Abstract:
A lifting device ( 10 ) includes a base frame ( 12 ), the base frame having associated drive means: a lifting arm ( 44 ) connected at a first end thereof to a frame ( 42 ), the lifting arm being pivotally movable with respect to the frame and being movable between a withdrawn condition and an extended lifting condition; and a lifting cradle being movable between open and engaged positions. The device is suitable for use in the movement of hospital beds and trolleys.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a lifting and transporting device. The device of the invention is useful for lifting and moving, amongst other items, a bed or a trolley. 
   BACKGROUND OF THE INVENTION 
   Whilst a variety of lifting devices are known there are no devices of which the inventor is aware that are specifically adapted for lifting and moving hospital beds. Nevertheless, from time to time there is a need to move around hospital beds and, furthermore for hospital employees to do so in a safe manner that both protects their health, the safety of their co-workers and also protects the bed itself which is generally a valuable item. Similar comments apply in relation to the movement of complex and heavy chairs of the type that are used in hospitals. 
   SUMMARY OF THE INVENTION 
   Therefore, according to the invention there is provided a lifting device characterised by
         a base frame said frame having associated drive means;   a lifting arm connected at a first end thereof to the frame said lifting arm being pivotally movable with respect to the frame and being movable between a withdrawn condition and an extended lifting condition; and   a lifting cradle located at a tree end of said lilting arm, said lifting cradle being  20  movable  20  between open and engaged positions.       

   In a preferred form of the invention the when the lifting arm sin the withdrawn condition the arm is secured within the frame so that the device maintain a low profile as to be useable to move articles from a position close to a ground surface. The device of the invention is thus suitable for maneuvering below relatively low horizontal edges and rails for lifting purposes. 
   Preferably, a hydraulically or electrically power driven actuator is used for effecting movement of the lifting arm between the withdrawn and extended conditions. Thus, the operator is relieved of the need to manually effect a lifting action—which may be beneficial in the base where heavy or repeated lifting operations are to be undertaken. However, it is to be appreciated that the invention may also be embodied in forms where a manually pumped hydraulic lifting system is used. 
   More preferably still the movement of the lifting arm between the withdrawn condition and the extended lifting condition and the movement of the lifting cradle between the open and engaged positions occurs sequentially under the operation of a single actuator. In this way the lifting arm is gradually able to lift and then engage the article to be lifted in a single smooth operation. Such a combined sequential operation can be effected in an arrangement in which the lifting arm moves only a predetermined distance and is stopped by from further movement by vertically applied pressure such that action of the actuator is then concentrated on the cradle and whereby the cradle has at least a portion thereof adapted to rotate in response to movement of the actuator to thereby complete the operation. 
   In a convenient form of the invention the lifting arm is acted on by both a linear actuator and, in an opposing direction by biasing means that serve to moderate the action of the actuator 
   Preferably, the frame includes both positioning wheels mounted thereon for positioning beneath an article to be lifted and drive wheels associated with said drive means. 
   It is convenient that the drive means are operated by two electric motors coupled to reduction gear boxes powered by one or more rechargeable batteries thereby eliminating the need to have any mains power supplied to the device during operation. 

   
     DESCRIPTION OF DRAWINGS 
     The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment in conjunction with the accompanying drawings. In the drawings: 
       FIG. 1  illustrates in perspective view a lifting device in accordance with the present invention; 
       FIG. 2  illustrates an upper perspective view of the lifting device of  FIG. 1 ; 
       FIG. 3  shows a side view of the lifting device of  FIG. 1  in a lowered position; 
       FIG. 4  shows a side view of the lifting device of  FIG. 1  in a partially raised position; and 
       FIG. 5  shows a side view of the lifting device of  FIG. 1  engaging a horizontal bar of a bed. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In the embodiment illustrated in the drawings a bed lifter  10  includes a frame  12  on which are mounted forward and rearward wheels  14  and  16  respectively. The frame  12  is of sufficient width to pass between the corner legs of a single width hospital bed. 
