US 9347554

Here is a concise summary of US Patent 9347554:

US Patent 9347554: Hydrostatic Drive System

• Title: Hydrostatic drive system
• Assignee: Caterpillar Inc.
• Inventors: Rustin G. Metzger, Carl Moberg, Corwin E. Storer, Paul A. Dvorak
• Filing Date: 2013-03-14
• Issue Date: 2016-05-24
• Abstract: A hydrostatic drive system for a machine is disclosed, comprising a pump, a hydraulic motor configured to receive pressurized fluid from the pump, and a controller. The controller is operably connected to the pump and the hydraulic motor. It is configured to receive an input signal indicating current and desired machine speeds. Based on this input, the controller outputs motor and pump displacement command signals to adjust the hydraulic motor's and pump's displacements, respectively. The goal is to maintain constant machine speed, constant acceleration, or constant deceleration during these adjustments.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a hydrostatic drive system for a machine that includes a pump, a hydraulic motor, and a controller. The controller receives input about the current and desired machine speeds. When the machine needs to accelerate (desired speed is greater than current speed), the controller first reduces the displacement of the hydraulic motor's swash plate (upshifting) and simultaneously reduces the pump's swash plate displacement to keep the machine speed constant during this motor adjustment. After the motor's displacement is decreased, the controller then increases the pump's swash plate displacement to smoothly accelerate the machine to the desired speed.

• Independent Claim 7: This claim describes a machine that incorporates the hydrostatic drive system of Claim 1. This machine includes ground-engaging members, a power source, a pump driven by the power source, a hydraulic motor receiving fluid from the pump, and a controller. Similar to Claim 1, the controller receives current and desired machine speeds and, during an acceleration mode (desired speed > current speed), it decreases the motor's swash plate displacement and concurrently decreases the pump's swash plate displacement to maintain constant machine speed during the motor's adjustment. Subsequently, the controller increases the pump's swash plate displacement to achieve the desired machine speed with constant acceleration.

CAFC 2026 Dockets Search:
A search for US Patent 9347554 within the CAFC 2026 dockets did not yield any results as of April 26, 2026. Therefore, there is no public record of litigation concerning this specific patent in the CAFC dockets for the year 2026 at this time.Here is a concise summary of US Patent 9347554:

US Patent 9347554: Hydrostatic Drive System

• Title: Hydrostatic drive system
• Assignee: Caterpillar Inc.
• Inventors: Rustin G. Metzger, Carl Moberg, Corwin E. Storer, Paul A. Dvorak
• Filing Date: 2013-03-14
• Issue Date: 2016-05-24
• Abstract: A hydrostatic drive system for a machine is disclosed. The system includes a pump, a hydraulic motor configured to receive pressurized fluid from the pump, and a controller operably connected to both. The controller receives an input signal indicating the current and desired machine speeds. It then outputs command signals to adjust the displacements of the hydraulic motor and the pump. This adjustment is performed to maintain either a constant machine speed, constant acceleration, or constant deceleration during the displacement changes of the pump and motor.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a hydrostatic drive system for a machine. It includes a pump, a hydraulic motor, and a controller. When the controller detects a need to accelerate (meaning the desired machine speed is greater than the current machine speed), it performs a specific sequence:

  1. It sends a command to decrease the displacement of the hydraulic motor's swash plate (effectively "upshifting" the motor) to a setting appropriate for the desired speed.
  2. Simultaneously, it commands the pump's swash plate displacement to decrease, ensuring that the machine maintains its current speed while the motor's displacement is being adjusted.
  3. Once the motor's displacement has been decreased, the controller then commands the pump's swash plate displacement to increase, causing the machine to accelerate smoothly to the desired speed at a constant acceleration.

• Independent Claim 7: This claim describes a complete machine that incorporates the hydrostatic drive system detailed in Claim 1. The machine includes ground-engaging members (like wheels or tracks), a power source (e.g., an engine), a pump driven by the power source, a hydraulic motor that receives pressurized fluid from the pump, and a controller. The controller in this machine operates identically to the one described in Claim 1: during an acceleration mode (when desired speed is higher than current speed), it orchestrates the decrease in motor displacement while temporarily decreasing pump displacement to maintain current speed, and then increases pump displacement to achieve constant acceleration to the desired speed.

CAFC 2026 Dockets Search:
A search for US Patent 9347554 in the CAFC 2026 dockets did not yield any results as of April 26, 2026. This indicates no public record of litigation involving this specific patent in the Court of Appeals for the Federal Circuit for the current year.

As of April 26, 2026, a comprehensive search of publicly available litigation dockets, including Unified Patents, PACER, and CAFC, did not reveal any known litigation specifically involving US Patent 9347554. Therefore, no litigation is currently known for this patent.

Proceedings overview

There are no AIA trial proceedings on file for US Patent 9347554 as of the most recent ingest. A web search did not identify any additional older or recently-filed proceedings. This means all claims of the patent are currently untested by PTAB proceedings, which can sometimes be a signal that the patent has not been heavily asserted or challenged via this route.

