Patient support apparatus with lift mechanism

A patient support apparatus supports a patient and includes a litter. A base is disposed below the litter. A lift mechanism is configured to move the litter and the base relative to one another between extended and collapsed positions. The lift mechanism includes first and second frame assemblies each including an outer frame member and an inner frame member arranged to move within the outer frame member. First and second rollers and first and second slide members are disposed between the outer and inner frame members. The first and second rollers are arranged to roll along at least one of the outer and inner frame members with a load exerted on the lift mechanism from the litter. The first and second slide members are arranged to slide along at least one of the outer and inner frame members with a load exerted on the lift mechanism from the base.

BACKGROUND

Patient support systems facilitate care of patients in a health care setting. Patient support systems comprise patient support apparatuses such as, for example, hospital beds, stretchers, cots, tables, wheelchairs, and chairs. Many types of conventional patient support apparatuses generally include a base and a litter upon which the patient is supported.

Often, patient support apparatuses have one or more powered devices to perform one or more functions on the patient support apparatus. These functions may include lifting and lowering the litter or the base via a lift mechanism and/or raising a patient from a horizontal position to an inclined position, or vice versa, via one or more actuator mechanisms, and the like. Because the patient support apparatus is generally mobile, electrical connection to a power outlet of the one or more powered devices is not always available, and as such the apparatus typically includes a battery which is coupled to the various powered devices to allow the powering of such devices as the apparatus is moved between locations (e.g., after being unloaded from an emergency vehicle).

For patient support apparatuses which utilize lift mechanisms, powered actuators may be employed to facilitate relative movement between the base and the litter between a plurality of vertical configurations, including for example a retracted configuration or an extended configuration. Here, it will be appreciated that other types of lift mechanisms may be configured without powered actuators, and may rely on caregivers to manually or semi-manually (e.g., with spring-assisted or similar mechanisms) facilitate relative movement between the litter and the base.

Some types of patient support apparatuses employ lift mechanisms with one or more telescoping leg assemblies including a main rail and an inner rail that moves relative to the main rail, such as via linear slides provided to facilitate telescoping movement of the inner rail relative to the main rail. It will be appreciated that linear slides can be subjected to significant loads and wear during use. Here, depending on the specific configuration of the patient support apparatus, linear slides may need to be replaced if excessive wear occurs. Moreover, depending on the environment in which these types of patient support apparatuses are utilized, debris and other contaminants may accumulate during use, which may result in decreased performance and wear of the linear slides, causing decreased performance of the lift mechanisms. Other types of conventional patient support apparatuses may employ an arrangement of wheels to facilitate telescoping movement of the inner rail relative to the main rail, but these types of designs are typically bulky, utilize several wheels for each rail, are generally more complicated to manufacture and assemble, are generally difficult to service, and can still result in decreased performance in response to the accumulation of debris and other contaminants.

A patient support apparatus designed to overcome one or more of the aforementioned challenges is desired.

DETAILED DESCRIPTION

Referring toFIG. 1, a patient support apparatus20is shown for supporting a patient in a health care and/or transportation setting. The patient support apparatus20illustrated inFIG. 1is configured as a wheeled cot. In other embodiments, however, the patient support apparatus20may be configured as a hospital bed, stretcher, table, wheelchair, chair, or similar apparatus utilized in the transportation and care of a patient.

The patient support apparatus20comprises a litter22with a patient support deck24configured to support the patient. The patient support deck24may be defined by one or more articulable deck sections, for example, a back section26and a foot section28(as well as a seat section, a leg section, or any other suitable arrangement of sections), to facilitate care and/or transportation of the patient in various patient positions. The litter22extends generally longitudinally between a first litter end30(e.g., adjacent to the patient's head) and a second litter end32(e.g., adjacent to the patient's feet). In addition, the litter22also extends generally laterally between a first side end34(e.g., adjacent to the patient's left side) and a second side end36(e.g., adjacent to the patient's right side).

