Famous Patents
3M employee and church chorister Art Fry needed something to temporarily mark pages in his hymnal. He was in luck because his colleague, Spencer Silver, accidentally developed a glue that was too weak for other purposes. After initially discouraging consumer response, Post-it Notes became a hit in 1979.
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| Number | Title | Issue Date |
| 7647858 | Differential piston A differential piston (1), designed as an annular piston, having pressure chambers (8, 9) with at least one of the pressure chambers (8, 9) being pressurized from radially inside the differential piston (1), via a hollow shaft (29)... | 01/19/2010 |
| 7581486 | Hydraulic system A hydraulic system includes a reservoir for a hydraulic fluid, a pump, a high-pressure line network, a low-pressure line network and operating cylinders each of which can be connected to the high-pressure line network or to the low-pressure line network via control ... | 09/01/2009 |
| 7228781 | Hydraulic control in a hydraulic system, especially for the operation of scrap cutters The invention relates to hydraulic control in a hydraulic system for the operation of a machine tool such as a press for processing material of a certain type, especially for the operation of the scrap cutters. Said control allows for impact attenuation and combined... | 06/12/2007 |
| 7216577 | Vacuum booster with low force loss A vacuum booster includes a housing defining a control volume in which a movable diaphragm separates the control volume into an apply chamber and a vacuum chamber. A power piston extends through and engages the diaphragm and has an axial bore containing a valve asse... | 05/15/2007 |
| 7131238 | Method of testing seismic braces Braces for bracing objects in structures against forces due to earthquakes are tested by subjecting components of the braces for attaching the braces to the object or structure to cyclic loading of approximately 15 cycles. The cyclic forces are applied to different ... | 11/07/2006 |
| 6817859 | Drive device for a movable part, especially a mold closure device for an injection molding machine, and method for operating such a drive device A drive for a movable part, such as a mold closure platen, includes two hydraulic cylinder-and-piston units defining first and third pressure chambers in a first of the hydraulic units and defining fourth and fifth pressure chambers in a second of the hydraulic unit... | 11/16/2004 |
| 6712587 | Hydraulic amplifier pump for use in ultrahigh pressure liquid chromatography A hydraulic amplifier system for an ultra-high pressure liquid chromatography system. The hydraulic amplifier system includes a hydraulic cylinder comprising a primary piston chamber in which a primary piston is disposed and a secondary piston chamber in which a sec... | 03/30/2004 |
| 6269733 | Force servo actuator with asymmetric nonlinear differential hydraulic force feedback A hydraulic force servo system provides apparatus for compensating for unequal loading forces applied to an actuator piston, and for unequal areas on opposite faces of the piston. Asymmetric nonlinear differential hydraulic force feedback from the output ... | 08/07/2001 |
| 5836400 | Three speed circuit for hydraulic tool A hydraulic tool having a ram or other working element propelled by pressurized fluid. The tool has a lever which is squeezed to develop fluid force in a pump. The fluid circuitry automatically operates the ram selectively at any one of three operating sp... | 11/17/1998 |
| 5662021 | Control system for a movement actuator An improved control system for a movement actuator is disclosed for moving a member between a retracted position and an extended position. The movement actuator comprises a cylinder having a piston with a fluid supply providing pressure to a first and a s... | 09/02/1997 |
| 5611259 | Hydraulic circuit for driving a ram of hydraulic press The hydraulic circuit directional control valve 20 is provided in a line connected with a lower chamber 13 of the hydraulic cylinder 1 and the B-port of the servo valve 3. A check valve 22 permitting oil flowing into the P-port of the servo valve 3 from t... | 03/18/1997 |
| 5575150 | Stiffness enhanced electrohydrostatic actuator Disclosed is a stiffness enhanced electrohydrostatic actuator for aircraft flight controls which eliminates the requirement for a central hydraulic system. The actuator replicates the blocked port condition of the central hydraulic system to provide stati... | 11/19/1996 |
