Abstract:
The invention provides an easily adjustable foot-operated pedal assembly, such as a brake pedal for use in heavy equipment, that can be placed in multiple positions to accommodate people of differing heights and body shapes. The pedal is mounted in an assembly including a dual linkage operating apparatus having one element of that linkage that freely rotates about a shaft. A second link of the pedal linkage is connected to a fixed link through an adjustment mechanism. The fixed link is fixedly mounted to the same shaft as the pedal link. The adjustment mechanism incorporates a latch that has multiple settings yielding three or more pedal positions. The pedal is urged upwardly to effect adjustment to raise the pedal. A latch bar of the pedal assembly is urged up to allow lowering of the pedal.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to adjustable foot pedals used as operator input devices in various types of equipment. One such application would be as a brake pedal in a heavy duty vehicle, such as a truck, tractor, fork lift truck, or an armored military vehicle. 
     In machinery of all types and particularly heavy duty vehicles, operators of different heights can be required to operate the machinery. In one applicable embodiment, that being a heavy duty vehicle, a suspended or floor mounted brake pedal is not efficient or comfortable to everyone in the spectrum of individuals that may be asked to operate the vehicle. This is especially true if the seat of the vehicle cannot be adjusted to accommodate persons of different sizes. It is well known to provide a height adjustable brake pedal. Some of these brake pedals or machine operating pedals will have releasable adjusting links on the underside of the brake pedal. Such location could interfere with the movement of the brake pedal. 
     In addition to the vehicle applications mentioned above it is contemplated that an adjustable pedal of the type disclosed herein could find applicability in other applications. For instance, in a factory environment there are many machines that require foot activated input from the machine operator. In particular situations where the machine operator is sitting in a seat or a chair the adjustability of the foot pedal could be a desirable feature. From an ergonomic standpoint the proper leg extension of the operator can reduce stress related injuries and lead to higher productivity and operator comfort on the job. 
     Studies have indicated that a significant portion of the male population can be accommodated by a foot pedal design having an extension of a given travel or “throw.” For instance, approximately ninety five percent of men in the age group typical of men in the United States military can effectively operate a foot actuated control pedal if the travel or throw of the pedal linkage is restricted to twenty eight degrees and the pedal is adjustable from a positive eighteen degree position to a negative eighteen degree position. This adjustment and travel range is also an effective operating range for five percent of the female population. In the case of heavy machinery operation this population range for both males and females will accommodate the majority of operators. 
     In a study performed at the FMC Corporate Technology Center in Santa Clara, Calif. in April 1997 the existing M88A2 brake pedal operation was evaluated. Through extensive use of a program called “JACK” (a human figure modeling and analysis software program) the inventors were able to determine the movement, reach and stretch requirements for both ninety-five percent male and five percent female operators. Industry standards and particularly military specification standards such as MIL-STD-1472 were not being attained and accommodated by all pedal systems. 
     To meet the scope of the range of potential operators of heavy machinery it is desirable to have a foot operated pedal that can have at least three adjustment positions. These would include an intermediate height position, a first extension position, which provides an eighteen degree adjustment up (or positive adjustment) from the intermediate position and a second extension position, which provides an eighteen degree adjustment down (or negative adjustment) from the intermediate adjustment position. 
     It is also desirable that total travel of the pedal be approximately twenty eight degrees in any adjustable configuration. That is to say that if the throw or travel of the pedal is about twenty eight degrees of rotary or arcuate motion the operation of the pedal linkage will be comfortable and efficient for the normal heavy machinery operator. 
     SUMMARY OF THE INVENTION 
     The invention provides a foot pedal using two separate levers or linkage links, which pivot around a common shaft and are connected together by an adjustable latch. The position of the foot pedal relative to the floor of the host vehicle or relative to the seating location of the operator of the host vehicle will be adjustable by means of a notched link in the pedal operating linkage. An arcuate slot in the assemble will prevent the over extension of the linkage thereby providing a mechanism to minimize the opportunity of the pedal getting out of adjustment. That is, the pedal will still have a range of operating travel or scope that will assure the usefulness of the pedal assembly. 