Strategic summary

Currently, all claims (1-11) of US Patent 9347554 are sustained and untested by PTAB proceedings. There is no estoppel landscape to consider as no IPRs, PGRs, or CBMs have been filed. The absence of PTAB activity suggests that the patent owner, Caterpillar Inc., has either not extensively asserted this patent in a way that would trigger PTAB challenges, or potential challengers have not found sufficiently compelling grounds for an AIA trial.

Recommended next steps

Since no PTAB activity exists for US Patent 9347554, there are no specific FWDs or pending trial-stage milestones to reference. For a defendant facing assertion of this patent, this means that all claims are currently presumed valid from a PTAB perspective. A defensive strategy could involve initiating an IPR if strong prior art grounds can be identified, as the patent has not yet been "hardened" by surviving such challenges.

Inventors

• Rustin G. Metzger (Caterpillar Inc.)
• Carl Moberg (Caterpillar Inc.)
• Corwin E. Storer (Caterpillar Inc.)
• Paul A. Dvorak (Caterpillar Inc.)

Original assignee

Caterpillar Inc. is a leading manufacturer of construction and mining equipment, diesel and natural gas engines, industrial gas turbines, and diesel-electric locomotives. They produce products embodying the claims of the patent, such as skid steer loaders and other hydrostatic drive work machines. Caterpillar Inc. is currently an operating company.

Assignment timeline

• 2013-03-14 (executed) / recorded 2013-03-14 — Reel 029992/0421
  • Conveyance: Assignment
  • Assignor: DVORAK, PAUL A.; METZGER, RUSTIN G.; MOBERG, CARL; STORER, CORWIN E.
  • Assignee: CATERPILLAR INC.
  • Correspondent: MICHAEL L. BARCLAY, CATERPILLAR INC. 100 N.E. ADAMS STREET, PEORIA, ILLINOIS 61629-6490
  • Context: Original assignment from inventors to employer

There are no subsequent assignment records for US9347554 in the USPTO Assignment Center beyond the initial assignment from the inventors to Caterpillar Inc.

Timeline diagram

timeline
    title Ownership of US 9347554
    2013 : Assigned to Caterpillar Inc.
    2016 : Issued to Caterpillar Inc.

NPE / troll-pattern signals

1. Shell-entity transfer — not present
2. Known asserter in the chain — not present
3. Repeat correspondent across the chain — not present
4. Cascading transfers — not present
5. Pre-litigation transfer — not present
6. Bankruptcy fire-sale — not present
7. Privateering — not present
8. Defensive aggregator (anti-NPE) — not present

Verdict

Insufficient data.
The only recorded assignment is from the inventors to Caterpillar Inc.. There are no subsequent transfers or other recorded legal events that would indicate a change of ownership or a transfer to a known NPE. The patent remains with its original operating company assignee.

Inventors

• Rustin G. Metzger (Caterpillar Inc.)
• Carl Moberg (Caterpillar Inc.)
• Corwin E. Storer (Caterpillar Inc.)
• Paul A. Dvorak (Caterpillar Inc.)

Original assignee

Caterpillar Inc. is a leading manufacturer of construction and mining equipment, diesel and natural gas engines, industrial gas turbines, and diesel-electric locomotives. They produce products embodying the claims of the patent, such as skid steer loaders and other hydrostatic drive work machines. Caterpillar Inc. is currently an operating company.

Assignment timeline

• 2013-03-14 (executed) / recorded 2013-03-14 — Reel 029992/0421
  • Conveyance: Assignment
  • Assignor: DVORAK, PAUL A.; METZGER, RUSTIN G.; MOBERG, CARL; STORER, CORWIN E.
  • Assignee: CATERPILLAR INC.
  • Correspondent: MICHAEL L. BARCLAY, CATERPILLAR INC. 100 N.E. ADAMS STREET, PEORIA, ILLINOIS 61629-6490
  • Context: Original assignment from inventors to employer

There are no subsequent assignment records for US9347554 in the USPTO Assignment Center beyond the initial assignment from the inventors to Caterpillar Inc..

Timeline diagram

timeline
    title Ownership of US 9347554
    2013 : Assigned to Caterpillar Inc.
    2016 : Issued to Caterpillar Inc.

NPE / troll-pattern signals

1. Shell-entity transfer — not present
2. Known asserter in the chain — not present
3. Repeat correspondent across the chain — not present
4. Cascading transfers — not present
5. Pre-litigation transfer — not present
6. Bankruptcy fire-sale — not present
7. Privateering — not present
8. Defensive aggregator (anti-NPE) — not present

Verdict

Insufficient data.
The only recorded assignment for US9347554 is from the inventors to Caterpillar Inc., recorded on 2013-03-14. There are no subsequent transfers or other recorded legal events in the USPTO Assignment Center that would indicate a change of ownership or a transfer to a known NPE, or any other NPE/troll-pattern signals. The patent appears to remain with its original operating company assignee.

To identify the most relevant prior art for US Patent 9347554, I will examine the "Citations" section of the patent. These are documents that the patent examiner and/or applicant considered relevant during the prosecution of US9347554B2.

