Patents by Inventor Douglas Dean Korthals
Douglas Dean Korthals has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7458311Abstract: A return to neutral mechanism for a dual hydrostatic transmission includes a plurality of return to neutral control arms, each return to neutral control arm biased toward a neutral position. Each return to neutral control arm moves in response to forward or reverse movement of an operator control, such as a stick or foot pedal. Additionally, switches are mounted to the return to neutral control arms. The switches enable starting of the engine if every return to neutral control arm is in a neutral position, and disable starting of the engine if at least one return to neutral control arm is out of the neutral position.Type: GrantFiled: August 14, 2006Date of Patent: December 2, 2008Assignee: Deere & CompanyInventor: Douglas Dean Korthals
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Patent number: 7430861Abstract: A shift controlled bypass orifice for a hydrostatic transmission includes a pump valve body with high pressure ports through which hydraulic fluid flows between a pump and a motor, a bypass orifice extending between the high pressure ports and the outside of the pump valve body, a bleed poppet movable between a closed position blocking the bypass orifice and an open position opening the bypass orifice, and a poppet push pin moving the bleed poppet toward the open position if the hydrostatic transmission is in neutral, and toward the closed position if the hydrostatic transmission is in forward or reverse.Type: GrantFiled: August 24, 2006Date of Patent: October 7, 2008Assignee: Deere & CompanyInventor: Douglas Dean Korthals
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Patent number: 7401456Abstract: A variable width mower deck has three cutting chambers mounted under a top deck surface. Two of the cutting chambers may be moved between a retracted cutting position and an extended cutting position. An endless belt engages the pulleys on each spindle to rotate the rotary cutting blades. The left and right cutting chambers move between the retracted and extended positions while maintaining engagement between the endless belt and the pulleys.Type: GrantFiled: November 8, 2005Date of Patent: July 22, 2008Assignee: Deere & CompanyInventor: Douglas Dean Korthals
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Publication number: 20080047264Abstract: A shift controlled bypass orifice for a hydrostatic transmission includes a pump valve body with high pressure ports through which hydraulic fluid flows between a pump and a motor, a bypass orifice extending between the high pressure ports and the outside of the pump valve body, a bleed poppet movable between a closed position blocking the bypass orifice and an open position opening the bypass orifice, and a poppet push pin moving the bleed poppet toward the open position if the hydrostatic transmission is in neutral, and toward the closed position if the hydrostatic transmission is in forward or reverse.Type: ApplicationFiled: August 24, 2006Publication date: February 28, 2008Inventor: Douglas Dean Korthals
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Publication number: 20080034958Abstract: A return to neutral mechanism for a dual hydrostatic transmission includes a plurality of return to neutral control arms, each return to neutral control arm biased toward a neutral position. Each return to neutral control arm moves in response to forward or reverse movement of an operator control, such as a stick or foot pedal. Additionally, switches are mounted to the return to neutral control arms. The switches enable starting of the engine if every return to neutral control arm is in a neutral position, and disable starting of the engine if at least one return to neutral control arm is out of the neutral position.Type: ApplicationFiled: August 14, 2006Publication date: February 14, 2008Inventor: Douglas Dean Korthals
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Publication number: 20070101693Abstract: A variable width mower deck has three cutting chambers mounted under a top deck surface. Two of the cutting chambers may be moved between a retracted cutting position and an extended cutting position. An endless belt engages the pulleys on each spindle to rotate the rotary cutting blades. The left and right cutting chambers move between the retracted and extended positions while maintaining engagement between the endless belt and the pulleys.Type: ApplicationFiled: November 8, 2005Publication date: May 10, 2007Inventor: Douglas Dean Korthals
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Patent number: 6935106Abstract: A neutral start switch arrangement is provided for a work vehicle having a motor driving a hydrostatic pump, the hydrostatic pump driving a hydraulic motor which drives a wheel. The hydrostatic pump typically has an input control shaft, the rotation of which moves the hydrostatic pump from the neutral position to the forward or reverse drive position. A selectively rotatable control arm is fixed to the input control shaft. A first arm is mounted for rotation about the input control shaft axis. A second arm is mounted for rotation about the input control shaft axis. The control arm and the first and second arms are configured for the control arm to be rotated from a neutral drive position to rotate the first arm in a forward drive rotary direction or the second arm in a second rotary direction corresponding to the reverse drive. A first leg extends from the first arm and a second leg extends from the second arm, and a spring is stretched between the first and second legs.Type: GrantFiled: August 26, 2003Date of Patent: August 30, 2005Assignee: Deere & CompanyInventor: Douglas Dean Korthals
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Patent number: 6848532Abstract: A transmission control system, such as for a self-propelled, walk-behind lawn mower, is provided for controlling first and second hydrostatic transmissions in which each one of the transmissions has a hydraulic dump actuator and a brake actuator. The transmission control system includes a control lever and a linkage. The linkage is engaged with the control lever, the hydraulic dump actuators, and the brake actuators of the first and second hydrostatic transmissions. The control lever and the linkage have a drive position which place both of the hydraulic dump actuators in a drive mode, a neutral position which place both of the hydraulic dump actuators in a neutral mode, and a brake position which place both of the brake actuators in a brake mode. The transmission control system can have a shift slot pattern which defines the drive, neutral, and brake positions of the control lever.Type: GrantFiled: May 15, 2002Date of Patent: February 1, 2005Assignee: Deere & CompanyInventor: Douglas Dean Korthals
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Patent number: 6782964Abstract: A platform included as part of a mower, the platform providing a surface upon which an operator stands while operating the mower. The platform is springably or suspendably mounted on the frame of the mower to cushion the operator and thereby decrease the amount of physical exertion which may be experienced by the operator over long periods of operation. The platform is further associated with a power control mechanism operatively connected with the platform whereby operation of the mower attachment(s) are selectively controllable by the operator stepping onto or off of the platform.Type: GrantFiled: October 11, 2002Date of Patent: August 31, 2004Assignee: Deere & CompanyInventors: Douglas Dean Korthals, Randall Joseph Bischel, Ellis Rudolph West
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Publication number: 20030213639Abstract: A transmission control system, such as for a self-propelled, walk-behind lawn mower, is provided for controlling first and second hydrostatic transmissions in which each one of the transmissions has a hydraulic dump actuator and a brake actuator. The transmission control system includes a control lever and a linkage. The linkage is engaged with the control lever, the hydraulic dump actuators, and the brake actuators of the first and second hydrostatic transmissions. The control lever and the linkage have a drive position which place both of the hydraulic dump actuators in a drive mode, a neutral position which place both of the hydraulic dump actuators in a neutral mode, and a brake position which place both of the brake actuators in a brake mode. The transmission control system can have a shift slot pattern which defines the drive, neutral, and brake positions of the control lever.Type: ApplicationFiled: May 15, 2002Publication date: November 20, 2003Applicant: Deere & CompanyInventor: Douglas Dean Korthals