Mineral oils: processes and products – Oxidation of mineral oils – To form asphalts – tars or pitches
Patent
1986-02-05
1988-05-10
Love, John J.
Mineral oils: processes and products
Oxidation of mineral oils
To form asphalts, tars or pitches
180 41, 251282, 251903, 254423, 261DIG38, 208DIG1, B60S 900
Patent
active
047430370
ABSTRACT:
A system for automatically levelling a vehicle, such as a recreational vehicle, relative to gravity includes a plurality of extensible jacks, preferably hydraulic, disposed at strategic positions on the vehicle underside. Switches sense the downward tilting of the vehicle relative to gravity at the strategic positions and produce signals to operate the jacks in accordance with such tilting. Before the jacks are extended, air bags in the vehicle are deflated. When the hydraulic pressure in a hydraulic circuit exceeds a first value, the jacks are extended in a particular sequence depending upon the particular directions in which the vehicle is tilted relative to gravity. A delay is preferably provided between the operations of each jack and the next jack in the sequence to eliminate transients in the next jack operation. When the vehicle has been levelled, jacks not previously extended are extended until they engage the ground with a second pressure less than the first pressure. Such jacks are extended by opening bleeder valves associated with such jacks and maintaining a relief valve closed. The pressure in such jacks is limited to the second particular pressure after such extension by closing the bleeder valve at such reduced pressure while opening the relief valve. While the vehicle is travelling, the hydraulic fluid in the jacks is slowly bled to a reservoir by opening the bleeder valves and the relief valve. In this way, hydraulic forces cannot accumulate in the jacks to the first particular pressure to operate the jacks.
REFERENCES:
patent: 3817493 (1974-06-01), Hanser
patent: 4061309 (1977-12-01), Hanser
patent: 4084830 (1978-04-01), Daniel, Jr. et al.
patent: 4165861 (1979-08-01), Hanser
HWH Corporation
Love John J.
Rice Kenneth R.
Schwartz Charles H.
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