In the representative embodiment illustrated herein, the litter22generally includes a support frame38configured to support the patient support deck24. It will be appreciated that the support frame38may take on various configurations and may include a variety of components. For example, inFIG. 1, the support frame38includes longitudinal rails40which extend between the first and second litter ends30,32. In some embodiments, additional components or features of the patient support apparatus20may be directly or indirectly coupled to one or more longitudinal rails40. In the example shown inFIG. 1, the litter22includes a foot end handle42coupled at the second litter end32and arranged for user engagement. The illustrated foot end handle42includes various grip regions arranged for user engagement (not shown in detail). However, it will be appreciated that the litter22could have other configurations without departing from the scope of the present disclosure, and may employ different types of handles or grip regions arranged at other locations about the patient support apparatus20. In some embodiments, the handles or grip regions may be similar to as is described in U.S. Pat. No. 10,369,063, titled “Patient Transport Apparatus with Adjustable Handles,” the disclosure of which is hereby incorporated by reference in its entirety. Other configurations are contemplated.

The illustrated support frame38also supports loading wheels44adjacent to the first end30of the litter22. As shown inFIG. 1, the loading wheels44may extend from the support frame38proximal to the back section26of the patient support deck24, and are employed to facilitate loading and unloading of the patient support apparatus20from a vehicle. In some embodiments, the loading wheels44may be positioned and configured to facilitate loading and unloading the patient support apparatus20into an ambulance. The support frame38may also support side rails (not shown) arranged as egress barriers for the patient on the patient support deck24, and may also employ grips or handles arranged for engagement by a caregiver (e.g., an emergency medical technician (EMT), or another medical professional) to move or manipulate the patient support apparatus20. In some embodiments, the side rails include a hinge, pivot, or similar mechanism to allow the side rails to be adjustably positioned relative to the patient support deck24. The support frame38may support one or more vertical support members (not shown) configured to hold a medical device or medication delivery system, such as a bag of fluid to be administered via an intravenous line. The vertical support member may also be configured for the operator of the patient support apparatus20to push or pull on the vertical support member to manipulate or move the patient support apparatus20. Other configurations are contemplated.

As is best shown inFIGS. 1 and 3A-3B, the patient support apparatus20also generally includes a base46disposed below the litter22. The base46extends longitudinally between a first base end48proximate the first litter end30, and a second base end50proximate the second litter end32. The base46is arranged to support the litter22and is configured to engage a floor surface52. The base46may include longitudinally-extending rails54extending between the first and second base ends48,50and crosswise-extending rails56coupled to the longitudinally-extending rails54. In this representative, illustrative embodiment, the base46has a generally rectangular profile. However, it will be appreciated that the base46may have other configurations sufficient to support the litter22, as described in greater detail below, without departing from the scope of the present disclosure.

In the representative embodiments illustrated herein, the base46includes a plurality of caster wheel assemblies58operatively connected adjacent to each corner of the base46defined by the longitudinally-extending rails54and the crosswise-extending rails56. The wheel assemblies may be configured to swivel to facilitate turning of the patient support apparatus20. The wheel assemblies may include a swivel locking mechanism to prevent the wheel assemblies from swiveling when engaged. The wheel assemblies may also include wheel brakes to prevent rotation of the wheel. However, other configurations are contemplated, and it will be appreciated that any suitable number of caster wheel assemblies58, or other types of wheels (e.g., powered, non-powered) or other movement-promoting systems (e.g., treads) may be utilized without departing from the scope of the present disclosure.

