  174  with a battery  176  that functions as a source of electrical power. A down valve  178  is also provided. During operation, the electric motor  172  operates the hydraulic pump  204  to move the lift platform from the ground level position of  FIG. 4  to the stowed position of  FIG. 1  through the floor level position of  FIGS. 2-3 . The down valve  178  is provided to move the lift platform  70  from the stowed position of  FIG. 1  into the ground level position of  FIG. 4 . The electrical control circuit  159  also incorporates a plurality of control switches. For example, limit switches  162  and  164  control stow and deploy movements of the lift platform  70 . The limit switches  162  and  164  are interlocked, by wires, with a manually operable pendant  190  and are essentially coupled to the battery  176 . The limit switches  162  and  164  are employed to annunciate positions of the lift platform  70 . One of the limit switches, for example, such as limit switch  162  can be positioned to cooperate with the exterior surface of a switch cam  166 , best shown in  FIGS. 11-12 , so as to control stowed position of the lift platform  70  of  FIG. 1 . The other one of the limit switches, for example, such as limit switch  164  can be positioned to cooperate with the exterior surface of the switch cam  166  so as to control deployed position of the lift platform  70  of  FIG. 4 . A pressure switch  180  is mounted on a pump body and is operable to determine a pressure of stowing lift platform  70  with a load on it. When the roll stop  136  is provided, a roll stop interlock switch  184  is mounted under the rolls stop  136  and is operable to detect the position of the roll stop  136 . As has been disclosed above, the restraint belt interlock switch  186  is mounted within the buckle  126  and is operable to output a signal, controlling movement of the lift platform  70  should the belt  124  being unbuckled during occupant transport. The electrical control circuit  159  also incorporates a controller  160 . Additional components within the electrical control circuit  159  may include a counter  214  configured to count movement cycles of the lift platform  70  between below floor level and stow position, fuse/circuit breaker(s)  216  and a threshold warning device light  226  that provides a visible annunciation/warning. The lift  10  is configured to also provide an audible warning by way of a buzzer device (not shown) that can be mounted on the back of the controller  160  or the control enclosure  202 . 
     Now in a reference to  FIG. 7 , therein is illustrated the control assembly  200 . The control assembly  200  comprises a control enclosure  202 . Various controls and annunciators are mounted on or within the control enclosure  202 . As it is best shown in  FIG. 7 , the controller  160  is mounted within the control enclosure  202 . Also mounted within the control enclosure  202  is a hydraulic pump  204  that is operable by the electric motor  172 . The hydraulic pump  204  is connected to the reservoir  206 . The reservoir  206  contains hydraulic fluid. There is also a manually operable handpump  210  with a pressure relieve valve module  212 . A handle  210 A of the manually operable handpump  210  is generally mounted on an exterior surface of the control enclosure  202 . Also provided on the exterior surface of the control enclosure  202  are interface/interlock connector  220 , pendant connector  222  and ON/OFF switch  224 . The interface/interlock connector  220  can electrically connect at least the controller  160  with another system within the vehicle (not shown), for example such as a door system (not shown) and/or 
     In an example, the hydraulic pump  204  with the electric motor  172  can comprise a prime moving system of the lift  10 . In an example, the hydraulic pump  204  with the electric motor  172  and down valve  178  can comprise a prime moving system of the lift  10   
     Now in a reference to  FIGS. 7-8 , therein is illustrated a power interface to the control assembly  200 . Such power interface is being best illustrated in  FIG. 8  as an encapsulated decouplable power interface. Such encapsulated decouplable power interface can be provided by a high capacity, power connector  230  that can be manufactured by Anderson Power Products under a Cat. No. 1321G or any other suitable electrical power connector. Such power connector  230  comprises a first (control assembly mounted) part  232  and a second (cable mounted) part  234 . The power connector  230  is incorporated into control enclosure  202  and provides a decouplable power connection combined with keeping the “live” end of the cable protected in the event it is decoupled. Both the lift part  232  and the cable part  234  of the power connector  230  are protected with the control enclosure  202  that cannot be lost and nearly impossible to improperly install. The integral cover overcomes disadvantages of separate covers that protect power interface from ground sources as a risk of a high current short circuit exists but that can be improperly installed or lost, thus amplifying the risk of a high current short circuit. Moreover, in the event the power interface is disconnected for service, power lug  236  is protected by the first part  232  and/or the second part  234 , to ensure that the end of the cable is protected. As such, the risk of a high current short circuit either during normal service or during service is at least substantially reduced if not eliminated. 
     On some conventional platform lifts, a power interface is provided external to the control (pump) enclosure. Further, such power interface relies on the use of an insulating, elastomeric “boot” to cover the power lug. In the event the “boot” is not properly installed and a conductive object is placed across the powerlug and an otherwise “grounded” part of the vehicle (as most vehicles are configured with a “chassis ground”), nearly any metallic object inside the vehicle will represent a ground. Such contact can result in a very high current short circuit which can cause a fire. 
     With the above described power interface, both sides of the power cable are protected by a plastic housing. When the connection is made, there is literally no way to contact the power lug  236  inside the housing. Further, even when the power interface is disconnected, both ends of the cable are individually protected at least further reducing if not completely eliminating the possibility of a short circuit. 
     The lift  10  can be adapted with a device configured to control movement of the lift platform  70 . The device can be also referred to as a lift platform movement control device. The lift platform movement control device can be provided as a bridgeplate and threshold area monitoring system  239 . The bridgeplate and threshold area monitoring system can be also referred to as a bridgeplate and threshold safety warning system. The bridgeplate and threshold area monitoring system comprises a distributed sensor array. More specifically, in the exemplary embodiment of  FIGS. 3 and 9-10 , the distributed sensor array is illustrates as comprising a first sensor array with two sensors  240  and a second sensor array with two sensors  250 . The first and second sensor arrays are being further illustrated as acoustic sensor arrays. 
     The two sensors  240  are configured to monitor the threshold area  28  by way of a sensor detection plume  241 . Two sensors  250  are configured to monitor transfer bridgeplate area by way of sensor detection plume  251  while the lift platform  70  is in the floor level position. The sensor detection plumes  241 ,  251  are best shown in  FIG. 9 . A controller  160 , to be described later in this document, is configured to prevent operation (movement of the lift platform  70 ) while this area is occupied by any one of the wheelchair (not shown) and a standing occupant, resulting in an interrupted detection plume  241  and/or  251 . 
     While the lift platform  70  is in the stowed position of  FIG. 1 , the sensor pairs can be in a de-activated state. In an example, such de-activated state can include the sensors being in a power-off state. In an example, such de-activated state can include a condition where the output signals from the sensors are being essentially ignored by the controller  160 . In other words, in this state, the sensors  240 ,  250  may not generate a respective sensor detection plume  241 ,  251  and may not generate an output electrical signal when, thus indicating absence of an object, for example such as the wheelchair. As the lift platform  70  moves from the stowed position into the floor level position, the controller  160  activates sensors  240 ,  250  and causes the sensors  240 ,  250  to generate the respective sensor detection plumes  241  and  251 . The controller  160  can activate the sensors  240 ,  250  upon receipt of a deployed command (“Down” function) from the pendant  190  even before the lift platform  70  starts to move. This means that in this state either one or both of the two sensors  240  and two sensors  250  will generate an electrical output signal when the object breaks the respective sensor detection plume  241 ,  251 . The controller  160  can be configured such that when the lift platform  70  reaches floor level position, an object detected by any of the first and second sensor arrays will result in the “Down” function being disabled. When no objects are detected and the “Down” function is selected, the front sensors  240  can be configured to cease function, i.e. stop generating the output signal, while the rear sensors  250  can continue to monitor the threshold area  28 . In the event, an object is detected in the threshold area  28  while the lift platform  70  is below the floor level position, an audible and visual warning system can be activated. 
     The front sensors  240  are illustrated as being mounted to the lower parallel arms  34 , while the rear sensors  250  are illustrated as being located in the structure at the rear of the baseplate  21  and, more particularly, being mounted within the uprights  22 . Each sensor  240  is mounted in a collar  242 A. Each sensor  250  is mounted in a collar  242 B. Collars  242 A and  242 B orient the sensor  240 ,  250  so that its respective sensor detection plume  241 ,  251  is optimal. The collar  242 B for each rear sensor  250  is arranged on a slight forward-facing angle and mounted directly in the structure. Each front sensor  240  is suspended, by way of the collars  242 A, in a sensor mounting brackets  244 A,  244 B that serve a dual purpose of holding and protecting the sensor  240  as each lower parallel arm  34  moves through its normal motion. The collars  242 A,  242 B and sensor mounting brackets  244 B are best shown in  FIG. 10 . 
     The orientation of the front sensors  240  is such that the collar  242 A is angled in two directions, the combination of which maintains the orientation of the sensor detection plume  241  as the lower area (below sensor) begins to move. 
     Each exemplary sensor  240 ,  250  can be a two-wire, piezoelectric device of the type shown in  FIG. 10 , being equipped with a cable  246  and a connector  248  for ease of installation and wiring connection. This type of sensor is inexpensive, plentiful in terms of procurement from different manufacturers and reasonably reliable in terms of mean time between replacements due to sensor failure. This type of sensor works as both a speaker and a microphone depending on the polarity of the voltage applied. Accordingly, the controller  160  connects different polarity voltage to each sensor with a pair of sensors. 
     The above described sensors  240 ,  250  provide acoustic sensor arrays. Though the detection volume for these types of devices are specified with an angle and a maximum distance, it has been determined that the practical detection volume is shaped more like a watermelon rather than a cone. Accordingly, it is possible to locate these sensors quite close to the ground without fear of false detection. 
     Further, the acoustic sensor array also covers the area over the transition area over the transfer plate between the vehicle floor and the lift platform  70 . In a combination with the controller  160 , movement of the lift platform  70  can be disabled (i.e. controlled) in the event the transition area is occupied, thus significantly reducing the possibility of accidents caused by operator error. 
     Thus, it would be understood that the above described acoustic sensor array provides a non-contactless object detection method. 
     In an example, the above described acoustic sensor array overcomes difficulties of other sensing approaches that are either not comprehensive in their coverage of the threshold area  28  or are prone to malfunction in the event of contamination. For example, a system of infrared beams to cover the vehicle threshold area  28  while leaving the transition area unprotected operates on a “line of sight” basis. Such system works on a “line-of-sight” basis. Though it is difficult to park a wheelchair in the threshold area without being detected, thinner objects like crutches, canes and some prosthetics can fit “between” the beams and avoid being detected. As such, an object that does not appear on the line between an emitter and receiver pair will not be detected. The above acoustic sensor array monitors a volume in front of the sensor rather than aligned with sensors in a linear path, thereby increasing an ability to detect objects in the monitored area. As a volume, it is much easier to reliably detect a wider range of objects. 
     In an example, the above described acoustic sensor array overcomes difficulties of monitoring the threshold and transition plate areas with a pressure sensitive mat on the surface of the lift platform  70  or on the surface of the baseplate  21 . Though this technology/technology can be efficient in terms of area size, it is susceptible to foreign matter intrusion under the plate. Objects like pebbles or hard candy can become lodged between the pressure plate and the lift&#39;s base plate rendering the system inactive and prone to “false positive” readings. Such foreign matter intrusion is of special consideration in areas where sand is used to counter the effects of snow and ice. Once the foreign matter is stuck under the pressure mat, operation of the lift platform can be prevented. Additionally, the detection sensitivity of the pressure sensitive mat reduces away from area were load is directly applied. 
     In an example, the above described acoustic sensor array does not require internal component motion as in a case with tension devices employed to monitor the bridgeplate area. Such device needs to move to load the tension device so that the detection can occur. Accordingly, some standee occupants who might not be very surefooted may be startled by the movement and may fall. 
     In an example, the above described acoustic sensor array can be a cost-effective alternative solution to a video-based monitoring system at least for the reason that it does not require the computing power to monitor the target area over a wide range of operating conditions. 
     In an example, the described acoustic sensor array does not require adjustments by an operator to set the size of the operating plume volume to a size that is too small to be effective in an effort to avoid “false negative” condition. Such adjustments are generally necessary for a single senor system generating a conical sensing shape. 
     In an example, the described acoustic sensor array is integrated into the lift structure, enabling the entire system to be tested prior to shipment. Moreover, as it is integrated into the lift structure, the time required to install the lift is significantly less as compared with the conventional wheelchair lifts. Furthermore, the integrated sensor array does not require a separate field installation remotely from the wheelchair lift, generally in the vehicle header over the doorway, and a subsequent adjustment by others. 
     Multiple sensors in the above described acoustic sensor array not only cover the area to be monitored more effectively, the possibility of a single point failure resulting is a “false positive” is significantly reduced. 
     Thus, in summary, the above described bridgeplate and threshold area monitoring system  239  is configured to monitor both the transition area as well the threshold area  28 . The above described bridgeplate and threshold area monitoring system  239  is also configured to control the downward motion of the lift platform  70  from the floor level position and stop such downward motion when an object is detected in the transition area. Thus, the above described bridgeplate and threshold area monitoring system  239  can be referred to as a platform movement control device. The above described bridgeplate and threshold area monitoring system  239  is additionally configured, through the controller  160  and annunciators, to annunciate object detection. The annunciation can comprise at least one of audible and visible annunciation. 
     Now in a particular reference to  FIGS. 11-12 , the bridgeplate and threshold area monitoring system  239  also comprises a platform position sensor. Such platform position sensor is being illustrated as a potentiometer  258  that provides inputs to the controller  160  in order to control operation of the sensors  240 ,  250 . The operation of the potentiometer  258  is independent from the operation of the limit switches  162  and  164 . The output signals from the potentiometer  258  are thus used by the controller  160  to determine the position of the lift platform  70 . Moreover, as the lift platform  70  moves away from the floor level position and toward the ground, the controller  160  can be configured to provide at least one of a visual and an audible signal to warn oncoming occupants inside the vehicle that the lift platform  70  is not at the occupant floor level position. 
     The potentiometer  258  comprises a through aperture  258 A that is sized and shaped to receive a pin  168 A of a mounting member  168 . The mounting member  168  is inserted into a cavity of a switch cam  166 . The switch cam  166  is fastened to the end of the pivot  34 A that the stationary end of the cylinder  36  pivots on. The above members are fastened to a stationary mounting bracket  35  with the plate  169 . In this arrangement, the potentiometer  258 , the mounting member  168  and the switch cam  166  are pivoting together with the pivoting of the pivot  34 A. 
     In a further reference to  FIGS. 11-12 , the mounting and actuation of the potentiometer  258  is integrated with the mounting and actuation of the limit switches  162  and  164 . However, as has been described above, the potentiometer  258  is electrically separated from the limit switches  162  and  164  within the control circuit  159 . The limit switches  162  and  164  control end positions of the lift platform  70 , while potentiometer  258  determines the position of the lift platform  70 . When the lift platform  70  is fully stowed, pressing the “Deploy” function on the handheld control pendant  190  will unfold the lift platform  70  to a point where the lower limit switch  164  changes state. Similarly, when the lift platform  70  is at the ground level, pressing the “Up” function on the handheld control pendant  190  will raise the lift platform  70  to the point where the upper limit switch  162  changes state. 
     It can also be seen from  FIGS. 11-12  that the limit switch  162  can be connected with a spring and screw arrangement  162 A so as to adjust position of the limit switch  162  relative to the exterior surface of the switch cam  166 . Likewise, the limit switch  164  can be connected with a spring and screw arrangement  164 A so as to adjust position of the limit switch  164  relative to the exterior surface of the switch cam  166 . Although, limit switches  162  and  164  have been illustrated as mechanical type roller switches, other switch types, for example such as proximity type switches, reed type switches, etc, can be used within the lift  10 . 
     During the development of the monitoring system, it became apparent that the areas the required monitoring to affect a suitable threshold warning device and a suitable transition area monitor were not the same. Moreover, the timing of these systems related to the position of the lift platform  70  were quite different as well. Accordingly, it became apparent that a means of determining multiple positions as well as the ability to monitor different areas would be necessary as well. Though it would be possible to affect such monitoring with cam operated switch(s), the potentiometer  258  can ensure maximum flexibility in establishing the range over which the sensors  240 ,  250  must be active during operation. 
     Any potential issues related to backlash in the rotating mechanism, comprising the mounting member  168  and the switch cam  166 , driving the potentiometer  258  and the unit-to-unit repeatability of assigning a resistance value to the vehicle floor level loading position can be overcome with an onboard memory and the software used in the controller  160  that monitors operation of the lift  10 . In an example, backlash can be addressed during design phase, by measuring multiple units in order to determine the average value of the backlash in the system. In an example, backlash can be determined after the lift  10  is assembled and the offset required for a specific lift  10  can be set in the initial programming of the controller  160 . As the “effect” of the backlash is dependent on the direction the platform is moving, inputs to the controller  160  can be configured to read direction of the lift platform  70  as being selected by the operator through a handheld control pendant  190  that essentially comprises control switches that can be of a pushbutton type. 
     The operation of the controller  160  is best illustrated in a combination with the electrical control circuit  159  of  FIG. 6 . The controller  160  can be a microprocessor-based controller. The controller  160  can be a programmable logic (PLC) controller. The controller  160  can be configured as a relay circuit. The controller  160  is configured to control operation of the sensors  240 ,  250  based on inputs from the potentiometer  258  and control operation of the light assembly  500 . The controller  160  can be also configured to receive various input signals from limit switches and potentiometer  258 , process the inputs in accordance with position and motion defining logic and output signals to control operation of the lift  10 , including control of the motion of the lift platform  70  and control of various annunciators employed within the lift  10 . 
     For monitoring operation of the sensors  240 ,  250 , the logic within the controller  160  incorporates use of the resistance values from the potentiometer  258 . In a non-limiting example, the method of monitoring motion of the lift platform  70  can comprise a step of dividing the motion of the lift platform  70  into four zones, as shown in Table 1 below, although more or less zones are also contemplated herewithin. In an example, Zone and 1 and Zone 2 can be integrated with each other, where the Amber warning light is turned on essentially when the lift platform  70  begins to move. The orientation of these zones is essentially same relative to the vehicle floor level position. Accordingly, one step involved setting up a system into which the vehicle floor level loading position can be programmed or “memorized”. Accordingly, the other positions could be programed as “fixed” values. Each zone in Table 1 is associated with resistance measured by the controller  160  from the potentiometer  258 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Lift Platform Motion Zones 
               