     One object of the invention to provide an adjustable pedal assemble that will be efficient when used by ninety five percent of all males and of five percent of the females between the ages of eighteen and fifty of the population of United States. 
     It is another object of the invention to provide a easily adjustable pedal that can be adjusted as the vehicle is being operated. 
     It is another object of the invention to provide an adjustable pedal that is comfortably accommodates people of different heights when they are seated in non-adjustably operator&#39;s seats. 
     It is another object of the invention to provide an adjustable pedal, where the axis of rotation for adjustment is the same as the axis of rotation in the use of the pedal. 
     A further object of the invention is to provide a pedal assembly that will have the same range of operating motion at each end of the adjustment range, that is that regardless of the position of the pedal adjustment location there will still be a range of pedal motion that will be sufficient to operate the downstream mechanism controlled by the pedal linkage. 
     On other object of the invention is to provide a heavy duty pedal assemble that is purely mechanical in operation making it appropriate for use in heavy duty operating environments. 
     It is also an object of the invention to provide a pedal design that limits total pedal travel from the existing fifty degrees of pedal travel to a new total travel of approximately twenty-eight degrees of arcuate pedal travel regardless of the pedal adjusted stop position. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be understood through a reading of this specification in conjunction with a perusal of the following drawing figures. Unless specifically noted, it is intended that the words and phrases in the specification and the claims are given the ordinary and accustomed meaning to those of ordinary skill in the applicable arts. If any other special meaning is intended for any word or phrase, the specification will clearly state and define the special meaning. 
     Likewise, the use of the words “function” or “means” in the Detailed Description of the Drawings is not intended to indicate a desire to invoke the special provisions of 35 U.S.C. 112, Paragraph 6, to define the invention. To the contrary, if the provisions of 35 U.S.C. 112, Paragraph 6 are sought to be invoked to define the inventions, the claims will specifically state the phrases “means for” or “step for” and a function, without also reciting in such phrases any structure, material or act in support of the function. Even when the claims recite a “means for” or “step for” performing a function, if they also recite any structure, material or acts in support of that means or step, then the intention is not to invoke the provisions of 35 U.S.C. 112, Paragraph 6. Moreover, even if the provisions of 35 U.S.C. 112, Paragraph 6 are invoked to define the inventions, it is intended that the inventions not be limited only to the specific structure, material or acts that are described in the preferred embodiments, but in addition, include any and all structures, materials or acts that perform the claimed function, along with any and all known or later-developed equivalent structures, material or acts for performing the claimed function. 
    
    
     The drawing figures presented herein for illustration purposes include: 
     FIG. 1 is a perspective view of a preferred embodiment of the foot operated pedal assembly in a position intermediate two extremes of adjustment; 
     FIG. 2 is a perspective view of the foot operated pedal assembly shown in FIG. 1 adjusted to an extreme position wherein the pedal is in a “high” position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view of a preferred embodiment of an adjustable pedal assembly  10 , comprising a shaft  12 , a pedal link or lever  13 , a fixed link or lever  14 , and a adjusting mechanism  15 . The pedal lever link  13  has a first end and a second end. The first end of the pedal link  13  is rotatably mounted to the shaft  12 , so that the pedal link  13  may rotate with respect to the shaft  12 , with the shaft  12  being the center of rotation for the pedal link  13 . The second end of the pedal link  13  supports a pedal  17 . The fixed link  14  has a first end and a second end. The first end of the fixed link  14  is fixed to the shaft  12  so that the fixed link  14  cannot rotate freely with respect to the shaft  12 . Displacement of the fixed link  14  perpendicular to the center line of the shaft  12  causes rotation of the shaft  12 . In the preferred embodiment, a key  19 , kept in a keyway formed in the shaft is used to fix the fixed link  14  to the shaft  12 . The shaft  12  is connected to linkage of a brake system of a heavy duty vehicle. 
