Access ladder assembly for a movable machine

An access ladder assembly for a machine includes a fixed section, a movable section, a biasing member, a locking member, and a release assembly. The fixed section includes a pair of guide members and a fixed step. The movable section is mounted on and is movable along the fixed section between extended and retracted positions. The movable section includes a pair of sidewalls, and at least one horizontal step and is biased towards the retracted position by the biasing member. The locking member locks the movable member at the extended position. The release assembly operates to release the locking member. A manually engagable actuator of the release assembly may be disposed adjacent the fixed step. The movable section may include rails that slide within a hollow portions of the guide members as the movable section moves between the extended and retracted positions.

TECHNICAL FIELD

This disclosure relates generally to ladder assembly and, more particularly, to a retractable ladder system for assisting in the ingress to and egress from a movable machine.

BACKGROUND

Machines such as cold planers or rotary mixers, may be used to remove an upper layer of material from a ground surface such as a roadway. Such machines may be configured with a rotary milling drum that engages the ground surface during a material cutting or milling operation. In order to adjust the cutting or milling depth, the machines may include hydraulic cylinders that adjust the elevation or height of the machine, including the milling drum, relative to the ground surface.

The machines also typically include an operator station together with a ladder to facilitate the ingress and egress from the operator station. In some instances, the minimum distance from the ground surface to the first or lower step of the ladder may be set or specified by governmental regulations. In other instances, the minimum distance from the ground surface to the first or lower step of the ladder may be set or specified by customer requirements. If the lower step or another component of the ladder is too close to the ground, the ladder or an object on the ground may be damaged if the machine is lowered to begin a material removing operation without raising the ladder or a lower portion thereof.

U.S. Patent Publication No. 2001/003008 discloses a ladder unit for climbing up and down a construction machine. The ladder unit includes a guide mounted on a body frame and the ladder is longitudinally slidable on the guide between a storage position and a decent position. A locking mechanism prevents the decent of the ladder and can be activated from a location on a catwalk. A balance weight is provided to return the ladder to the storage position.

The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.

SUMMARY

In one aspect, an access ladder assembly for a machine includes a fixed section, a movable section, a biasing member, a locking member, and a release assembly. The fixed section includes a pair of spaced apart, parallel guide members and a horizontal fixed step. The movable section is mounted on the fixed section and is movable along the fixed section and includes a path between an extended position and a retracted position. The movable section includes an engagement surface, a pair of spaced apart sidewalls, and at least one horizontal step extending therebetween. The biasing member is configured to bias the movable section towards the retracted position. The locking member is movable between a locked position and an unlocked position, wherein at the locked position, the locking member extends into the path of the movable section and engages the engagement surface of the movable section to prevent movement of the movable section from the extended position to the retracted position, and at the unlocked position, the locking member is spaced from the path of the movable section. The release assembly is operatively associated with the locking member and includes a manually engagable actuator disposed adjacent the fixed step of the fixed section. The manually engagable actuator is movable between a first position and a second position, wherein at the second position, the locking member is moved to the unlocked position.

In another aspect, an access ladder assembly for a machine includes a fixed section, a movable section, a biasing member, a locking member, and a release assembly. The fixed section includes a pair of spaced apart parallel guide members with the guide members having a hollow portion and a horizontal fixed step. The movable section is mounted on the fixed section and is movable along the fixed section and includes a path between an extended position and a retracted position. The movable section includes a pair of spaced apart sidewalls and at least one step extends therebetween. The movable section further includes a pair of follower members, with each of the follower members configured to slidably move within the hollow portion of one of the guide members as the movable section moves between the extended position and the retracted position. The biasing member is configured to bias the movable section towards the retracted position. The locking member is movable between a locked position and an unlocked position, wherein at the locked position, the locking member is configured to prevent movement of the movable section from the extended position to the retracted position, and at the unlocked position, the movable section is movable from the retracted position to the extended position. The release assembly is operatively associated with the locking member and is movable between a locked position and a released position, wherein upon moving the release assembly to the released position, the locking member is moved to the unlocked position.

