Motors: expansible chamber type – With motive fluid valve – Relatively movable serial valves
Patent
1980-11-17
1983-11-29
Garrett, Robert E.
Motors: expansible chamber type
With motive fluid valve
Relatively movable serial valves
91445, 91451, 91452, F15B 1108, F15B 13042
Patent
active
044175027
DESCRIPTION:
BRIEF SUMMARY
This application and expired U.S. Pat. No. 3,127,688 disclose differing respective improvements on an expired earlier U.S. Pat. No. 3,068,596.
Patents of only partial relevance because they do not address the hose line breakage problem include but are not limited to U.S. Pat. Nos. 3,805,678, 3,906,840, 4,006,667, 4,194,532 and 4,204,459. Another patent, U.S. Pat. No. 3,072,096, is included as a further background disclosure because of its relevance to preventing a cylinder from hydraulically dropping its load because of fluid line rupture.
The earlier expired U.S. Pat. No. ,068,596 relates to an hydraulic scraper-and-tractor combination wherein the hydraulic system for the scraper bowl is provided with two valves, one to prevent the existence of high pressure in the flexible conduit or hose which communicates between the controls on the tractor and the bowl actuating jacks when the weight of the bowl and its contents is imposed on the fluid in the system, and one to provide means under control of the tractor operator to enable quick lowering or dropping of the bowl when desired. One valve is a load locking check valve hydraulically disposed in posterior order with respect to the bowl actuating jack for affording free flow of fluid from the controls on the tractor to such jack and having a normal fluid blocking position for blocking flow of fluid from the jack back into the flexible hose going to the controls. What more particularly is disclosed is a load locking check valve having a control chamber which, when vented, effects opening of the check valve to afford flow of fluid from the load supporting chamber into and through the flexible hose and which includes restriction means in communication with the load supporting chamber, and the check valve being responsive to fluid pressure in the load supporting chamber to bias the check valve to its fluid blocking position to block fluid delivered by the check valve into the flexible hose for stopping flow from the jack to the controls on the tractor.
The other valve according to the patent disclosure is hydraulically disposed in anterior order with respect to the jack and serves as a quick-drop valve in lowering the scraper bowl by hydraulically short circuiting the rod end of the jack to empty directly into the head end thus preventing evacuation of the head end of the jack during bowl lowering.
The referred to expired improvement patent U.S. Pat. No. 3,127,688 is a disclosure to prevent the load from losing its supporting pressure from hydraulic short circuiting of the jack in event a quick drop hose connected to depressurize the valve for quick drop springs a leak or fails so as unwantedly to actuate the quick drop valve. Oversimplified, the patent teaches that reversing the order of the two halves so that the check valve is anterior and the quick drop valve is posterior with respect to the jack will safeguard against loss of load with quick drop hose failure. In other words, it can never be because of leakage or breaking of the quick drop hose that the scraper bowl will be accidentally dropped, because the anterior load check valve will be serving in its normally closed condition according to the patent to prevent flow of fluid short circuiting through the quick drop valve from the rod end to the head end of the jack.
As its distinction, the instant invention prevents loss of the load in event that other flexible hose, viz., the one communicating from the tractor controls via the load lock valve to the head end of the jack, itself springs a leak or fails; this invention for purposes of the present discussion is not confronted with the quick drop hose problem or with other unwanted depressurization of a quick drop valve because the quick drop valve will be added here only as and if preferred and is in no way essential to a showing or an understanding hereof.
In its broader aspects, this invention contemplates any ways and means whatever of automatically sensing the flexible hose has leakage to the outside while the load lock valve upstream thereof is open, a
REFERENCES:
patent: 3448685 (1969-06-01), Kroth
patent: 3906840 (1975-09-01), Bianchetta et al.
patent: 3908515 (1975-09-01), Johnson
patent: 4004607 (1977-01-01), Freese
patent: 4063489 (1977-12-01), Parquet et al.
patent: 4102250 (1978-07-01), Schexnayder
patent: 4138929 (1979-02-01), Peterson
Deutsch B. E.
Dresser Industries Inc.
Garrett Robert E.
Klein Richard L.
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