Abstract:
A cargo bar of the type wedged in place in a cargo vehicle to prevent shifting of the cargo. A ratchet mechanism for extending the bar includes an advancement pawl, a release pawl and an eccentric ratchet head acting between the pawls. The ratchet head is connected with the ratchet housing by a pin fitting through an elongated slot. In normal operation, the ratchet head is limited in its movement by a projecting foot contacting the ratchet housing. To effect easy release of the cargo bar, the head can be shifted linearly as allowed by the slot and then pivoted further by the ratchet handle so that an angled surface on the head cams against the holding pawl to release it using the leverage of the handle. Force limitation is achieved by providing an extending collar on one bar which contacts the release pawl to prevent further reciprocation of the ratchet head when the maximum allowed force level is reached.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to cargo bars that are used to restrain freight in truck bodies and other vehicles. More particularly, the invention is directed to a cargo bar which is constructed so that it can be easily released and also to prevent excessive force from being applied by the bar. 
     BACKGROUND OF THE INVENTION 
     Freight vehicles such as over the road trailers and smaller trucks commonly use cargo bars which hold boxes and other freight containers in place. The cargo bar extends across the truck body between the opposite side walls and in some cases vertically between the floor and ceiling. It is placed where it acts as a barrier that prevents the cargo from shifting due to sudden starts and stops or other forces that may be encountered in transit. 
     In order to function effectively, the cargo bar must be wedged tightly in place so that it can withstand the forces that are exerted by the cargo. One commonly used type of cargo bar is constructed with pads on opposite ends of the bar which bear against the vehicle walls (or the floor and ceiling). A jack or ratchet mechanism operated by a reciprocating handle extends the bar to tightly secure it in place in extension between the walls or between the floor and ceiling. In a typical ratchet mechanism, one set of pawls advance the bar when the handle is reciprocated and another set of pawls hold the bar and prevent it from retracting before the next stroke is effected. 
     One of the principal problems with this type of cargo bar is that it is difficult to release. The bar is often necessarily tightened to the point where it exerts up to 300 pounds or even more to function adequately. In order to release the bar to permit the cargo to be unloaded, this force must be overcome with a greater force applied to the holding pawls. Often, a hammer or the like must be forcefully struck against the holding pawl to release them. This can cause injury to workers and damage to the pawls or other equipment and is burdensome in any event. 
     Another problem is that the ratchet can be operated so aggressively that it applies excessive force to the trailer walls. The walls can be bent or otherwise permanently damaged by the bar if this occurs. Although measures have been taken in the past to limit the force that can be exerted by the cargo bar, using hydraulic pressure relief or mechanical techniques, there is ample room for improvement to reduce the cost, complexity and reliability of the force limitation system. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a cargo bar in which the holding pawls are easily released and in which the force that can be applied by the bar is limited. 
     More particularly, it is an object of the invention to provide a cargo bar that is specially constructed to make use of the leverage of the ratchet handle for release of the holding pawls. In this regard, the ratchet head is pivoted to the ratchet housing through a slotted opening which allows the ratchet to be operated normally. When the cargo bar needs to be released, the slotted opening allows the ratchet head to be shifted to a release position where a strategically located angled surface of the ratchet head acts in camming fashion to release the holding pawls when the ratchet handle is further operated to pivot the ratchet head beyond its normal operating range. 
     Another important feature of the invention is an improved mechanism for limiting the force that can be applied by the cargo bar. This is accomplished by a spring loaded tubular collar which is mounted such that it progressively moves toward the holding pawls as the cargo bar is extended to exert increasing force. The spring which acts against the collar is selected so that it is compressed to exert the maximum allowable force (300 pounds, for example) at the point where the collar is butted up against the holding pawls. Thereafter, the collar provides a mechanical stop that prevents the ratchet head from pivoting in the area between the advancement pawls and the holding pawls. As a result, the ratchet can no longer be operated and the cargo bar cannot be extended beyond the length at which it applies the maximum allowable force. 
     Among the other objects of the invention are to provide a cargo bar of the character described which has a rugged construction, which is simple and economical to manufacture, and which functions reliably over an extended operating life. 
     Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views: 
     FIG. 1 is a fragmentary side elevational view showing a cargo bar constructed according to a preferred embodiment of the present invention extended between the opposite sidewalls of a vehicle body; 
     FIG. 2 is an enlarged fragmentary view, partially in section, showing the detail identified by numeral  2  in FIG. 1; 
     FIG. 3 is a fragmentary sectional view similar to FIG. 2, but showing the ratchet head reciprocated in normal operation to its extreme position wherein it abuts the ratchet housing; and 
     FIG. 4 is a fragmentary sectional view similar to FIGS. 2 and 3, but showing the ratchet head pivoted beyond its normal operating position wherein it releases the holding pawls of the ratchet mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings in more detail and initially to FIG. 1, numeral  10  generally identifies a cargo bar constructed in accordance with a preferred embodiment of the present invention. The cargo bar  10  is used in a cargo vehicle such as an over the road trailer having opposite side walls  12  and  14 . The cargo bar  10  is extended between the side walls  12  and  14  to prevent cargo from within the vehicle body from shifting. Alternatively, the cargo bar  10  can be employed in a vertical position in which it extends between the floor and ceiling of the vehicle body to act similarly as a barrier preventing the cargo from shifting unduly during transit. 
