Abstract:
The invention concerns moving of load units laden on pallets or load sheets. The invention provides a load truck ( 10 ) (FIG.  2 ) for moving load units ( 40 ). The truck ( 10 ) includes a load support structure ( 12 ) and a travelling member ( 28 ) for pushing a load unit ( 40 ) from the structure ( 12 ). It includes also a hydraulic cylinder assembly ( 32 ), acting between the member ( 28 ) and a member ( 26 ) fixed with respect to the structure ( 12 ), for displacing the member ( 28 ). The invention further provides a method (FIG.  6 ) of offloading a load unit ( 40 ) from a load truck ( 10 ). It involves anchoring the truck ( 10 ) during at least a last stage of forward pushing of the load unit ( 40 ) from the truck ( 10 ) by means of a load shifting mechanism ( 25 ) of the load truck ( 10 ), thereby to restrain the load truck ( 10 ) against rearward displacement and push the load unit ( 40 ) against an object ( 48 ).

Description:
FIELD OF THE INVENTION 
       [0001]    THIS INVENTION relates to a load truck and a method of offloading a load unit. The invention relates, more particularly, to a load truck for moving load units laden on pallets or slip sheets and to a method of offloading such a load unit. 
       BACKGROUND ART 
       [0002]    A known method of moving load units for the purpose of transportation and storage is to palletise them. A large variety of load trucks exists to move palletised load units. These include low-lift pallet trucks and fork lift trucks. Pallet trucks may be propelled manually or by a motor. Some pallet trucks and fork lift trucks are operated by a ride-on operator and others by an operator on foot. 
         [0003]    A more recently developed method of moving load units for the purpose of transportation and storage is to load them onto slip sheets instead of pallets. Proper moving of load units laden on slip sheets requires specialised load trucks. These include fork lift trucks fitted with so-called push/pull mechanisms for pulling load units onto their forks and for pushing them from the forks, and so-called roller forks. In some such load trucks, the push/pull mechanism includes a travelling push/pull member which is connected to a fixed part by means of a scissor mechanism, which maintains a fixed orientation of the push/pull member, and a hydraulic cylinder assembly acting between components of the scissor mechanism for effecting displacement of the push/pull member. 
         [0004]    Typically, load trucks used for moving palletized or load sheet laden load units may be classified into low-lift trucks and fork lift trucks. Low-lift trucks provide for only limited lifting of a load unit to clear the ground, whereas fork lift trucks provide for sufficient lifting of a load unit for inter alia stacking purposes. A low-lift truck may be either human propelled or motor propelled. Fork lift trucks typically are motor propelled. There are motor propelled, ride-on variants of both low-lift trucks and fork lift trucks. Walk-along load trucks, which are operable by a human operator on foot, may be either operator propelled or motor propelled. Operator propelled low-lift trucks, sometimes referred to as hand trucks, typically represent the low cost end of the spectrum of load trucks. 
         [0005]    A disadvantage of commercially available load trucks for moving load units laden on pallets or slip sheets is cost. A first aspect of the invention aims to provide an economical load truck for moving load units laden on pallets or slip sheets. 
         [0006]    It is sometimes required to place a load unit laden on a pallet or a slip sheet against an object, for example a front wall of a shipping container or another load unit. Such placement has two main advantages, namely assisting in load stability and optimising space utilization. In practice, the Applicant has found that, using a lightweight load truck, particularly a low-lift truck, for placing a load unit often results in a gap being left between the load unit and the object against which it was to be placed. A second aspect of the invention provides a method aimed at addressing this problem. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    According to a first aspect of the invention there is provided a load truck including:
       a load support structure for a load unit, the structure defining a front end, a rear end, and a longitudinal direction; and   a load shifting mechanism including:
           a fixed member, fixed with respect to the load support structure at a position rearwardly spaced from the front end of the load support structure;   a travelling member defining an upright front face, above the load support structure and transverse to the load support structure, for operatively pushing a load unit from the load support structure, the travelling member being displaceable in the longitudinal direction between a rearward position, intermediate the front end of the load support structure and the fixed member and spaced apart from the said front end, and a forward position, at the said front end; and   an actuation mechanism operable for displacing the travelling member between the rearward position and the forward position, characterized in that the actuation mechanism includes a hydraulic cylinder assembly having opposite ends thereof connected to the fixed member and the travelling member, respectively, and being operable to exert opposing forces between the members to displace the travelling member from the rearward to the forward position.   
