Land vehicles – Wheeled – Running gear
Reexamination Certificate
1999-07-12
2001-08-28
DePumpo, Daniel G. (Department: 3611)
Land vehicles
Wheeled
Running gear
C267S064120, C188S265000, C188S300000
Reexamination Certificate
active
06279932
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to tandem axles of semi trucks, and is particularly concerned with a lock pin release device for assisting in release of the lock pin of a tandem axle to permit adjustment of the position of the tandem wheels of the trailer depending on the load.
The tandem wheels of a semi truck trailer are releasably secured in position by means of oppositely directed lock pins engaging in any one of a series of openings in the trailer frame. The lock pins are linked to the tandem axle. The wheels often have to be moved to a different position to provide the best support depending on the load distribution in the trailer. The tandem axle must be released in order to re-position the wheels. The tandem axle lock pins are normally released manually by the driver pulling on a release rod which is linked to the two lock pins by means of a modified bell crank arrangement. It can be very difficult for the driver to pull out the release rod manually, particularly when the lock pins are not properly aligned in the respective frame openings. The driver may return to the truck cab and move the truck slightly in order to attempt to center the lock pins better. After each movement, the driver must return to the release rod and attempt to pull it again, unless a second person is available to pull the rod after each movement of the truck. Thus, it may take the driver 30 minutes or more to re-position the tandem wheels.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new and improved device and method for assisting in release of the tandem axle of a semi truck.
According to one aspect of the present invention, a lock pin release device for a semi truck is provided, which comprises a cylinder having opposite first and second ends, a piston slidably mounted in the cylinder, a shaft secured to the piston and extending out of the first end of the cylinder, the shaft having an outer free end, an enlarged head at the outer free end of the shaft having a flat face for bearing against the frame of a semitrailer adjacent a tandem axle release rod, the piston and shaft being movable between a retracted position in which substantially all of the shaft is within the cylinder and the head is located adjacent the first end of the cylinder, and an extended position in which a major portion of the shaft extends out of the cylinder; a biasing mechanism in the cylinder between the second end of the cylinder and the piston biasing the piston and shaft into the extended position, a releasable latch mechanism at the second end of the cylinder for releasably securing the shaft in the retracted position, and a hook member projecting from the cylinder for releasable engagement with a handle of a tandem axle release rod, whereby, when the flat face of the head is placed against the frame with the hook engaging the release rod handle and the cylinder projecting outwardly from the frame, and the latch mechanism is released, the piston and shaft move towards the extended position to pull out the release rod and release the semi tandem axle.
Preferably, the biasing mechanism comprises compressed gas between the second end of the cylinder and the piston. When the latch is released with the device in position and the hook member engaging the release rod handle, cylinder pressure is applied to the release rod. If the lock pin or pins are not properly centered, for example if they are engaging the edge of the opening to prevent release, the truck driver can simply move the truck slightly. As soon as the lock pins are properly aligned, the piston shaft will be able to extend and pull out the release rod. The fully extended second end of the cylinder will be visible in the driver's side mirror, so that the driver will know when the tandem axle is released.
The latch mechanism preferably comprises a latch member pivotally mounted in a diametrical groove in the first end of the cylinder, with a through bore through which the piston shaft slidably projects. The piston shaft has an indent or groove adjacent the head, and the latch member has a latch finger movable between a first position engaging the indent to hold the head of the shaft in the retracted position adjacent the first end of the cylinder, and a second position in which the latch member is pivoted slightly to move the latch finger out of the indent. Preferably, the hook member projects from the opposite side of the latch member. A biasing spring urges the latch finger into the first position.
The cylinder may be provided with an indicator extension at its second end which is of sufficient length and size to be readily visible to the truck driver when the cylinder and release rod are extended. This avoids the need for the truck driver to have to move the truck, step out of the cab to check whether the release rod is movable, return to the cab to move the truck again, and repeat the process until the release rod is released. The tool or device of this invention reduces this to a one step operation, comprising simply engaging the piston head against the frame and the hook over the release rod handle, releasing the latch, and moving the truck one time only if necessary until movement of the cylinder is seen from the cab.
According to another aspect of the present invention, a method of releasing a semi truck tandem axle is provided, which comprises the steps of compressing a piston rod into a retracted position in a cylinder, latching the piston rod in the retracted position, engaging an enlarged head at the outer end of the piston rod against a semitrailer frame adjacent a manual release rod for the tandem axle so that the cylinder projects perpendicularly outwardly from the frame, engaging a hook on the cylinder around a handle of the release rod, and releasing the latch to release the piston rod so that the piston rod is urged outwardly from the cylinder and bears against the frame to bias the cylinder and release rod outwardly away from the frame in order to release the tandem axle. If the release rod is not able to move, due to the tandem axle lock pin or pins binding against the edge of the frame opening or openings, the method includes the step of moving the truck until the or each lock pin is aligned with respective frame opening, permitting the cylinder and release rod to move outwardly.
The release device or tool and method of this invention considerably reduces the time and effort required to re-position the tandem wheels of a semi-truck. As noted above, it sometimes took 30 minutes or more to release the tandem axle by manually pulling out the release rod. With the release device of this invention, it is possible to release the tandem axle in less than five minutes.
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White James R.
White William G.
Brown Martin Haller & McClain LLP
DePumpo Daniel G.
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