Abstract:
A loader which can provide the operator with enhanced safety comprises a vehicle body carrying a canopy and a rotating vehicle axle, a seat bar mounted to the canopy for swinging movement between a raised position and a lowered, operator restraint position, a parking lever shiftable between a brake position and a release position and cooperatingly associated with the seat bar, an axle lock operatively connected to the seat bar and the parking lever and operable to lock or release the vehicle axle, and conditional force delivery mechanism for normally allowing the axle lock to brake the vehicle axle and for causing the axle lock to release the vehicle axle only when the seat bar is in the lowered position with the parking lever shifted into the release position.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a loader and more specifically to a parking brake device for a skid steer loader of the type which, even at the time of a parking lever being released, can keep front axles of the loader locked against any rotating movement until and unless a seat bar is swung down into a lowered position. 
     BACKGROUND OF THE INVENTION 
     Typical loaders include a vehicle body and a canopy mounted on the body for enclosing an operator&#39;s seat. The canopy is provided with a front opening that allows the operator to gain access to the operator&#39;s seat. Some types of loaders are expected to run over rough terrain, make sudden stops and turns, and are subject to sudden tilting and lurching. A skid steer loader is a type of loader in which the operator often encounters rough ride conditions. 
     For the operator to be protected safely under the rough ride conditions, need exists for safety devices that can restrain the body of the operator to the seat. The conventional safety devices include a seat bar pivotally mounted to the opposite side walls of the canopy for swing movement about a pivot axis between a raised position and a lowered position. The seat bar remaining in the raised position permits the operator to take or leave the seat through the front opening of the canopy. The operator would be restrained between the seat and the seat bar in case where the seat bar assumes the lowered position. This will keep the operator adhered to the seat even under the rough ride conditions, thus removing the possibility of the operator being thrown from the seat due to the sudden movement of the loader. 
     In addition to the seat bar, the skid steer loader is provided with a parking brake device which can lock right and left, independently rotatable, front axles against any rotation when the loader is parked and not in service. The conventional parking brake device consists usually of a parking lever manually shiftable between parking and release positions, a rotating disk affixed to the respective one of the right and left front axles and having a plurality of circumferentially disposed notches, a locking pawl releasably engageable with one of the notches of the rotating disk, and a motion delivery mechanism for operatively connecting the parking lever to the locking pawl such that the locking pawl comes into engagement with the notches of the rotating disk as the parking lever is shifted into the parking position. 
     In the course of driving the skid steer loader referred to above, there may take place such an instance that the parking lever is shifted into the release position by the operator to thereby allow movement of the loader while the seat bar is still in the raised position wherein the operator is not restrained at all. In this instance, the operator would be put in danger and sometimes may be thrown out of the seat particularly when the loader begins to move suddenly. In order to avoid such accident, need has existed for a parking brake device which cooperates with the seat bar in order to bring the loader into a non-parking condition. 
     SUMMARY OF THE INVENTION 
     With the foregoing problems in mind, it is therefore an object of the invention to provide a loader that can keep its parking condition until and unless a seat bar is swung down into a lowered, operator restraint position with a parking lever shifted into a release position, thus providing the loader operator with enhanced safety. 
     In accordance with the invention, there is provided a loader comprising: a vehicle body carrying a canopy and a rotating vehicle axle; a seat bar mounted to the canopy for swinging movement between a raised position and a lowered, operator restraint position; a parking lever shiftable between a brake position and a release position and cooperatingly associated with the seat bar; axle lock means operatively connected to the seat bar and the parking lever and operable to brake or release the vehicle axle; and conditional force delivery means for normally allowing the axle lock means to brake the vehicle axle and for causing the axle lock means to release the vehicle axle only when the seat bar is in the lowered position with the parking lever shifted into the release position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, feature, advantages of the invention will become apparent from a review of the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a side elevational view showing a skid steer loader employing an improved parking brake device in accordance with the invention, with portions thereof removed for simplicity; 
     FIG. 2 is a partially enlarged view best showing the coupling manner and the positional relationship of a parking cable and a control cable attached to a seat bar; 
     FIG. 3 is a schematic operational view illustrating the parking brake device wherein a front axle is braked with a parking lever in a brake position and a seat bar in a raised position; 
     FIG. 4 is a view similar to FIG. 3 but illustrating the parking brake device wherein the front axle is still braked with the parking lever remaining in the brake position and the seat bar swung into a lowered position; 
     FIG. 5 is a view similar to FIG. 3 but illustrating the parking brake device wherein the front axle is still braked with the parking lever shifted into a release position and the seat bar swung into the raised position; and 
     FIG. 6 is a view similar to FIG. 3 but illustrating the parking brake device wherein the front axle is released for free rotation, with the parking brake in the release position and the seat bar swung into the lowered position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 and 2, it will be noted that a skid steer loader is partially illustrated by way of example which employs a parking brake device according to the invention. The skid steer loader includes a vehicle body  10  having a side frame  12  and a hood frame  14 . An operator&#39;s seat  16  is mounted on the hood frame  14 , while a canopy  18  is attached to the side frame  12  to enclose the operator&#39;s seat  16 . The canopy  18  consists of a side wall  20  and has a front opening (not shown) for operator entrance and egress. Rotatably mounted on the vehicle body  10  are front and rear rotating vehicle axles  22 ,  24  which are drivingly connected to each other by a chain drive mechanism not shown in the drawings. 
     The skid steer loader also includes a seat bar  26  mounted to the side wall  20  of the canopy  18  for swinging movement about a pivot axis  28  between a lowered, operator restraint position as indicated in phantom lines in FIG. 1 and a raised, non-protective position as shown in solid lines. The seat bar  26  will secure the operator to the seat  16 , when in the lowered position, to protect the operator under rough ride conditions, but will allow the operator to leave the seat  16  when in the raised position. 
