Hoisting Stops Upon Load Being Raised To A Predetermined Position (e.g., Anti-two Blocking) Patents (Class 212/281)
  • Patent number: 11554934
    Abstract: A system structured to transport a load carrying structure along the vertical direction while maintaining a substantially horizontal orientation thereof. A lifting assembly includes at least one lifting devices movably connected to the load carrying structure via a corresponding hoist line. The lifting device is configured to control the hoist line to accomplish raising or lowering of the load caring structure. A detection assembly, including at least one inclinometer determines an angle of inclination of the load carrying structure during the vertical travel thereof. A control assembly is operatively associated with the lifting assembly and the detection assembly to adjust the operative speed of the lifting device and length of the hoisting line upon a determination of an angle of inclination of the load carrying structure deviating from a predetermined angle of inclination indicative of a level orientation of the load carrying structure.
    Type: Grant
    Filed: November 7, 2019
    Date of Patent: January 17, 2023
    Inventor: Agostino Saverio Mattoli Chiavarelli
  • Patent number: 11535464
    Abstract: A load lifting and carrying apparatus that has a base with a distal end designed to horizontally couple to a vehicle frame. A dividable vertical frame has a top and a bottom end, the bottom end coupled to a proximal end of the base and supported by a horizontal bracket support. The upper portion of the vertical frame is narrower than and designed to slide at least partly into the lower portion, at least one pair of holes aligned on the upper and lower portion and coupled by at least one bolt assembly. A vertically foldable cantilevering coplanar arm is coupled to a proximal and distal rotatable pully assembly, the middle portion of the coplanar arm assembly removably coupled to a support arm. A winch assembly mounted to the lower portion of the vertical frame is designed to pull a cable over the pulleys to provide a lifting force for towing.
    Type: Grant
    Filed: May 27, 2021
    Date of Patent: December 27, 2022
    Assignee: SCORPION OFF ROAD PRODUCTS, LLC
    Inventors: Austin Taylor Bass, Clinton Ray Gaskins
  • Patent number: 10947093
    Abstract: A remote operation terminal T for remotely operating a mobile crane C is configured to include: a mode selection unit 34 for selecting an operation mode corresponding to work of the mobile crane C from a plurality of operation modes; an operation unit 35, 36 for instructing the mobile crane C on operation; and a control unit T1 that, when the operation mode is selected by the mode selection unit 34, assigns the operation corresponding to the selected operation mode to the operation unit 35, 36, and transmits an operation signal from the operation unit 35, 36 to the mobile crane C. Thereby, various operations can be performed by remote operation while securing safety.
    Type: Grant
    Filed: February 2, 2017
    Date of Patent: March 16, 2021
    Assignee: TADANO LTD.
    Inventors: Hiroyuki Hayashi, Masato Miyoshi
  • Patent number: 10633225
    Abstract: An information presentation system includes: an overload preventing device that derives a load factor which is an index of a load applied to a rope; a data logger that accumulates data on the load factor derived by the overload preventing device and data on a time length for which a load corresponding to the derived load factor has been applied to the rope, the data on the load factor and the data on the time length being associated with one another, and generates lifting rope statistical information and raising rope statistical information indicating a relationship between the load factor and the cumulative time for each rope; and a presenting unit that presents the lifting rope statistical information and the raising rope statistical information generated by the data logger.
    Type: Grant
    Filed: March 30, 2016
    Date of Patent: April 28, 2020
    Assignee: KOBELCO CONSTRUCTION MACHINERY CO., LTD.
    Inventors: Takayoshi Hirate, Eiji Miya, Keisuke Fukumoto, Toru Nakazawa
  • Patent number: 10384433
    Abstract: An extractor system for extracting an object secured to another object or a base surface is disclosed, which may include an oscillator, an attachment base, and an oscillation control mechanism to limit the transmission of oscillation forces after the object has become unsecured, and preserve the target object in good condition. The attachment base may be a vacuum suction cup or temporary adhesive. The control system may be a mechanical lifting system or an electronic control adapted to cease or minimize application of vibrational force when the object becomes unsecured. Methods of extracting an object or separating two objects secured to each other are also disclosed, including identification or creation of partial unbonded areas beneath the target object to initiate the de-bonding process prior to application of vibrational forces.
