Abstract:
A carriage for transport of a load, for example a load pallet, along a rail pair in a so-called deep racking store, has a carrier arrangement which, in a deactivated transport position, passes under a load resting on the rail pair. The carrier arrangement is disposed, in an activated lifting position, to carry the load from beneath so that it is free of the rail pair. The carriage has a supporting frame or chassis provided with at least four wheels. The carrier arrangement is rigidly connected to the frame or chassis and each wheel is journalled in an associated arm. The arm is pivotally journalled in the frame so as to be able to raise and lower the wheel in relation to the frame. The am is operated by an operating device.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a carriage for transporting a load, preferably a pallet, along a rail pair in a so-called deep racking store, comprising carrier means which, in a deactivated transport position of the carriage, are disposed to pass under a load resting on the rail pair and which, in an activated lifting position, are disposed to carry from beneath the load free from the rail pair, the carriage having a supporting chassis/frame provided with at least four wheels.  
       BACKGROUND ART  
       [0002]     In so-called deep racking stores, use is made of pairs of rails for supporting stored loads which as a rule rest on pallets. Each rail pair is of considerable length so that a plurality of pallets may be disposed along a rail pair.  
         [0003]     In a deep racking store, use is often made of a plurality of rail pairs above one another up to such a height which is accessible to a fork-lift truck or other lifting device. In addition, use is often made of a plurality of vertical stacks of rail pairs in side-by-side relationship so that the rail pairs form a grid pattern of both considerable height and width where each rail pair displays, as was mentioned above, considerable length.  
         [0004]     For transporting pallets along a rail pair, use is made of a carriage which rolls on the rail pair and is designed in such a manner that, in a deactivated position, it may pass under loads resting on the rail pair. If, on the other hand, it is transferred to an activated lifting position, it lifts from beneath a load resting on the rail pair so that the load is free of the rail pair and can, with the aid of the carriage, be transported along the rail pair.  
         [0005]     It will readily be perceived that a pallet lifted up by, for example, a fork-lift truck and placed at an end region of a rail pair may readily be transported with the aid of the carriage to the inner end of the rail pair. The carriage may thereafter return to the outer end of the rail pair to fill the rail pair with additional loads until the complete rail pair is fully loaded.  
         [0006]     As a rule, one and the same carriage is employed for transporting loads on different rail pairs, for which reason the carriage is moved from one rail pair to another as required.  
         [0007]     In order to lift the load, the carriage has a lifting device with at least so great a lifting distance that the carriage, with the lifting device in a deactivated position, may pass under a load resting on the rail pair while, in an activated lifting position, it lifts the load so high that it is free of the rail pair.  
         [0008]     In a prior art carriage of the type described by way of introduction, the lifting device comprises a parallelogram or pantograph mechanism which, in the vertical direction, acts on carrier means disposed on the carriage so that these may be raised and lowered in relation to the carriage. The pantograph mechanism has an upper arm pivotally connected to the carrier means and a lower arm pivotally connected to the chassis or frame of the carriage, the arms also being interconnected to one another and, at this connecting point, further connected to a linear prime mover. Both of the arms are pivotal under the action of the prime mover between a position where they lie approximately in line with one another and where the carrier means are raised, and a position where the arms make an angle with one another and where the carrier means are lowered so that the carriage can pass under a load resting on a rail pair.  
         [0009]     The above-described pantograph mechanism functions satisfactorily, but has insufficient load carrying capacity.  
         [0010]     Constructions are also previously known in the art where the wheels of the carriage are adjustable in the vertical direction so that the entire carriage is raised and lowered in relation to the rail pair when the load is to be lifted up or deposited on a rail pair.  
       PROBLEM STRUCTURE  
       [0011]     The present invention has for its object to design the carriage intimated by way of introduction such that this will display considerably greater lifting capacity than prior art carriages are capable of performing. Further, the present invention has for its object to design the carriage so that it will be simple and economical in manufacture, at the same time as needing but simple maintenance and possessing long service life.  
       SOLUTION  
       [0012]     The objects forming the basis of the present invention will be attained if the carriage intimated by way of introduction is characterised in that the carrier means are rigidly connected to the chassis, that each wheel is journalled in an associated arm which is pivotally journalled in the chassis for raising and lowering the wheel in relation to the chassis, the arm being further operable by means of an operating device. 