     The adjusting mechanism  15  is connected between the second end of the pedal link  13  and the second end of the fixed link  14 . In this embodiment, the adjusting mechanism  15  comprises a latch bar  21  and a latch mechanism generally  22 . The first end of the latch bar  21  is mechanically connected to the second end of the pedal link  13 , through a mounting bracket  50 . The latch bar  21  is freely rotatable with respect to the pedal link  13 . The latch bar  21  has three notches, two visible and marked as  24 . Fewer or more notches could be used to increase the range of selections available however in the preferred embodiment three notches has worked well. These notches  24  extend from a center line, not shown, in the latch bar  21  to a bottom edge of the latch bar  21 . The notches are angled so that going from the center line to the bottom edge of the latch bar the notches  24  are angled towards the first end of the latch bar  21  which is the end furthest away from the pedal assembly. The latch mechanism, generally  22 , comprises a support bar  26  having a first end and a second end. 
     The first end of the support bar  26  is rotatably connected to the second end of the fixed link  14 . 
     The second end of the support bar  26  is split in the fashion of a clevis, so that the support bar  26  forms a “Y” shape. The latch bar  21  is restrained in the clevis gap, slot or space of the support bar  26 . A catch, comprising a clevis pin  27 , is connected to the second end of the support bar  26 . The pin  27  bridges the clevis gap or split in the support bar  26 . The clevis pin  27  is a diameter that allows the clevis pin  27  to fit into each of the three notches  24 . The latch bar  21  is inboard in the clevis slot relative to the clevis pin  27  location, as shown in FIG.  1 . 
     A hinge mounted pawl  29  is rotatably connected to the support bar  26 , so that the pawl  29  rests on and is urged against the latch bar  21  in the normal operating mode of the pedal latch assembly. A first spring  31  is connected between the pawl  29  and the support bar  26  on a first side of the support bar  26 , and a second spring  32  is connected between the pawl  29  and the support bar  26  on a second side of the support bar  26 . The springs are anchored at one end to the support bar  26  and at the other end to a location on the pawl  29  outboard of the hinge pin or pivot point of the pawl  29  to support bar  26  with the spring line relatively below the pawl pivot point. This will urge the pawl  29  to rotate toward the support bar and keep tension on latch bar  21 . 
     A first end of the support bar shaft  23 , in the form of a shaft  35 , forms a stop means link which is inserted through the arcuate aperture  36  in the pedal link  13 . 
     In operation, the adjustment point of the pedal assembly  10  embodied in FIG. 1 is in either a first, second, or third position. FIG. 1 shows the pedal assembly  10  in the second position, with the clevis pin  27  being in the second notch of the latch bar  21 . 
     When a force is applied to the pedal  17  in a downward motion, the pedal link  13  rotates around the shaft  12  in a clockwise direction as shown in the projection. The movement of the pedal link  13 , puts a compression force on the latch bar  21 . The compression force on the latch bar  21  places a force at the second notch onto the clevis pin  27 . The angle of the notches  24  prevents the compression force from moving the clevis pin  27  out of the second notch. The force on the clevis pin  27  causes the fixed link  14  to also rotate in a clockwise direction. This will result in shaft  12  rotation in a clockwise direction, which causes the shaft  12  to initiate operation of the downstream mechanism such as a master cylinder in a hydraulic braking system. 
     To raise the pedal  17  from the intermediate position shown in FIG. 1 to the extreme position shown in FIG. 2, the operator&#39;s foot is used to displace the pedal  17  upward, which causes the pedal link  13  to rotate around the shaft  12  in a counter clockwise direction. The movement of the pedal link  13 , pulls the latch bar  21  towards the pedal  17 . Since the pedal link  13  is not fixed to the shaft  12 , the shaft  12  and the fixed link  14  remain stationary. As the latch bar  21  moves in the direction of the pedal  17 , the angle of the second notch allows the clevis pin  27  to push up on the link bar  21  moving the link bar  21  upward against the pawl  29  and forces from the first and second springs  31 ,  32 . When the latch bar  21  reaches sufficient height, the clevis pin  27  escapes from the confines of the second notch and the latch bar  21  is moved so that the third notch is moved towards the clevis pin  27 . When the opening of third notch reaches the clevis pin  27 , the follower  35  reaches a first end of the aperture  36 , which prevents the pedal link  13  from being moved any further. When the upward force, generated by an operator&#39;s foot or hand, on the pedal  17  is removed, gravity forces acting on the pedal link  13  pulls the pedal  17  downward, which rotates the pedal link  13  in a clockwise direction, causing the pedal link  13  to push on the latch bar  21 . In addition to the force of gravity on the latch bar  21 , the pawl  29  and forces from the first and second springs  31 ,  32  causes the clevis pin  27  to slide into the third notch, as shown in FIG.  2 . 