            
           
           
               
               
               
               
            
               
                   
                 Zone 
                 Resistance Range 
                 Controller Action 
               
               
                   
               
               
                   
                 1 
                 0-1,300 Ω 
                 No Action 
               
               
                   
                   
                 (Stowed to Partially 
                   
               
               
                   
                   
                 Deployed) 
                   
               
               
                   
                 2 
                 1,301-1,839 Ω 
                 1. Turn on Amber warning light 
               
               
                   
                   
                 (Floor Level) 
                 2. S3 &amp; S4 AND S1 &amp; S2- 
               
               
                   
                   
                   
                 “Down” Interlock Only 
               
               
                   
                 3 
                 1,840-1,900 Ω 
                 1. Maintain Amber warning light 
               
               
                   
                   
                 (Occupied  
                 2. S3 &amp; S4 Relay ONLY 
               
               
                   
                   
                 Transition  
                 3. S1 &amp; S2 Buzzer and Flash 
               
               
                   
                   
                 range) 
                 226 (Beacon Light) 
               
               
                   
                 4 
                 1,901-10,000 Ω 
                 1. Maintain Amber warning light 
               
               
                   
                   
                 (Below Floor  
                 2. S1 &amp; S2 Buzzer and Flash 
               
               
                   
                   
                 Level) 
                 226 (Beacon Light) 
               
               
                   
               
            
           
         
       
     