     
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0013]     The present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawings. In the accompanying Drawings:  
         [0014]      FIG. 1  shows a carriage according to the present invention resting on a rail pair, a part of the one rail having been cut away for purposes of clarity and the carriage being in a deactivated transport position, i.e. in a lowered position;  
         [0015]      FIG. 2  shows the carriage according to  FIG. 1  in an activated lifting position, i.e. in a raised position;  
         [0016]      FIG. 3  in a view corresponding to  FIG. 1  is a vertical cross section through the carriage;  
         [0017]      FIG. 4  in a view corresponding to  FIG. 2  is a vertical cross section through the carriage; and  
         [0018]      FIG. 5  shows a mounting unit included in the carriage with two wheels mounted thereon. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0019]      FIGS. 1 and 2  show a rail  1  included in a rail pair in a deep racking store, the rail having, along its upper defining edge, a substantially horizontal support surface  2  which is intended for carrying a load, preferably a pallet. The support surface  2  is, in  FIGS. 1 and 2 , at right angles to the plane of the Drawing and extends towards the observer from this plane.  
         [0020]     The rail  1  further has a running surface  3  which is also horizontal and preferably parallel with the support surface  2  and is intended for supporting a carriage  4  according to the present invention. The support surface  2  and the running surface  3  are connected to one another by the intermediary of a wall  5  extending in the vertical direction of the rail, and further a downwardly directed flange  6  which extends downwards from that edge of the running surface  3  which is turned to face towards the other rail included in a rail pair.  
         [0021]     In a rail pair, the two running surfaces  3  lie as horizontal shelves in between both of the walls  5  in the rail pair, while the support surfaces  2  extend away from one another from the upper edge portions of the walls  5 .  
         [0022]     It will be apparent from  FIGS. 1 and 2  that the carriage  4  has wheels  7  which are rotary with wheel axles  8 . In the right sides of both Figures, the wheels have been removed for purposes of clarity and it will be apparent that the axles  8  are carried by and rotary in bearings  9 , in the illustrated embodiment roller bearings.  
         [0023]     On its upper side, the carriage  4  has carrier means  10  which are fixedly secured in the carriage and are thus rigidly connected to a chassis/frame included in the carriage. The carrier means  10  are disposed to engage from beneath with a load resting on a rail pair and lift the load so high that the load is free of the support surfaces  2  of the rail pair when the carriage  4  with the load is to be run along a rail pair. When the carriage  4  is to be run along the rail pair without a load, the carrier means  10  are located on a lower level, so low that the carriage  4  may freely pass under a pallet resting on the rail pair.  
         [0024]     In  FIG. 1 , the carriage is in a deactivated transport position, i.e. the lowered position, while in  FIG. 2 , the carriage is in an activated lifting position, i.e. the raised position, and it will be apparent on a comparison between these two Figures that the wheel  7  and the axle  8  in  FIG. 1  are of considerably higher vertical extent in relation to the carriage than is the case in  FIG. 2 . From this it follows that the whole carriage  4  is raisable and lowerable for raising and lowering of the carrier means  10  by a corresponding lowering and raising of the wheels  7 , respectively. For raising and lowering the wheels in relation to the carriage and in particular its chassis and carrier means  10 , use is made of an operating device disposed in the carriage which, in turn, is connected to a prime mover. The operating device will be described in greater detail below.  
         [0025]     It will be apparent from  FIGS. 3 and 4  that the wheels  7  are each journalled via their axles  8  in their associated arm  11 , both of the arms illustrated in  FIGS. 3 and 4  each having an outer portion  12  and an inner portion  13 . The two arms  11  are journalled in their central regions with journalling devices  14  with pivot shafts  15  in relation to the supporting chassis of the carriage.  
         [0026]     For operating the wheels  7  and their axles  8  in the vertical direction, the carriage has an operating device  16  which is disposed for pivoting both of the arms  11  about the pivot shafts  15 . The operating device  16  includes an excenter or crank device which engages with the inner ends of the inner portions  13  of the arms  11 .  
         [0027]     The operating device  16  has a drive shaft  17  which, for its rotation, is connected to a prime mover (not shown on the Drawings), for example an electric motor.  
         [0028]     The wheels  7  of the carriage extend in the lateral direction outside the chassis or supporting frame of the carriage so that this be located in between the two downwardly directed flanges  6  on the rails included in a rail pair (see  FIG. 1 ). In order to journal the axles  8  as close to the wheels as possible, the outer arm portions  12  are located a greater distance from the longitudinal centre line of the carriage than is the case for the inner arm portions  13 . Between these arm portions, connecting members or sleeves  18  are provided which mutually rigidly connect the two arm portions and which are included in the journal devices  14  of the arms.  