    Type: Grant
    Filed: December 5, 2016
    Date of Patent: August 20, 2019
    Assignee: Suma Consulting and Investments, Inc.
    Inventor: Mauricio Ricardo Rodriguez
  • Patent number: 10233057
    Abstract: Various hoisting systems with anti-two-block sensing devices are provided. In one embodiment, an apparatus includes a hoisting system having a hoisting line, a sleeve positioned on the hoisting line, and an anti-two-block sensing device installed about the hoisting line so as to allow the hoisting line to move through the anti-two-block sensing device. The anti-two-block sensing device includes a detector positioned to detect a sleeve component when the sleeve is present within the anti-two-block sensing device. Additional systems, devices, and methods are also disclosed.
    Type: Grant
    Filed: January 29, 2016
    Date of Patent: March 19, 2019
    Assignee: KEPPEL LETOURNEAU USA, INC.
    Inventors: Timothy Saker, Timothy Williams
  • Patent number: 10233058
    Abstract: Various hoisting systems with anti-two-block sensing devices are provided. In one embodiment, an apparatus includes a crane having a hoisting line and an anti-two-block sensing device installed about the hoisting line. The anti-two-block sensing device includes an upper chandelier, a lower trigger assembly suspended from the upper chandelier, and a detector positioned to detect movement of the lower trigger assembly with respect to the upper chandelier. The lower trigger assembly can include two plates each having a hoisting line aperture and a slot that allows transverse installation of the plate about the hoisting line. Further, the two plates can be positioned such that their slots are offset from one another and the plates cooperate to fully surround the hoisting line. Additional systems, devices, and methods are also disclosed.
    Type: Grant
    Filed: January 29, 2016
    Date of Patent: March 19, 2019
    Assignee: KEPPEL LETOURNEAU USA, INC.
    Inventors: Timothy Williams, Timothy Saker
  • Patent number: 9725240
    Abstract: Methods of storage and/or retrieval of items from storage racks using carts include electronically determining a size of an item and determining a storage position in a row for the item based on the determined size. The size can be determined by reading indicia on the item and consulting a database to determine a size of the item based on the read indicia. Other methods include electronically determining a characteristic of an item and determining a load movement limit protocol for the item based on the determined characteristic. The protocol may limit velocity or acceleration of movement of the item.
    Type: Grant
    Filed: March 6, 2014
    Date of Patent: August 8, 2017
    Assignee: Signode Industrial Group LLC
    Inventor: Rafael Salichs
  • Patent number: 8905250
    Abstract: A power generator is associated with a crane boom at or near the tip of the boom. The generator responds to movement of the lifting cable to initiate the transmission of a signal to a crane controller. The signal serves as a start-up or a wake-up signal to the crane controller which may then immediately analyze operation of, for example, an anti-two block device associated with the boom tip. The crane controller may then control the operation of the crane in accordance with signals received from the anti-two block device or immediately identify malfunctions of the anti-two block device and control the crane operations accordingly.
    Type: Grant
    Filed: April 16, 2010
    Date of Patent: December 9, 2014
    Assignee: Manitowoc Crane Companies, LLC
    Inventor: Martin R. Stander
  • Patent number: 8863965
    Abstract: Provided is a two-block sensing system (or device) that may be attached to an end of a lifting device, for example, a crane. The sensing device may include an A2B mount, a touch bar pivotally connected to the A2B mount, a link pivotally connected to the A2B mount, and a switch operatively connected to the touch bar so that if the touch bar is rotated with respect to the A2B mount, the switch becomes one of activated and deactivated.
    Type: Grant
    Filed: December 2, 2011
    Date of Patent: October 21, 2014
    Assignee: Stellar Industries, Inc.
    Inventors: Timothy J. Davison, Jeramy R. Voortmann, Matthew W. Schroeder
  • Patent number: 8813981
    Abstract: A crane assembly includes an anti-two block system having a rigid body, a sensor configured to detect upward loading of the body, and a spring biasing the body to a pin of a sheave. The body includes a base, two extensions projecting perpendicularly upward from the base and extending outside the sheave on opposite sides thereof, and a fitting on upper ends of the extensions. The fitting couples to the pin of the sheave such that the body is configured to rotate about the pin. The crane assembly further includes a controller comprising logic configured to prevent movement of a hook in response to a signal from the sensor of the anti-two block system. The weight of the body of the anti-two block system rotates the body such that the extensions are substantially aligned with a cable between an end of a boom and a hook as the boom rotates.