     It is to be understood that potentiometer  258  can be replaced with additional limit switches and redesigned switch cam  166 , as the platform position sensor, where the additional limit switches would be positioned to provide incremental position signals to the controller  160 . It is to be further understood that the above described rotary potentiometer  258  can be replaced with a linear type potentiometer, as the platform position sensor, that would be mounted on the cylinder  36 . 
     The lift platform movement control device can be provided as a device  260 , particularly as the bridgeplate  130  can be a component of the lift platform  70 . Briefly, the device  260  comprises a cam-shaped edge surface on each end of the bridgeplate; two arms, each arm being pivotally mounted at a rear of the platform and being spring loaded for a downward bias such that in a default state the platform can be disposed generally horizontally in a bridging position, the two arms being rigidly connected therebetween so that the two arms substantially rotate in unison with each other, the two arms being in a contact with the platform; two cables, each cable from the two cables having one end connected to a respective arm and having an opposite end connected to a lower arm of a platform moving mechanism; and a cam operated mechanism, the cam operated mechanism configured to pull the cable as the platform is being lowered, through the platform moving mechanism, from a floor level position; where each cable is configured (routed) to pull against a respective arm, as the platform is being lowered from the floor level position and raising the respective arm against the cam-shaped edge surface into a generally vertical barrier position. 
     Now in reference to  FIGS. 13-16  with a further reference to  FIG. 5 , the device  260  comprises a flange  131  on each end of the bridgeplate  130 . Each flange  131  can be provided as a separated member that is fastened to the bridgeplate  130 . The flange  131  has two ends. An edge abutment  132  is disposed on one end. The other end is in a pivotal connection with the platform  70  at a pivot  135 . An edge surface is provided between the two ends and has a convex edge surface portion  133  and a concave edge surface portion  134  disposed between the convex edge surface portion  133  and the edge abutment  132 . At least the convex edge surface portion  133  provides a cam-shaped edge surface during operation of the lift  10  as it will be explained further in this document. The edge abutment  132  extends outwardly from the convex edge surface portion  133 . There is a first pivotal connection (pivot)  135  between another end of the flange  131  and the rear end of the lift platform  70 . The device  260  further comprises two first arms  262 . Each first arm  262  is being spring loaded for a downward bias, such that in its default state, the bridgeplate  130  is in its bridging (deployed) position. Such position can be also referred to as one terminal position of the bridgeplate  130 . Each first arm  262  being disposed adjacent a respective flange  131  and has an arc shaped defining two ends. A second pivotal connection (pivot)  264  connects one end of each first arm  262  to the rear end of the lift platform  70  with. A rod  266  rigidly connects opposite ends of the two first arms  262 . In other words, two first arms  262  are being rigidly connected therebetween, by way of the rod  266 , so that the two arms substantially rotate in unison with each other. Two optional rollers or bearings  267  can be also provided. Each roller  267  is mounted on the rod  264  for a rotation thereabout and is being disposed adjacent a respective first arm  262 . 
     Each roller  267  contacts the convex edge surface portion  133  and the concave edge surface portion  134  of a respective flange  131  during operation of the lift  10 . When the roller  267  contacts the concave edge surface portion  134 , the roller  267  is stopped against the abutment  132 . Rollers  267  reduce rotational friction between the first arms  262  and flanges  131 . However, it is contemplated herewithin the rod  267  can directly contact the can-shaped edge surface. The peripheral surface of the rod  267  can be also coated with a polymer to reduce friction during operation. Device  260  further comprises a cam operated mechanism that is configured to pull the cables  300  as the lift platform  70  is being lowered, through the parallelogram mechanism  30 , from a floor level position, where each cable  300  is configured (routed) to pull against a respective first arm  262 , as the lift platform  70  is being lowered from the floor level position and raising the respective first arm  262  against the cam-shaped edge surface into a generally vertical barrier position. The cam operated mechanism comprises two second arms  270 . Each second arm  270  is mounted stationary on one end of the base  20  and, more particularly to one or both of the supports  26  and  27 . Each second arm  270  comprises an upwardly disposed straight edge surface portion  272 , an upwardly disposed concave edge surface portion  274  and a generally vertically disposed riser  276 . The riser  276  connects the upwardly disposed straight edge surface portion  272  with the upwardly disposed concave edge surface portion  274 . An extension  278  is provided on each lower arm  34  in the parallelogram mechanism  30 . The extension  278  extends outwardly from the pivotal connection  34 A. Two movable links  280  are also provided. Each movable link  280  comprises a Z-shaped body, a roller  282  mounted for a rotation on one end of the link  280 , a sheave  284  mounted on an opposite end of the movable link  280 , and a third pivotal connection  286  between a respective extension  278  and the sheave  284  mediate the ends of the movable link  280 .  FIGS. 15-16  also illustrates a cable spool  298 , being mounted within the arm  34  at a distance from the housing  294 . It would be understood that the device  260  comprises two cable spools  298 , each cable spool  298  being mounted within the respective lower arm  34 . Two cables  300  are spaced apart with each other about a width of the lift platform  70 . Now in a particular reference to  FIG. 15 , each cable  300  is aligned with a respective lower arm  34 . Each cable  300  has one end thereof affixed to a respective first arm  262  and has another end thereof anchored to lower arm  34 , for example at an anchor  302 . Each cable  300  is being wrapped around each of a respective sheave  284 , the spool  298 , the pivotal connection  34 B between the lower arm  34  and the vertical arm  38 , a sheave  268  on the respective first arm  262  and pivots  42 A and  44 A in the elbow assembly  40 , where each pivot  42 A and  44 A can be also adapted with a sheave for ease of movement of the cable  300 . In this position, the roller  267  is lodged within the concave edge surface portion  134  of a respective flange  131 . In operation, each movable link  280  moves upwardly on a respective second arm  270  and outwardly from the one end of the lift platform  70  when the parallelogram mechanism  30  moves the lift platform  70  from the stowed position toward the deployed position. When the movable link  280  moves in this way, each cable  300  rotates a respective first arm  262  in a first direction, being a clockwise direction in  FIGS. 13-15 , in a response to an upward and outward movement of the respective movable link  280 . Further, the respective first arm  262 , when rotating in the first direction, causes, through a respective flange  131 , and more particularly through the convex edge surface portion  133 , a rotation of the bridgeplate  130  into a generally vertical barrier position, which is one terminal position of the bridgeplate  130 . In this manner, when the bridgeplate  130  is raised to the top of its travel any force onto now generally vertical bridgeplate  130 , that attempts to pivot the bridgeplate  130  in the opposite direction toward the bridging position, will only force the roller  267  against the abutment  132 . In other words, the abutment  132  functions as a stop to prevent undesirable movement of the roller  267 . Thus, the first arm  262  is configured to absorbs the load without transferring this load to the operating cable  300 . Now, each movable link  280  moves downwardly on a respective second arm  270  and inwardly toward the one end of the lift platform  70  when the parallelogram mechanism  30  moves the lift platform  70  from the deployed position toward the stowed position. Further, each first arm  262  rotates in a second direction, being a counter-clockwise direction in  FIGS. 13-15 , due to the spring-load bias. Then, the respective first arm  262 , when rotating in the second direction, causes, through the respective flange  131 , a rotation of the bridgeplate  130  into a generally horizontal bridging position. 
     Thus, the bridgeplate  130  is mounted for a pivotal movement between two terminal positions: a bridging position where the bridgeplate  130  is disposed generally horizontally to bridge the gap between the baseplate  21  and the end  76  of the first lift platform section  74  when the lift platform  70  is being in the floor level position and an inboard barrier position where the bridgeplate  130  is disposed generally vertically. 
     Furthermore, the bridgeplate  130  deploys quickly and locks in the inboard barrier position. In this position, the bridgeplate  130  forms a barrier that is substantially vertical and is locked, by way of at least first arms  262  and flanges  131  cooperating with each other, so that the mechanism that raises and lowers the bridgeplate  130  is not be loaded in the event of impact by a wheelchair (not shown) onto the when the bridgeplate  130  when lift platform  70  is particularly in the deployed (ground level loading/off-loading) position. 
     Thus, the device  260  controls movement of the bridgeplate  130  in at least that failure of the bridgeplate  130  to remain in the vertical barrier position will not meet applicable standards and will prevent designed operation of the lift platform  70 . 
     On some conventional lifts in use, the mechanism that articulates the bridgeplate is also a structure that absorbs the load in the event of an impact when the lift is at ground level. With the above described mechanism, in the event a load is applied to the bridgeplate  130  at ground level, the mechanism that articulates the bridgeplate  130  is not loaded. Accordingly, it is less likely to experience malfunctions that are the result of undetected damage to the articulation mechanism. 
     The lift  10  can comprise a tension overload annunciation device  290 , best illustrated in  FIGS. 5 and 16 . The tension overload annunciation device  290 , when provided, is mounted within one or both lower parallel arms  34 . Each tension overload annunciation device  290  comprises a spring  292 . The spring  292  is seated, at one end, on the pivot  34 B. The spring  292  is connected, at the other end, to the cable  300  through a movable hollow housing  294 . As is further illustrated in  FIG. 16 , the other end of the spring  292  rests against an exterior wall surface of the housing  294  and the cable  300  is connected to the housing  294 , for example, with a clevis  296 . A bridgeplate cable overload switch  182  is mounted stationary in one arm  34  and within the housing  294 . In other words, a movement of the housing  294  does not move the cable overload switch  182 . A switch target  182 A is mounted with the housing  294  for a movement therewith. The bridgeplate cable overload switch  182  is operable to detect tension of the cable  300  based on the load disposed on the lift platform  70  during operation. The switch  182  may not detect any load with the properly operable acoustic sensors  240 ,  250 . Without acoustic sensors  240 ,  250 , with the occupant load on the lift platform  70 , the tension onto the cable  300  increases with the target  182 A moving to engage a roller arm on the bridgeplate cable overload switch  182 . Thus, the bridgeplate cable overload switch  182  can be used as a redundant load monitoring (safety) device. Although, bridgeplate cable overload switch  182  has been illustrated as mechanical type limit roller switches, other switch types, for example such as proximity type switches, reed type switches, etc, can be used within the lift  10 . 
     Thus, in an event the cable  300  is overloaded, the cable  300  pulls against the heavy spring  292  mounted at the front of one of the lower parallel arms  34 . As the spring  292  compresses, the bridgeplate cable overload switch  182  is activated and generates an output signal that is used by the controller  160  to disable the “Down” function, initiated for example, through the pendant  190 . 
     Furthermore, in an unlikely failure event of acoustic sensors  240  and  250 , the tension overload annunciation device  290  can serve as a secondary means of detecting a load on the bridgeplate  130 , thereby enhancing occupant safety. Further, in the event of mis-use or other unforeseen circumstances, should the cable  300  become overloaded, the tension overload annunciation device  290  stops the downward movement of the lift platform  70  preventing further loading of the cable  300  and possible cable breakage. 
     It will be understood that the tension overload annunciation device  290  is integrated with the device  260 , in at least with the connection between the cable  300  and the housing  294 . The tension overload annunciation device  290  is also configured to control movement of the lift platform  70 . 
     The lift platform movement control device can be provided as a lift platform lock  400  of  FIGS. 17-21 . Such lock  400  is configured to mechanically retain the lift platform  70  in a stowed position of  FIG. 1 . More specifically, the lock  400  is integrated with the control enclosure  202 . Since the lift platform  70  is retained in a stowed position, the lock  400  can be referred to as a stow lock or as a lift platform lock. 
     Briefly, the lock can comprises an actuator, the actuator mounted on a vertically disposed stationary wall, a movable portion thereof is configured to move in a vertical direction; a first arm, the first arm mounted in a pivotal connection with each of the actuator and the vertically disposed stationary wall; a second arm with a hook-shaped portion, the second arm being fastened to the first arm, the second arm configured to move linearly along a length of the first arm and to pivot with the first arm; and a spring, the spring connected to each of the second arm and the vertically disposed stationary wall; the actuator operable to pivot the first and second arms upwardly into an unlock position; the spring operable to pivot the first and second arms downwardly into a lock position; the hook-shaped portion engaging a target on a lift platform in the lock position during use of the lock. 