         [0029]     Between the insides of the wheels  7  and the roller bearings included in the bearings  9  of the wheels, there are provided spacer sleeves which surround the wheel axles. The roller bearings in the bearings  9  are axially fixed in the outer arm portions  12  of the arms so that axial loadings on the wheels are transferred to these arm portions via the spacer sleeves and the roller bearings. In order to avoid flexural movements in the outer portions  12  of the arms, these are provided with guides whose purpose is to prevent axial movement of the wheel and the outer portions  12  of the arms in relation to the chassis of the carriage by transferring thereto the above-mentioned loadings. The guides include elongate apertures  19  in the outer portions  12  of the arms, the apertures being concentric about the pivot shafts  15  of the arms and being disposed at the outer ends of the outer arm portions  12  in particular outside the wheel axles  8 . As is apparent from  FIGS. 3 and 4 , stub shafts extend through these apertures  19  which, at their ends facing towards the observer of  FIGS. 3 and 4 , have heads or washers  20  which prevent movement towards the observer of  FIGS. 3 and 4  of the outer end portions of the arms  11 . In such instance, the fixing of the outer portions  12  of the arms takes place in the longitudinal direction of the wheel axles  8  in that the stub shafts with the heads  20  are fixed in the chassis of the carriage. On the rear side (in  FIGS. 3 and 4 ) of the arms, these abut against sliding guides which are rigidly connected to the chassis.  
         [0030]     It should be mentioned that the wheels  7  pairwise have a common and through-going axle  8  whereby the wheels are interconnected to each other in the axial direction, so that, in principle, both of the guides for the outer portions  12  of the arms will thereby share an axial loading on the wheels. It should also be mentioned that the wheel axles  8  are parallel with the pivot shafts  15  of both arms  11 .  
         [0031]     It will be apparent from  FIG. 5  that, on each side of the carriage, the arms  11  and the operating device  16  disposed there are mounted in a mounting unit  21  which, in its turn, is secured in the chassis of the carriage. The mounting unit  21  has two outer or first walls  22  which are at right angles to the pivot shafts  15  of the arms  11 , as well as two inner or second walls  23  which are parallel with the outer walls  22  and which are located a distance inside them. The distance between the outer and inner walls is such that the sleeves  18  which the connect the outer portions  12  of the arms  11  with the inner portions  13 , as well as the arms proper, will have space without axial play between the mutually facing sides of these walls. The journals of the arms  11  are supported by the above-mentioned first and second walls  22  and  23 .  
         [0032]     It will further be apparent from  FIG. 5  that the two inner walls  23  in the mounting unit  21  are interconnected int. al. by the intermediary of an additional inner or third wall  24 . This wall  24  supports a bearing  25  for the drive shaft  17  and is therefore at right angles to both the drive shaft  17 , the pivot shafts  15  and the wheel axles  8 .  
         [0033]     As was mentioned above, the operating device  16  includes an excenter  26  which is radially offset in relation to the drive shaft  17  ( FIGS. 3 and 4 ). On the excenter, there are disposed two roller bearings side-by-side, i.e. closely joined together in the axial direction. In  FIGS. 3 and 4 , only the roller bearing most proximal to the observer of the Figure is visible.  
         [0034]     The two roller bearings supported by the excenter  26  each have an inner ring  27  and an outer ring  28 . The outer ring on the roller bearing located most proximal in  FIGS. 3 and 4  is accommodated in an aperture in the inner portion  13  of the left arm in the Figures, while the roller bearing located most distal from the observer of the Figure has its outer ring accommodated in a corresponding aperture in the inner portion  13  of the right arm  11  in the Figures, whose inner portion  13  in the Figures is located behind the inner portion of the left arm. In the vertical direction, the apertures in the inner portion  13  of the arms are of approximately the same extent as the diameter of the outer rings of the two roller bearings, so that the outer rings may be accommodated substantially without play in the apertures in the vertical direction. On the other hand, in the horizontal direction the apertures are of greater extent so that rotation of the excenter  26  a complete revolution may be put into effect without the outer rings of the bearings coming to contact with the left and right defining surfaces in the apertures in  FIGS. 3 and 4 .  
         [0035]     The operating device  16  has an upper and lower dead point, the arms  11  in the lower dead point of the operating device having their outer portions  12  raised, while the opposite applies when the operating device  16  is located in the upper dead point. As a result, the major advantage will be afforded that loadings on the wheels in the vertical direction will not be transferred to the prime mover that drives the operating device  16  when the carriage is located in its activated lifting position and in its deactivated transport position, in other words the operating device is “self-locking” when the wheels  7  are located in their maximum raised and maximum lowered positions in relation to the chassis.  
         [0036]     In the foregoing, the bearings  9  of the wheels  7  have been described as roller bearings. Possibly, other types of bearings could be employed, for example bearings with different types of bushings. The same circumstance applies to the bearings for the drive shaft  17  and the bearings between the excenter  26  and the apertures of the arms  11 . Possibly, one variation could be conceivable where both of the roller bearings on the excenter  26  are replaced by a bearing whose outer ring engages with the apertures in the two arms  11 .