Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
1999-11-10
2001-08-14
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Articulated vehicle
C280S442000, C280S446100, C280S445000
Reexamination Certificate
active
06273446
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to steerable trailers and more particularly to system that controls steering of a trailer.
BACKGROUND OF THE INVENTION
A great difficulty in the operation of articulated vehicles is control of the towed component, particularly while backing. Drivers of large tractor/trailer vehicles develop a high degree of skill in this procedure but only after training and substantial driving experience. However, smaller trailers are widely used by non-professional drivers for diverse purposes, for example, such as towing recreational trailers or small rental trailers and the like. Often these trailers must be backed in to locations which are confined or otherwise limited in size. Many drivers have little or no experience in this procedure and are able to barely maneuvered the trailer during the back up operation. This often can result in property damage and/or an embarrassed driver.
It is an object of this invention to provide a trailer which can be steered while being towed, particularly when being backed.
Another object of the invention is to provide a steering system which can sense the relative position of the towing vehicle to the trailer and to control the steerable wheels of the trailer relative thereto.
Yet another object of the invention is to provide a steering system for a trailer which is inactivated when the trailer is moving in a forward direction to allow for normal forward pulling operation.
SUMMARY OF THE INVENTION
The present invention relates to a steering system for trailers having one or more axles, one axle of which carries steerable wheels. The mechinism operates when the trailer is moving to control the direction of the wheels by sensing the relative position of the towing vehicle to the trailer. In one embodiment of the invention the steering system includes a locking assembly which operates to lock the steerable wheels of the trailer when the trailer is moving forward for towing the trailer in the conventional fashion.
In more detail, the trailer is provided with a trailer hitch which extends forward to attach to a corresponding hitch on the towing vehicle. An extending arm, referred to as the position arm, is secured to the towing vehicle and the end of the piston rod of a hydraulic master cylinder carried by the trailer is pivotally attached to the piston arm. A slave cylinder carried by the trailer adjacent to the steerable wheels is in hydraulic communication with the master cylinder for pivoting the steerable wheels in response to the movement of the master cylinder piston rod. A pair of hydraulic lines communicate between the master cylinder and the slave cylinder to extend or retract the slave cylinder piston rod.
The steerable wheels are rotatably and pivotally connected to an axle by conventional steering knuckles. A pivot arm is affixed to the steering knuckle of one of the wheels and to a tie rod extending from the steering knuckle of the opposite wheel. The extending end of the piston rod of the slave cylinder is connected to one of the steering knuckles. During the towing operation, steering the towing vehicle changes the relative angle between the position arm and the trailer hitch causing of the piston rod of the master cylinder to extend or retract to compress hydraulic fluid through one or another of the hydraulic lines which in turn activates the slave cylinder to extend or withdraw its piston rod. Extension or retraction of the slave cylinder piston rod acts on the pivot arm to turn the steerable wheels to steer the trailer in the essentially the same track as the towing vehicle.
In one embodiment of the invention a clutch and lock system locks the steerable wheels of the trailer in a direction parallel to the center axis of the trailer so they cannot be steered while the trailer moves forward. A valve in both hydraulic lines is positioned to recycle hydraulic fluid to the master cylinder so that activation of the master cylinder during normal forward towing is not communicated to the pivot arm. Upon reversing the direction of rotation of the steerable wheels, the clutch and lock system releases to activate the steering system.
REFERENCES:
patent: 3753580 (1973-08-01), Folkert
patent: 3834480 (1974-09-01), McGee
patent: 4219208 (1980-08-01), Fuller et al.
patent: 4345775 (1982-08-01), Merrifield
patent: 4824135 (1989-04-01), McGregor
patent: 5244226 (1993-09-01), Bergh
patent: 3919561 (1990-12-01), None
patent: 1498635 (1989-08-01), None
Johnson Brian L.
Magic Axle Systems Ltd
Vanderburgh John E.
Yeagley Daniel
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