Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
1998-05-13
2001-10-30
Hurley, Kevin (Department: 3619)
Land vehicles
Wheeled
Articulated vehicle
C280S432000, C280S901000
Reexamination Certificate
active
06308977
ABSTRACT:
The present invention relates generally to a self-adjusting fifth wheel hitch assembly for use on pickup trucks and similar vehicles used to tow fifth wheel trailers. The hitch assembly having the features of the present invention allows fifth wheel trailers to be towed using short bed pickup trucks and other trucks having a relatively short distance between the rear portion of the passenger compartment and the rear axle.
BACKGROUND OF THE INVENTION
Fifth wheel trailers and tow vehicles for fifth wheel trailers are generally well known in the art. Fifth wheel trailers are much longer, roomier, and heavier than typical tent campers and travel trailers, and thus a fifth wheel trailer typically requires a specially modified, relatively heavy tow vehicle such as a heavy duty pickup truck. The front portion of a fifth wheel trailer extends over the rear portion of the tow vehicle so that a portion of the trailer's weight is carried directly over the rear axle of the tow vehicle. In order to accommodate the weight of the trailer a special hitch assembly is required.
The front portion of the trailer includes a pin box which includes a support plate and a downwardly extending hitch pin. A base plate having an aperture and a latch mechanism is mounted to the tow vehicle, and the support plate carried by the pin box rests on the base plate with the hitch pin secured in the aperture by the latch mechanism. The support plate rotates relative to the base plate with the hitch pin acting as a pivot point. Typically, grease or other lubricant is applied between the support plate and the base plate. The fifth wheel trailer is thus able to pivot relative to the tow vehicle about a vertical axis to facilitate cornering and parking. Normally, the hitch assembly is mounted directly over or a short distance in front of the rear axle of the tow vehicle in order to maintain proper weight distribution.
The vehicle most commonly used to tow fifth wheel trailers is a pickup truck having an 8 foot bed length. On such a truck, there is typically at least 53 inches between the centerline of the rear axle and the rear of the cab. The maximum width for a fifth wheel trailer is 102 inches as dictated by federal highway regulations, which amounts to 51 inches on each side of the pivot point. Thus, in order to prevent contact between the trailer and the cab during cornering, there must be at least 51 inches of clearance between the pivot point and the rear of the cab (sometimes more depending on the fore/aft location of the pivot pin relative to the front of the trailer).
Recently, there has been a consumer trend towards extended cab pickup trucks, which have longer, roomier cabs. These trucks have greatly expanded interior cargo volume and also have specially designed rear jump seats for accommodating additional passengers. Unfortunately, most of these extended cab pickups are built on a standard wheelbase chassis because consumers prefer the driving characteristics of a shorter truck, and accordingly, the bed of these trucks is typically 6 feet long rather than 8 feet long. Although these shorter bed pickups have the towing capacity to handle fifth wheel trailers, they do not have enough clearance between the axle and the rear of the cab to allow the trailer to pivot to 90 degree angle without contacting the cab, which could damage the truck and severely injure any occupants. In most circumstances, a fifth wheel trailer will contact the cab of a short bed pickup at angles much less than 90 degrees.
A number of approaches have been contemplated to adapt fifth wheel trailers to short bed pickup trucks, all of which have their drawbacks. One possible approach is to use a hydraulically operated sliding base to force the hitch assembly, and hence the pivot point, rearward away from the truck cab. Such a system would be expensive, difficult to maintain and would have to be driver actuated. Hence such a system would involve a significant delay or lag time. In an accident such as a jackknife such a system would operate too slowly to prevent the trailer from contacting and most likely damaging the cab.
Another approach, which also uses a sliding base, requires the operator to exit the truck, unlock the base, lock the brakes on the trailer and pull the truck forward. This temporarily moves the pivot point rearward so that the trailer can pivot relative to the truck to a certain extent without contacting the cab. However, before resuming driving, the driver must lock the trailer brakes, back the truck towards the trailer, again exit the truck and lock the sliding hitch, and return to the truck. Obviously, such a system is impractical in many situations, such as negotiating sharp turns in traffic, and is practically useless in an emergency.
Accordingly, there exists a need for an improved sliding hitch assembly that allows fifth wheel trailers to be towed using short bed pickup trucks, but which prevents contact between the trailer and the truck during normal operations. There also exists a need for a sliding hitch assembly that slides automatically in response to pivoting movement between the trailer and the tow truck and that does not require the expense, maintenance and lag time of hydraulic systems, and does not require the operator to exit the vehicle in order to lock or unlock the hitch assembly.
SUMMARY OF THE INVENTION
The sliding hitch assembly according to the present invention allows fifth wheel trailers to be towed safely and conveniently using short bed pickup trucks. The present sliding hitch assembly automatically moves rearward away from the truck cab in response to the pivotal movement between the trailer and the truck that typically occurs during normal driving situations such as cornering, parking, etc. The hitch assembly responds almost immediately to any turns, thus substantially eliminating any lag or delay, and no operator input is needed at any time. Thus in normal operating conditions, and even in many jackknife situations, the hitch assembly slides rearward far enough so that the trailer will not contact the truck cab.
The present sliding hitch assembly includes a sliding, rotating base plate that is mounted on a pair of rods. A lever arm extends from the base plate, and a cam follower attached to the end of the lever arm engages a stationary slot that extends substantially perpendicular to the rods. Any rotation of the base plate causes the cam follower to move within the slot towards one slot ends, which in turn causes the base plate to slide back and forth along the rods. Thus, as the base plate is rotated the base plate moves between a forward position, in which the cam follower is at the center of the slot, and a rearward position, in which the cam follower is near one of the slot ends. When in the forward position, the hitch pin receiving aperture, and thus the pivot point of the trailer, is directly or slightly in front of the axle centerline. As the base plate rotates relative to the truck, the lever arm mechanism causes the base plate to slide rearwardly on the rods, effectively moving the pivot point of the trailer away from the rear of the truck cab.
In order to effectuate this sliding movement, the sliding base plate must pivot relative to the truck in tandem with the trailer, and accordingly the connection between the trailer and the truck must be modified. As in the prior art, the base plate aperture includes a latch mechanism to receive and retain the hitch pin. However, the present base plate includes a rectangular cutout or depression surrounding the base plate aperture. The standard pin box is also modified by adding a rectangular locking plate to the support plate, with the locking plate effectively being concentric with the hitch pin. When the hitch pin is positioned in the base plate aperture according to standard practice, the locking plate on the pin box registers with and locks into the cutout in the base plate. Thus, when the trailer pivots relative to the tow truck during turning, cornering, etc., the support plate carried by the pin box and the base plate locked
Pulliam Andrew
Pulliam Randall
Baker & Daniels
Hurley Kevin
LandOfFree
Sliding hitch for fifth wheel trailers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sliding hitch for fifth wheel trailers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sliding hitch for fifth wheel trailers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2612389