     Now in more details, the exemplary lock  400  comprises an actuator  410  that is disposed inside the main control enclosure  202 . The actuator  410  serves as the prime mover for the lock  400 . The actuator  410  has a stationary portion  412  that is affixed to a vertically disposed wall of the control enclosure  202 . A movable portion  414  of the actuator  410  moves in a vertical direction. The lock  400  also comprises a first arm  430 . The first arm  430  has a first end  432 A and a second end  432 B spaced apart from the first end  432 A along a length of the first arm  430 . There is also a first elongated slot  434  through a thickness of the first arm  430  between the first and second ends,  432 A and  432 B respectively. A length of the first elongated slot  434  is aligned normal to the length of the first arm  430 . A first connection  424  is provided between the first end  432 A and a vertical wall  203  of a stationary lift control enclosure  202 . The first connection  424  is configured to allow a pivotal movement of the first arm  430  about the vertical wall  203 . The first connection  424  comprises an aperture  424 A through the thickness of the first arm  430  adjacent the first end  432 A thereof, an aperture  424 B though a thickness of the vertical wall and fasteners  424 C. There is also a second arm  440 . The second arm  440  has a first end  442 A and a second end  442 B. The second end  442 B is spaced apart from the first end  442 A of the second arm  440  along a length of the second arm  440 . The second arm  440  also has a void  447  between two second elongated slots  446 . A spring seat  452  upstands on one edge of the second arm  440  adjacent the first end  442 A of the second arm  440 . A notch  448  is provided in a second edge of the second arm  440  adjacent the second end  442 B and a taper  449  in the second end  442 B of the second arm  440 , the taper  449  and the notch  448  defining a hook-shaped portion of the second arm  440 . The lock  400  also comprises a second connection  426  between the first arm  430  and the second arm  440 . The second connection  426  is configured to move the second arm  440  along a length of the first arm  430 . The second connection  426  comprises two apertures  446 A through the thickness of the first arm  430  between the first and second ends,  432 A and  432 B respectively, thereof, the two second elongated slots  446  through the thickness of the second arm  440  between the first and second ends,  442 A and  442 B respectively. A length of each second elongated slot  446  is aligned along the length of the first arm  430 . Each second elongated slot  446  is aligned, during use, with a respective aperture  446 A in the first arm  430 , and fasteners  446 B fastening the second arm  440  to the first arm  430  at each second elongated slot  446  aligned with the respective aperture  446 A. A third connection  428  connects the movable portion  414  and the first end  432 A of the first arm  430 . The third connection  428  comprises a link  416  pivotally coupled to a free end of the movable portion  414  and to a flange  438  on the first end  432 A of the first arm  430 . The lock  400  additionally comprises a tension spring  450 . The tension spring  450  has a first end attached to the spring seat  452  on the second arm  440  and has an opposite second end attached to a spring seat  454  on the vertical wall  203 . In use, the actuator  410 , when energized during use of the lock  400 , moves the movable portion  414  in an upward direction and pivots the first arm  430  and the second arm  440  at the first connection  424  about the vertical wall  203  in the upward direction into an unlock position. The tension spring  450  is configured to pivot the first arm  430  and the second arm  440  in a downward direction into a lock position when the actuator  410  is deenergized. The hook-shaped portion engages a target  420  on a lift platform  70  when the lift platform  70  is in the stowed position. When the lift platform  70  is in the stowed position, the lock assembly  400  is being in the lock position. 
     Power is provided to the actuator  410  via a small, solid state control board, that can be a part of the controller  160 , located near the actuator  410 . From the stowed position, when the lift “Deploy” function is activated, the lock control energizes the actuator  410  for approximately 0.75 seconds while the target  420 , mounted to the lower part of the vertical arm  38 , moves clear of the hook portion of the second arm  440 . The target  420  is adapted with an enlarged head so as to prevent lateral disengagement 
     Approximately half way along its length, the first arm  430  is retained by a first connection  424  to check the upward and downward motion of the hook portion. A tension spring  450  serves to return the second arm  440  to the locked position where the hook portion engages the target  420 . The lock  400  is accessible for service when the lift platform  70  is at ground level. 
     The taper  449  on the front of the hook portion enables the system to be “self-locking” when the lift platform  70  is being stowed. As the lift platform  70  is stowed, the target  420  located on the side of the vertical arm  38  contacts the taper  449  of the hook portion. The contact angle is such that the hook portion is forced upwardly as the lift platform  70  reaches its stowed position. Once the target  420  clears the taper  449 , the second arm  440  returns to the locked position with the target  420  being disposed within the notch  448 . 
     When provided, the lock  400  is configured to hold the lift platform  70  in its stowed position should the lift&#39;s prime moving system slip over time while the lift platform  70  is stowed. In a non-limiting example, the slippage may occur due to seal degradation and leakage of the hydraulic fluid. The lock  400  is integrated into the control assembly  200 . Being integrated into the control assembly  200 , the lock  400  can be pre-assembled and mounted to the lift  10  as a unit, thus simplifying the assembly process, reducing the possibility of assembler error and increasing efficiency saving time and cost. Furthermore, the integrated lock  400  can be bench-tested independently of the lift platform  70 , thus further reducing overall cost and improving efficiency. The lock  400  is illustrated in  FIG. 17  as being mounted on the right side of the lift platform  70 . However, the design is modular in that the same parts can be assembled to perform their intended function on the left side of the lift platform  70  in application where the control assembly  200  is also mounted on the left side of the lift  10 . 
     In the event the lift platform  70  drifts out against the lock, the controller  160  is configured to activate the “Stow” function so as to unload the hook portion prior to enabling deployment of the lift platform  70 . 
     It became apparent that locating the lock actuating system within the control assembly would simplify assembly. However, this would mean locking the lift platform  70  from only one side. Doing so has proven quite adequate. 
     It would be understood the second connection  426  allows s linear movement of the second arm  440  relative to the first arm  430  along the arrows A-A, best illustrated in  FIG. 19 . Such linear movement allows an adjustment of the hook portion of the second arm  440  due to manufacturing and installation tolerances. Such adjustment allows repeated engagement between the second arm  440  and the target  420 . 
     However, on the lift  10  that is not a subject to manufacturing and installation tolerances, it is contemplated herewithin that the lock  400  can be only provided with the first arm  430  that incorporates the notch  448  and the taper  449  and the spring seat  452  of the second arm  440 . In an example, the apertures  424 A and  424 B can be made after the first arm  430  is fitted about the target  420 . Thus, in this embodiment, the lock  400  comprises an actuator, the actuator mounted on a vertically disposed stationary wall, a movable portion thereof is configured to move in a vertical direction; an arm with a hook-shaped portion, the arm mounted in a pivotal connection with each of the actuator and the vertically disposed stationary wall; and a spring, the spring connected to each of the arm and the vertically disposed stationary wall; the actuator operable to pivot the arm upwardly into an unlock position; the spring operable to pivot the arm downwardly into a lock position; the hook-shaped portion engaging a target on a lift platform in the lock position during use of the lock. 
     When operating lift  10  in the diminished light conditions, for example such as evening, night or early morning) and/or diminished visibility conditions, for example such as fog, rain, snow and the like, it may be necessary not only to illuminate a top surface of the lift platform but also warn the traffic that the lift platform is being operated. 
     Accordingly, in an embodiment, the above described lift  10  can comprise an optional light  500  positioned and operable to be visible from the area outside of the lift platform  70  that can, among other things, notify traffic that the lift platform  70  has been deployed or in a process of being one of deployed and disposed in the floor level position or being retracted into the sltowed position. Now in a reference to  FIGS. 22-23 , the light  500  is illustrated as a light assembly  500  that comprises a housing  510 . The housing  510  can be provided as an extrusion. The extrusion can comprise any one of an aluminum material, a plastic material, a carbon fiber material and any combination thereof. The housing  510  can be provided as a casting comprising a metal. The housing  510  defines a hollow interior  512  and a pair of recessed exterior surfaces or grooves  524  that span the length of the housing  510 . The housing  510  also defines a cavity  518  that runs along a length of the housing  510  between terminal ends  514 ,  516  and that becomes a bottom cavity during use of the lift  10 . There are also two end caps  520 , each with an abutment  522  sized and shaped to fit into the hollow interior  512 . Each end cap  520  closes a respective open end  514 ,  516  of the housing  510 . Each end cap  520  can comprise molded plastic or casted metal that can be an aluminum. The light assembly  500  further comprises two light members that can be provided as light strips  530 . The light strip  530  comprises one or more LEDs. The light strip  530  being sized and shaped to fit into respective groove  524 . In other words, the housing  510  is configured as a mounting member for the light strips  530 . A replaceable ground contact  528  is also provided and also being sized and shaped to fit within the hollow interior  512 . When two light strips  530  are provided, each light strip  530  can be configured to emit different color light. In a non-limiting example, one light strip  530  in the light assembly  500  can be configured to emit a clear light on one side, while another light strip  530  can be configured to emit an amber light on the other side. The clear light side can face the surface of the lift platform  70  while the amber side can face the outside of the lift platform  70 . Furthermore, each light strip  530  can be operated to emit light of a different type. 
     In a non-limiting example, the inside light strip  530  can be operated as “constant on”, the outside light strip  530  can be operated as a flashing light. Although, the outside amber light can be also operated as “constant on”. Thus, different color LEDs are contemplated herewithin for at least one of the outside and inside light applications. It is also contemplated that individual LEDs can replace a continuous light strip  530 . 
     Thus in an embodiment, a light assembly comprises an extrusion, the extrusion comprises, during operation of the modular light assembly, a bottom cavity along a length of the extrusion, a hollow interior and two side grooves along the length of the extrusion and on both sides thereof; two light emitting diode (LED) strips, each LED strip being sized and shaped to fit into a respective groove, the two LED strip coupled to a source of electric power during operation of the modular light assembly to illuminate both sides of the extrusion; a load bearing ground contact; and two ends caps, each end cap with an abutment sized and shaped to fit into the hollow interior, the each end cap terminating a respective end of the extrusion. 
     It would be understood that the light assembly  500  can be provided with a single light strip  530  even when the housing  510  is adapted with two grooves  524 . It would be further understood that the light assembly  500  can be adapted with a single groove  524  and, accordingly, with a single light strip  530 . The single light strip  530  can be positioned to either emit light toward the surface of the lift platform  70  or emit light external to the lift platform  70 . 
     At least in reference to  FIGS. 2-4 , the lift  10  is illustrated as comprising four (4) light assemblies  500 , each light assembly  500  being disposed on and along an exposed edge of the first lift platform section  74  and the second lift platform section  100 . Although it is contemplated that less than four light assemblies  500  can be provided. In an example, two light assemblies  500  can be provided with each light assembly  500  being disposed on and along an exposed edge of the second lift platform section  100  or being disposed on and along an exposed edge of the first lift platform section  74 . 
     As it can be seen in  FIG. 6 , the light assembly  500  and, more particularly, the light strips  530  are electrically coupled to the controller  160 . The controller  160  controls operation of the light assembly  500  in controlling activation and deactivation of the light strips  530  based on the position or movement of the lift platform  70  as well as mode of operation. 
     It would be understood that the light assemblies  500  can provide both a means of lighting the platform surface and a (DOT compliant) means of warning to traffic that the lift platform  70  is being operated. 
