Patent Document

FIELD OF THE INVENTION 
   Background of the Invention 
   The invention refers to a steering arm for walking/rider pallet truck. 
   There exists a kind of pallet truck which is steered by a steering arm or pole. A subspecies is a walking pallet truck where the operator grips the steering arm and handles the pallet truck by drawing or pushing the arm. Another sub-species refers to a pallet truck wherein the operator stands on a platform of the truck and actuates the steering arm. It is understood that the steering arm for the rider type is shorter than that for the exclusive walking type. In the first case, the steering arm is pivotally supported on the upper side of a housing part of the pallet truck. 
   The general structure of a steering arm for a pallet truck is that a steering rod is linked to the pallet truck or a steering shaft, respectively, and carries a steering head. The steering head includes gripping portions which are to be engaged by the operator and actuation elements for the control of functions of the pallet truck, e.g. of the driving motor, the brake or the lifting cylinder for the load supporting means. Conventional embodiments for the steering head have a similar structure. It is symmetrical to the longitudinal axis of the steering arm. A central horn extends as an elongation of the steering rod into the steering head, and gripping portions are located on both sides of the horn which extend transverse to the steering rod, the gripping portion with the outer ends being connected to leg portions. The leg portions are connected to a transverse portion which is attached to the steering rod. By this on both sides of the horn portion gripping openings are formed. 
   Finally, it is known to design the pallet trucks for the walking and rider operation as well. If designed for the rider operation the truck can serve as commission pallet truck. If load carriers are to be loaded or unloaded pallet trucks designed for the walking operation are preferred. In trucks for the rider operation the operator stands on a platform and engages with one hand a holding bail. The other hand engages a gripping portion of the steering head and thus controls the steering arm. Such a pallet truck has become known by U.S. Pat. No. 6,382,359 B1. In particular in standing operation considerable steering forces are necessary. To support the steering operation it is known that the operator frequently uses his thigh. With his thigh he presses against the steering rod which usually is of metal. Such operation frequently is uncomfortable. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a steering arm for a walking/rider pallet truck such that the steering support by the thigh of the is less uncomfortable if compared with conventional trucks. 
   In the invention at least the lateral surfaces of the steering rod are provided with a cushion. According to an embodiment of the invention such a cushion can be directly foamed onto the rod or tube of the steering arm. However, also separate cushion portions or pads can be manufactured to be attached to the surfaces of the steering rod. It is particularly preferable to provide an integrally molded portion which is mounted to the steering arm in a suitable member. 
   A cushion layer on the steering arm which may extend into the steering head has a plurality of advantages. The supporting actuation of the steering rod by the thigh of operator is more comfortable. The operator feels this as a reduction of the pressure feeling on his thigh. When using the pallet truck in a cold storage depot the cushion as an insulating effect relative to the steering arm which usually is made of metal and thus attains the cold of the cold storage depot. A further advantage of a molded cushion is that the outer shape of the steering arm can be designed with an optimum appearance, e.g. by spherical shapes, other parting lines for the components, scarred surfaces or the like. Finally, the advantage is achieved that the steering rod can be manufactured with low expense since the rod is not visible from exterior. 
   While the steering rod in conventional pallet trucks has a circular or rectangular cross section an embodiment of the invention provides that the steering rod is U-shaped in cross section. The cushion portion can be U-shaped or C-shaped in cross section and adapted to the profile of the steering rod. It is understood that suitable means are to be provided to retain the cushion safely at the steering rod. To this purpose a cover plate is provided which is attached to the lower side of the steering rod through threaded connections. The cover plate clamps both portions of the C-shaped cushion portion tightly against the steering rod which undergrip the steering rod from below. By this the cushion is positively attached to the steering arm. 
   For the purpose of appearance and also for a positive attachment the molded cushion portion may extend into the steering head. Therefore, according to a further embodiment of the invention the molded cushion portion has two leg portions extending laterally at the upper end. The leg portions extend cup-like in cross sections towards the steering head. The leg portions engage the front surfaces of the steering head on both sides of the steering rod, preferably such that the outer surfaces thereof are in the same plane as the remaining surface portions of the front side of the steering head. It is conventional to compose such steering heads of a lower and an upper shell or cup, the shells for example being interconnected by screws of the like. In such embodiment lower and upper edge portions of the shells may engage accordingly formed grooves of the leg portions of the molded cushion portion in order to fix them to the steering head. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment is hereinafter explained along accompanying drawings which show: 
       FIG. 1  is a diagrammatic view of a steering arm according to the invention from above, 
       FIG. 2  is a diagrammatic view of the steering arm of  FIG. 1  from below 
       FIG. 3  is a diagrammatic view on a cushion portion for the steering arm of  FIG. 1  from above, 
       FIG. 4  is a diagrammatic view on the cushion portion of  FIG. 3  from below, 
       FIG. 5  is a lateral view of the cushion portion of  FIGS. 3  or  4 , 
       FIG. 6  is a cross section through the illustration of  FIG. 4  taken along line  6 - 6 , 
       FIG. 7  is a cross section through the illustration of  FIG. 1  taken along line  7 - 7 , and 
       FIG. 8  is a cross section through the illustration of  FIG. 2  taken along line  8 - 8 . 
   