As shown inFIG. 1, the patient support apparatus20also comprises a lift mechanism60extending between the litter22and the base46to effect relative movement between the litter22and the base46between a plurality of vertical configurations VC, including a collapsed configuration CC (e.g., as is depicted schematically inFIGS. 2A and 2D), an extended configurations CE (e.g., as is depicted schematically inFIGS. 2B-2C), as well as additional vertical configurations VC between the collapsed configuration CC and the extended configuration CE. As will be appreciated from the subsequent description below, in addition to being configured for selective (e.g., user-selected) operation for moving between different vertical configurations VC, the lift mechanism60is also operable between a transport mode MT (seeFIGS. 2A-2B) and a suspended mode MS (seeFIGS. 2C-2D). In the transport mode MT, the base46is disposed in engagement with the floor surface52(e.g., via contact between the wheel assemblies58and the ground) and supports the litter22for movement relative to the base46(compareFIGS. 2A-2B). In the suspended mode MS, the base46is spaced from the floor surface52, and the litter22supports the base46(e.g., via contact between the loading wheels44and the floor of an ambulance cargo area) for movement relative to the litter22(compareFIGS. 2C-2D). Thus, the lift mechanism60can move between the different vertical configurations VC when the patient support apparatus20is utilized in either the transport mode MT or the suspended mode MS.

FIGS. 2A and 2Dschematically depict a “maximum” or “near-maximum” collapsed configuration CC with the litter22arranged generally adjacent to (and partially nested over) the base46, whileFIGS. 2B-2Cschematically depict a “maximum” or “near-maximum” extended configuration CE with the litter22arranged vertically above the base46. As will be appreciated from the subsequent description below, various vertical configurations VC are contemplated by the present disclosure, including other collapsed configurations CC and/or other extended configurations CE (e.g., other than “maximum” or “near-maximum” configurations). For example,FIGS. 3A, 4, and 6each depict an extended configuration CE that is “lower” than the schematic representation shown inFIGS. 2B-2C, andFIGS. 3B, 5, and 7each depict a collapsed configuration that is “higher” than the schematic representation shown inFIGS. 2A and 2D. Thus, in embodiments consistent with the present disclosure, the litter22is arranged further away from the base46in the extended configuration CE than in the collapsed configuration CC. Accordingly, it will be appreciated that the terms “collapsed” and “extended” are used herein for illustrative, non-limiting purposes, and do not necessarily refer to a specific, discrete vertical configuration VC.

The extended configuration CE generally refers to an arrangement of the lift mechanism60where the distance between the base46and the litter22is relatively large (more specifically, larger than the collapsed configuration CC). The extended configuration CE may be utilized when a patient is laying on the patient support deck24in a hospital room or other non-transport setting, or when the patient is being transported by a caregiver between locations (e.g., between an ambulance and a hospital setting). In some embodiments, the extended configuration CE may be referred to as a transport configuration (e.g., defined such as a vertical configuration VC that is not necessarily a “maximum” extended configuration CE). In the collapsed configuration CC, on the other hand, the distance between the base46and the litter22is relatively small (more specifically, smaller than the extended configuration CE). The collapsed configuration CC may be utilized when the patient support apparatus20is being/has been loaded into an ambulance, or when the caster wheel assemblies58coupled to the base46are not otherwise utilized to move along floor surfaces52(e.g., when the patient support apparatus20is carried by multiple caregivers across rough terrain).

While moving between the vertical configuration VC, the lift mechanism60may move either the base46or the litter22relative to the other of the litter22or the base46depending on how the patient support apparatus20is supported during use (e.g., operating in the transport mode MT or the suspended mode MS). In instances where the patient support apparatus20is supported at the litter22(e.g., in the suspended mode MS), the lift mechanism60effectively moves the base46relative to (e.g., for movement towards or away from) the litter22between the plurality of vertical configurations VC. In instances where the patient support apparatus20is supported at the base46(e.g., in the transport mode MT), the lift mechanism60effectively moves the litter22relative to (e.g., for movement towards or away from) the base46between the plurality of vertical configurations.