     A method of using the lift  10  can comprise a step of lighting the lift platform  70 , a step of lighting the area outside of the lift platform  70  and a further step of notifying, with a light visible external to the lift platform  70 , an oncoming traffic that the lift platform  70  is one of being deployed at the ground, in a process of being deployed (lowered) toward the ground and in a process of being retracted (raised) toward the stowed position. 
     A method of annunciating operation of a vehicle&#39;s lift with a lift platform can comprise steps of providing one or more light members on the lift platform; and actuating the one or more light members to emit light visible external to the lift platform when the lift platform is being lowered or raised external to the vehicle. 
     A method of annunciating operation of a vehicle&#39;s lift with a lift platform can comprise steps of mounting one or more light members on the lift platform in a position to emit light visible external to the lift platform; and actuating the one or more light members to emit the light when the lift platform is at least one of being deployed at a ground, in a process of being lowered toward the ground and in a process of being raised toward a stowed position within the vehicle. 
     On some conventional platform lifts, halogen type lights are mounted to the vertical arms, about three feet from the ground mounted. On some conventional platform lifts, lights are mounted on the underside of the handrails. The nearer the light source is at the occupant&#39;s level, the less comfort occupants experience. As most occupants are in wheelchairs, the height of the vertical arm mounted lights can be at an eye-level for the majority of occupants. Position of the above described light assembly  500  on the side barriers of the lift platform  70  is inches from the surface of the lift platform  70  and well below the occupant&#39;s eye level, thus increasing occupant comfort. Furthermore, light strips  530  are placed within a modular housing  510 , thus facilitating ease of replacement. A further advantage of the modular construction is that the light assembly  500  can be assembled with white light on one side and amber on the other. Combined with a means of flashing the amber light, such configuration provides not only a superior distribution of platform surface light but also superior visibility of the equipment at night to oncoming vehicles. 
     The underside of the lift platform  70  and lower extremities of the vertical arms  38  of the lift  10  come into a contact with the ground or any other surface (for example such as a boarding platform surface) during operation of the lift  10 . When the ground is aggressive and uneven, the protective coatings on these extremities become scratched and damaged subjecting the underlying unit to corrosion during repetitive use. This condition is of special concern in areas where snow and ice prevail and even more so when sand and gravel are mixed in. 
     Accordingly, in an embodiment of  FIG. 24 , the above described lift  10  can comprise a replaceable, load bearing ground contact device  540  that contacts the ground ahead of the lower extremity of the vertically disposed arms  38 , thus significantly reducing the amount of painted surface that comes in contact with the ground thereby reducing coating damage and, correspondingly, the propensity for corrosion damage. As the ground contact device wears, it can be replaced and routine intervals at significantly less cost and “downtime” than repainting. 
     The replaceable, load bearing ground contact device  540  can be manufactured from molded plastic. The replaceable, load bearing ground contact device  540  comprises a cavity  542  that fits closely about the pivot  38 A which is between the lift platform  70  and the lower end of arms  38 . In so doing, as the replaceable, load bearing ground contact devices  540  touch the ground, the load is transferred evenly to the bearing support structure and into the vertical arm structure. In an example, a single fastener  546  can be used to hold the replaceable, load bearing ground contact device  540  in place. The wearable, replaceable surface on the lower end of each vertical arm  38  by way of ground contact device  540  reduces the likelihood of finish damage leading to corrosion. Further, because replaceable ground contact device  540  reduces the amount of the underside surface that contacts the ground, the amount of foreign matter (mud and slush) that can be picked up and transferred to the inside of the vehicle is also minimized. 
       FIG. 25  illustrates an exemplary lift  10 A that comprises a base  20 , a parallelogram mechanism  30  mounted on the base  20 , a lift platform  70 A that is carried by the parallelogram mechanism  30 , a control assembly  200  for actuating the lift platform  70 A through the parallelogram mechanism  30 , an occupant retention apparatus that incorporates a bridgeplate  130  and an roll stop  136 , both pivotally coupled to the lift platform  70 A, and an electrical control circuit  159  to accomplish different motion patterns and annunciations. The lift platform  70 A is illustrated as a single piece platform. Also illustrated are sensors  240  and  250 . The control assembly  200  is illustrated as being disposed on the left side of the lift  10 A. Light assembly  500  is not illustrated in  FIG. 25  but can be installed in accordance with above described embodiments. Similarly, lock  400  can be integrated with the control assembly  200  on the left side of the lift  10 A. 
       FIG. 26  illustrates an exemplary lift  10 B that comprises a base  20 , a parallelogram mechanism  30  mounted on the base  20 , a lift platform  70 B that is carried by the parallelogram mechanism  30 , a control assembly  200  for actuating the lift platform  70 A through the parallelogram mechanism  30 , an occupant retention apparatus that incorporates a bridgeplate  130  and an roll stop  136 , both pivotally coupled to the lift platform  70 B, and an electrical control circuit  159  to accomplish different motion patterns and annunciations. The lift platform  70 B is illustrated as a two-piece split platform, hinged in a direction that is perpendicular to the base  20 . Also illustrated are sensors  240  and  250 . The control assembly  200  is illustrated as being disposed on the left side of the lift  10 B. Light assembly  500  is not illustrated in  FIG. 26  but can be installed in accordance with above described embodiments. Similarly, lock  400  can be integrated with the control assembly  200  on the left side of the lift  10 B. The handrails  120 A are being illustrated as essentially having a U-shape, however the above illustrated handrails  120 A can be also used within any one of the above described lifts. 
       FIGS. 27-28  illustrate an exemplary lift  10 C that comprises a base  20 A, a parallelogram mechanism  30  mounted on the base  20 A, a lift platform  70 B that is carried by the parallelogram mechanism  30 , a control assembly  200  for actuating the lift platform  70 B through the parallelogram mechanism  30 , an occupant retention device that incorporates a bridgeplate  130 A and an roll stop  136 A, both pivotally coupled to the lift platform  70 B, and an electrical control circuit  159  to accomplish different motion patterns and annunciations. The lift platform  70 B is illustrated as a two-piece split platform, hinged in a direction that is perpendicular to the base  20 . Also illustrated are sensors  240  and  250 . The control assembly  200  is illustrated as being disposed on the left side of the lift  10 C. Light assembly  500  is not illustrated in  FIGS. 27-28  but can be installed in accordance with above described embodiments. Similarly, lock  400  can be integrated with the control assembly  200  on the left side of the lift  10 C. Lift  10 C is configured so that the lift platform  70 B also slides across the base  20 A to bias the lift platform  70 B and the parallelogram mechanisms  30  toward the control assembly  200  in the stowed position. 
       FIG. 29  illustrates an exemplary lift  10 D that comprises a base  20 B, a mechanism  30 A mounted on the base  20 A, a lift platform  70 D that is carried by the mechanism  30 A, a control assembly  200 A for actuating the lift platform  70 D through the mechanism  30 A, an occupant retention apparatus that incorporates a bridgeplate  130 B and an roll stop  136 B, both pivotally coupled to the lift platform  70 D, and an electrical control circuit  159  configured to accomplish different motion patterns and annunciations. The lift platform  70 D is illustrated as a one-piece platform. Also illustrated are sensors  240  and  250 . One sensor  240  is mounted to the lower arm, as is described above. The other sensor  240  is mounted on a remotely disposed mounting member  630 , that can be a simple plate-shaped member. One sensor  250  is mounted external to the control assembly  200 A. The other sensor  250  is mounted on a remotely disposed mounting member  630 . The control assembly  200 A is illustrated as being disposed on the left side of the lift  10 B. Light assembly  500  is not illustrated in  FIG. 29  but can be installed in accordance with above described embodiments. The mechanism  30 A comprises a linear actuator  610  mounted within a hollow interior of a tubular member  614 . The linear actuator  610  is configured to fold and unfold the lift platform  70 D through an arm  44 A 0  and gas spring  640 . The arm  620  is pivotally connected to the exterior of the tubular member  614  with pivots  622  and  624 . Arms  616  and  618  are pivotally coupled to each of the control assembly  200 A and the tubular member  614 . Light assembly  500  is not illustrated in  FIG. 29  but can be installed in accordance with above described embodiments. 
     Accordingly, in various embodiments: 
     Embodiment A. A lift for a vehicle, the lift comprising: 
     a platform configured to support an occupant thereon; 
     a parallelogram mechanism to move the platform between a stowed position and a deployed position, the parallelogram mechanism comprising two lower arms, two upper arms, two vertical arms and two cylinders, each cylinder is in a first pivotal connection between a stationary end of each cylinder and a lower arm and in a second pivotal connection between a movable end of each cylinder and an upper arm; 
     a base to mount the parallelogram mechanism to a vehicle floor, each lower arm is in a pivotal connection with each of the base and a respective vertical arm, each upper arm is in a pivotal connection with each of the base and the respective vertical arm; 
     a hydraulic system to move the platform through the parallelogram mechanism; 
     an occupant retention apparatus; 
     a bridgeplate mounted at one end of the platform for a movement between two terminal positions; 
     a control unit to control a movement of one of the platform, and the bridgeplate; and 
     a platform movement control device. 
     Feature A. The lift of Embodiment A, wherein the platform movement control device comprises: 
     two first sensors, each sensor from the two first sensors mountable to a respective lower arm in the parallelogram mechanism, the two first sensors configured to monitor a transfer bridging plate area when the platform is at a vehicle floor level position; 
     two second sensors, each sensor from the two second sensors mountable, when installed on the vehicle, rearward of the two first sensors, the two second sensors configured to monitor vehicle door threshold area while the platform is at the vehicle floor level position; 
     collars, each collar mounting each sensor so that each sensor is oriented to generate a first detection plume between the two first sensors and a second detection plume between the two second sensors; and 
     a platform position sensor comprising a potentiometer being mounted on one lower arm in the parallelogram mechanism, the potentiometer being actuatable by a pivot connecting one cylinder to the one lower arm, the potentiometer configured to incrementally provide signals associated with positions of the platform between the stowed position and a vehicle floor level position; 
     each sensor from the two first sensors and the two second sensors comprising a piezoelectric, ultrasonic device capable of creating a detection volume in front of each sensor during operation of the lift; 
     the two first sensors generating a first control signal when the first detection plume is being interrupted; 
     the two second sensors generating a second control signal when the second detection plume is being interrupted; 
     the controller being responsive to the signals from the potentiometer to selectively activate and deactivate the two first sensors and the two second sensors; 
     the controller being responsive to one of the first and second control signals to control a movement of the bridgeplate and providing and interlock to prevent the movement of the platform when an occupant detected within the transfer bridgeplate area or within the vehicle door threshold area. 
     Feature B. The lift of Embodiment A, wherein the platform movement control device comprises: 
     two sensors, each sensor from the two sensors mountable to a respective lower arm in the parallelogram mechanism, the two sensors mounted in locations to monitor a transfer bridgeplate area when the platform is at a vehicle floor level position, each sensor comprising a piezoelectric, ultrasonic device capable of generating a detection plume in front of each sensor during operation of the lift; and 
     two collars, each collar mounting a respective sensor so that each sensor is oriented to generate the detection plume between the two sensors; and 
     a platform position sensor comprising a potentiometer being mounted on one lower arm in the parallelogram mechanism, the potentiometer being actuatable by a pivot connecting one cylinder to the one lower arm, the potentiometer configured to incrementally provide signals associated with positions of the platform between the stowed position and a vehicle floor level position; 
     the two sensors generating a control signal when the detection plume is being interrupted when the detection plume is being interrupted; 
     the controller being responsive to the signals from the potentiometer to selectively activate and deactivate the acoustic sensors; 
     the controller being further responsive to the control signal from the acoustic sensors to control a movement of the platform and to prevent the movement of the platform. 
     Feature C. The lift of Embodiment A, wherein the platform movement control device comprises: 