     When a force is applied to the pedal  17  in a downward motion, such as when an operator depresses the pedal, the pedal link  13  rotates around the shaft  12  in a clockwise direction. The movement of the pedal link  13 , puts a compression force on the latch bar  21 . The compression force on the latch bar  21  places a force at the third notch onto the clevis pin  27 . The angle of the notches  24  prevents the force from moving the clevis pin  27  out of the second notch. The force on the clevis pin  27  causes the fixed link  14  to rotate in a clockwise direction. This will rotate the shaft  12  in a clockwise direction, which causes the shaft  12  to rotate as well and ultimately initiate braking. 
     To lower the pedal  17  from the third position, so that the pedal assembly  10  is able to accommodate people that prefer a lower pedal location, the operator&#39;s foot or hand is used to displace the latch bar  21  upward against the forces of gravity and the pawl  29  with its first and second springs  31 ,  32 . This will cause the clevis pin  27  to become disengaged from the third notch. The force of gravity on the pedal link  13  causes the pedal link  13  to rotate in a clockwise direction, which pushes on and moves the link bar  21  until the follower  35  reaches a second end of the aperture  36 . The interference between the follower  35  and the second end of the slot  36  prevents the pedal link  13  from being moved any further. When the upward force on the latch bar  21  is removed, gravity on the latch bar  21  and pawl  29  and the forces from the first and second springs  31 ,  32  pull the latch bar  21  downward, so that the clevis pin  27  enters the first notch. The first notch location representing the extreme of travel in the bottom or lowest position. 
     When a force is applied by an operator to the pedal  17  in a downward motion, the pedal link  13  rotates around the shaft  12  in a clockwise direction. The movement of the pedal link  13 , puts a compression force on the latch bar  21 . The compression force on the latch bar  21  places a force from the first notch onto the clevis pin  27 . The angle of the notches  24  prevents the force from releasing the clevis pin  27  from its location in the first notch. The force on the clevis pin  27  causes the fixed link  14  to rotate in a clockwise direction, which rotates the shaft  12  in a clockwise direction. This causes the shaft  12  to initiate linkage displacement with resulting braking in an embodiment used to actuate a brake. 
     Because the preferred embodiment set forth in this specification does not use a link directly below the pedal, the pedal location relative to a floor surface may be relatively close. Since the fixed link  14  and the pedal link  13  have the same axis of rotation, all the force applied to pedal is transferred to the brake system. Given this geometry the position of the pedal in its adjustment location will not cause an increase the angle of travel. 
     As can be scene from the above disclosure the pedal assembly is easy to adjust. Simply pulling up on the pedal will move the adjustable pedal from the “lowest” position to the intermediate position or from the intermediate position to the “highest” position. To move the pedal from the “highest” position to the intermediate position or from the intermediate position to the “lowest” position the operator will simply lift up on the latch bar  21 . The follower and aperture, prevent the pedal from being moved too far. 
     Other embodiments of the invention may use other adjusting mechanisms connected between the fixed link and the pedal link. The aperture  36  in the pedal link  13  forms a cam. Other types of follower and cam devices may be used. The plurality of notches on the latch bar may be replaced by a plurality of pegs, with the single clevis pin being replaced by a single notch in the clevis gap or space. Therefore, the single clevis pin may be a bar or a notch or other device. Latching pin interfaces can be a plurality of notches or pegs or other devices that can be caught by a latching device allowing a plurality of adjustable positions. The latch bar may have two or more adjustable positions. 
     While the preferred embodiment of the present invention has been shown and described herein, it will be appreciated that various changes and modifications may be made therein without departing from the spirit of the invention as defined by the scope of the appended claims. For instance, the preferred embodiment is disclosed in the context of a brake pedal assembly for use in a heavy duty vehicle. The invention of the adjustable pedal linkage could find equal applicability in foot operated equipment such as production work stations in a manufacturing environment. Such alternative embodiments are contemplated by the inventor.