Patent Publication Number: US-6220176-B1

Title: Travelling mechanism, especially for lifting devices

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a travelling mechanism, especially for a lifting device such as a hoist. 
     2. Discussion of the Prior Art 
     U.S. Pat. No. 2,470,060 discloses a travelling mechanism that can be used, in particular, for lifting devices. This travelling mechanism comprises a rail that consists of flange parts and web parts. Two running wheels, which are located opposite to each other, roll on the flange inner sides of the rail. To guide the travelling mechanism, guide rollers rest in front of and behind each running wheel, on both sides, parallel to the web. The running wheels and the guide rollers are rotatably-mounted in lateral bars. The two bars are spaced relative to each other and connected to each other by means of a connecting element in the manner of a traverse. However, this travelling mechanism can be used only for a predetermined flange width. It is assembled completely prior to use and then placed on the travelling rail. A change in the distance between the two lateral bars and thus between the running wheels is not possible. This travelling mechanism thus can be used only in rail profile systems with a constant flange width, whereby an optimal distance is selected between the web and the running wheels to attain the desired statically advantageous stress on the travelling rail and the travelling mechanism. 
     From European reference EP 0 078 085 A1, another travelling mechanism is known, which comprises a travelling rail and running wheels. The wheels are located opposite to each other and rest on the flange parts of the travelling rail. Guide rollers are not provided in this travelling mechanism. To adjust to different web widths, the bilaterally arranged bars, in which the running wheels are rotatably-mounted, are adjustable with respect to their spacing. Seen in the direction of travel, connecting traverses equipped with slots are located in front of and behind the travelling rail. The slots run in pairs on both sides of the web at a right angle to the direction of travel. The connecting traverse is attached to the bars with screws, which are inserted through the slots. This makes it possible to adjust the distance between the two bars. 
     Due to the intrinsic weight of the trolley, the clearance between the wheel flange and the flange side can be adjusted only by great force. However, the crucial disadvantage of this travelling mechanism is that, although adjustment to different flange widths is possible, the running wheels are, in the case of wider flanges, farther from the web. This leads to known disadvantages: The travelling rail is unfavorably stressed, and the flange is subjected to higher bending stress, which results in a larger profile having to be used. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a travelling mechanism that can be adjusted to different flange widths, whereby the running wheels always run relatively close to the web. 
     According to the invention, the travelling mechanism is adjustable to different flange widths by the use of connecting traverses of different lengths. Moreover, the distance between the axles is variable independently of the running wheels for the purpose of adjusting the guide rollers to the flange width. Advantageously, this allows the travelling mechanism to be easily adjusted to different flange widths. Moreover, the flange width can be adjusted even after the travelling mechanism has been mounted on the travelling rail. After adjustment of the guide roller spacing, it is possible, e.g., by test driving, to check whether the distance is sufficient and, if necessary, to undertake fine-tuning without great expense. In addition, in this travelling mechanism, the distance between the web and the running wheels remains constant regardless of the flange width, which leads to statically favorable stress on the travelling rail. 
     In a further embodiment, a slot extending at a right angle to the direction of travel and arranged on a horizontal plane is provided above each guide roller, through which slot the vertical rotational axis of the associated guide roller is run. The slot makes it possible to change the position of the guide roller relative to the web simply by moving the rotational axis inside the slot. 
     Adjusting the guide roller spacing is very simple when each rotational axis position can be fixed within two end positions defined by the length of the slot. 
     To avoid rotation of the fixed rotational axis and thus prevent loosening of the fixed position, each rotational axis is embodied as a bolt flattened on both sides, the larger diameter of which is larger than the slot width. 
     Simple prepositioning of the rotational axis is attained when, for each slot, a measurement strip is arranged between the end positions to determine the particular rotational axis position. 
     The stability of the web can be increased by equipping the lateral surfaces of the connecting traverse with a slot arranged at a right angle to the longitudinal direction of the connecting traverse, into which slot a complementary projection arranged on and belonging to the bar end engages in a positive-locking manner when the travelling mechanism is mounted. The slot connection prevents the bars from rotating relative to each other. 
     Advantageously, the slot is oriented in the direction of travel. In this way, rotational forces can be absorbed especially effectively. 
     When the bars are embodied asymmetrically, the assembly of the travelling mechanism can be further simplified by embodying the connecting traverse and one of the two bars in a single piece. 
     A very economical embodiment is obtained when the bar ends are attached to the connecting traverse at both ends by means of screws and clamping sleeves. 
     When the lateral surfaces of the web traverses are arranged in the area vertically below the support of the running wheels, the result, due to the low bending moment, is reduced tensile stress on the screw connections. 
     A load suspension means can be supported on the web traverse in a simple manner. 
     A travelling mechanism that runs very evenly and stably is attained when the load suspension means is supported in articulated fashion in a ball socket embodied on the upper side of the connecting traverse. 
     To prevent the travelling mechanism from pitching in the travelling direction, the lower end of the C-shaped load suspension means is equipped with a rotary-mounted sliding piece, which engages in a guide slot arranged on the lower side of the connecting traverse and oriented at a right angle to the direction of travel. The guide slot frees the pendulum motion of the load only at a right angle to the direction of travel. 
     A stable and compact travelling mechanism is attained when the bars, above the support points of the running wheels on the flange parts, are embodied to project toward the web. 
     The range of possible flange widths can be enlarged when the two bars form a C that is open at the top and has, on its inner sides at the level at which the guide rollers contact the flange parts, a vertical surface parallel to the running direction. Advantageously, the distance between the two vertical surfaces is equal to the greatest flange width of the lower flange. 
    