     two acoustic sensors mounted in locations to monitor vehicle door threshold area while the platform is at the vehicle floor level position, each acoustic sensor from the two acoustic sensors comprising a piezoelectric, ultrasonic device capable of generating a detection plume in front of each sensor; 
     two collars, each collar mounting a respective acoustic sensor to generate the detection plume between the two acoustic sensors during operation of the lift; and 
     a potentiometer being mounted on one lower arm in the parallelogram mechanism, the potentiometer being actuatable by a pivot connecting one cylinder to the one lower arm, the potentiometer configured to incrementally provide signals associated with positions of the platform between the stowed position and a vehicle floor level position; 
     the two acoustic sensors generating a control signal when the detection plume is being interrupted; 
     the controller being responsive to the signals from the potentiometer to selectively activate and deactivate the acoustic sensors; 
     the controller being further responsive to the control signal from the acoustic sensors to control a movement of the platform and to prevent the movement of the platform when the detection plume is being interrupted. 
     Feature D. The lift of Embodiment A, wherein the platform movement control device comprises: 
     two acoustic sensors, each acoustic sensor from the two acoustic sensors comprising a piezoelectric, ultrasonic device, the two acoustic sensors mounted and operable to generate a detection plume over one of a transfer bridgeplate area and vehicle door threshold area when the platform is at a vehicle floor level position; 
     two collars, each collar mounting a respective acoustic sensor to generate the detection plume between the two acoustic sensors during operation of the lift; and 
     a potentiometer being mounted on one lower arm in the parallelogram mechanism, the potentiometer being actuatable by a pivot connecting one cylinder to the one lower arm, the potentiometer configured to incrementally provide signals associated with positions of the platform between the stowed position and a vehicle floor level position; 
     the two acoustic sensors generating a control signal when the detection plume is being interrupted; 
     the controller being responsive to the signals from the potentiometer to selectively activate and deactivate the acoustic sensors; 
     the controller being further responsive to the control signal from the acoustic sensors to control a movement of the platform and to prevent the movement of the platform when the detection plume is being interrupted. 
     Feature E. The lift of Embodiment A, wherein the platform movement control device comprises: 
     a flange on each end of the bridgeplate, the flange having two ends, an edge abutment disposed on one end, and an edge surface between the two ends, the edge surface having a convex edge surface portion and a concave edge surface portion disposed between the convex edge surface portion and the edge abutment, the edge abutment extending outwardly from the convex edge surface portion. 
     a first pivotal connection between another end of the flange and the one end of the platform; 
     two first arms, each first arm being disposed adjacent a respective flange and having an arc shaped defining two ends; 
     a second pivotal connection between one end of each first arm and the one end of the platform; 
     a rod rigidly connecting opposite ends of the two first arms; 
     two bearings, each bearing is mounted on the rod for a rotation thereabout and is being disposed adjacent a respective first arm, each bearing contacts a convex surface of a respective flange during operation of the lift; 
     two second arms, each second arm is mounted stationary on one end of the base, each second arm comprises an upwardly disposed straight edge surface portion, an upwardly disposed concave edge surface portion and a generally vertically disposed riser, the riser connecting the upwardly disposed straight edge surface portion with the upwardly disposed concave edge surface portion; 
     an extension on each lower arm in the parallelogram mechanism, the extension extending outwardly from a pivotal connection between each lower arm and the stationary end of each cylinder; 
     two movable links, each movable link comprising a Z-shaped body, a roller mounted for a rotation on one end of the link, a sheave mounted on an opposite end of the movable link, and a third pivotal connection between a respective extension and the sheave mediate ends thereof; 
     two tension devices, each tension device is mounted within a respective lower arm, each tension device comprising a spring; 
     two cable spools, each cable spool mounted within the respective lower arm adjacent a respective tension device; and 
     two cables spaced apart with each other about a width of the platform, each cable having one end thereof affixed to a respective first arm and having another end thereof affixed to a respective tension device, each cable being wrapped around each of the sheave, the cable spool, the pivotal connection between the lower arm and the vertical arm, a sheave on the respective second arm and sheaves in the elbow; 
     each movable link moving upwardly on a respective second arm and outwardly from the one end of the platform when the parallelogram mechanism moves the platform from the stowed position toward the deployed position; 
     each cable, rotates a respective first arm in a first direction and extends a respective spring, in a response to an upward and outward movement of a respective movable link; 
     the respective first arm, when rotating in the first direction, causes, through a respective flange, a rotation of the bridgeplate into a generally vertical barrier position; 
     each movable link moving downwardly on a respective second arm and inwardly toward the one end of the platform when the parallelogram mechanism moves the platform from the deployed position toward the stowed position and when the respective spring compresses and returns to an original position; 
     each cable, rotates a respective first arm in a second direction, in a response to a downward and inward movement of the respective movable link; 
     the respective first arm, when rotating in the second direction, causes, through a respective flange, a rotation of the bridgeplate into a generally horizontal bridging position. 
     Feature F. The lift of Embodiment A, wherein the platform movement control device comprises: 
     a cam-shaped edge surface on each end of the bridgeplate; 
     two arms, each arm being pivotally mounted at a rear of the platform and being spring loaded for a downward bias such that in a default state the platform can be disposed generally horizontally in a bridging position, the two arms being rigidly connected therebetween so that the two arms substantially rotate in unison with each other, the two arms being in a contact with the platform; 
     two cables, each cable from the two cables having one end connected to a respective arm and having an opposite end connected to a lower arm of a platform moving mechanism; and 
     a cam operated mechanism, the cam operated mechanism configured to pull the cable as the platform is being lowered, through the platform moving mechanism, from a floor level position; 
     each cable configured to pull against a respective arm, as the platform is being lowered from the floor level position and raising the respective arm against the cam-shaped edge surface into a generally vertical barrier position. 
     Feature G. The lift of Feature F, wherein the cam operated mechanism comprises: 
     two other arms, each other arm is mounted stationary on one end of the base, each other arm comprises another cam-shaped edge surface having an upwardly disposed straight edge surface portion, an upwardly disposed concave edge surface portion and a generally vertically disposed riser, the riser connecting the upwardly disposed straight edge surface portion with the upwardly disposed concave edge surface portion; 
     an extension on each lower arm in the parallelogram mechanism, the extension extending outwardly from a pivotal connection between each lower arm and the stationary end of each cylinder; 
     two movable links, each movable link comprising a Z-shaped body, a roller mounted for a rotation on one end of the link, a sheave mounted on an opposite end of the movable link, and a third pivotal connection between a respective extension and the sheave mediate ends thereof; 
     the roller rotating, during operation, on another cam-shaped edge surface. 
     Feature H. The lift of Feature F, wherein the platform movement control device further comprises a tension overload annunciation device installed within one lower arm, the tension overload annunciation device comprises: 
     a hollow housing deposed for a movement within the one lower arm, the hollow housing having a connection with one end of a respective cable; 
     a spring, the spring being seated, at one end, on a pivot between the one lower arm and a respective vertical arm, the spring resting against an exterior wall surface of the hollow housing. 
     a switch mounted stationary within the one lower arm and within the hollow housing, the switch being independent from the movement of the hollow housing; and 
     a switch target being mounted with the hollow housing for the movement therewith; 
     the switch operable by the switch target to generate an output signal when the cable being overloaded due to a load on the platform. 
     Feature K. The lift of Embodiment A, wherein the platform movement control device comprises: 
     a first arm, the first arm having a first end, a second end spaced apart from the first end along a length of the first arm, a first elongated slot through a thickness of the first arm between the first and second ends, a length of the first elongated slot aligned normal to the length of the first arm; 
     a first connection, the first connection being between the first end and a vertically disposed wall of a stationary control enclosure, the first connection configured to allow a pivotal movement of the first arm about the vertically disposed wall, the first connection comprising a first aperture through the thickness of the first arm adjacent the first end thereof, a second aperture though a thickness of the vertically disposed wall and a fastener passing through the first and second apertures; 
     a second arm, the second arm having a first end, a second end spaced apart from the first end of the second arm along a length of the second arm, a spring seat upstanding on a first edge of the second arm adjacent the first end of the second arm, a first edge notch in the second arm between the first and second ends, the first edge notch sized and shaped to allow access to the first elongated slot during operation of the platform movement control device, a second edge notch in the second edge of the second arm and a taper in the second end of the second arm, the taper and the second notch defining a hook-shaped portion of the second arm; 
     a second connection, the second connection being between the first arm and the second arm so that the second arm pivots with the first arm, the second connection configured to move the second arm along a length of the first arm, the second connection comprising two third apertures through the thickness of the first arm between the first and second ends thereof, two second elongated slots through a thickness of the second arm between the first and second ends, a length of each second elongated slot aligned along the length of the first arm, each second elongated slot is aligned, during use, with a respective third aperture in the first arm, and fasteners fastening the second arm to the first arm at each second elongated slot aligned with the respective third aperture; 
     an actuator, the actuator having a stationary portion affixed to the vertically disposed wall and a movable portion disposed for a linear movement in a vertical direction; 
     a third connection, the third connection being between a free end of the movable portion and the first end of the first arm, the third connection comprising a link pivotally coupled to the free end of the movable portion and to a flange on the first end of the first arm; and 
     a tension spring, the tension spring having a first end attached to a spring seat on the second arm and having an opposite second end attached to a spring seat on the vertically disposed wall; 
     the actuator, when energized during the operation of the platform movement control device, moves the movable portion in an upward direction and pivots the first arm and the second arm, at the first connection about the vertically disposed wall in the upward direction, into an unlock position; 
     the tension spring configured to pivot the first arm and the second arm in a downward direction into a lock position when the actuator is deenergized; 
     the hook-shaped portion selectively engages, during the operation, a target on a platform in the lock position and disengages the target in the unlock position; 
     the platform being prevented from a movement when the hook-shaped portion selectively engages the target. 
     Feature L. The lift of Embodiment A, wherein the platform movement control device comprises: 
     an actuator comprising a movable portion being configured to move in a vertical direction; 
     a first arm, the first arm mounted in a pivotal connection with each of the actuator and a stationary member; 
     a second arm with a hook-shaped portion, the second arm being fastened to the first arm, the second arm configured to move linearly along a length of the first arm and to pivot with the first arm; and 
     a spring, the spring connected to each of the second arm and the stationary member; 
     the actuator operable to pivot the first and second arms upwardly into an unlock position; 
     the spring operable to pivot the first and second arms downwardly into a lock position; 
     the hook-shaped portion selectively engages, during an operation of a platform, a target on a platform in the lock position and disengages the target in the unlock position; 
     the platform being prevented from a movement when the hook-shaped portion selectively engages the target. 
     Feature M. The lift of Feature L, wherein the platform movement control device being attached to a control enclosure in the lift. 
     Feature N. The lift of Embodiment A, further comprising an electrical power connector, the electrical power connector defining an encapsulated decouplable power interface between a control enclosure and an external source of electric energy. 
     Feature P. The lift of Embodiment A, further comprising a light assembly, the light assembly being mounted on the platform. 