    Type: Grant
    Filed: March 20, 2012
    Date of Patent: August 26, 2014
    Assignee: Oshkosh Corporation
    Inventor: Brad G. Ethington
  • Patent number: 8657134
    Abstract: The present disclosure relates to a hoisting limit switch for limiting the maximum allowed hoisting height of a hoisting cable, wherein the hoisting limit switch includes a read-write device for reading and writing data, and a means from which the operating condition of the hoisting limit switch can be read out by the read-write device.
    Type: Grant
    Filed: October 13, 2010
    Date of Patent: February 25, 2014
    Assignee: Liebherr-Werk Ehingen GmbH
    Inventor: Erwin Morath
  • Patent number: 8376158
    Abstract: There is provided a heavy construction installation method which does not need a secondarily transport in a construction field even if an installation position of a heavy construction is apart from a berthing position of a transport ship. A movable area where a ground plane is reinforced so that a heavy hoisting machine for installing a heavy construction in a building is movable is constructed so as to include a circle drawn around an installation position in the building with a maximum operating radius of the heavy hoisting machine relative to a weight of the heavy construction being as a radius, and a circle drawn around a loaded position of the heavy construction at a transport ship coming alongside a landing place with the maximum operating radius being as a radius.
    Type: Grant
    Filed: February 17, 2010
    Date of Patent: February 19, 2013
    Assignee: Hitachi Plant Technologies, Ltd.
    Inventors: Yuji Kaneko, Ryohel Miyahara, Sumito Maezawa, Kensuke Morita, Takashi Okano
  • Publication number: 20120241403
    Abstract: A crane assembly includes an anti-two block system having a rigid body, a sensor configured to detect upward loading of the body, and a spring biasing the body to a pin of a sheave. The body includes a base, two extensions projecting perpendicularly upward from the base and extending outside the sheave on opposite sides thereof, and a fitting on upper ends of the extensions. The fitting couples to the pin of the sheave such that the body is configured to rotate about the pin. The crane assembly further includes a controller comprising logic configured to prevent movement of a hook in response to a signal from the sensor of the anti-two block system. The weight of the body of the anti-two block system rotates the body such that the extensions are substantially aligned with a cable between an end of a boom and a hook as the boom rotates.
    Type: Application
    Filed: March 20, 2012
    Publication date: September 27, 2012
    Inventor: Brad G. Ethington
  • Patent number: 8070413
    Abstract: A control system for a machine which includes a load handling apparatus for moving a load relative to a body of the machine. The machine includes a pivot about which a tipping moment is produced by the load. The load handling apparatus includes an actuator capable of moving the load to a position at which the tipping moment is at a threshold value. The control system is responsive to a tipping moment sensor to control operation of the actuator to progressively reduce the speed of movement of the load as the threshold value of the tipping moment is approached.
    Type: Grant
    Filed: July 2, 2003
    Date of Patent: December 6, 2011
    Assignee: J. C. Bamford Excavators Limited
    Inventors: Richard Anthony Brooks, Peter Jowett
  • Publication number: 20110253662
    Abstract: A power generator is associated with a crane boom at or near the tip of the boom. The generator responds to movement of the lifting cable to initiate the transmission of a signal to a crane controller. The signal serves as a start-up or a wake-up signal to the crane controller which may then immediately analyze operation of, for example, an anti-two block device associated with the boom tip. The crane controller may then control the operation of the crane in accordance with signals received from the anti-two block device or immediately identify malfunctions of the anti-two block device and control the crane operations accordingly.
    Type: Application
    Filed: April 16, 2010
    Publication date: October 20, 2011
    Inventor: Martin R. STANDER
  • Publication number: 20110089131
    Abstract: The present disclosure relates to a hoisting limit switch for limiting the maximum allowed hoisting height of a hoisting cable, wherein the hoisting limit switch includes a read-write device for reading and writing data, and a means from which the operating condition of the hoisting limit switch can be read out by the read-write device.