Referring now toFIGS. 1-7, the lift mechanism60generally comprises a frame assembly (more specifically, a first frame assembly62aand a second frame assembly62b) extending between the litter22and the base46to facilitate movement between the plurality of vertical configurations VC. To this end, the first and second frame assemblies62a,62bare each pivotably coupled to each of the base46and the litter22. More specifically, the first frame assembly62ais pivotally coupled to the base46proximate the first base end48, and is pivotally coupled (and, as is described in greater detail below, also slidably coupled) to the litter22proximate the second litter end32; while the second frame assembly62bis pivotally coupled to the base46proximate the second base end50, and is pivotally coupled to the litter22proximate the first litter end30. In the representative embodiments illustrated herein, and as is depicted inFIGS. 3A-3B, the first and second frame assemblies62a,62bare arranged in a X configuration, and each has a respective left frame subassembly62al,62bland a respective right frame subassembly62ar,62br.

The left frame subassemblies62al,62bland the right frame subassemblies62ar,62brare spaced laterally from each other and are generally configured as “mirrored” or otherwise complimentarily-configured and laterally-spaced versions of each other, and have corresponding structural features and components which facilitate concurrent, linked, and stable motion as the lift mechanism60moves between the plurality of vertical configurations VC. As will be appreciated from the subsequent description below, many of the components and structural features of the first and second frame assemblies62a,62bemploy similar configurations to each other. Here, while specific differences between the first and second frame assemblies62a,62bwill be explained in detail, it will be appreciated that the first and second frame assemblies62a,62bmay each utilize multiple components that have similar or even identical configurations (e.g., one component associated with the left frame subassembly62al,62bland another corresponding component associated with the respective right frame subassembly62ar,62br). Accordingly, for the purposes of clarity, consistency, and brevity, subsequent description of the lift mechanism60will generally employ discrete reference numerals for the components and structural features of the first frame assembly62a,and similar but discrete reference numerals for the corresponding components and structural features of the second frame assembly62b,but will not otherwise delineate further between the left frame subassemblies62al,62bland the right frame subassemblies62ar,62br.Put differently, the drawings and description below may make reference to certain components and structural features which are utilized on both the left frame subassemblies62al,62bland the right frame subassemblies62ar,62br,which may only be introduced a single time as being part of the first and/or second frame assemblies62a,62b;these are to be considered as separate but corresponding parts of the left and right frame subassemblies unless otherwise indicated.

As is best shown inFIGS. 4-7, each of the first and second frame assemblies62a,62bgenerally comprises an outer frame member64a,64bdefining an interior66a,66b,and an inner frame member68a,68barranged to move within the interior66a,66bof the outer frame member64a,64bwhen the litter22and the base46move relative to one another between the plurality of vertical configurations VC. The inner frame member68a,68bgenerally includes an upper exterior surface70a,70bfacing towards the litter22, and an opposing lower exterior surface72a,72bfacing towards the base46.

As noted above, and as is best depicted inFIG. 1, the first frame assembly62ais pivotally and slidably (or translatably) coupled to the litter22. To this end, and in the representative embodiment illustrated herein, the first frame assembly62aincludes a slide interface74coupled to the outer frame member64a,and a guide body76defining a channel78is coupled to the litter22. The slide interface74is disposed within the channel78of the guide body76for pivoting movement within the channel78, and for sliding movement along the channel78, as the lift mechanism60moves between the plurality of vertical configurations VC.

The guide body76may be coupled to a variety of locations on the litter22. For example, as shown best inFIG. 1, the guide body76may be coupled to the support frame38. More specifically, in the illustrated example, the guide body76is coupled to an underside of the longitudinal rail of the support frame38of the litter22adjacent to the second litter end32. As the slide interface74moves between the plurality of different positions within the channel78, the lift mechanism60moves between the plurality of vertical configurations VC. In this way, movement of the slide interface74in the channel78corresponds to movement between the vertical configurations VC. In the illustrated embodiment depicted inFIG. 1, the channel78has a curvilinear profile defined by a “linear” region that the slide interface74moves along as the lift mechanism60moves towards the extended configuration CE, and also by a “curved” region that the slide interface75moves along as the lift mechanism approaches the extended configuration CE. However, it will be appreciated that other configurations are contemplated, and the channel78may have various configurations, profiles, shapes, and the like, including without limitation straight, zig-zag, S-shaped, curved, diagonal/sloped, or any combination thereof.

