Abstract:
The invention relates to a ladder assembly for equipment, the ladder assembly comprising a ladder pivotally mounted to a mount; an actuation mechanism that includes a drive that engages a rotational actuator, the rotational actuator operatively connected to the ladder; wherein the drive causes rotation of the rotational actuator causing the ladder to pivot about the mount.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a ladder assembly for equipment. In particular, the invention relates to a ladder assembly for a bulldozer and therefore will be described in this context. However, it should be appreciated that ladder assembly may be used for any earthmoving equipment and vehicles such as dozers, graders, scrapers, loaders, trucks, excavators, compactors, rollers, tracked drilling units, draglines and other vehicles and units of a similar type. 
       BACKGROUND OF THE INVENTION 
       [0002]    Earthmoving vehicles such as bulldozers, scrapers, graders and the like equipment are an integral part of many operations such as mines and quarries. Most earthmoving equipment that is used in mines and quarries is relatively large. Therefore an operator cannot safely enter a cabin of the earthmoving equipment by simply climbing over the earthmoving equipment. Accordingly, a ladder is usually required to gain access to the earthmoving equipment. 
         [0003]    Most earthmoving equipment includes a fixed ladder which provides access to the cabin. Unfortunately this fixed ladder often provides a hindrance to operation of the earthmoving equipment. The ladder can obstruct the view of an operator to parts of the earthmoving equipment. Although the earthmoving equipment is large, precision operation of the earthmoving equipment is often required and an obstructed view makes precision operation difficult. 
         [0004]    Further, the fixed ladder can easily be destroyed during normal use of the earthmoving equipment. In quarries and mines, there is often a lack of space to maneuver the earthmoving equipment. Accordingly, a fixed ladder can easily become squashed between the earthmoving equipment and a fixed object such as a rock wall. This requires a replacement ladder at a substantial cost. However, the cost of having the earthmoving equipment which is not in operation is often even higher than the replacement cost of the ladder. 
         [0005]    In order to address the above issues, various pivotally movable ladders have mounted to earthmoving vehicles. The ladder is typically connected to a hydraulic ram which moves the ladder from a deployment position in which an operator can utilize the ladder to access the cabin of the earthmoving equipment to a storage position in which the ladder is stored while the early moving equipment is being operated. 
         [0006]    Although many of the ladders provide excellent access for an operator to the cabin of the earthmoving equipment, when ladder is in the deployed position, many of the ladders still are a hindrance to operation of the earthmoving equipment when located in the storage position. That is, the ladders still obstruct an operator&#39;s view and can be easily broken during operation of the earthmoving equipment. 
         [0007]    The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. 
       OBJECT OF THE INVENTION 
       [0008]    It is an object of the invention to overcome or alleviate one or more of the disclosures or provide the consumer with the useful or commercial choice. 
       SUMMARY OF THE INVENTION 
       [0009]    In one form, although not necessary the only or broadest form, the invention relates to a ladder assembly for equipment, the ladder assembly comprising: 
         [0010]    a ladder pivotally mounted to a mount: 
         [0011]    an actuation mechanism that includes a drive that engages a rotational actuator, the rotational actuator operatively connected to the ladder; 
         [0012]    wherein the drive causes rotation of the rotational actuator causing the ladder to pivot about the mount. 
         [0013]    Preferably the drive is in the form of a linear actuator. The linear actuator may include a ram. The ram may be a pneumatic or hydraulic ram. The liner actuator may further include a rack which is attached to the ram. 
         [0014]    The rotational actuator may be attached directly to the ladder. The rotational actuator may include a shaft. The shaft is normally able to be rotated. The rotation of the shaft is typically caused by movement of the linear actuator. 
         [0015]    The shaft is typically attached to a rotational member. Preferably, the rotation member is usually directly attached the linear actuator. The rotation member may be of any form such as a lever, pulley or gear, cog and pinion. The shaft may also be directly attached to the ladder. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    An embodiment of the invention, by way of example only, will now be described with reference to the accompanying figures in which: 
           [0017]      FIG. 1  is a perspective view of an bulldozer having an attached ladder assembly in a deployment position according to an embodiment of the invention; 
           [0018]      FIG. 2  is a perspective view of the ladder assembly in a deployment position as shown in  FIG. 1 ; 
           [0019]      FIG. 3  is a perspective view of an bulldozer having an attached ladder assembly in a storage position according to an embodiment of the invention; and 
           [0020]      FIG. 4  is a perspective view of an bulldozer having an attached ladder assembly in a storage position as shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]      FIGS. 1 to 4  show a ladder assembly  100  mounted to a bulldozer  10  that able to be used to allow an operator to enter cabin of the bulldozer  10  as well as operate the bulldozer  10  without physical or visual impediment. The ladder assembly  100  includes a ladder  300 , a pair of handrail mounts  200 , an actuation mechanism  400  and a ladder support  500 . 
         [0022]    The handrail mounts  200  are used to pivotally mount the ladder  300 . They are also used to assist an operator when climbing up or down the ladder  300 . The handrail mounts  200  are connected to a platform  210  using fasteners  211 . One of the handrails  200  is located in front of the other of the handrails  200 . Each handrail mount  200  is formed from a base  220 , an upwardly extending column  230  and two handrails  240 . 