In still another aspect, a machine includes a frame, a prime mover mounted on the frame, a ground-engaging drive mechanism operatively connected to the prime mover, an operator station, an elevation control mechanism to adjust a height of the machine relative to a ground surface, and an access ladder assembly for providing access to the operator station. The access ladder assembly includes a fixed section, a movable section, a biasing member, a locking member, and a release assembly. The fixed section includes a pair of spaced apart, parallel guide members and a horizontal fixed step. The movable section is mounted on the fixed section and is movable along the fixed section and includes a path between an extended position and a retracted position. The movable section includes an engagement surface, a pair of spaced apart sidewalls, and at least one horizontal step extending therebetween. The biasing member is configured to bias the movable section towards the retracted position. The locking member is movable between a locked position and an unlocked position, wherein at the locked position, the locking member extends into the path of the movable section and engages the engagement surface of the movable section to prevent movement of the movable section from the extended position to the retracted position, and at the unlocked position, the locking member is spaced from the path of the movable section. The release assembly is operatively associated with the locking member and includes a manually engagable actuator disposed adjacent the fixed step of the fixed section. The manually engagable actuator is movable between a first position and a second position, wherein at the second position, the locking member is moved to the unlocked position.

DETAILED DESCRIPTION

A machine10, such as a cold planer, is illustrated inFIG. 1and includes a frame12(FIG. 2) and a prime mover13such as an engine. A plurality of ground-engaging drive mechanisms such as tracks14are configured to engage a ground surface140below the machine10and may be driven by the prime mover13to propel the machine10along the ground surface. The machine10may include a plurality of elevation control mechanisms15, such as hydraulic cylinders, to adjust the height of the machine relative to the ground surface140. Although machine10is shown in a “track-type” configuration, other configurations, such as a wheeled configuration, may be used.

Machine10may include a milling system, generally indicated at16, configured to cut or grind a top layer of the ground surface140. The milling system16, may include a milling drum or roller (not shown) and a conveyor system17. The milling drum may be rotatably supported on the frame12and is configured for power rotation relative thereto during operation. The milling drum may have a generally cylindrical shape and includes a plurality of cutting elements or bits (not shown) that are disposed along an outer surface of the milling drum and are configured to contact the ground surface140to perform a milling operation. The cutting depth of a milling operation may be adjusted by controlling the movement of the elevation control mechanisms15.

The milling drum (not shown) may be enclosed within a shield or shroud structure18. The position of the shroud structure18relative to the ground surface140may be movable or adjustable through the use of control members19such as hydraulic cylinders. The conveyor system17may be operatively associated with the milling drum to transport or convey cut or milled material removed from the ground surface140to a suitable machine such as a haul truck (not shown) spaced from the machine10.

Machine10may include an operator station20that an operator may physically occupy and provide input to control the machine. Operator station20may include one or more input devices (not shown) through which the operator may issue commands to control the propulsion system and steering system of the machine as well as operate various implements associated with the machine10such as the milling system16.

In order to facilitate access to the operator station20, an access ladder assembly25may be provided adjacent the operator station. In the depicted embodiment, the access ladder assembly25is located adjacent a rear end21of the machine10and is mounted to a portion of the frame12(FIG. 2). As depicted, the access ladder assembly25may be aligned with one or more additional steps22and the machine10may further include hand rails23to facilitate the ingress and egress from the operator station20.

Referring toFIGS. 3-7, the access ladder assembly25is illustrated in greater detail in a deployed or extended position at which an operator may readily step from the ground surface140onto the ladder assembly or from the ladder assembly onto the ground surface. Access ladder assembly25may include an upper or fixed section26, a lower or movable section60, a release assembly100, and one or more biasing members130.

The fixed section26may include a pair of spaced apart, vertical guide members27that are generally parallel. The guide members27may be elongated hollow or tube-like members having a lower end28and an upper end29. The guide members27may have a generally rectangular cross-section and an outer surface defined by an inward facing surface30, an outward facing surface31, a forward facing surface32, and a rearward facing surface33. As used herein, the phrase “inward facing” and the word “inwardly” refer to facing towards an a vertical axis extending through the center of the access ladder assembly25, the phrase the phrase “outward facing” refers to facing away from the vertical axis extending through the center of the access ladder assembly, the phrase “forward facing” refers to facing towards the front of the machine10, and the phrase “rearward facing” refers to facing towards the rear of the machine. In addition, each guide member27may include an elongated slot35extending from the lower end28of the guide member partway towards the upper end29of the guide member along the inward facing surface30of the guide member. In the depicted embodiment, the elongated slots35extend to a location, generally depicted at36, spaced from the upper end29of the guide members27about one third of the length of the guide members.