The first and second frame assemblies62a,62bmay be pivotally coupled to one another between the litter22and the base46such that the first and second frame assemblies62a,62bare arranged in an X configuration. To this end, the first frame assembly62aand the second frame assembly62bmay be pivotally coupled to each other at a pivot axle80(seeFIGS. 4-7) to form an X-frame. More specifically, the outer frame members64a,64bof the first and second frame assemblies62a,62bmay be pivotally coupled to each other at the pivot axle80.

The outer frame members64a,64bof each of the frame assemblies62a,62bare generally hollow and support the inner frame members68a,68bfor movement. More specifically, the inner frame members68a,68bare supported for movement within the outer frame members64a,64bto extend and retract the frame assemblies62a,62b.In the representative embodiments shown inFIGS. 4-7, the inner frame members68a,68bextend out of the outer frame members64a,64btoward the base46. As such, the inner frame members68a,68bof each of the first and second frame assemblies62a,62bare pivotally coupled to the base46. Similarly, the outer frame members64a,64bof each of the first and second frame assemblies62a,62bare pivotally coupled to the litter22. More specifically, the inner frame members68a,68bare coupled to the base46, and the outer frame members64a,64bare coupled to the support frame38of the litter22.

However, it will be appreciated that other configurations are contemplated and, in some embodiments, the inner frame members68a,68bmay extend out of outer frame members64a,64btoward the support frame38(not shown). Here, the frame assemblies may be operatively attached to the base46or to the support frame38via the inner frame members68a,68b.However, in other embodiments, one or more of the frame assemblies may be of a fixed length and, thus, could exclude the inner frame member68a,68b.Other configurations are contemplated.

As shown inFIGS. 4-7, the first and second frame assemblies62a,62beach generally comprise first rollers82a,82band second rollers84a,84b,as well as first slide members86a,86band second slide members88a,88b,disposed between the outer frame members64a,64band the inner frame members68a,68b.The first rollers82a,82band the first slide members86a,86bare arranged adjacent one another. The first rollers82a,82bare disposed along the respective lower exterior surfaces72a,72bof the inner frame members68a,68b,and the first slide members86a,86bare disposed along the upper exterior surfaces70a,70bof the respective inner frame members68a,68b.The second rollers84a,84band the second slide members88a,88bare adjacent to each other, and are disposed in spaced relation from the first rollers82a,82band the first slide members86a,86b.The second rollers84a,84bare disposed along the upper exterior surfaces70a,70bof the respective inner frame members68a,68b,and the second slide members88a,88bare disposed along the lower exterior surfaces72a,72bof the respective inner frame members68a,68b.Each of the components introduced above will be described in greater detail below.

With continued reference toFIGS. 4-7, the inner frame members68a,68beach generally include an inner chamber90a,90bextending longitudinally along the inner frame member68a,68b.In some embodiments, the inner frame members68a,68bmay also define apertures92a,92bthat opens into the inner chamber90a,90b.The first rollers82a,82bmay be disposed within the respective inner chambers90a,90band extend through the respective apertures92a,92binto rolling contact with a lower interior surface94a,94bof the outer frame members64a,64b,and may be spaced from an upper interior surface96a,96bof the outer frame members64a,64b.In some embodiments, the outer frame members64a,64bmay define respective openings98a,98b,and the second rollers84a,84bmay extend through the openings98a,98binto rolling contact with the upper exterior surface70a,70bof the inner frame members68a,68b.