   The frame  12  is constructed of three interconnected portions, namely a front section including a housing  18 , intermediate frame section  20  and a rearward portion of the frame  12  in the form of a rearward extension formed by plates  22 . 
   The housing  18  has an uppermost level surface that sits just below the level of the forward wheels  14 . The forward wheels  14  are drive wheels and also serve to locate the frame  12  beneath a bed to be lifted. The forward wheels  14  are powered by drive means in the form of two motors (not shown) located within the housing  18  between the drive wheels  14 . The rearward wheels  16  are castor located below the frame  12 . 
   Immediately to the rear of the forward housing is the intermediate frame section  20 . The intermediate frame section  20  is considerably narrower in width than the housing  18  and the side plates  22  define a channel in which is supported a linear actuator  24 . The actuator  24  is secured at either side to the side plates  22  by means of pins  26 . The actuator  24  is freely rotatable about the pins  26 . 
   It can be seen from the drawings that the frame  12  forms a relatively low rise open platform that is suited to be positioned below any horizontal cross members on beds and other equipment without producing any mechanical interference with the equipment. Further, the rear of the housing  18  has angled and cut out portions that allow the platform and actuator to attain its lowest position. 
   Behind the actuator  24  is the rearward portion of the frame  12  in the form of a rearward extension of the plates  22  that form a platform  28 . The platform  28  extends the full width of the frame  12  and includes side-walls  30  that serve to locate and position a pair of batteries  32  thereon. The batteries  32  provide power to the motors and are rechargeable batteries thereby eliminating the need to have any mains power supplied to the device during operation. 
   The rearward wheels  16  are positioned beneath the platform  28 . 
   As seen in  FIG. 2 , a handle  34  is positioned at the rear of the frame  12 . The handle  34  is pivotally connected to the frame  12  and, furthermore includes controls therein that operate the motor and the actuator  24 . A control unit  36  is located at the top of the handle  34 . The control unit is operatively connected to both the motors and the actuator  24 . The control unit  36  allows for variable speed control for forward and backward movement of the device  10 . Forward and backward movement is instigated through lever  38  and a brake  40  allows the operator to stop the device quickly in an emergency. Electronic control units are available for purchase and an off the shelf item is readily adapted to suit the needs of the present device. Variable speed indicators and controllers may be incorporated into the control unit together with more sophisticated options such as a battery power gauge to display the availability of power from each battery included in the unit. 
   As can be seen from  FIG. 2  a space is created between the batteries  32 . On inside edges of the batteries  32  an open space therebetween is defined by upstanding brackets  42 . The brackets  42  assist both in locating of the batteries  32  and as a point of attachment for a lifting arm  44 . 
   In the embodiment under consideration the lifting arm  44  takes the form of a pair of vertically spaced bars  46  each pivotally attached to the brackets  42  at uppermost and lowermost points  48  and  50  respectively. The lifting arm  44  extends forwardly over the frame  12  and includes a lifting cradle  52  carried on the end of the arm  44 . The cradle  52  is pivotally attached to each of the bars  46  at uppermost and lowermost pivot connections  54  and  56  respectively. A pair of rear flanges  55  on the lifting cradle  52  serves as points of attachment for the bars  46  through pivot connections  54  and  56 . 
   The bars  46 , the portion of the brackets  42  between the uppermost and lowermost lifting points  48  and  50 , and the lifting cradle  52  together form a pivoting parallelogram arrangement that may be moved around the connection points  48  and  50  from lowered positions as shown in  FIG. 3  to a raised position as shown in  FIGS. 4 and 5 . Further, as previously noted the actuator  24  is a withdrawn condition rests in the intermediate section  20  of the frame  21 . In addition, the rear of the housing  18  has angled and cut out portions that allow the lifting cradle  46  and forward potions of the lifting arm  44  to be lowered so that a lower limb of the cradle is generally level with an upper surface of the housing  18 . 
   The lifting arm  44  is biased into a raised position by a spring  58 . The spring  58  is secured at its base to the rearward portion of the platform  12  and is a snug fit in a collar  60  located on the underside of the lower bar  46  of the lifting arm  44 . 