A horizontal fixed step40may extend between the guide members27generally adjacent the upper end36of the elongated slots35. As depicted, each end41of the horizontal fixed step40may be U-shaped and dimensioned to receive a portion of one of the guide members27between the legs of the U-shape. The horizontal fixed step40may be secured to the guide members27in any desired manner. In one embodiment, the guide members27and the horizontal fixed step40may be welded together.

A U-shaped foot well43may also extend between the guide members27. The foot well43may be secured to the guide members27along the forward facing surface32of the guide members. The foot well43may be secured to the guide members27and any desired manner. In one embodiment, the guide members27and the foot well43may be welded together.

A mounting flange44may be secured to the upper and29of each guide member27to facilitate securing the access ladder assembly25to the frame12of the machine10. As depicted, the mounting flange is 44 are planar and include an aperture45through which a fastener150, such as a bolt, may extend to secure the access ladder assembly25to the frame12.

Each guide member27may include a first or outward facing biasing member or spring mounting hole or bore47(FIG. 7) adjacent the lower end28and that extends through the outward facing surface31of the guide member and a second or inward facing biasing member or spring mounting hole or bore48that extends through the inward facing surface30and is aligned with the outward facing bore. As described in more detail below, each pair of bores defined by an outward facing spring mounting bore47and an inward facing spring mounting bore48may be configured to receive a fastener151, such as a bolt, that supports the upper end132of biasing member130.

Each guide member27may further include a first or forward facing travel limiting hole or bore50adjacent the upper end29and that extends through the forward facing surface32of the guide member and a second or rearward facing travel limiting hole or bore51that extends through the rearward facing surface33and is aligned with the forward facing hole. As described in more detail below, each pair of bores defined by a forward facing travel limiting bore50and rearward facing travel limiting bore51may be configured to receive a fastener152, such as a bolt, that functions as a travel limiting stop member.

One of the guide members27may include mounting components for facilitating the mounting and operation of the release assembly100and locking assembly120as described in further detail below. The guide member having the mounting components may be identified herein as27′ to distinguish it from the other guide member when referring to an aspect of the guide member that is unique to the inclusion of the additional components. More specifically, guide member27′ may include an L-shaped bracket55having a horizontal bore56extending through the cantilevered leg of the bracket. In embodiments, the L-shaped bracket55may be positioned adjacent the location at which the horizontal fixed step40is secured to the guide member27′. In one embodiment, the L-shaped bracket55may be positioned slightly above the location at which the horizontal fixed step40is secured to the guide member27′. The bracket55may be secured to the guide member27′ in any desired manner. In one embodiment, the bracket55may be welded to the guide member27′. A cylindrical lock mounting member57may be mounted on and extend into the guide member27′ at a location spaced from and vertically aligned with the bracket55. The inner surface58of the cylindrical lock mounting member57may have threads along a portion thereof. The cylindrical lock mounting member57may be secured to the guide member27′ in any desired manner. In one embodiment, the tubular guide member may be welded to the guide member27′.

The movable section60may include a pair of generally parallel, spaced apart, vertical members or rails61and a step section77. The rails61may be elongated hollow or tube-like members with a lower end62and an upper end63. The rails61may have a generally rectangular cross-section configured to be slidably received within a hollow portion of the guide members27of the fixed section26. In an embodiment, the guide members27and rails61may be dimensioned so that the configuration of the rails generally matches the configuration of the guide members and permits the rails to act as follower members that are guided by and slide within the guide members. As depicted, the rails61have a generally rectangular cross-section and an outer surface defined by an inward facing surface65, an outward facing surface66, a forward facing surface67, and a rearward facing surface68, corresponding to the inward facing surface30, the outward facing surface31, the forward facing surface32, and the rearward facing surface33of the aligned guide member27.

A resilient bumper69may be disposed adjacent the lower end62of each rail61. In an embodiment, the resilient bumper69may be formed of an elastomeric material.

Each rail61may include a first or outward facing biasing member or spring mounting aperture or slot70adjacent the upper end63and that extends through the outward facing surface66of the rail and a second or inward facing biasing member or spring mounting aperture or slot71that extends through the inward facing surface65and is aligned with the outward facing slot. As described in more detail below, each pair of slots defined by an outward facing spring mounting slot70and an inward facing spring mounting slot71may be configured to receive an element, such as a spring mounting projection88, that engages the lower end131of biasing member130.