         [0023]    The ladder  300  is used to enable a person to gain access to and from the bulldozer  10 . The ladder  300  includes spaced apart stiles  310  which are interconnected with a series of steps  311 . Railings  312  are mounted to each of the stiles. The ladder  300  is mounted adjacent the platform  210  using the handrail mounts  200 . The ladder is pivotally mounted to one of the handrail mounts  200  via a pivot pin  320 . 
         [0024]    The ladder  300  is split into a first ladder section  330  and a second ladder section  340 . The first ladder section  330  is pivotally movable with respect to the second ladder section  340  using section hinges  360 . A ladder actuator  350 , in the form of a ladder pneumatic ram  351 , is connected to both the first ladder section  330  and the second ladder section  340 . The operation of the ladder actuator  350  rotates the second ladder section  340  with respect to the first ladder section  330 . 
         [0025]    The actuation mechanism  400  is used to rotate the ladder  300  between a deployment position and a storage position. The actuation mechanism includes a linear actuator  410  and a rotary actuator  420 . The linear actuator  410  formed from an actuation pneumatic ram  411  that is attached to a rack  412 . The pneumatic ram is attached to a handrail mount  300 . The rack  412  is movable within a guide (not shown). 
         [0026]    The rotary actuator  420  is formed from a pinion  412  which is connected to a shaft  422 . The pinion  421  is positioned so that pinion  421  meshes with the rack of the linear actuator. The shaft  422  is fixed to a stile  310  and the ladder  300 . An axis of the shaft  422  is in alignment with an axis of the pivot pin  320  to enable the ladder to be pivotally movable. A housing  423  is used to mount the shaft via bearings (not shown). The housing  423  is fastened to a handrail mount  300  and platform  210 . 
         [0027]    The ladder support  500  is mounted to a top of the bulldozer  10 . The ladder support includes an attachment portion  510  which is used to attach the ladder support to the roof of a bull dozer and a support arm  520  which is used to support the ladder  300  when the ladder assembly  100  is in the storage position. Two alignment members  530  are located on the support arm  520  to align, position and hold the ladder  300  during operation of the bulldozer  10 . 
         [0028]    In use the ladder assembly  100  is movable between a deployment position, as shown in  FIGS. 1 and 2 , and a storage position, as shown in  FIGS. 3 and 4 . The deployment position allows an operator to move to and from the bulldozer using the ladder  300 . The storage position allows the operation of the bulldozer with impediment of the ladder  300 . 
         [0029]    In order to move the ladder assembly  100  from the deployment position to the storage position, a pilot valve (not shown) must be activated. This is normally activated by releasing of a handbrake of the bulldozer. However, it would be appreciated by a person skilled in the art that the pilot valve may be activated using some other activation source such as the ignition of the bulldozer 
         [0030]    Once the pilot valve is activated, air is supplied to the ladder pneumatic ram  351  and the actuation pneumatic ram  411 . The ladder pneumatic ram  351  causes the second ladder section  330  to rotate with respect to the first ladder section  330  inclining the second ladder section  340  with respect to the first ladder section  330 . 
         [0031]    The actuation pneumatic ram  411  extends moving the rack  412  downwardly with respect to the handrail mounts  200 . This causes the rack  412  to rotate the pinion  412  which in turn causes rotation of the shaft  422 . As the ladder  300  is pivotally mounted by the shaft  422  and the pivot pin  320 , the ladder  300  is caused to rotate with respect to the handrail mounts  200 . The ladder  300  is rotated until the second ladder section  340  engages with the alignment members  530  located on the support arm  520  of the ladder support  510 . 
         [0032]    In order to move the ladder  300  from the deployment position to the storage position, the handbrake is engaged to activate the pilot valve. This causes air to be supplied to the ladder pneumatic ram  351  and the actuation pneumatic ram  411 . The ladder pneumatic ram  351  causes the second ladder section  330  to rotate with respect to the first ladder section  330  straightening the second ladder section  340  with respect to the first ladder section  330 . 
         [0033]    The actuation pneumatic ram  411  extends moving the rack  412  upwardly with respect to the handrail mounts  200 . This causes the rack  412  to rotate the pinion  421  which in turn causes rotation of the shaft  422 . As the ladder  300  is pivotally mounted by the shaft  422  and the pivot pin  320 , the ladder  300  is caused to rotate with respect to the handrail mounts  200 . The ladder  300  is rotated until the second ladder section  340  engages with the ground. 
         [0034]    It should be appreciated that timing of the activation of the ladder pneumatic ram and the actuation pneumatic ram may be varied according to design. 
         [0035]    The ladder assembly  100  provides a straightforward yet effective way in which an operator can gain access to the equipment yet the ladder assembly does not inhibit use of the equipment. This is largely due to the fact that the ladder can be rotated through a large range of motion that is not provided by prior art ladders that are connected soles to a ram. 
         [0036]    In this Specification, the terms “comprise”, “comprises”, “comprising” or similar terms are intended to mean a non-exclusive inclusion, such that a system, method or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed. 
         [0037]    It will also be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.