Patent Application
20160068149
The valve of the present invention is an improvement to a typical push-pull valve such as described in the U.S. Pat. No.3,095,244 brake system and control valve therefor issued Jun. 25,1963 to H. M. VALENTINE. ET AL. and assigned to Bendix-Westinghouse Automotive air brake company, Elyria, Ohio, a corporation of Delaware.
This invention relates to compressed air operated brake systems for vehicles and more particularly to systems including one or more spring actuators for applying the brakes through the action of a spring under certain conditions as well as the depletion of said air for pre-trip and D.O.T. regulatory inspection of said system as well as safe parking procedures.The Department of Transportation and the National Highway Traffic Safety Administration have regulations requiring the depletion of air pressure for every air brake operated vehicle in order to perform a pre-trip inspection of said system low pressure warning devices before the beginning trip of every day. Also, Department of Transportation officers may require the depletion of said air supply at any time during any trip if they wish to perform an inspection of said system. In addition, federal regulations require all school bus drivers to deplete air from the braking system to below approximately 40 p.s.i. every time the vehicle is parked post trip. To date, the standard method of air depletion used in the field is to repetitively pump or fan the foot brake pedal until service air pressure is depleted to desired p.s.i. This process causes excessive wear on all moving parts of the braking system every day and every time the test is performed. In addition, as for the parking of air brake supplied commercial vehicles and more particularly school busses, these vehicles do not have a park position on the transmission and places all parking features on the spring brakes. The primary danger in this design is that as long as the air brake system has a pressure above approximately 40 p.s.i., the standard push pull parking brake valve can be released by anyone and the vehicle is capable of unwanted and uncontrolled roll off. As a result of this dangerous condition, federal guidelines are in place requiring school bus drivers to deplete system air pressure to below 40 p.s.i. every time the vehicle is post-trip parked by fanning the foot brake pedal. This method leaves room for human error of not depleting air pressure to proper p.s.i., as well as afore mentioned wear and tear of braking system. As of yet, all other commercial vehicles are not required to deplete system air pressure for final parking which leaves possibly every parked commercial air brake supplied vehicle sitting with the ability of unwanted, uncontrolled roll off. The present invention mechanically depletes the air pressure of said system to achieve low pressure warning system test as well as safe parking procedures.
One of the principle objects of the present invention is to provide a novel safety brake construction for vehicles equipped with a conventional compressed air braking system, which is so constituted as to mechanically apply the brakes by causing the system pressure to drop below a predetermined value.
A further objective is to provide a novel parking brake construction wherein the vehicle operator must be in the cab of the vehicle in order to operate vehicle air compressor for the purpose of releasing the brakes of a parked vehicle.
Another objective is to provide a mechanical device designed to remove air pressure from a vehicle's air brake system in order to force the brakes to be applied to said vehicle, and prevent possibility of releasing said brakes without full ability to crank and operate said vehicle to rebuild air pressure to a predetermined pressure above approximately 40 p.s.i.
A further objective is to provide a novel parking brake construction for any vehicle, machinery or equipment that uses air brakes.
Still a further objective is to provide in an arrangement of the above character a novel construction wherein springs are employed for automatically applying the brakes by depleting the system air pressure to a predetermined pressure, and wherein the springs may only be released by an operator controlled device in the cab once the system pressure is rebuilt to a pressure significantly high enough to permit the vehicle to safely proceed under the control of the compressed air braking system.
Another advantage is to provide a novel air depletion valve construction for the system expressed, which is manually operable to force the safety spring brake actuators to apply the brakes by reducing the system air pressure to a predetermined p.s.i. to prevent accidental or unwanted roll off of parked vehicle.
Still another advantage is to provide a novel means to mechanically decrease system air pressure for achieving regulated procedures of performing vehicle air brake low pressure warning test.
And yet another advantage is to deplete system air pressure to proper p.s.i. in order to mechanically apply spring brakes for parking to meet school bus regulatory parking procedures.
Yet another objective includes the incorporation of the brake system air depletion valve in a compressed air braking system in a novel manner as to permit relatively,simple installation in conventional air brakes systems while retaining all the desirable operating characteristics of such systems.
A still further objective includes the provision of a novel valve of the above type which comprises relatively few parts, accomplished with minimal manufacturing changes and may be readily connected in existing types of air brake systems.
The above and further objectives of the invention will appear more fully hereinafter from a consideration of the following detailed description when taken in connection with the accompanying drawings which disclose one form of the invention. It will be expressly understood, however, that the drawings are employed for purposes of illustration only and are not to be taken as a definition of the limits of the invention, reference being had for this purpose to the appended claims.
Referring to the drawings wherein similar reference characters refer to similar parts throughout the several views:
The novel brake system air depletion valve of the present invention is illustrated in
System also includes a two position control valve 92, which in one position is adapted to conduct reservoir pressure from the conduit 26 to the spring actuators 62 and 64 to the left of pistons 76 therein by way of supply conduit 94, 96, 98 and 100. Under these conditions, as soon as the pressure admitted to actuators 62 and 64 reaches a predetermined pressure, as for example above 40p.s.i., pistons 76 will be moved to compress the springs 78 and release the brakes.