    
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings show: 
     FIG. 1 is a cross-section through a travelling mechanism pursuant to the present invention; 
     FIG. 2 is a top view of the travelling mechanism in FIG. 1; and 
     FIG. 3 is a side view of the travelling mechanism in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a cross-section through a travelling mechanism that rides on a lower flange  1  of a travelling rail  1   a . Two running wheels  2 , which are located opposite to each other, rest on the inner lateral surfaces of the lower flange  1 . The running wheels  2  are rotatably-mounted in bars  4 , which are arranged on both sides of the flange web  3  and are embodied, above the support points of the running wheels  2  on the flange parts, so as to project toward the web  3 , whereby their rotational axis is oriented perpendicular relative to the direction of travel. As FIG. 1 shows in schematic fashion, one of the running wheels  2  is directly driven by motor. This running wheel  2  can thus roll in the carrier deeply and near the web, so that no toothed wheel flange is required. The lower bar ends  4   a  are connected to each other below the travelling rail  1   a  via a horizontal connecting traverse  5 , whose lateral surfaces are equipped with a slot  6  at a right angle to its longitudinal direction. Into this slot  6  engages a complementary projection  7  arranged on the associated lower bar end  4   a . The slot  6  and the projection  7  are oriented in the direction of travel and have rectangular cross-sections. In addition, the bar ends  4   a  are attached to the connecting traverse  5  on both sides by means of screws. (However, instead of using screws  8  with associated internal threads in the connecting traverse  5 , it is also possible to use screws  8  and clamping sleeves.) In FIG. 1, the lateral surfaces of the connecting traverse  5  are located in an area vertically below the support of the running wheels  2 . 
     Laterally, on both sides of the web, two guide rollers  9 , which are located opposite to each other and whose rotational axis  10  (see FIG. 2) runs perpendicular relative to that of the running wheels  2 , rest in front of and behind each running wheel  2  on the lateral surfaces of the lower flange  1 . 
     The guide rollers  9  are also rotatably-mounted in the associated bar  4 . The two bars  4  form a C open at the top, which, on its inner sides, at the level at which the guide rollers  9  contact the flange parts, has a vertical surface  19  oriented parallel to the running direction. The distance between the two surfaces  19  is equal to the greatest width of the lower flange  1 . A horizontal surface  20 , which is located above the support points of the running wheels  2 , is arranged above the surface  19 . 
     As FIG. 2 shows in a top view of the travelling mechanism, the guide rollers  9  are located opposite to each other in pairs. The distance of the guide rollers  9  to each other is adjustable, so that the guide rollers  9  can be adjusted to the given flange width. The vertical rotational axes  10  of the guide rollers  9  are inserted through longitudinal slots  11  embodied on the bars  4 . In FIG. 2, the four longitudinal slots  11  are located on a common horizontal plane and run parallel to the rotational axis  10  of the running wheels  2 . The rotational axes  10  are embodied as bolts  12 , which, flattened in the upper area on two sides  10   a , are run in slots  11   a . The two flattened sides  10   a  lie parallel to each other as well as parallel to the longitudinal direction of the bolts  12 . The desired rotational axis position is adjustable inside the two end positions  13  defined via the longitudinal slot  11 , specifically, by tightening the fixing nut  14 . To determine the given rotational axis position, a measuring strip (not shown) can be arranged, on each longitudinal slot  11  between the end positions  13 , on a side of each bar  4 . 
     FIGS. 1 and 3 show a load suspension means  15 , which is supported in articulated fashion on the upper side of the connecting traverse  5 . The C-shaped load suspension means  15  has a spherical head  16 , which is mounted in articulated fashion in a complementary ball socket  17  (see FIG.  1 ). The lower end of the load suspension means  15  is equipped on its inner side with a rotary-mounted sliding piece  17   a  that engages into a guide slot  18  embodied on the lower side of the connecting traverse  5  and oriented at a right angle to the direction of travel. 
     Alternatively, however, it is possible for the connecting traverse  5  and one of the bars  4  to be embodied in a single piece. In this case, during assembly, only one bar  4  must be attached to the L-shaped bar/connecting traverse part. 
     The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various ways within the scope of protection defined by the appended patent claims.