     The cargo bar  10  is formed by a pair of separate bars  16  and  18  which carry respective pads  20  and  22  on their outer ends. The bars  16  and  18  are arranged in line, and the pads  20  and  22  bear against the respective side walls  12  and  14  of the vehicle body (or between the floor and ceiling) when the cargo bar  10  is in place. With additional reference to FIGS. 2-4, the cargo bar  10  includes a ratchet mechanism which is generally identified by numeral  24  and which operates to effect extension of the cargo bar  10 . The ratchet mechanism  24  includes a ratchet housing  26  which is located at the junction or intersection between the two bars  16  and  18 . Bar  18  is smaller than bar  16  and fits partially inside of bar  16  in telescopic fashion so that the ratchet mechanism  24  can be operated to extend bar  18  relative to bar  16 , thus extending the overall length of the cargo bar  10  to wedge the cargo bar tightly in place between the side walls  12  and  14  (or between the floor and ceiling of the vehicle body). 
     The ratchet housing  26  may take the form of a square tube having end caps  28  and  30  on its opposite ends. Bar  16  extends out of the ratchet housing  26  through an opening  32  formed an end cap  28 . The other bar  18  extends out of the ratchet housing through an opening  34  formed in the other end cap  30 . The interior of the ratchet housing  26  is provided with a pair of partitions  36  and  38  which are spaced apart and which may be secured to the walls of housing  26  by welding or any other suitable manner. The inner end of bar  16  is provided with a tubular collar  40  which extends inwardly from the end of bar  16  around bar  18  such that bar  18  can slide axially within collar  40  as the cargo bar is extended and retracted. The collar  40  has a free end  41  and an enlarged flanged end  42  which is suitably secured to the end of bar  16  (as by welding, for example). The collar  40  extends freely through an opening formed in partition  36 . A compression spring  44  is coiled around the body of collar  40  and acts against the partition  36  at one end and the flange  42  at the other end. 
     Three pawls  46  form an advancement pawl which is included in the ratchet mechanism  24  and which serves to advance bar  18  relative to bar  16  when the ratchet mechanism is operated. The pawls  46  are adjacent to one another and have openings  48  through which bar  18  extends. Bar  18  similarly extends through an opening in partition  38  which is adjacent to the pawls  46 . The pawls  46  are flat plate elements that are adjacent to one another and extend through an opening  50  formed in the top wall of housing  26 . The upper ends of the pawls  46  are thus located outside of the ratchet housing  26 . The pawls  46  are located adjacent to partition  38  in the volume of the ratchet housing  26  between partition  38  and end cap  30 . A compression spring  52  acts against the pawls  46  at one end and against the end cap  30  at the opposite end. 
     The ratchet mechanism  24  also includes a pair of holding pawls  54  which act together to form a holding pawl for the ratchet mechanism. The pawls  54  have openings  56  through which bar  18  extends. The pawls  54  are in the volume of housing  26  located between the partitions  36  and  38 . Pawls  54  extend out of housing  26  at their top ends through the opening  50  and out of housing  26  at their lower ends through an opening  58  formed in the bottom surface of housing  26 . A compression spring  60  is compressed between the pawls  54  at one end and partition  38  at the other end. 
     The ratchet mechanism  24  has an elongated handle  62  carrying a ratchet head  64  on one end. The ratchet head  64  has an irregular shape and is pivotally mounted to a horizontal pin  66  which extends between a pair of brackets  68  that are spaced apart and extend upwardly from the top of the ratchet housing  26 . The ratchet head  64  is located between the brackets  68 . The ratchet head  64  is formed on its free end as an eccentric cam  70  having a curved edge that is eccentric relative to the axis formed by pin  66 . The head  64  also includes a projecting foot  72  which projects downwardly at a location spaced from the cam  70 . The foot  72  has an angled surface  74  which faces the holding pawls  54 . Another angled surface  76  is formed on the projecting foot  72  on the side opposite surface  74 . A flat bottom surface  78  is formed at the bottom of the foot  72  and connects the two angled surfaces  74  and  76 . 
     The cam  70  has an elongated opening or slot  80  through which pin  66  extends to mount the ratchet head  64  to the ratchet housing. The pin  66  is located such that the cam  70  operates in the space between the advancement pawls  46  and the holding pawls  54 . The elongated shape of the slot  80  allows the ratchet head to shift on the pin  66  for a purpose that will be explained in more detail. 