    Type: Application
    Filed: October 13, 2010
    Publication date: April 21, 2011
    Applicant: LIEBHERR-WERK EHINGEN GMBH
    Inventor: Erwin Morath
  • Patent number: 7515389
    Abstract: The invention relates to a method and a device for safely disconnecting electric drives, wherein disturbances of the electric drive which are independent from the driving and lifting speed are recognized in a delay-free manner by retaining the safety function and are used for disconnecting the electric drive. The signals of the sensors (7.1, 7.2, 8.1, 8.2) are detected in a redundant manner and are redundantly compared to preselected threshold values in evaluation devices (2.1, 2.2) such that the electric drive (12) is safely disconnected in a redundant manner without using mechanical position devices if the preselected threshold value of the electric drive (12) is exceeded.
    Type: Grant
    Filed: February 26, 2004
    Date of Patent: April 7, 2009
    Assignee: Gottwald Port Technology GmbH
    Inventors: Ronald Kleine, Andreas Kruschinski, Frank Demelius
  • Publication number: 20080302750
    Abstract: An anti-two block switch assembly for a crane is disclosed for preventing the crane from a two-blocking condition. The switch assembly includes a rotatable joint which allows the assembly to rotate about more than one axis. The switch assembly is also provided with a mounting plate and a mounting rod for mounting the switch assembly to the crane.
    Type: Application
    Filed: June 10, 2008
    Publication date: December 11, 2008
    Inventor: Simon K. Worboys
  • Publication number: 20040108292
    Abstract: A crawler vehicle having a lower works comprising a carbody and a pair of crawler assemblies. Each of the crawler assemblies are removably connected to the carbody by a plurality of carbody to crawler connections. The carbody to crawler connection each comprise at least one keyway for aligning the connection components of the crawler assembly with the connection components of the carbody, and for preventing these connection components from becoming misaligned in response to eccentric forces or deflections generated between the carbody and each of the crawler assemblies.
    Type: Application
    Filed: December 6, 2002
    Publication date: June 10, 2004
    Inventors: Harley Smith, Joel Zick
  • Patent number: 6618999
    Abstract: A safety apparatus for a lifting structure having a crown and at least one traveling block, and an oil derrick having a crown bumper, wherein the safety apparatus comprises at least two support beams attached to crown of the lifting structure; a plate secured between the support beams; a bumper pad secured to the plate and adapted to be positioned at the crown of the lifting structure to cushion any impact with the traveling block if the traveling block is lifted towards the crown without stopping and the oil drilling rig apparatus, comprises: a derrick having a lower end for mounting on a platform, an upwardly projecting frame, and an upper, crown end; a traveling block suspended from the upper crown end within the derrick frame; drive means linked to the traveling block for driving the traveling block up and down the frame in a predetermined travel path; and a crown bumper comprising: at least two support beams attached to the derrick; a plate secured between said support beams; a bumper pad secured to the
    Type: Grant
    Filed: October 4, 2001
    Date of Patent: September 16, 2003
    Assignee: JM Clipper Corporation
    Inventor: Michael Joe Reynolds
  • Publication number: 20030127408
    Abstract: A wire or cable is provided internally of an extensible boom to connect a switch, control or other element, such as an anti-two block switch, at one end of the extensible boom to elements or controls at the other end, such as controls for operating the crane. The wire or cable is itself inextensible, and is normally maintained taut. Wire control elements are provided to permit movement of the wire to accommodate extension and retraction of the telescopic boom sections. The wire internal to the extensible boom is fully protected from the environment and external hazards.
    Type: Application
    Filed: February 20, 2003
    Publication date: July 10, 2003
    Applicant: National Crane Corporation
    Inventor: William D. Schneider
  • Publication number: 20020179559
    Abstract: A boom positioning device for high-position working, capable of ensuring a desired positional accuracy even in positioning a work location at the tip end of a boom from a distant place, the device comprising an imaging means (4) having a multi-axis driving unit and provided with a boom tip-end position computing means (2) for computing the position and attitude of the boom tip-end from positions of respective axes of the boom detected by a boom respective-axis-position detecting means (1) and with a distance measuring means (3) for detecting the distance from the boom tip-end position to a work object, a first boom working amount calculating means (11) for calculating, from an output from the distance measuring means (3) and an output from a measuring error judging means (10), a boom working amount up to an approach enabled area where the measuring accuracy of the distance measuring means (3) is guaranteed, and a second boom working amount calculating means (15) for calculating, from a distance from the boom
    Type: Application
    Filed: May 31, 2002
    Publication date: December 5, 2002
    Inventors: Yukio Hashiguchi, Shinji Murai, Shinichi Ishikawa
  • Patent number: 6343703
    Abstract: In the anti-two block device, a non-contact measuring device detects in one form or another the distance between a boom nose and a load-bearing member supported thereby. If the distance detected is less than a predetermined threshold value, the device triggers a warning or other operation to assist an operator in preventing anti-two blocking.
