Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
2000-05-31
2002-04-23
Olszewski, Robert P. (Department: 2167)
Land vehicles
Wheeled
Articulated vehicle
C188S11200R
Reexamination Certificate
active
06375211
ABSTRACT:
TECHNICAL FIELD
The present invention is generally related to self actuated hydraulic trailer braking systems and, more particularly, to an apparatus for alerting an operator of a vehicle which is towing a trailer when the hydraulic brake fluid of the trailer brake system is low.
BACKGROUND OF THE INVENTION
Self-actuated trailer surge brakes are known in the art. Typically, surge brakes have movable sections, a forward unit which is positioned adjacent the ball hitch of the trailer and a rear unit which is positioned rearwardly of the forward unit. The units move with respect to each other when a trailer surges forwardly or rearwardly with respect to the towing vehicle, typically due to the deceleration or acceleration of the towing vehicle. When the rear unit of the surge brake mechanism moves forwardly relative to the forward unit of the surge brake mechanism, the relative movement between the forward and rear units is used to actuate the hydraulic brakes of the trailer. The relative forward motion of the rear unit causes a member on the forward unit to actuate a master brake cylinder on the rear unit. Upon being actuated, the master brake cylinder pressurizes the wheel cylinders to apply the brakes of the trailer.
Although the provision of a surge brake for a trailer prevents the trailer from over running the towing vehicle, the relative movement of the forward and rearward units of the surge brake also creates a potential problem of the jarring of the trailer and towing vehicle when the forward and rearward units clash as they reach the limits of their relative movements.
In order to eliminate the jarring between the forward and rearward units of the surge brake, prior art surge brake mechanisms typically include a hydraulic surge dampener for dampening the relative motion of the rear unit with respect to the front unit of the trailer hitch, and therefore between the trailer and the towing vehicle. The surge dampener relieves the jarring between the units both when the towing vehicle accelerates and decelerates with respect to the trailer. When the towing vehicle accelerates the dampener permits a full and smooth extension of the rear unit with respect to the forward unit, thus eliminating a jarring impact when the front unit fully extends with respect to the rear unit. Likewise, the dampener cushions the movement of the rear unit toward the forward unit of the trailer hitch when the brakes of the vehicle are applied. Typically, the prior art dampener is integrated in parallel with the surge brake mechanism. Without the dampener mechanism, the jarring impact caused by the clash between the rear unit and the forward unit would prematurely decrease the life span of the surge brake mechanism.
However, a problem with such prior mechanisms is that the master brake cylinder can be depleted of hydraulic fluid without the knowledge of the operator of the vehicle. The brake assembly does not give the vehicle operator an indication that the hydraulic brake fluid is depleted and the brakes are not operable.
SUMMARY OF THE INVENTION
Briefly described, the present invention is directed to a self actuated hydraulic braking mechanism for a trailer which includes a master cylinder and a hydraulic dampener, and a single brake fluid reservoir for supplying brake fluid to both the master cylinder and to the hydraulic dampener. When the brake fluid becomes dissipated from the reservoir, it eventually becomes dissipated or “starved” from the dampener and the master cylinder. When there is an inadequate amount of brake fluid in the dampener the dampener begins to fail, in that it begins to inadequately suppress the jarring between the surging of the trailer toward the towing vehicle when the brakes of the towing vehicle are applied, or the surging of the towing vehicle away from the trailer when the towing vehicle accelerates. The operator of the vehicle soon senses the increased surging and jarring between the trailer and the towing vehicle and, as a result, realizes that the brake fluid of the trailer brake system is low and needs replenishing.
Another feature of the invention is a self actuating brake latch which holds the master cylinder of the brakes in an actuated condition in response to the trailer becoming detached from the towing vehicle. A tether or cable is attached between the towing vehicle and the brake mechanism and operates the brake latch when tension is applied to the cable, as when the trailer hitch becomes inadvertently detached from the towing vehicle.
Therefore, it is an object of the present invention to provide an operator of a towing vehicle with a warning when there is an inadequate amount of hydraulic brake fluid in the hydraulic brake fluid reservoir of the surge brakes of a trailer hitch apparatus.
It is another object of the present invention to provide for an integrated dampening/braking apparatus in a hydraulic surge brake of a trailer.
It is another aspect of the invention to provide for a device for manually priming the brakes of a trailer, such that air can be bled from the hydraulic brake lines of the trailer.
It is another object of the invention to provide for an improved device to actuate the brakes of the trailer when the trailer and the towing vehicle becomes separated, and a device that latches the brakes in actuated position when the towing vehicle and trailer become separated.
Still another object of the present invention, is to provide that the latching mechanism can be easily disengaged by the operator.
Other objects, features and advantages of the invention will become apparent from reading the following specification, when taken in conjunction with the accompanying drawings.
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Fischer Andrew J.
Olszewski Robert P.
Thomas, Kayden, Hostemeyer & Risley, L.L.P.
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