A vertically elongated mounting bracket75may extend inwardly from the inward facing surface65of each rail61. The mounting brackets75may include mounting holes or bores76to receive fasteners153, such as bolts, to secure the rails61to the step section77as described in more detail below. Each mounting bracket75may have a thickness configured to permit the bracket to slide within and be guided by a slot35along the inward facing surface30of a guide member27. The mounting bracket75may be secured to the rail61in any desired manner. In one embodiment, the mounting bracket75may be welded to the rail61.

The step section77may include a pair of spaced apart vertical sidewalls78with each having a lower end79and an upper end80to define a generally rectangular structure. A horizontal lower step81extends between and is secured to the sidewalls78adjacent the lower end79of the vertical sidewalls78. The horizontal lower step81may be secured to the sidewalls78in any desired manner. In one embodiment, the horizontal lower step81may be secured to the sidewalls78with fasteners154such as bolts.

A bracket82extends upward from each sidewall78. Each bracket82includes an inwardly facing surface83and an outwardly facing surface84. Each bracket82may include a lower vertical section85secured to the upper end80of each sidewall78and an outwardly angled upper section86that extends upward from the vertical section85. A flange87may extend perpendicularly from the outwardly facing surface84of each bracket82and includes a pair of mounting holes or bores (not shown) through which fasteners153, such as bolts, may extend to secure the step section77to the rails61during assembly. The flange87may further include a biasing member or spring mounting projection88that extends in a cantilevered manner outward or away from the outwardly facing surface84. The lower surface90of the spring mounting projection88may include an angled notch91in which the loop133at the lower end131of biasing member130may be disposed.

The brackets82may be secured to the sidewalls78in any desired manner. In one embodiment, the brackets82may be secured to the sidewalls78with fasteners155such as bolts. Flanges87may be secured to the brackets82in any desired manner. In one embodiment, the flanges87may be welded to the brackets82.

An horizontal upper step95extends between and is secured to the inwardly facing surfaces83of the brackets82along the vertical section85of each bracket. The horizontal upper step95may be secured to the brackets82in any desired manner. In one embodiment, the horizontal upper step95may be secured to the brackets82with fasteners156such as bolts.

Release assembly100may include a release lever101and a clevis assembly110. The release lever101may be generally elongated and includes a lower end102and an upper end103. A vertical slot104extends along the release lever101adjacent the lower end102and is oriented generally along the axis of the lever. A hole or bore105may be disposed generally centrally between the lower end102and the upper end103and functions as the mounting and pivot point for the release lever101upon mounting the release lever on the guide member27′ and permits movement of the release lever between a first or locked position (FIGS. 5-6) and second or released position (FIGS. 8, 10).

A manually engagable actuator such as a pedal106may be disposed or located adjacent the upper end103of the release lever101. As depicted, the pedal106is generally planar and configured to be actuated or depressed by engagement with a foot of an operator. In embodiments, the release lever101may be configured so that the pedal106is disposed adjacent the horizontal fixed step40to permit an operator to press the pedal when standing on the horizontal fixed step. As depicted, the pedal106is positioned above or slightly above the horizontal fixed step40.

The clevis assembly110may include a clevis111having a pair of spaced apart legs112interconnected by a bight113. Each leg112may include a hole or bore114. When assembled, the lower end102of the release lever101is positioned within the space115between the legs112with the bores114aligned with the slot104in the lower end of the release lever. A clevis pin116may be inserted through the slot104and bores114and secured to the clevis111.

A locking assembly120may be mounted within the cylindrical lock mounting member57and is configured to lock the movable section60in the downward or extended position. The locking assembly120may be generally cylindrical and have an outer housing121and a locking member122within and movable relative to the outer housing. The outer surface123of the outer housing121may include threads configured to be threadingly received within the threaded inner surface58of the cylindrical lock mounting member57to secure the locking assembly therein120. As a result, the locking member122may slide relative to the outer housing121and the cylindrical lock mounting member57between a locked position (FIGS. 5-6) and an unlocked position (FIGS. 8, 10). A lock biasing member indicated generally at125, such as a spring, may be disposed between the outer housing121and the locking member122to bias the locking pin towards a locked position and into the guide member27as depicted inFIG. 6.