    Type: Grant
    Filed: December 4, 1998
    Date of Patent: February 5, 2002
    Assignee: Grove U.S. L.L.C.
    Inventors: Jon E. Fleagle, Dennis W. Eckstine, William W. Banks, Francis R. Eyler
  • Patent number: 6068145
    Abstract: An anti-two block system for a crane having a body formed of a first plate and a second plate, a weighted member connected to the second plate of the body so as to contact a travelling member of the crane when the travelling member moves upwardly beyond a desired level, and a valve affixed to the first plate of the body. The valve is movable between a first position closing the valve and a second position opening the valve. The valve serves to pass fluid flow therethrough in response to a contact between the travelling member and the weighted member. The first plate is connected to the second plate. A spring is interactively connected between the plates so as to urge the second plate upwardly along the first plate when the travelling member contacts the weighted member. The weighted member has a weight so as to overcome the resistance of the spring such that the valve resides in the first position in the absence of contact between the weighted member and the travelling member.
    Type: Grant
    Filed: August 3, 1998
    Date of Patent: May 30, 2000
    Assignee: MSI Crane & Equipment Co.
    Inventor: Stephen Luke
  • Patent number: 5992655
    Abstract: A replacement assembly is provided for retrofitting old, discontinued, mechanically-operated, low-drive, Caterpillar sidebooms with a hydraulically-operated fail-safe sideboom system. Conversion of discontinued, mechanically-operated, low-drive, Caterpillar sidebooms is accomplished by replacing the entire existing mechanical assembly with a single frame-mounted hydraulic assembly comprising a boom winch, a load winch, and preferably a single hand-operated joystick control. This single frame assembly is configured to be received by the existing foundation on discontinued Caterpillar sidebooms. Joystick technology is provided which negates cumbersome clutches and related multiple controls by affording a sideboom operator the ability to completely control the functions of both the boom and the load with a single joystick control which replaces the six conventional hand-operated mechanical controls that exist on the discontinued Caterpillar sidebooms.
    Type: Grant
    Filed: May 24, 1999
    Date of Patent: November 30, 1999
    Inventors: Alan S. Greenberg, Giordano Grassi
  • Patent number: 5946748
    Abstract: Disclosed is a multipurpose body-turn-over apparatus mainly including an elevator support, a cantilever elevator fixed to the elevator support, a driving mechanism mounted on the cantilever elevator, and a controller for setting operating time and speed, reverse, and pause of the driving mechanism, as well as adjusting height of the elevator support. The driving mechanism drives a driven assembly to reciprocate, so that ropes hanging from two ends of the driven assembly to connect a net thereto are alternately pulled up and lowered, causing a patient lying on the net to turn over regularly to avoid bedsore due to lying on bed for a prolonged time. Means other than the net may also be selectively connected to the ropes to help patient do rehabilitation exercises or complete skeletal traction. The apparatus may be designed into heavy-duty or light model to meet different requirements and can be freely moved for use with different sick beds.
    Type: Grant
    Filed: February 17, 1998
    Date of Patent: September 7, 1999
    Inventor: Yi-Lung Wang
  • Patent number: 5838246
    Abstract: A safety apparatus for a derrick on an oil drilling rig includes a cable having a first end for connection to one side of the derrick at a predetermined location spaced below the crown. A series of pulleys is secured to the oil derrick to define a predetermined path for the cable extending from the fixed first end across the derrick at the predetermined location and then down the derrick to a location adjacent the lower end. The portion of the cable extending across the derrick is positioned in the path of a traveling block as it is pulled up the derrick. An alarm device is linked to the cable to produce an output alarm signal if the cable is pulled up by the traveling block as it approaches the top of the derrick, giving the operator a warning that the traveling block should be stopped to avoid impact with the crown.