   The lifting cradle  48  attached to the forward ends of the lifting arm  44  consists of a right-angled bracket adapted to collect and receive a horizontal cross member of a  62  bed or other item to be lifted. The lifting cradle  52  is open to the rear of the device  10  to thus To assist in understanding the invention the cross member  62  is indicated generally in dotted lines without illustration of the remaining portions of the bed. 
   The lower horizontal limb of the lifting cradle  52  is formed in two parts a front section  64  and a rear section  66 . A hinge  68  connects the two sections  64 ,  66  and thus the front section is able to pivot around the hinge  68  towards the rear section  64  as shown in  FIG. 5 . 
   Positioned below the lifting arm  44  and lifting cradle  52  is the actuator  24 . As previously described the actuator  24  is secured in the frame  12  by means of rearward pins  26 . It can also be seen from the drawings that at its forward end the piston  70  of the actuator  24  is connected through attachment plate  72  to the underside of the front section  64  of the lifting cradle  52 . 
   At rest, the actuator  24  assumes a withdrawn position as shown in  FIG. 3 . In the position shown in  FIG. 3  the actuator  24  is pulled into the intermediate frame section  20  of the frame  12 . The lifting arm  44  is drawn downwardly against the action of the spring  58 . As the actuator is operated the piston  70  emerges the spring  58  acts against the lifting arm  44  to thereby raise the level of the lifting arm  44  and lifting cradle  52  towards the horizontal cross member  62 . The coil spring  58  serves to assist in collecting the cross member  62  in the lifting cradle. As the position of the lifting cradle is raised to the cross member  62  and bed end are thereby lifted off the ground and are supported for movement. 
   As has been noted, the downward pressure exerted by the spring  58  moderates the upward movement of the lifting arm  44 . As the lifting arm  44  is raised it comes into contact with the cross member  62 . The cross member  62  creates a resistance to the lifting action counterbalancing the biasing action of the spring  58 . Thus, as the lifting arm  44  attains the position shown in  FIG. 4 , with the lifting cradle slightly elevated with respect to the rear part of the lifting arm  44  further travel by the piston  70  does now affect the lifting arm  44  but begins to act on the lower limb of the lifting cradle  52  and the piston  70  now acts through the front portion  64  of the lifting cradle  52 . Because the position of the lifting arm  44  is fixed the front portion  64  of the lifting cradle is now rotated around the hinge  68  thus embracing the bed cross member  62 . 
   It can therefore be seen that the influence of the spring  58  on the lifting mechanism is such that the lifting cradle  52  is maintained in the open position and only begins to rotate into the engaged position shown in  FIG. 5  when an object resisting the spring action is encountered, that is by the exertion of downward pressure. 
   Operation of the device  10  is controlled through the control panel  36  on the handle  34 . The operator thus drives the device  10  to a position where the front wheels  14  are positioned below a bed cross-member  62 . The lifting device  10  is especially suitable for moving devices having castor wheels at the opposite end to the lifted end of the bed as is the case with most hospital beds. However, it is noted that the device  10  is also suitable for operation with object having fixed axle wheels at the lifted end. 
   The low level frame  12  is able to fit neatly below the cross member  62  and the actuator  24  activated. The lifting arm  44  rises under the combined influence of the spring  58  and actuator  24  as described and the lifting cradle  52  collects the bed cross member  62  therein. At the point where the lifting arm reaches the cross member  62  the piston action then continues and, as described rotates the front part  64  of the cradle  46  around the hinge  68  to engage the cross member. The lifting device  10  now supports the weight of the bed at one end and the bed can be moved by operation from the control unit  36 . The front wheels  14  principally take the load of the bed. Thus, the rear castor wheels  16  are relatively free and can swivel allowing controlled movement of the bed even in confined spaces. The two powered driven wheels are independently powered to effect steering of the machine and bed combination. Castor wheels at the opposite end of the bed carry the remaining weight of the bed. 
   The invention has been described by way of example. The examples are not, however, to be taken as limiting the scope of the invention in any way. Modifications and variations of the invention such as would be apparent to a skilled addressee are deemed to be within the scope of the invention.