The locking member122may be secured to the bight113of the clevis111to facilitate movement of the locking member. In one embodiment, the locking member122may be secured to the bight113through a fastener157such as a bolt. Other manners of securing the locking member122to the clevis111are contemplated.

The release lever101may be mounted to the L-shaped bracket55on one of the guide members27of the fixed section26with a fastener158, such as a bolt, that extends through both the bore56in the bracket and the bore105in the release lever. Through such a configuration, the release lever101is movable or pivotable between a first or locked position (FIGS. 5-6) and second or released position (FIGS. 8, 10). At the locked position, the locking member122extends through the guide member27at the rearward facing surface33into the path of the rail61. The engagement between the clevis111and the locking member122together with the functionality of the lock biasing member125biases the release assembly100towards the locked position.

As depicted, the access ladder assembly25includes two biasing members130with one being associated with each pair of guide member27and rails61. The biasing members130may be configured as extension springs with a lower end131and an upper end132. Each biasing member130may include a hook or loop133at each end. As may be seen inFIGS. 6-7, each biasing member130may extend through an aligned hollow portion of a guide member27and an aligned portion of a rail61which defines a follower hollow portion and slides through the guide member. The biasing members130operate to bias or pull the movable section60towards the fixed section26. Other forms and other numbers of biasing members or elements are contemplated. The biasing members130may be configured to provide a sufficient force to pull the movable section60upward upon unlocking the locking assembly120while permitting the movable section to move downward in a controller manner upon an operator stepping on the horizontal upper step95with the locking member122in an unlocked position.

Each of the components of the fixed section26, the movable section60, the release assembly100, the locking assembly120, and the biasing members130may be formed of any desired material. In one embodiment, each of the components may be made of steel. Each of the horizontal steps40,81,95may have any desired shape. As depicted, each of the horizontal steps40,81,95may be generally tubular with a generally flat upper surface and shoe engagement projections96, if desired.

To assemble the access ladder assembly25, the fixed section26may be assembled in the form depicted inFIG. 7but without the fasteners152that function as travel limiting stop members mounted in the forward facing travel limiting bores50and the rearward facing travel limiting bores51. In addition, the fasteners150that extends through the apertures45in the mounting flanges44are also excluded from the assembly.

The step section77of the movable section60may also be assembled in the form depicted inFIG. 7but without installing the fasteners153that are used to secure the step section to the rails61.

The upper end132of a biasing member130may be inserted into each of the guide members27from the lower end28. The loop133at the upper end132of the biasing member130may be aligned with the outward facing spring mounting bore47and the inward facing spring mounting bore48and a fastener151extended through the loop and the bores.

Tension may be applied to the loop133at the lower end131of each biasing member130to extend the biasing member so that the lower loop extends out of the lower end28of the guide member27. The lower end131of a biasing member130may be inserted into each of the rails61through the upper end63until the loop133at the lower end131is aligned with the outward facing spring mounting slot70and the inward facing spring mounting slot71of one of the rails. The step section77may then be positioned so that the spring mounting projection88on each side thereof extends through the loop133at the lower end131of biasing member130, the outward facing spring mounting slot70, and the inward facing spring mounting slot71. The step section77may be secured to the rails61with fasteners153.

The rails61may be inserted into the lower end28of the guide members27with the mounting brackets aligned with and extending into the slots35of the guide members. A fastener152may be inserted into each pair of forward facing travel limiting bores50and rearward facing travel limiting bore51to secure the rails61within the guide members27and thus secure the movable section60to the fixed section26.

Release assembly100and locking assembly120may be mounted on guide member27′ by threadingly inserting the locking assembly120into the cylindrical lock mounting member57. The clevis111of the release assembly100may be secured to the locking member122with a fastener157. The bore105of the release lever101may be aligned with the bore56in the L-shaped bracket55and a fastener158inserted through the two bores to secure the release lever to the guide member27′. The release lever101may then be pivoted so that the slot104at the lower end102of the release lever is aligned with the bores114in the clevis111. The clevis pin116may be inserted through the slot and the bores and the clevis pin secured to the clevis111.

Other manners and sequences of assembling the access ladder assembly25are contemplated.

INDUSTRIAL APPLICABILITY

The industrial applicability of the access ladder assembly25described herein will be readily appreciated from the forgoing discussion. The foregoing discussion is applicable to machines that utilize an access ladder assembly at a work site. Such machines may be used at a roadwork site, a mining site, a landfill, a quarry, a construction site, a forest, a farm, or any other area in machines are used that include access ladder assemblies to assist in climbing onto and off of the machines.