    Type: Grant
    Filed: May 13, 1997
    Date of Patent: November 17, 1998
    Assignee: Luz Marie Vorhees
    Inventor: Ronald J. Voorhees
  • Patent number: 5730305
    Abstract: A crane safety apparatus for displaying a schematic diagram of a part of a crane mechanism on a two-dimensional screen dynamically as the crane mechanism is operated, and displaying on the same screen a predetermined operation zone as a visually discriminative zone pattern. The operation zone pattern is displayed on the screen in response to the key command by an operator during a selected crane operation mode, while referring to the schematic crane mechanism diagram currently displayed on the screen.
    Type: Grant
    Filed: November 2, 1994
    Date of Patent: March 24, 1998
    Assignee: Kato Works Co., Ltd.
    Inventors: Akinori Ichiba, Yukio Tsutsumi
  • Patent number: 5645181
    Abstract: Rope extension is detected as a rope shift distance at predetermined time intervals. A rope extension amount is obtained as the accumulated value of the shift distances. The rope shift accumulated value is automatically reset to 0 when a hook structure reaches an overhoist position to renew the reference position of the rope extension amount and to correct any measurement errors of the rope extension amount. From this rope extension amount, a hanging length of the hook structure from a boom or jib top is obtained and used to calculate a hook lifting distance. The calculated hook lifting distance, or hook structure position, is displayed on a display screen relative to a fixed index or pattern. An operator can monitor the state of the hook structure from the display.
    Type: Grant
    Filed: June 23, 1994
    Date of Patent: July 8, 1997
    Assignee: Kato Works Co., Ltd.
    Inventors: Akinori Ichiba, Yukio Tsutsumi
  • Patent number: 5632391
    Abstract: A weight for operating the lift-limiting switch of a crane, especially a telescoping-boom crane, is composed of two identical castings connected together by a hinge at one side and having a lock on the opposite side which, when actuated, holds the two members around the crane cable but which can be opened to allow the weight to be placed over the cable or to be removed therefrom.
    Type: Grant
    Filed: April 10, 1995
    Date of Patent: May 27, 1997
    Assignee: Kidde Industries, Inc.
    Inventor: Gerd Erdmann
  • Patent number: 5579931
    Abstract: An improved method and system for a liftcrane in which a load is lifted through the combined action of first and second hoist drums. The method and system use a first rope wound on one hoist drum and a second rope wound on the second hoist drum. The ends of the ropes opposite the hoist drums are linked together to transmit tension between them. The load is coupled to the ropes. If the take up speed of one of the ropes exceeds the take up speed of the other, the linked ends of the ropes will shift. This condition is detected and the operation of at least one of the first and second hoist drums is modified to bring the take up rates into balance. This system is advantageously used with a hoist block sheave arrangement. This system can also be used with a single rope in which each of the ends of the single rope are wound on a separate one of the hoist drums and the load is coupled to the middle of the rope.
    Type: Grant
    Filed: March 18, 1994
    Date of Patent: December 3, 1996
    Assignee: Manitowoc Engineering Company
    Inventors: Arthur G. Zuehlke, David J. Pech
  • Patent number: 5454474
    Abstract: The disclosure involves a material handling machine, e.g., a crane, having a control circuit switch and a power limit switch. Disclosed is a new weight assembly having first and second weights. The control switch is maintained at a position by the first weight and the power switch is maintained at a position by the second weight which is positioned above the first weight. The weights are telescoped to one another so that vertical weight alignment is assured as the crane hoist bottom block contacts and lifts the first weight. If the bottom block continues its upward travel past a maximum desired elevation, the first weight (urged by the bottom block) lifts the second weight, permitting the power limit switch to trip and preventing the bottom block from continuing upward. And the new assembly is ideal where the space available for limit switch weights is restricted.
    Type: Grant
    Filed: October 13, 1994
    Date of Patent: October 3, 1995
    Assignee: Harnischfeger Corporation
    Inventor: Steven L. James
  • Patent number: 5455567
    Abstract: An automatic signaling system from a tractor-trailer being accidentally lifted with the cargo by the overhead traveling crane includes a height-change sensor for triggering a pulse generator which drives a strobe light that is seen by a discriminator mounted above on the crane. The discriminator is coupled into the hoisting circuitry only and does not affect the "lowering" circuitry; it will interrupt hoisting only if the discriminator sees strobe flashes of a particular predetermined frequency and pulse duration.
    Type: Grant
    Filed: July 18, 1994
    Date of Patent: October 3, 1995
    Inventor: Donald E. Simmons