| 5542336 | Positioning apparatus and method utilizing PWM control of a double-acting hydraulic cylinder A double-acting hydraulic cylinder is controlled by a pair of three-way solenoid valves respectively fluid connected to the two ends of the cylinder and energized in parallel with a continuous stream of pulse width modulated (PWM) pulses to create a mean ... | 08/06/1996 |
| 5540048 | Continuously variable hydrostatic transmission including a pulse width modulation ratio controller A controller for changing the ratio of a continuously variable hydrostatic transmission, as determined by the angular position of a swashplate, including an actuator having a cylinder slidingly receiving a piston to define a pair of chambers. A pair of so... | 07/30/1996 |
| 5481959 | Automatic air balancer system An automatic air balancer system capable of maintaining various kinds of load at a predetermined position and then moving the load at a desired speed, or applying a desired mechanical force to various kinds of object. The system includes a device for cont... | 01/09/1996 |
| 5370037 | Control valve means The present invention relates to a valve control apparatus for operating a working piston, comprising a main valve spool including a smaller piston face subjected to compressed air from a reservoir and a larger piston face facing a main control space, fur... | 12/06/1994 |
| 5370038 | Regeneration circuit for a hydraulic system Regeneration valves are useful in directing fluid expelled from a contracting chamber of a hydraulic actuator to its expanding chamber to increase the actuation speed of the actuator. The present remotely controlled regeneration circuit improves the contr... | 12/06/1994 |
| 5127315 | Brake motor subassembly and process for adjusting such a subassembly A brake motor subassembly comprises a control piston (10) having an internal cavity delimited by a base wall (18) and, at the periphery, by a stepped bore (20, 22, 24) and having a mechanical actuating device acting on the control piston via an automatic ... | 07/07/1992 |
| 4958548 | Hydraulic drive mechanism A hydraulic drive mechanism for a punching or an embossing tool, with a double-acting drive hydrocylinder with differently large piston areas, the rapid feed operation, the working feed operation, as well as the rapid retraction operation being controllab... | 09/25/1990 |
| 4877217 | Fail-safe blowout preventer A fail-safe mechanism for closing the rams in a conventional blowout preventer. The mechanism includes a ram shaft having an enlarged outer end that is exposed to well pressure which exerts a constant closing force. The closing force is opposed by a hydra... | 10/31/1989 |
| 4807517 | Electro-hydraulic proportional actuator An electro-hydraulic proportional servoactuator is disclosed which has built-in fail-safe systems which cause the power turbine nozzles to return to a zero degree angular position in the event of either an electrical system failure or a hydraulic system f... | 02/28/1989 |
| 4744286 | Brake motor subassembly The brake motor subassembly with automatic play compensation limitation by way of a stepped pilot piston (20), comprising a first cylindrical peripheral surface of larger diameter (21) sliding in an inner bore (7) of the control piston (1) and a second cy... | 05/17/1988 |
| 4700612 | Electropneumatic drive system for crust breaking devices and process for operating the same The drive system for cells for fused salt electrolytic production of aluminum is supplied with compressed air via a compressed air network with compressor and compressed air reservoir. It comprises at least one working cylinder with piston and piston rod,... | 10/20/1987 |
| 4606257 | Electropneumatic drive system for crust breaking devices and process for operating the same The drive system for cells for fused salt electrolytic production of aluminum is supplied with compressed air via a compressed air network with compressor and compressed air reservoir. It comprises at least one working cylinder with piston and piston rod,... | 08/19/1986 |
| 4587886 | Power steering device A power steering device having a fluid pressure cylinder of a single rod type providing like output characteristics for steering both rightwardly and leftwardly. A rod-side chamber and a head-side chamber of the fluid pressure cylinder have different pres... | 05/13/1986 |
| 4579040 | Power steering device A power steering device having a fluid pressure cylinder of a single rod type providing like output characteristics for steering both rightwardly and leftwardly. A rod-side chamber and a head-side chamber of the fluid pressure cylinder have different pres... | 04/01/1986 |