               
 
         [0013]    The applicant has found that the configuration of the actuation mechanism permits the use of a smaller hydraulic cylinder assembly and/or lower hydraulic pressure than is the case with a conventional push/pull mechanism in which a hydraulic cylinder assembly acts between components of a scissor mechanism. This results in a potential cost and weight saving in a load truck, in accordance with the invention. 
         [0014]    The hydraulic cylinder assembly may have a central axis disposed in the longitudinal direction of the load support structure. The hydraulic cylinder assembly may be a telescopic cylinder assembly. The hydraulic cylinder assembly may be double acting. In this case, the actuation mechanism is a push/pull mechanism and may be provided with a slip sheet gripping mechanism for gripping a slip sheet for pulling a load unit laden on the slip sheet onto the load support formation. 
         [0015]    The load shifting mechanism may include a scissor mechanism interconnecting the travelling member and the fixed member for maintaining a fixed orientation of the travelling member relative to the load support structure. 
         [0016]    The load truck may be a low-lift truck, in which the load support structure is adjustable only within a limited height range near ground level. The load truck may be operable by a human operator on foot. It may be propelled by the operator. The applicant particularly believes that such a load truck may provide an economical and practical means for moving load units laden on slip sheets. 
         [0017]    It must be appreciated that the load truck of the invention may be of any type essentially as herein envisaged, i.e. a low-lift truck or a fork lift truck, human propelled or motor propelled, and ride-on or walk-along. 
         [0018]    According to a second aspect of the invention there is provided a method of offloading a load unit against an object, the method including:
       supporting the load unit on a load support structure of a load truck, the load support structure defining a front end, a rear end, and a longitudinal direction and the load truck including a load shifting mechanism operable to push the load unit from the load support structure in a forward direction of the load support structure;   positioning the load truck for offloading the load unit adjacent to the object, with the front end of the load support structure facing the object; and   by operation of the load shifting mechanism, pushing the load unit from the load support structure in the longitudinal direction,
 
characterized in that, during at least a last stage of the pushing of the load unit, the load truck is anchored by means of anchoring means to a fixed securing formation in a configuration in which the load truck is restrained against displacement in a rearward direction of the load support structure, resulting in the load shifting mechanism pushing the load unit into abutment with the object.
       
 
         [0022]    The problem referred to above of a gap being left during offloading is thereby ameliorated by the method of the second aspect of the invention. Advantages include optimisation of space usage and load stability. 
         [0023]    The load truck used in the method may be a low-lift truck, in which the load support structure is adjustable only within a limited height range near ground level. 
         [0024]    The load truck may be operable by a human operator on foot. It may be propelled by the operator. 
         [0025]    In the method, the fixed securing formation may include a pair of securing members provided in a shipping container at opposite sides of a floor of the container. The anchoring means may include two lengths of tie element on opposite sides of the load truck and having respective ends thereof remote from the load truck releasably engaged with the respective securing members. 
         [0026]    The two lengths of tie element may be two lengths of a single tie element. Each length of tie element may, for example, be a length of chain, rope, belt, cable, lashing, or the like. 
         [0027]    It must be appreciated that the method of the invention may be applied to any type of load truck essentially as herein envisaged, i.e. a low-lift truck or a fork lift truck, human propelled or motor propelled, and ride-on or walk-along. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention is described below by way of example with reference to and as illustrated in the accompanying diagrammatic drawings. 