In the other position of control valve 92, the supply conduit 94 is shut off and conduit 96 is connected to the atmosphere through and exhaust 124 of the valve 92 to permit application of the brakes by means of the spring actuators 62 and 64. Conduits 98 and 100 are connected through a quick release valve 106. Such valves include and exhaust connection 108 which automatically would vent the conduits 98 and 100 whenever the pressure in 96 drops to a value slightly lower than that in conduits 98 and 100. In the form shown, the exhaust 108 is connected through the conduit 109 with the outlet or service conduit 50. With such an arrangement, air pressure may be conducted to the spring actuators by way of conduits 96 or 109 depending upon which pressure is greater, the valve 106 thus functioning as a selectively operable valve. Valve 92 may be manually moved to the two positions referred to above. Such valve is also constructed as to be automatically moveable from said one to the said other position to automatically permit spring brake actuation whenever the system pressure in supply conduit 94 is depleted by current invention to a predetermined pressure of approximately 40 p.s.i. thus providing an effective safety system for automatically and mechanically applying the brakes. Valve 7 of the current invention is interconnected with valve 92, conduits 94, 9, 26, 24, 32, reservoirs 12 and 14, and low pressure indicator 30 for complete system air depletion to a predetermined pressure below 40 p.s.i.
Novel means are employed by the present invention in order to control the spring actuators 62 and 64. As shown, such means include a two position brake system air depletion valve 7, to be described herein after in detail, which in one position is to be closed and have no effect on the air brake system. In the other or open position of the brake system air depletion valve 7, the supply conduit 26 is open to the atmosphere through a pressure regulated exhaust 77 of valve 7 to deplete the air from tanks 12 and 14 to a predetermined p.s.i.and therefor applying brakes by means of the spring actuators 62 and 64. In addition, all spring brake actuators connected to the system in series with air depletion valve 7 would be applied when air pressure in the system reaches a predetermined pressure below approximately 40 p.s.i.
It will be understood by those skilled in the art, that since compressor 10 is for the purpose of supplying air pressure to the system, the engine should be turned off before employing valve 7, as valve 7 is for depleting reservoir pressure. Also, let it be known, control valve 92 is for parking, but as long as system has an air pressure above approximately. 40 p.s.i, valve 92 can be moved to the release position by unauthorized persons and vehicle is capable of unwanted uncontrolled roll off. The brake system air depletion valve 7 is designed to prevent spring brakes from being removed by unauthorized persons, by reducing air pressure to below a predetermined pressure of approximately 40 p.s.i. Therefore, vehicle must be cranked and ran for a period of time long enough to rebuild air pressure to above 40 p.s.i. before spring brakes can be released.
The present invention is designed to mechanically remove the air from reservoirs 12 and 14 to a predetermined p.s.i. low enough to cause valve 92 to move to the emergency position and cause spring brake actuators 62 and 64 to apply brakes as expressed above when pressure is reduced to a predetermined pressure of below 40 p.s.i., as well as causing the low air pressure warning indicator 30 to be made active.
Referring more particularly to
As soon as the pressure within the actuators 62 and 64 has built up to a value above the minimum value of approximately 40 p.s.i. to effect a release of the spring brake application, the operator may manually move the valve 92 from the emergency to the release position where upon full reservoir pressure will be conducted to the actuators 62 and 64. Valve 92, thus effectively locks reservoir pressure in the actuators 62 and 64 in order to maintain them in the release position after they have been released.
The vehicle may then be operated in the same manner as any vehicle equipped with a conventional air brake system. The valve 92 may be manually moved to its emergency position anytime desired, for example, when it is desired to park the vehicle. When this occurs, conduit 96 is connected with exhaust port 124 and the spring brake actuators are vented to the atmosphere through the brake valve and exhaust 108 as perviously described.
It will also be recalled that if the system pressure drops to the minimum value of approximately 40 p.s.i, the valve 92 will automatically move to the emergency position, spring brake operation and low pressure warning indicator activation will occur.
Should the pressure in the system be less than the minimum value, the spring brake actuators will remain in applied position and the low pressure warning indicator will remain activated. During such low pressure conditions, the valve 92 will remain in the emergency position even if the operator manually moves valve to other position, the valve will immediately return to prior position since a system pressure in excess of the minimum pressure is required to maintain the valve in the release position. The present invention thus provides in a conventional vehicle air brake system, a novel construction which enables a failsafe brake application through mechanical means, by causing the system pressure to drop below an operating value for final parking. The aforesaid mechanical means is disclosed as a spring brake actuator capable of air pressure depletion and such actuator has been incorporated in the system in such a manner as to be manually operable to apply the brakes in a manner requiring no special operations or techniques on the part of the operator. The two position valve is mounted in the cab so as to be readily operable every time the operator plans to park and exit the vehicle or perform the brake system low pressure warning test. The primary function of the present invention is to deplete the air pressure in the brake system and cause the spring brakes to be applied for safe after trip final parking of vehicle and to prevent accidental role-off of parked vehicle. A secondary function of the present invention is to deplete air pressure for the regulatory parking procedures of school busses. And thirdly, for regulatory low air pressure warning system test for pre-trip and Department of Transportation procedures.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form, detail and construction may be made therein without departing from the spirit and scope of the invention.