     In use, the cargo bar  10  is extended between the opposite walls  16  and  14  of the vehicle body (or between the floor and ceiling). In order to secure the cargo bar  10  in place, the ratchet handle  62  is reciprocated to extend bar  18  relative to bar  16 , thus increasing the overall length of the cargo bar to tightly wedge it between the walls  12  and  14 . 
     As the ratchet mechanism  24  is operated, the advancement pawls  46  are skewed slightly such that they angle to the right from bottom to top. The spring  52  maintains the lower ends of the pawls  46  against the partition  38 , while the cam  70  engages the upper portions of the pawls  46 . The holding pawls  54  are skewed oppositely and angle slightly to the left from bottom to top. The spring  60  maintains the lower ends of pawls  54  against the left edge of opening  58 . The upper ends of the pawls  54  are engaged by the cam  70 . 
     During each upward stroke of the ratchet handle  62 , the eccentric cam  70  is pivoted such that the upper end portions of pawls  46  and  54  are forced further apart. This forces the advancement pawls  46  to a more skewed position, and pawls  46  thus grip bar  18  and extend it to the right. The upper ends of the holding pawls  54  are forced to the left and allow bar  18  to extend to the right while biting into it to prevent it from retracting to the left. When the ratchet handle  62  is swung downwardly to complete the stroke, the holding pawls  54  act against bar  18  to hold it in place and prevent it from retracting. 
     During normal operation of the ratchet mechanism  24  in this manner, the bottom surface  78  of the projecting foot  72  contacts the top of ratchet housing  26  at portion  82  thereof adjacent to the opening  50  as shown in FIG.  3 . The surface  82  thus serves as a stop that limits the downward pivoting of the lever  62  in normal operation. 
     When it is desired to remove the cargo bar  10 , the holding pawls  54  must be released so that bar  18  can retract into bar  16 . Release of the holding pawls  54  requires that their upper ends be forced to the right in order to overcome the tension force that is applied by the bar  10 . In order to accomplish this, the handle  62  is pushed to the right far enough that the bottom surface  78  of foot  72  clears the surface  82  on housing  26  and can enter the opening  50 . Shifting of the ratchet head  64  to the right is accommodated by the slot  80 . The pin  66  is normally located in the right portion of slot  80  as shown in FIGS. 2 and 3 when the ratchet mechanism is operated normally. When the ratchet handle and head are moved to the release position of FIG. 4, the pin  66  is located in the left end portion of slot  80 . The slip connection provided by the pin  88  and slot  80  allows the foot  72  to enter opening  50  and thus move downwardly farther than it can during normal operation of the ratchet mechanism. 
     Once the handle  62  has pushed the head  64  to the right far enough that foot  72  can clear the top of housing  26  and enter opening  50 , the ratchet handle  62  can be moved further downwardly which causes the angled surface  74  to slide along the edge portion of one of the holding pawls  54 . Due to the angled or inclined orientation of surface  74 , its movement downwardly along the upper end portion of the pawls  54  forces the upper end portions of the pawls to the right by camming or wedging action which releases them from their holding position on the bar  18 . Bar  18  is then freed and can retract into bar  16  so that the cargo bar  10  is released and can be removed. In this manner, the length of lever  62  is effectively used to provide leverage which allows the ratchet mechanism to be released easily and without the need to forcefully strike the holding pawls with a hammer or other tool. 
     The cargo bar  10  has a force limitation feature which is provided in part by the collar  40 . As bar  18  is progressively extended relative to bar  16 , the flange  42  becomes progressively closer to the partition  36 , thus progressively compressing spring  44 . Spring  44  is selected such that when a maximum allowable force (300 pounds, for example) is applied by the cargo bar  10 , the free end  41  of collar  40  is butted against the closer holding pawl  54 , as shown in FIG.  3 . Once the end of collar  40  is butted against pawl  54 , the upper ends of pawls  54  cannot be forced to the left due to the interference of the collar  40 . Consequently, the eccentric cam  70  has insufficient space in which to operate between the pawls  46  and  54 , and the ratchet mechanism is prevented from operating to further extend the bar  18 . In this manner, once the desired maximum force limit is reached, the ratchet mechanism  24  cannot be operated in order to increase the force applied by the cargo bar  10 . As a result, undue force cannot be applied by the cargo bar to possibly damage the vehicle walls  12  and  14 . 
     It should be understood that the easy release feature exhibited by the cargo bar of the present invention can be provided without the force limitation feature. Conversely, the force limitation feature can be provided separately and independently from the easy release feature. However, the easy release feature and the force limitation feature can be conveniently and effectively combined in a single unit, and it is thus preferred that the cargo bar  10  be provided with both features in combination. 
     It should also be understood that the ratchet mechanism may be provided with any desired number of advancement pawls  46  or any desired number of holding pawls  54 , and that the construction and shape of the pawls can be varied without detracting from the benefits of the present invention. 
     From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.