     It can be seen that a parking lever  30  is pivotally attached to the side frame  12  of the vehicle body  10  for shifting movement between a brake position indicated in solid lines in FIG. 1 and a release position shown in phantom lines. The parking lever  30  is normally biased toward the brake position by means of a spring  32  and manually shiftable by the operator between the brake and release positions. 
     A right side parking cable  34  is slidably removed in an elongated cable holder  36  which in turn remains fixedly secured to the side frame  12  of the vehicle body  10  by a mounting bracket  38 . Likewise, a left side parking cable  40  is slidably supported on the side frame  12  in a parallel relationship with respect to the right side parking cable  34 . The parking cable  34  is operatively connected at its first end to a locking pawl  42  via an extension spring  44  and a rotary link  46 . The locking pawl  42  is slidably attached to the vehicle body  10  by a mounting bracket  43  for movement between an engaged position wherein it comes into engagement with one of the circumferentially disposed notches  50  of a locking disk  48  which is fixedly secured to the front vehicle axle  22  for rotation therewith as a unit and a disengaged position wherein it is disengaged from the notches  50  of the locking disk  48  to allow rotation of the front vehicle axle  22 . 
     The rotary link  46  is pivotally attached to the vehicle body  10  for rotation about a link pivot axis  52  and has first through third arms  54 ,  56 ,  58  extending in three different directions. The first arm  54  of the rotary link  46  is connected to the parking cable  34 , while the second arm  56  is pivotally coupled with the locking pawl  42 . Retained between the third arm  58  of the rotary link  46  and the vehicle body  10  is a tension spring  60  which resiliently urges the rotary link  46  in a counterclockwise direction so that the parking cable  34  can be pulled away from a control cable set forth later and further that the locking pawl  42  can normally engage with the notches  50  of the locking disk  48  to prevent rotation of the front vehicle axle  22 . 
     A control cable  62  is rigidly affixed at its first end to the seat bar  26  in such a manner that the control cable  62  can be pulled away from the parking cable  34  when the seat bar  26  is swung down into the lowered position but pushed toward the parking cable  34  when the seat bar  26  is raised up. The second ends of the parking cable  34  and the control cable  62  are overlapped at least partially and interconnected with each other by an intermediate coupling plate  64  such that the second end of the control cable  62  can move relative to the second end of the parking cable as the seat bar is swung into the raised position or the lowered position. 
     As clearly shown in FIG. 2, the intermediate coupling plate  64  is fixedly secured to the second end of the parking cables  34 ,  40  and has an aperture  66  which is formed through the thickness thereof to slidably receive the second end of the control cable  62 . A stopper head  68  is provided at the second end of the control cable  62  to prevent separation of the control cable  62  from the coupling plate  64 . It should be appreciated that a compression spring  70  is retained between the mounting bracket  38  and the coupling plate  64  to resiliently bias the coupling plate  64  and hence the parking cables  34 ,  40  toward the control cable  62 , thus avoiding any unwanted loosening of the parking cables  34 ,  40 . A spring retainer shaft  72  projects from the mounting bracket  38  in a concentrical relationship with the compression spring  70 . 
     Referring again to FIGS. 1 and 2, it can be seen that a bell crank  74  is pivotally attached to the side frame  12  of the vehicle body  10  for rotation about a crank pivot axis  76 . The bell crank  74  has a first arm  78  operatively associated with the parking lever  30  by means of a connecting rod  80  and a second arm  82  provided with a cable holder  84  at its free end. The cable holder  84  is adapted to allow sliding movement of the control cable  62  therethrough when the pulling force of pushing force is applied to the control cable  62  by the swinging movement of the seat bar  26 . In the event that the bell crank  74  is rotated by the shifting movement of the parking lever  30 , however, the control cable holder  84  will be swung about the crank pivot axis  76  together with the control cable  62 , thereby pushing or pulling the control cable  62  independently of the seat bar  26 . 
     Operation of the inventive parking brake device employed in the skid steer loader will now be described with reference to FIGS. 3 through 6. 
     As illustrated in FIG. 3, the front vehicle axle  22  is braked in case where the parking lever  30  is in the brake position and the seat bar  26  is in the raised position. Under this condition, no pulling force is applied to the parking cable  34  because the control cable  62  is pushed toward the parking cable  34  firstly by the counterclockwise rotation of the bell crank  74  and secondly by the upward swinging movement of the seat bar  26 . 
     As shown in FIG. 4, the front vehicle axle  22  remains braked in case where the parking lever  30  is in the brake position and the seat bar  26  is swung into the lowered position. Under this condition, no pulling force is applied to the parking cable  34  because the control cable  62  is pushed toward the parking cable  34  by the counterclockwise rotation of the bell crank  74 . 
     As illustrated in FIG. 5, the front vehicle axle  22  remains braked in case where the parking lever  30  is shifted into the release position and the seat bar  26  is swung into the raised position. Under this condition, no pulling force is applied to the parking cable  34  because the control cable  62  is pushed toward the parking cable  34  by the upward swinging movement of the seat bar  26 . 
     As indicated in FIG. 6, the front vehicle axle  22  will be released for free rotation if the parking lever  30  is shifted into the release position and the seat bar  26  is swung into the lowered position. Under this state, pulling force is exerted to the parking cable  34  because the control cable  62  is pulled away from the parking cable  34  firstly by the clockwise rotation of the bell crank  74  and secondly by the downward swinging movement of the seat bar  76 . 
     While the invention has been shown and described with reference to a preferred embodiment, it should be apparent to one of ordinary skill in the art that many changes and modifications may be made without departing from the scope of the invention as defined in the claims.