           [0029]    In the drawings: 
           [0030]      FIG. 1  shows a rear three-dimensional view of a load truck, in accordance with the first aspect of the invention, in a first operative configuration thereof; 
           [0031]      FIG. 2  shows a rear three-dimensional view of the load truck of  FIG. 1 , in a second operative configuration thereof; 
           [0032]      FIG. 3  shows a side view of the load truck of  FIG. 1 , in the first operative configuration; 
           [0033]      FIG. 4  shows a side view of the load truck of  FIG. 1 , in the second operative configuration; and 
           [0034]      FIGS. 5 to 7  show respectively three steps in a method, in accordance with the second aspect of the invention, of offloading a load unit against an object, in this example in a shipping container using the load truck of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    In the drawings, an embodiment of a load truck, in accordance with the first aspect of the invention, is designated generally by reference numeral  10 . The load truck  10  is a low-lift truck. 
         [0036]    With reference particularly to  FIGS. 1 and 2 , the load truck  10  includes:
       a load support structure in the form of a fork  12  including two parallel, spaced apart fork beams  14 ;   a bogie mounting assembly  16  mounted on rear ends of the fork beams  14 ;   a bogie  18  including a pair of rear wheels  20 ;   a pair of front wheels  21 , supporting the respective fork beams  14 ;   a lifting mechanism including a hydraulic jack  22 , for lifting and lowering the fork  12  on the wheels  20  and  21 ; and   a handle  24 .       
 
         [0043]    The fork beams  14  extend in a longitudinal direction of the fork  12 . The fork  12  has a front end  13 . 1  and a rear end  13 . 2 . Each fork beam  14  includes a series of longitudinally spaced load support rollers  15 . 
         [0044]    The load truck  10  is manually operated and propelled by a human operator on foot. The operator uses the handle  24  for actuating the hydraulic jack  22  for lifting and lowering the fork  12 . 
         [0045]    Insofar as the above features and the operation of the load truck  10  are known in relation to pallet trucks, they are not elaborated on in detail herein. 
         [0046]    In accordance with the invention, the load truck  10  includes a load shifting mechanism  25  including:
       an upright fixed member in the form of a fixed frame  26  mounted on the fork beams  14  just in front of the bogie mounting assembly  16 ;   an upright travelling member in the form of a travelling frame  28 , supported on the respective fork beams  14  by means of the two support wheels  38  which travel on the respective fork beams  14 ;   a scissor mechanism  30  interconnecting the frames  26  and  28 ; and   an actuator mechanism  27  including:
           a longitudinal double acting, telescopic, hydraulic cylinder assembly  32  acting between the fixed frame  26  and the travelling frame  28 ; and   a power pack  36  for powering the hydraulic cylinder assembly  32  by means of pressurised hydraulic oil.   
               
 
         [0053]    The scissor mechanism  30  provides for displacement of the travelling frame  28  between a rearward position, as shown in  FIGS. 1 and 5 , and a forward position, as shown in 
         [0054]      FIGS. 2 ,  4 , and  7 . The scissor mechanism  30  maintains the travelling frame  28  parallel to the fixed frame  26  so that an upright front face  29  (see  FIG. 3 ) of the travelling frame  28  is maintained upright and transverse relative to the fork  12 . 
         [0055]    A front end of the hydraulic cylinder assembly  32  is connected to a centre of the travelling frame  28  whereas a rear end of the hydraulic cylinder assembly  32  is connected to the fixed frame  26 . More particularly, a rear portion of the hydraulic cylinder assembly  32  passes through a centre of the fixed frame  26  and is connected thereto by means of two opposite brackets  34  projecting rearwardly from the fixed frame  26 , with a dowel pin  35  releasably interconnecting a rear end of the hydraulic cylinder assembly  32  and the brackets  34 . 
         [0056]    By operation of the power pack  36 , the hydraulic cylinder assembly  32  is selectively extended or contracted, thereby displacing the travelling frame  28  forwardly or rearwardly, respectively. 
         [0057]    The load truck  10  may be used in the configuration shown in  FIG. 1 , with the travelling frame  28  in its rearward position, for moving a palletized load unit in conventional fashion. 
         [0058]    Alternatively, the load truck  10  may be used for moving a load unit laden on a slip sheet. For this purpose, the load shifting mechanism  25  may be provided with a slip gripping mechanism (not shown) along a bottom edge  37  (see  FIG. 3 ) of the travelling frame  28 . Such a slip gripping mechanism may be essentially conventional and therefore does not require illustration or description herein. 