To effect movement of the lift mechanism60between the plurality of vertical configurations VC according to embodiments of the present disclosure, the first slide members86a,86bare arranged for sliding contact with the upper interior surfaces96a,96bof the respective outer frame members64a,64b,while the second slide members88a,88bare arranged for sliding contact with the lower exterior surfaces72a,72bof the respective inner frame members68a,68b.Furthermore, the first rollers82a,82bare arranged for rolling contact with the lower interior surfaces94a,94bof the respective outer frame members64a,64b,while the second rollers84a,84bare arranged for rolling contact with the upper exterior surfaces70a,70bof the respective inner frame members68,68b.Here, when operating in the transport mode MT (seeFIGS. 2A-2B) with the base46disposed in engagement with the floor surface52(e.g., via the caster wheel assemblies58) and supporting the litter22for movement relative to the base46, the first and second frame assemblies62a62bare loaded such that the rolling contact of the first rollers82a,82band of the second rollers84a,84btransfers load from the litter22to the base46. However, when operating in the suspended mode MS (seeFIGS. 2C-2D) with the base46spaced from the floor surface52and with the litter22supporting the base46(e.g., via the loading wheels44) for movement relative to the litter22, the first and second frame assemblies62a,62bare loaded such that the sliding contact of the first slide members86a,86band of the second slide members88a,88btransfers load from the base46to the litter22.

In the embodiments shown inFIGS. 4-9, the first rollers82a,82bare rotatably coupled to the respective inner frame members68a,68band are arranged to rotate along the lower interior surfaces94a,94bof the respective outer frame member64a,64bto reduce friction between the outer frame members64a,64band the inner frame members68a,68b.Here too, the second rollers84a,84bare rotatably coupled to the respective outer frame members64a,64band are arranged to rotate along the upper exterior surfaces70a,70bof the respective inner frame members68a,68bto reduce friction between the outer frame members64a,64band the inner frame members68a,68b.Here, it will be appreciated that movement from the extended configuration CE to the collapsed configuration CC moves the first rollers82a,82btowards the respective second rollers84a,84bwithin the interiors66a,66bof the respective outer frame members64a,64b.Furthermore, the first slide members86a,86bare coupled to the respective inner frame members68a,68b,and the second slide members88a,88bare coupled to the respective outer frame members64a,64b.Here, it will be appreciated that movement from the extended configuration CE to the collapsed configuration CC moves the first slide members86a,86btowards the respective second slide members88a,88bwithin the interiors66a,66bof the respective outer frame members64a,64b.

As noted above, the first and second rollers82a,82b,84a,84bare each arranged to roll along at least one of the outer and inner frame members64a,64b,68a,68bto reduce friction therebetween and facilitate movement of the litter22and the base46relative to one another as the lift mechanism60selectively moves between the plurality of vertical configurations VC. Furthermore, the first and second slide members86a,86b,88a,88bare each arranged to slide along at least one of the outer and inner frame members64a,64b,68a,68bto reduce friction therebetween and facilitate movement of the litter22and the base46relative to one another as the lift mechanism60selectively moves between the plurality of vertical configurations VC. It will be appreciated that the lift mechanism60is configured for selective (e.g., user-selected) movement between the plurality of vertical configurations in the transport mode MT (compareFIGS. 2A-2B), as well as in the suspended mode MS (compareFIGS. 2C-2D).

An example of moving the litter22and the base46relative to one another between the vertical configurations VC with a load exerted on the lift mechanism60from the litter22occurs when a patient is disposed on the litter22and the base46is disposed on the floor surface52(e.g., operation in. the transport mode MT). Here, the lift mechanism60generally moves the litter22up and down relative to the base46supported the floor surface52, and must overcome the load of the patient and the litter22. An example of moving the litter22and the base46relative to one another between the vertical configurations VC with a load exerted on the lift mechanism60from the base46occurs when the litter22is being loaded into an ambulance or other type of emergency vehicle (e.g., operation in the suspended mode MS). Here, the lift mechanism60moves the base46up and down relative to the litter22that is supported on a bay floor of ambulance, and must overcome the load of the base46.