     Feature R. The lift of Feature P, wherein the light assembly comprises: 
     a housing, the housing comprises, during operation of the light assembly, a bottom cavity along a length of the housing, a hollow interior and two side grooves along the length of the housing, each side groove from the two side grooves being disposed within one side surface of the housing; 
     two light emitting diode (LED) strips, each LED strip being sized and shaped to fit into a respective side groove, the two LED strips coupled to a source of electric power during operation of the light assembly to illuminate both sides of the housing; 
     a load bearing ground contact; and 
     two ends caps, each end cap having an abutment sized and shaped to fit into the hollow interior, each end cap terminating a respective end of the housing. 
     Embodiment B. A method of controlling a movement of a platform with a bridgeplate in a vehicle lift, the method comprises: 
     generating, with two first acoustic sensors, a first detection plume over a transfer bridgeplate area when the platform is at a vehicle floor level position; 
     generating, with two second acoustic sensors, a second detection plume over a vehicle door threshold area when the platform is at the vehicle floor level position; 
     receiving, at a controller, a signal being responsive to one of the first detection plume and the second detection plume being interrupted; and 
     at least preventing, with a controller in a response to the signal, a movement of the platform from the vehicle floor level position toward a deployed ground level position. 
     Feature A. The method of Embodiment B, further comprising selectively actuating and deactuating the two first acoustic sensors and the two second acoustic sensors with a potentiometer operable to incrementally provide signals based on resistance associated with positions of the platform between a stowed position and below the vehicle floor level position. 
     Feature B. The method of Embodiment B, wherein the selectively actuating and deactuating the two first acoustic sensors and the two second acoustic sensors comprises operating the potentiometer with a pivot in a parallelogram mechanism in the lift, the parallelogram mechanism configured to at least move the platform between the vehicle floor level position and a deployed ground level position. 
     Feature C. The method of Embodiment B, wherein the generating the first detection plume comprises orienting each first sensor from the two first sensors with a collar, the collar receiving each first sensor therewithin. 
     Feature D. The method of Embodiment B, wherein the generating the second detection plume comprises orienting each second sensor from the two second sensors with a collar, the collar receiving each second sensor therewithin. 
     Embodiment C. A method of controlling a movement of a platform with a bridgeplate in a vehicle lift, the method comprises: 
     generating, with two acoustic sensors, a detection plume over one of a transfer bridgeplate area and vehicle door threshold area when the platform is at a vehicle floor level position; 
     receiving, at a controller, a signal being responsive to o the first detection plume being interrupted; and 
     at least preventing, with a controller in a response to the signal, a movement of the platform from the vehicle floor level position toward a deployed ground level position. 
     Embodiment D. A method of controlling operation of a movable platform within a lift mountable in a vehicle, the method comprising the steps of: 
     mounting a pair of first sensors in a position to monitor a transfer bridging plate area when the lift platform is at a vehicle floor level position; 
     mounting a pair of second sensors in a position to monitor vehicle door threshold area while the lift platform is at the vehicle floor level position; and 
     interlocking the pairs of first and second sensors with a controller for the lift or for the vehicle so as to prevent operation of the lift platform when the lift platform is being occupied. 
     Feature A. The method of Embodiment D, wherein each sensor from the pairs of first and second sensors comprises: 
     a piezoelectric, ultrasonic device capable of creating a detection volume; and 
     a focusing collar receiving the piezoelectric, ultrasonic device. 
     Embodiment E. A platform lock, comprising: 
     a first arm, the first arm having a first end, a second end spaced apart from the first end along a length of the first arm, a first elongated slot through a thickness of the first arm between the first and second ends, a length of the first elongated slot aligned normal to the length of the first arm; 
     a first connection, the first connection being between the first end and a vertically disposed wall of a stationary lift control enclosure, the first connection configured to allow a pivotal movement of the first arm about the vertically disposed wall, the first connection comprising a first aperture through the thickness of the first arm adjacent the first end thereof, a second aperture though a thickness of the vertically disposed wall and a fastener passing through the first and second apertures; 
     a second arm, the second arm having a first end, a second end spaced apart from the first end of the second arm along a length of the second arm, a spring seat upstanding on a first edge of the second arm adjacent the first end of the second arm, a first edge notch in the second arm between the first and second ends, the first edge notch sized and shaped to allow access to the first elongated slot during operation of the platform lock, a second edge notch in the second edge of the second arm and a taper in the second end of the second arm, the taper and the second edge notch defining a hook-shaped portion of the second arm; 
     a second connection, the second connection being between the first arm and the second arm so that the second arm pivots with the first arm, the second connection configured to move the second arm along a length of the first arm, the second connection comprising two third apertures through the thickness of the first arm between the first and second ends thereof, two second elongated slots through a thickness of the second arm between the first and second ends, a length of each second elongated slot aligned along the length of the first arm, each second elongated slot is aligned, during use, with a respective third aperture in the first arm, and fasteners fastening the second arm to the first arm at each second elongated slot aligned with the respective third aperture; 
     an actuator, the actuator having a stationary portion affixed to the vertically disposed wall and a movable portion disposed for a linear movement in a vertical direction; 
     a third connection, the third connection being between a free end of the movable portion and the first end of the first arm, the third connection comprising a link pivotally coupled to the free end of the movable portion and to a flange on the first end of the first arm; and 
     a tension spring, the tension spring having a first end attached to a spring seat on the second arm and having an opposite second end attached to a spring seat on the vertically disposed wall; 
     the actuator, when energized during the operation of the platform lock, moves the movable portion in an upward direction and pivots the first arm and the second arm, at the first connection about the vertically disposed wall in the upward direction, into an unlock position; 
     the tension spring configured to pivot the first arm and the second arm in a downward direction into a lock position when the actuator is deenergized; 
     the hook-shaped portion selectively engages, during the operation, a target on a platform in the lock position and disengages the target in the unlock position; 
     the platform being prevented from a movement when the hook-shaped portion selectively engages the target. 
     Embodiment F. A platform lock for a lift in a vehicle, the platform lock comprising: 
     an actuator comprising a movable portion being configured to move in a vertical direction; 
     a first arm, the first arm mounted in a pivotal connection with each of the actuator and a stationary member; 
     a second arm with a hook-shaped portion, the second arm being fastened to the first arm, the second arm configured to move linearly along a length of the first arm and to pivot with the first arm; and 
     a spring, the spring connected to each of the second arm and the stationary member; 
     the actuator operable to pivot the first and second arms upwardly into an unlock position; 
     the spring operable to pivot the first and second arms downwardly into a lock position; 
     the hook-shaped portion selectively engages, during an operation of a platform, a target on a platform in the lock position and disengages the target in the unlock position; 
     the platform being prevented from a movement when the hook-shaped portion selectively engages the target. 
     Feature A. The platform lock of Embodiment F, wherein the stationary member comprises a vertically disposed exterior wall surface in a control enclosure, the control enclosure containing hydraulic components which are configured to move the platform between stow and deployed positions, the actuator is being mounted to the vertically disposed exterior wall surface. 
     Embodiment G. A platform lock for a lift in a vehicle, the platform lock comprising: 
     a first arm, the first arm having a first end, a second end spaced apart from the first end along a length of the first arm, a first elongated slot through a thickness of the first arm between the first and second ends, a length of the first elongated slot aligned normal to the length of the first arm; 
     a first connection, the first connection being between the first end and a vertically disposed wall of a stationary control enclosure, the first connection configured to allow a pivotal movement of the first arm about the vertically disposed wall, the first connection comprising a first aperture through the thickness of the first arm adjacent the first end thereof, a second aperture though a thickness of the vertically disposed wall and a fastener passing through the first and second apertures; 
     a second arm, the second arm having a first end, a second end spaced apart from the first end of the second arm along a length of the second arm, a spring seat upstanding on a first edge of the second arm adjacent the first end of the second arm, a first edge notch in the second arm between the first and second ends, the first edge notch sized and shaped to allow access to the first elongated slot during operation of the platform lock, a second edge notch in the second edge of the second arm and a taper in the second end of the second arm, the taper and the second notch defining a hook-shaped portion of the second arm; 
     a second connection, the second connection being between the first arm and the second arm so that the second arm pivots with the first arm, the second connection configured to move the second arm along a length of the first arm, the second connection comprising two third apertures through the thickness of the first arm between the first and second ends thereof, two second elongated slots through a thickness of the second arm between the first and second ends, a length of each second elongated slot aligned along the length of the first arm, each second elongated slot is aligned, during use, with a respective third aperture in the first arm, and fasteners fastening the second arm to the first arm at each second elongated slot aligned with the respective third aperture; 
     an actuator, the actuator having a stationary portion affixed to the vertically disposed wall and a movable portion disposed for a linear movement in a vertical direction; 
     a third connection, the third connection being between a free end of the movable portion and the first end of the first arm, the third connection comprising a link pivotally coupled to the free end of the movable portion and to a flange on the first end of the first arm; and 
     a tension spring, the tension spring having a first end attached to a spring seat on the second arm and having an opposite second end attached to a spring seat on the vertically disposed wall; 
     the actuator, when energized during the operation of the platform lock, moves the movable portion in an upward direction and pivots the first arm and the second arm, at the first connection about the vertically disposed wall in the upward direction, into an unlock position; 
     the tension spring configured to pivot the first arm and the second arm in a downward direction into a lock position when the actuator is deenergized; 
     the hook-shaped portion selectively engages, during the operation, a target on a platform in the lock position and disengages the target in the unlock position; 
     the platform being prevented from a movement when the hook-shaped portion selectively engages the target. 
     Embodiment H. A lift for a vehicle, the lift comprising: 
     a platform configured to support a person thereon; 
     a bridgeplate pivotally mounted on one end of the platform for a movement between two terminal positions; 
     a prime moving system comprising at least a four-bar linkage mechanism, a cylinder and a hydraulic pump, the prime moving system operable to move the platform between a stowed position and a deployed position and to move the bridgeplate between the two terminal positions; 
     a controller configured to receive inputs and provide outputs necessary to move the platform between the stowed position and deployed positions, the controller comprises a control enclosure, the hydraulic pump being disposed within the control enclosure; 
     a retention apparatus; and 
     a stow lock assembly integrated into the control enclosure, the stow lock assembly configured to hold the platform in its stowed position when the prime moving system slips over time while the platform is stowed, the stow lock assembly comprising: 
     an arm, 
     a pivotal connection between the arm and an exterior wall surface of the control enclosure, 
     a hook on the arm, the hook is accessible for service when the platform is at ground level, the hook comprising an angled edge surface on a front of the hook that enables the system to be self-locking when the platform is being stowed, the angled edge surface is configured such that when the hook contacts a target on the platform, the hook is forced upward as the platform reaches its stowed position, 
     a lock actuator mounted on an interior wall surface of the control enclosure, 