         [0059]    With reference now to  FIGS. 5 to 7  of the drawings, a method of offloading a load unit, in accordance with the second aspect of the invention, will now be described. It is sometimes required to place a load unit laden on a slip sheet against an object, for example a front wall of a shipping container or another such load unit. Such placement has two main advantages, namely assisting in load stability and optimising space utilization. In practice, the Applicant has found that, using a lightweight load truck for placing a load unit often results in a gap being left between the load unit and the object against which it was to be placed. The method of the second aspect of the invention aims to address this problem. 
         [0060]    In  FIG. 5 , a load unit  40  has been laden on a slip sheet  42  and supported on the fork  12  of the load truck  10 . The load truck  10 , with the load unit  40  thereon, has been pushed into a shipping container  44 , which has a floor  46  and an end wall  48 , into the position shown in which the front end  13 . 1  of the fork  12  abuts the end wall  48 . 
         [0061]    In  FIG. 6 , by operating the power pack  36  (see  FIG. 5 ), the hydraulic cylinder assembly  32  has been partially extended, causing forward displacement of the travelling frame  28 . The travelling frame  28 , with its face  29  bearing against the load unit  40 , has pushed the load unit  40  and slip sheet  42  into a position in which they are predominantly supported on the floor  46  and only minimally on the front end of the fork  12 . Such extension of the hydraulic cylinder assembly  32  has caused a rearward displacement of the load truck  10 . A gap  50  has been inadvertently left between the load unit  40  and the wall  48 , as the applicant has found often happens in practice. 
         [0062]    Anchoring means in the form of an anchoring accessory  52  is now used to anchor the load truck  10  to prevent further rearward displacement. The floor  46  of the container  44  has conventionally been provided with a number of securing lugs along opposite sides of the floor  46 , of which only one lug  54  is shown. The securing lugs  54  define a fixed securing formation on the floor  46 . Another such lug  54  is at a corresponding position on the opposite side of the floor  46  and of the load truck  10 . 
         [0063]    The anchoring accessory  52  comprises a tie element in the form of a lashing  56 , two hooks  58  on opposite ends of the lashing  56 , and a conventional manually operable tensioning mechanism  60  (not shown in detail). The hooks  58  are engaged with the respective lugs  54  and the lashing  56  has been placed around the back of the fixed frame  26  so that a length of tie element is defined on each side of the load truck  10 . The lashing  56  has been nominally tensioned by means of the tensioner  60 . The anchoring accessory  52  resists rearward displacement of the load truck  10 . 
         [0064]    In  FIG. 7 , by operating the power pack  36  (see  FIG. 5 ), the hydraulic cylinder assembly  32  has been completely extended. The load unit  40  and the slip sheet  42  have been pushed by the travelling frame  28  into a position in which they are entirely supported on the floor  46  in front of the fork  12 . The gap  50  of  FIG. 6  has been closed so that the load unit  40  is flush against the wall  48 . 
         [0065]    The load truck  10  may now be released by removing the anchoring accessory  52 . 
         [0066]    The Applicant submits that the configuration of the load shifting mechanism  25 , particularly the configuration of the hydraulic cylinder assembly  32  acting longitudinally between the travelling frame  28  and the fixed frame  26 , provides an efficient, economical, and practical load shifting arrangement. 
         [0067]    Although the load truck  10  in the above examples is a walk-along, human propelled, low-lift truck, it must be appreciated that different embodiments of a load truck, in accordance with the invention, may be of any type essentially as herein envisaged, i.e. a low-lift truck or a fork lift truck, human propelled or motor propelled, and ride-on or walk-along. So, for example, the load shifting mechanism  25  may alternatively be provided on a motor propelled fork lift truck. Similarly, the method of the second aspect of the invention may be applied to any type of load truck of the general type referred to herein. 
       INDUSTRIAL APPLICABILITY 
       [0068]    Both the load truck and the method of the invention are applicable in moving load units laden on pallets or slip sheets for the purpose of storage and transportation in a wide variety of industries.