While other configurations are contemplated, for the representative embodiments of the patient support apparatus20illustrated herein, the load exerted on the lift mechanism60from the litter22when in the transport mode MT is generally larger than the load exerted on the lift mechanism60from the base46in the suspended mode MS. Here too, it will be appreciated that, depending on the weight of the patient, the amount of load acting on the lift mechanism60in the in the transport mode MT may be significantly higher than when that same patient is supported on the litter22in the suspended mode MS. Here, utilization of the first rollers82a,82band the second rollers84a,84bin the arrangement described above of facilitates greater friction reduction and ease of load transfer when compared to the first slide members86a,86band the second slide members88a,88b.Put differently, the first rollers82a,82band the second rollers84a,84bare configured to carry significantly higher load in the illustrated embodiments than the first slide members86a,86band the second slide members88a,88b.However, it will also be appreciated that the first slide members86a,86band the second slide members88a,88bare generally less expensive to manufacture, and can be utilized to facilitate sufficient friction reduction in relatively low-load situations (e.g., operation in the suspended mode MS). As such, the utilization of the first rollers82a,82band the second rollers84a,84breduces friction between the outer frame members64a,64band the inner frame members68a,68bunder the higher loads exerted by the litter22and the patient in the transport mode MT, while utilization of the first slide members86a,86band the second slide members88a,88breduces friction between the outer frame members64a,64band the inner frame members68a,68bunder the lower loads exerted by the base46in the suspended mode MS. Here, it will be appreciated that the arrangement of the first rollers82a,82b,the second rollers84a,84b,the first slide members86a,86b,and the second slide members88a,88badvantageously affords significant opportunities for reduced friction in different use case scenarios without necessitating that the lift mechanism60have a complex or bulky design. Thus, the lift mechanism60affords opportunities for reduced cost while ensuring consistent, reliable performance.

As noted above, in some embodiments, opening98a,98bmay be formed in the outer frame members64a,64bin communication with the respective interiors66a,66band with the second rollers84a,84bat least partially extending therethrough. In the representative embodiments illustrated herein, the outer frame members64a,64bgenerally include a tube100a,100b(seeFIGS. 4-7, 14, and 15) and a carrier102a,102b(seeFIGS. 4-7, 12, and 13) mounted to the tube100a,100b.Here, it will be appreciated that a portion of the tube100a,100bmay generally define the opening98a,98b.The carrier102a,102bmay be mounted to the tube100a,100b(e.g., via fasteners; not shown) proximate to the opening98a,98b.The tube100a,100bmay include or otherwise define lateral walls104a,104boperatively attached thereto, arranged adjacent the opening98a,98b(seeFIG. 15) and extending generally vertically towards the litter22. Here, the lateral walls104a,104bsupport a roller shaft105a,105bextending over the opening98a,98band rotatably supporting the second roller84a,84b.In this way, the second roller84a,84bis rotatably coupled to each of the lateral walls104a,104b,extends through the opening98a,98b,and is positioned in rolling contact with the upper exterior surface70a,70bof the inner frame member68a,68b.

As shown inFIG. 14, in some embodiments, covers106a,106bmay releasably attached (e.g., via fasteners; not shown in detail) to the outer frame member64a,64b,and extend over the second rollers84a,84bto create a tortious path for ingress of contaminants towards the inner frame member68a,68band to help prevent damage to the second rollers84a,84band other components of the lift mechanism60. In some embodiments, the covers106a,106bextend over at least a portion of the lateral walls104a,104b.It will be appreciated that the covers106a,106bcould have a number of different shapes, configurations, profiles, and the like, and may be releasably attached to the outer frame members64a,64b(or to other parts of the lift mechanism60, such as the carrier102a,102b) in a number of different ways without departing from the scope of the present disclosure.

As noted above, the second slide members88a,88bare arranged adjacent to the second rollers84a,84b.In the representative embodiment illustrated herein, and as is best depicted inFIGS. 12-13, the second slide members88a,88bmay be formed as separate components from the carriers102a,102b,and may be releasably (or permanently) coupled thereto, such as with fasteners, adhesives, bonding, welding, and the like. In some embodiments, however, the second slide members88a,88bmay be formed as parts of (e.g., formed integrally with) the carriers102a,102b.Other configurations are contemplated.