   DETAILED DESCRIPTION 
   In  FIGS. 1 and 2  a steering arm  10  is depicted which has a structure generally known. As to this it is for example referred to the U.S. Pat. No. 6,382,359 B1. In this document a typical pallet truck for the walking/rider operation is shown which has a steering arm with a basic structure to which also the present invention refers. Therefore, it is expressly referred to this prior art. 
   As can be seen in  FIGS. 1 and 2  the steering arm  10  has a steering rod  12  and a steering head  14 . The structure of the steering rod  12  can be clearly seen in  FIG. 8 . It has a U-shaped profile with a web plate  16  and leg portions  18 ,  20 . The mentioned parts are attached to each other by welding. The shown U-profile at the end has two laterally spaced bearing eyes  22 ,  24 . The bearing eyes are provided for the mounting of a steering arm to a vertical steering shaft of a pallet truck not shown. By this the steering arm  10  can be pivoted about a horizontal axis and contemporarily rotate about a vertical axis in order to effect a steering motion. 
   As can be seen further in  FIGS. 1 and 2  the steering head  14  has two gripping portions  26 ,  28  on both sides of a horn portion  30 . The gripping portion  26 ,  28  at the outer ends are connected to leg portions  32 ,  34  which in turn are connected to a transverse portion  36 . The transverse portion  36  is attached to the steering rod  12 . The horn is centrally attached to the transverse portion and extends beyond the gripping portions  26 ,  28 . Such design is conventional and is not to be explained further in detail. As can be seen the described parts of the steering head  14  form two gripping openings  38 ,  40 . Individual actuation elements are provided on the steering head  14  for the control of functions of the pallet truck not shown. This is also not to be described in detail. 
   From  FIGS. 1 ,  2  and  8  it can be seen that the steering rod  12  or the U-shaped profile of the steering rod shown in  FIG. 8  is embraced by a cushion portion  42 . As can be seen in  FIG. 8 , the cushion portion  42  is C-shaped in cross section. A web portion  44  faces the web plate  16  and covers the web plate, leg portions  46 ,  48  extend approximately parallel to the leg portions  18 ,  20  and lower portions  50 ,  52  undergrip the leg portions  18 ,  20 , with grooves in the portions,  50 ,  52  accommodate lower edges of the leg portions  18 ,  20 . An intermediate space  54  is formed between the web portion  44  and the web portion  16  in  FIG. 8 . It results from the fact that the leg portions  18 ,  20  somewhat protrude beyond the web plate  16 . A further intermediate space is provided between the leg portions  46 ,  48  on one side and the associated sides of the leg portions  18 ,  20  on the other side. By this the cushion portion  42  which may be made of a suitable elastomeric cushion material, e.g. plastic foam, can be deformed inwardly upon a pressure thereon. 
   As can be seen further in  FIG. 8  a relatively thin cover plate  56  is provided which has a U-shaped profile in cross section by bent edges which engage corresponding grooves of portions  50 ,  52  of the cushion portion  42 . By means of screws one of which is shown at  58  the cover plate  56  can be attached to web plate  16 . This attachment secures the cushion portion  42  to the steering rod  12  in that it prevents the leg portions  18 ,  20  from disengagement with the associated grooves of portions  50 ,  52 . 
   The basic structure of the cushion portion  42  is shown in  FIGS. 3 and 4 . It can be seen that at the upper end thereof curved legs  60 ,  62  extend laterally away from each other. The legs  60 ,  62  engage the associated front curved surfaces of steering head  14  as shown in  FIGS. 1 and 2 . The mounting of the legs  60 ,  62  to the steering head  14  is described hereinafter in more detail. 
   An arcuately shaped portion  64  is provided at the other end of the cushion portion  42  as can be seen in  FIGS. 3 and 4 . The portion  64  extends upwardly beyond the web portion  44 . At the lower side it is adapted to the shape of the bearing eyes  22 ,  24  and engages the bearing eyes at the associated side as can be seen in  FIGS. 1 and 2 . Thus, the cushion portion  42  at the lower end is supported by the steering rod  12 . 
     FIG. 6  shows a cross section of the cushion portion  42  in the range of the steering rod  12 . The grooves which according to  FIG. 8  accommodate the leg portions  18 ,  20  are designated with  66 ,  68 . The grooves which accommodate the edges of the cover plate  57  are designated with  70 ,  71 . 
   It can be seen in  FIG. 7  that the housing of the steering head  14  is composed of an upper cup portion  74  and a lower cup portion  76 . The separation line which is defined by the cup portions  74 ,  76  are not shown in  FIG. 1 and 2 . The upper cup portion  74  is made of plastic material and the lower of aluminum. 
   As can be seen  FIG. 7 , the legs  60 ,  62  have a specific cross sectional profile with a first T-profile  78  and a second T-profile  80 , The associated edge portions of the cup portions  74 ,  76  are shaped complementarily so that it may engage the grooves formed by the T-profiles  78 ,  80  on opposing sides. Thereby the legs  60 ,  62  are positively retained by the housing of steering head  14 . 
   It should be mentioned with respect to  FIGS. 1 and 2  that the legs  60 ,  62  are attached to the cup portions  74 ,  76  of steering head  14  such that the outer surfaces of the housing of the steering head  14  and of the legs  60 ,  62  are aligned with each other without a step.

Technology Category: 7