     a pivotal connection between a movable portion of the lock actuator and the arm, and 
     a tension spring having one end connected to the arm and having another end connected to the exterior wall surface of the control enclosure; 
     the lock actuator operable to move the hook, in an upward direction, into an unlock position to disengage the target; 
     the spring configured to return the hook, in a downward direction, into a locked position. 
     Embodiment K. A stow lock assembly integratable into a control enclosure in a lift for a vehicle, the stow lock assembly configured to hold a platform in its stowed position when a prime moving system in the lift slips over time while the platform is stowed, the stow lock assembly comprising: 
     an arm in a pivoting connection with a rear part of the control enclosure; 
     a pivotal connection between the arm and an exterior wall surface of the control enclosure; 
     a hook on the arm, the hook is accessible for service when the platform is at ground level, the hook comprising an angled edge surface on a front of the hook that enables the system to be self-locking when the platform is being stowed, the angled edge surface is configured such that when the hook contacts a target on the platform, the hook is forced upward as the platform reaches its stowed position; 
     a lock actuator mounted on an interior wall surface of the control enclosure, 
     a pivotal connection between a movable portion of the lock actuator and the arm, and 
     a tension spring having one end connected to the arm and having another end connected to the exterior wall surface of the control enclosure; 
     the lock actuator operable to move the hook, in an upward direction, into an unlock position to disengage the target; the tension spring configured to return the hook, in a downward direction, into a locked position. 
     Embodiment L. A lift for a vehicle, the lift comprising: 
     a platform comprising a surface and two side barriers; 
     a bridgeplate pivotally mounted on one end of the platform for a movement between two terminal positions 
     a prime moving system comprising at least a four-bar linkage mechanism, a cylinder and a hydraulic pump, the prime moving system operable to move the platform between a stowed position and a deployed position and to move the bridgeplate between the two terminal positions; 
     a controller configured to receive inputs and provide outputs necessary to move the platform between the stowed position and deployed positions, the controller comprises a control enclosure, the hydraulic pump being disposed within the control enclosure; 
     an acoustic sensor array, comprising: 
     two first sensors, each of the two first sensors mountable to a respective lower arm in the four-bar linkage mechanism, the two first sensors configured to monitor a transfer bridging plate area when the platform is at a vehicle floor level position, and 
     two second sensors, each of the two second sensors mountable, when installed on the vehicle, rearward of the two first sensors, the two second sensors configured to monitor vehicle door threshold area while the platform is at the vehicle floor level position, 
     each sensor from the two first sensors and two second sensors comprising a piezoelectric, ultrasonic device capable of creating a detection volume in front of each sensor, and 
     a collar mounting each sensor so that each sensor is oriented to generate a first detection plume between the two first sensors and a second detection plume between the two second sensors; and 
     a potentiometer being mounted on one lower arm in the four-bar linkage mechanism, the potentiometer being actuable by a pivot connecting the cylinder to the one lower arm, the potentiometer configured to incrementally provide signals associated with positions of the platform between the floor vehicle level position and a deployed ground level position; 
     the controller being responsive to the signals to prevent operation of the platform being occupied. 
     Embodiment M. A lift for a vehicle, the lift comprising: 
     a platform comprising a surface and two side barriers; 
     a bridgeplate pivotally mounted on one end of the platform for a movement between two terminal positions 
     a prime moving system comprising at least a four-bar linkage mechanism, a cylinder and a hydraulic pump, the prime moving system operable to move the platform between a stowed position and a deployed position and to move the bridgeplate between the two terminal positions; 
     a controller configured to receive inputs and provide outputs necessary to move the platform between the stowed position and deployed positions, the controller comprises a control enclosure, the hydraulic pump being disposed within the control enclosure; and 
     a replaceable load bearing ground contact device that contacts a ground ahead of a lower extremity of a vertical arm in the four-bar linkage mechanism and at least reduces a contact between the lower extremity of the vertical arm with the ground, the replaceable load bearing ground contact device comprises molded plastic material, the load bearing ground contact device is configured to be attached to the lower extremity with a single fastener. 
     Embodiment L. A lift, comprising: 
     a platform comprising a surface and two side barriers; 
     a bridgeplate at a rear of the platform; 
     a prime moving system comprising at least a four-bar linkage mechanism and a cylinder, the prime moving system operable to move the platform between a stowed position and a deployed position; 
     a controller configured to receive inputs and provide outputs necessary to move the platform between the stowed position and the deployed position, the controller comprises a control enclosure; and 
     a lock, the lock configured to lock the bridgeplate in a generally vertical barrier position, the lock comprising: 
     a cam-shaped edge surface on each end of the bridgeplate; 
     two arms, each arm being pivotally mounted at a rear of the platform and being spring loaded for a downward bias such that in a default state the platform can be disposed generally horizontally in a bridging position, the two arms being rigidly connected therebetween so that the two arms substantially rotate in unison with each other, the two arms being in a contact with the platform; 
     two cables, each cable from the two cables having one end connected to a respective arm and having an opposite end connected to a lower arm of a platform moving mechanism; and 
     a cam operated mechanism, the cam operated mechanism configured to pull the cable as the platform is being lowered, through the platform moving mechanism, from a floor level position; 
     each cable configured to pull against a respective arm, as the platform is being lowered from the floor level position and raising the respective arm against the cam-shaped edge surface into a generally vertical barrier position. 
     Embodiment M. A lock for a lift with a platform and a bridgeplate, comprising: 
     a cam-shaped edge surface on each end of the bridgeplate; two arms, each arm being pivotally mounted at a rear of the platform and being spring loaded for a downward bias such that in a default state the platform can be disposed generally horizontally in a bridging position, the two arms being rigidly connected therebetween so that the two arms substantially rotate in unison with each other, the two arms being in a contact with the platform; 
     two cables, each cable from the two cables having one end connected to a respective arm and having an opposite end connected to a lower arm of a platform moving mechanism; and 
     a cam operated mechanism, the cam operated mechanism configured to pull the cable as the platform is being lowered, through the platform moving mechanism, from a floor level position; 
     each cable configured to pull against a respective arm, as the platform is being lowered from the floor level position and raising the respective arm against the cam-shaped edge surface into a generally vertical barrier position. 
     Embodiment N. A light assembly, comprising: 
     a housing, the housing comprises, during operation of the light assembly, a bottom cavity along a length of the housing, a hollow interior and two side grooves along the length of the housing, each side groove from the two side grooves being disposed within one side surface of the housing; 
     two light emitting diode (LED) strips, each LED strip being sized and shaped to fit into a respective side groove, the two LED strips coupled to a source of electric power during operation of the light assembly to illuminate both sides of the housing; 
     a load bearing ground contact; and 
     two ends caps, each end cap having an abutment sized and shaped to fit into the hollow interior, each end cap terminating a respective end of the housing. 
     Embodiment R. A lift for a vehicle, the lift comprising: 
     a lift platform comprising a surface and two side barriers; 
     a bridgeplate pivotally mounted on one end of the lift platform for a movement between two terminal positions a prime moving system comprising at least a four-bar linkage mechanism, a cylinder and a hydraulic pump, the prime moving system operable to move the lift platform between a stowed position and a deployed position and to move the bridgeplate between the two terminal positions; 
     a controller configured to receive inputs and provide outputs necessary to move the lift platform between the stowed position and deployed positions, the controller comprises a control enclosure, the hydraulic pump being disposed within the control enclosure; 
     light assemblies, each light assembly comprising: 
     a housing, the housing comprises, during operation of each light assembly, a bottom cavity along a length of the housing, the bottom cavity configured to interface with a top edge of a side barrier, a hollow interior and two side grooves along the length of the housing, each side groove from the two side grooves being disposed within one side surface of the housing, 
     two light emitting diode (LED) strips, each LED strip being sized and shaped to fit into a respective side groove, the two LED strips coupled to a source of electric power during operation of the light assembly to illuminate both sides of the housing, 
     a load bearing ground contact, and 
     two ends caps, each end cap having an abutment sized and shaped to fit into the hollow interior, each end cap terminating a respective end of the housing; 
     each light assembly configured to illuminate an interior and an exterior of the lift platform during operation of the lift. 
     Embodiment 5. A method of controlling operation of a vehicle lift with a movable lift platform having an occupant supporting surface and two side barriers, the method comprising the steps of: 
     mounting a light assembly on a top edge of one side barrier of the lift platform; and 
     actuating the light assembly to emit light visible external to the lift platform when the lift platform is being lowered or raised external to a vehicle. 
     Feature A. The method of Embodiment 5, wherein the step of mounting the light assembly comprises a step of mounting two light emitting members along opposite sides of the light assembly. 
     Feature B. The method of Embodiment 5, wherein the step of mounting the light assembly comprises a step of mounting another light assembly on another side barrier and the step of actuating both light assemblies to emit light visible external to both sides of the lift platform when the lift platform is being lowered or raised external to a vehicle. 
     Feature C. The method of Feature B, further comprising a step of configuring each light assembly to emit light of a different color. 
     Embodiment T. A method of controlling operation of a vehicle lift with a movable platform having an occupant supporting surface and two side barriers, the method comprising: 
     mounting one or more light members on both barriers of the lift platform in a position to emit light visible external to the lift platform; and 
     actuating the one or more light members to emit the light when the lift platform is at least one of being deployed at a ground, in a process of being lowered toward the ground and in a process of being raised toward a stowed position within a vehicle. 
     Embodiment U. A method of controlling operation of a movable platform within a lift mountable in a vehicle, the method comprising the steps of: 
     providing a cam-shaped edge surface on each end of a bridgeplate; 
     two arms, each arm being pivotally mounted at a rear of the platform and being spring loaded for a downward bias such that in a default state the platform can be disposed generally horizontally in a bridging position, the two arms being rigidly connected therebetween so that the two arms substantially rotate in unison with each other, the two arms being in a contact with the platform; 
     two cables, each cable from the two cables having one end connected to a respective arm and having an opposite end connected to a lower arm of a platform moving mechanism; and 
     a cam operated mechanism, the cam operated mechanism configured to pull the cable as the platform is being lowered, through the platform moving mechanism, from a floor level position; 
     each cable configured to pull against a respective arm, as the platform is being lowered from the floor level position and raising the respective arm against the cam-shaped edge surface into a generally vertical barrier position. 
     The chosen exemplary embodiments of the claimed subject matter have been described and illustrated, to plan and/or cross section illustrations that are schematic illustrations of idealized embodiments, for practical purposes so as to enable any person skilled in the art to which it pertains to make and use the same. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. It is therefore intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims. It will be understood that variations, modifications, equivalents and substitutions for components of the specifically described exemplary embodiments of the disclosure may be made by those skilled in the art without departing from the spirit and scope of the disclosure as set forth in the appended claims. 
     Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specified function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. § 112, ¶ 6. In particular, any use of “step of” in the claims is not intended to invoke the provision of 35 U.S.C. § 112, ¶ 6. 
     Furthermore, the Abstract is not intended to be limiting as to the scope of the claimed subject matter and is for the purpose of quickly determining the nature of the claimed subject matter.