As shown inFIGS. 12-13 and 15, the second rollers84a,84bmay define a pair of contact surfaces108a,108beach arranged for engagement with the upper exterior surface70a,70bof the inner frame member68a,68bwhich, in the illustrated embodiments, has a generally curved profile. The illustrated contact surfaces108a,108bhave generally frustoconical profiles, but other configurations are contemplated. In some embodiments, the second rollers84a,84balso define respective voids110a,110barranged between the contact surfaces108a,108band shaped to collect contaminants, debris, and the like therein. In the representative embodiments illustrated herein, the second rollers84a,84bhave the contact surfaces108a,108band voids110a,110bdescribed above, while the first rollers82a,82bhave rounded profiles (e.g., rounded wheels). However, other configurations are contemplated, and the first rollers82a,82bcould be provided with contact surfaces108a,108band/or voids110a,100bin some embodiments.

The contact surfaces108a,108bof the second rollers84a,84bare generally skewed relative to one another and converge towards an apex112a,112barranged adjacent to the void110a,110bto direct contaminants towards the apex112a,112band into the void110a,110bas the second rollers84a,84bmove in rolling contact along the upper exterior surfaces70a,70bof the respective inner frame members68a,68b.More specifically, the contact surfaces108a,108bare arranged in a generally V-shaped configuration. As shown inFIG. 13, the V-shaped contact surface is further defined as having a first inwardly sloping region114a,114band a second inwardly sloping region116a,116bseparated by a central grooved portion118a,118bthat defines the void110a,110b.The central grooved portion118a,118bincludes a pair of side portions120a,120bconnected by a back portion122a,122bthat collectively define the void110a,110b.The void110a,110bis designed to allow debris to accumulate in an area that is out of contact with the interface between the second roller84a,84band the corresponding inner frame member68a,68b.It will be appreciated that the debris collecting configuration effected by the second rollers84a,84bpromotes consistent smooth, sliding between the components of the first and second frame assemblies62a,62bas the lift mechanism60moves between the plurality of vertical configurations VC.

Those having ordinary skill in the art will appreciate that the lift mechanism60may move between the plurality of vertical configurations VC in response a caregiver selectively and manually applying force to facilitate operation or adjustment of the lift mechanism60, or components thereof. Additionally, or alternatively, the patient support apparatus20may include one or more actuators124, which may be coupled to any suitable component of the lift mechanism60and may be configured to selectively facilitate movement of the lift mechanism60between the plurality of vertical configurations VC in response to caregiver engagement with one or more user interfaces (not shown in detail). As shown inFIGS. 1 and 3A-7, the illustrated actuator124is realized as a hydraulic linear actuator connected to and extending between actuator brackets126. However, it will be appreciate that other types of actuators124, arranged in other ways, may be utilized in some embodiments without departing from the scope of the present disclosure. For example, the actuator124may be realized with one or more electric motors, pneumatic actuators, or any other suitable actuators124.

In the representative embodiment illustrated inFIG. 1, actuator124generally includes a cylindrical housing (not shown in detail) fastened or otherwise secured to one of the actuator brackets126, with the cylindrical housing supporting a reciprocal rod having a piston located within the cylindrical housing. A distal end of the reciprocal rod is connected by a joint to one of the actuator brackets126. The joint allows pivotal movement about two orthogonally related axes. Extension and retraction of the reciprocal rod facilitates movement of the outer frame members64a,64bof the lift mechanism60about the axis of the reciprocal rod. Similar actuators124are described in U.S. Pat. No. 7,398,571, titled “Ambulance Cot and Hydraulic Elevating Mechanism Therefor,” the disclosure of which is hereby incorporated by reference in its entirety. Furthermore, techniques for utilizing actuators124to manipulate the components of patient support apparatuses20can be similar to those described in United States Patent Application Publication No. US2018/0303689A1, titled “Emergency Cot with Litter Height Adjustment Mechanism,” the disclosure of which is hereby incorporated by reference in its entirety.