| 4562902 | Brake system A brake system for an off-highway vehicle which includes a fluid pressure actuated multi-disc brake and a fluid pressure control system. Engagement of the multi-disc brake is effected by a fluid operated piston having multiple effective pressure areas. Fl... | 01/07/1986 |
| 4552330 | Pressure medium actuated valve The pressure medium actuated valve has a pressure medium inlet port, an outlet port and a cylinder in which a piston connected to a closure member can slide. The piston sub-divides the cylinder into a first cylinder space and a second cylinder space. Two ... | 11/12/1985 |
| 4519573 | Device for the actuation of a slide valve A slide valve, in particular the piston of a switching valve, is actuated in both directions of adjustment by a pressure medium which acts on the annular face and/or the circular face of a regulating piston fixed one-sidedly to the slide valve. The equali... | 05/28/1985 |
| 4449896 | Hydraulic operated surface pumping unit The hydraulic operated surface pumping unit of this invention is a counterbalanced cross beam type pumping unit driven by a hydraulic cylinder. The pumping unit can be operated in a first mode of equal upstroke and down stroke speeds or in a second mode o... | 05/22/1984 |
| 4349175 | Valve actuator having a continuously charged accumulator An actuator is provided which is respondable to control fluid pressure for moving an operative means of a valve between open and closed positions. Valve means are movable between open and closed positions and communicate between the accumulator means and ... | 09/14/1982 |
| 4318333 | Bidirectional, multiple speed hydraulic actuator A bidirectional, multiple speed hydraulic actuator, including a differential piston (10, 24, 26). First and second ports (28, 30) are respectively in fluid communication with opposite sides of the piston and there is provided a pressure fluid supply line ... | 03/09/1982 |
| 4275642 | Air actuated fail-safe actuator encapsulated within accumulator tank A fail-safe, air actuated actuator mechanism is completely housed within and sealed interiorly of an accumulator tank in which a quantity of fail-safe actuating air is stored, under pressure.... | 06/30/1981 |
| 4253692 | Control system for material placement buckets A control system for opening and closing the clam shell gates of a material placement bucket makes use of a selfcompensating back pressure fluid system with a double-acting cylinder and piston. An air receiver is filled with high pressure air while air at... | 03/03/1981 |
| 4205208 | Double-flow compressed-gas operating mechanism for a high-voltage circuit-breaker An improved double-flow-type of compressed-gas operating mechanism is provided for actuating a high-voltage circuit-breaker including a double driving head, movable, actuating piston, having different opposite working areas to thereby accommodate the high... | 05/27/1980 |
| 4182219 | Hydraulic control system for two operating cylinders The invention relates to a hydraulic control system for a vehicle steering system or the like. The system includes two hydraulic cylinders each having a piston and a piston rod extending through one end thereof with the rod side of each piston having a sm... | 01/08/1980 |
| 4132290 | Locking mechanism for movable vehicle members A locking mechanism is provided for an apparatus having a first member movable relative to a second member providing a plurality of spaced holes therein including: a housing secured to the first member; a lock pin extendably retractably mounted in the hou... | 01/02/1979 |
| 4103592 | Valve operator A valve operator is disclosed for controlling an inlet valve to a large fluid-driven turbomachine such as a steam turbine. Such a valve is subject to a fast closing requirement under emergency trip conditions and at other times, the valve may be required ... | 08/01/1978 |
| 4046060 | Hydraulic control systems for use with mining apparatus A hydraulic control system for use with double-acting shifting rams in a mine working. The system has a pump for supplying pressure fluid and main and return feed lines or conduits connected to the pump and laid along the working. An adjustable pressure-r... | 09/06/1977 |
| 3981228 | Hydraulic control system A double-acting user has a first and an oppositely acting second pressure-fluid compartment. A source of pressure fluid receives fluid from a fluid reservoir. A first conduit has one section communicating with the first compartment of the user, and anothe... | 09/21/1976 |