In one embodiment, the access ladder assembly25may be used with a machine10such as a cold planer, a rotary mixer, or any other machine in which an upper layer of material is removed from a ground surface140such as a roadway. To perform a material cutting or milling operation with a cold planer, the frame12of the machine10, and thus the components thereon, maybe lowered to set the cutting or milling depth. The access ladder assembly25described herein readily facilitates movement of the ladder assembly between a retracted position and an extended position, and between an extended position and a retracted position.

The access ladder assembly25is depicted in its extended position or configuration inFIGS. 3-6. At such position, the movable section60and the biasing members130are in their extended position with the rails61disposed at their lowermost position within the interior of the guide members27. In an embodiment, the distance between the horizontal fixed step40and the horizontal upper step95may be approximately equal to the distance between the horizontal lower step81and the horizontal upper step.

The release assembly100is at its locked position with the locking member122of locking assembly120extending into the guide member27and blocking the path of the rail61. The upward force exerted by the biasing members130forces the rails61upward so that the upper surface of the rail within guide member27′ operates as an engagement surface and engages the locking member122and prevents upward movement of the rails61, and thus prevents upward movement of the movable section60.

To move the access ladder assembly from the extended position to the retracted position, an operator may depress or engage the pedal106to move the pedal towards the rearward facing surface33of the guide member27as depicted inFIG. 8. Such movement of the pedal106towards the rearward facing surface33will cause the release lever101to rotate or pivot about fastener158and thus move the lower end102of the release lever away from the rearward facing surface of the guide member27. The connection between the slot104in the release lever101, the clevis assembly110and the locking member122will cause the locking member to retract into the outer housing121of the locking assembly120and thus remove the locking member from the path of the rail61. The force provided by the biasing members130will then cause the movable section60to slide upward relative to the fixed section26. The movable section60may move upward until reaching its retracted position as depicted inFIG. 10.

In the retracted position, the movable section60and biasing members130are at their retracted positions with the rails61disposed at their uppermost position within the interior of the guide members27. In an embodiment, the distance between the horizontal fixed step40and the horizontal upper step95is less than the distance between the horizontal lower step81and the horizontal upper step.

The release assembly100is in its unlocked position with the locking member122of locking assembly120engaging and being biased against the rearward facing surface68of the adjacent rails61. Since the rearward facing surface68is flat, the only significant force preventing movement of the movable section60downward relative to the fixed section26is that provided by the biasing members130.

Accordingly, to move the access ladder assembly25from the retracted position to the extended position, an operator is merely required to step onto the horizontal upper step95and the weight of the operator will cause the movable section60to move downward relative to the fixed section26. In doing so, the rails61will slide downward within the inside of the guide members27until the resilient bumpers69engage the fasteners152that function as a travel limiting stop member. As the rails61slide downward within the guide members27, the locking member122will slide along the rearward facing surface68of one of the rails61. As the movable section60approaches or reaches its lower end of travel position, the upper end63of the rail61will be below the locking member122. The lock biasing member125of the locking assembly120will force the locking member out of the outer housing121and towards the forward facing surface67as best seen inFIG. 6. The locking member122will thus move from its unlocked position at which the end of the pin engages the rearward facing surface68of the rail to its locked position at which the end of the pin extends over or into the path of the rail61adjacent the rearward facing surface. Thus, the locking member122of the locking assembly120locks the movable section60in place and prevents its movement upward.

It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. For example, although the access ladder assembly25is depicted with a horizontal fixed step40extending between and mounted to a pair of spaced apart guide members27, the horizontal fixed step may not extend between and/or be mounted to the guide members.

In another example, the release assembly100may be configured with the pedal106positioned at a different location. For example, the release lever101could be longer so that the pedal106is adjacent the additional step22, between the additional step and the horizontal fixed step40, or at another location. Further, the release lever101may be longer and include an actuator positioned adjacent a hand rail23. Still further, the rails61and locking assembly120may be configured so that the locking member122is lockingly received within a locking aperture in the rearward facing surface68of the rail. In still another embodiment, the rails61and the sidewalls78may not be separate components but rather a unitary member that slides within the guide members27and supports the horizontal lower step81and the horizontal upper step95.