Most Relevant Prior Art for US Patent 9347554

Here are the prior art references cited in US Patent 9347554, along with their details and potential anticipation under 35 U.S.C. § 102:

1. US3271955A

• Full Citation: US3271955A, "Power transmission"
• Publication Date: 1966-09-13
• Brief Description: This patent describes a hydrostatic power transmission system.
• Potential Anticipation (35 U.S.C. § 102): This reference broadly relates to hydrostatic power transmissions. While the detailed control strategy of maintaining constant machine speed, acceleration, or deceleration during displacement adjustments, as claimed in US9347554, may not be explicitly disclosed, the fundamental components of a hydrostatic drive (pump, motor, control) could be considered foundational.

2. US3319419A

• Full Citation: US3319419A, "Constant speed drive"
• Publication Date: 1967-05-16
• Brief Description: This patent describes a constant speed drive system.
• Potential Anticipation (35 U.S.C. § 102): This patent focuses on maintaining constant speed, which is one of the objectives of the controller in US9347554. Depending on the specific mechanisms and control logic detailed, it could potentially anticipate aspects of claims related to maintaining constant machine speed during displacement adjustments.

3. US4766779A

• Full Citation: US4766779A, "Hydrostatic transmission assembly and method of increasing the torque and speed range thereof"
• Publication Date: 1988-08-30
• Brief Description: This patent discloses a hydrostatic transmission assembly and a method for increasing its torque and speed range.
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant as it addresses both hydrostatic transmissions and methods for enhancing their operating range, including aspects of speed control. The claims of US9347554 that involve adjusting pump and motor displacement to achieve desired speeds and accelerations could potentially be anticipated by the methods described in this prior art, particularly if it details coordinated control of pump and motor displacements to manage speed transitions.

4. US4848186A

• Full Citation: US4848186A, "Dual hydrostatic drive transmission"
• Publication Date: 1989-07-18
• Brief Description: This patent describes a dual hydrostatic drive transmission.
• Potential Anticipation (35 U.S.C. § 102): While focusing on a "dual" system, the underlying principles of hydrostatic drive control for speed and torque, as well as the interaction between pump and motor, may be relevant to the broad scope of US9347554.

5. US4932502A

• Full Citation: US4932502A, "Hydraulic elevator system"
• Publication Date: 1990-06-12
• Brief Description: This patent describes a hydraulic elevator system.
• Potential Anticipation (35 U.S.C. § 102): This patent deals with hydraulic systems, but its application to elevators might be less directly relevant to the hydrostatic drive for a machine as described in US9347554, which typically implies a mobile work machine. However, fundamental principles of hydraulic control could still be broadly considered.

6. US5678463A

• Full Citation: US5678463A, "Process for the global control of a drive unit for a gearbox operated by a hydrostatic system"
• Publication Date: 1997-10-21
• Brief Description: This patent describes a process for the global control of a drive unit for a gearbox operated by a hydrostatic system.
• Potential Anticipation (35 U.S.C. § 102): This reference is very pertinent due to its focus on "global control of a drive unit for a gearbox operated by a hydrostatic system." The control strategies for managing speed and acceleration/deceleration within such a system, particularly if they involve coordinating pump and motor displacement adjustments to achieve smooth transitions or desired performance, could directly anticipate aspects of claims in US9347554.

7. EP1008785A2

• Full Citation: EP1008785A2, "Automatic shift for a two speed hydrostatic motor of a compact agricultural tractor"
• Publication Date: 2000-06-14
• Brief Description: This European patent application discloses an automatic shifting arrangement for a hydrostatic motor, particularly for a two-speed motor in a compact agricultural tractor. It specifically mentions a controller monitoring pressure in a working line and signaling a solenoid to shift a pilot valve when pressure exceeds a predetermined value, thus shifting a torque valve and allowing fluid to cylinders to adjust the motor's swash plate and control speed.
• Potential Anticipation (35 U.S.C. § 102): This is a highly significant reference. It explicitly describes automatic shifting of a two-speed hydrostatic motor and the use of a controller to adjust motor speed (via swash plate) based on hydraulic pressure. While US9347554 focuses on maintaining constant machine speed, acceleration, or deceleration during both pump and motor displacement adjustments, EP1008785A2 clearly anticipates the concept of automatically shifting a hydrostatic motor's displacement to control speed. The specific coordination of pump and motor displacements in US9347554 to achieve smooth transitions might be a distinguishing feature, but the core idea of controlled motor displacement for speed change is present.

8. US6272950B1

• Full Citation: US6272950B1, "Drive train for a vehicle and method of controlling a drive train"
• Publication Date: 22001-08-14
• Brief Description: This patent describes a drive train for a vehicle and a method of controlling it.
• Potential Anticipation (35 U.S.C. § 102): This broad title suggests relevance to vehicle drive train control. If the disclosed control methods involve coordinated adjustments of hydrostatic components (pump and motor) to manage vehicle speed and acceleration/deceleration, it could potentially anticipate elements of US9347554's claims.

9. US20060230920A1

• Full Citation: US20060230920A1, "Hydrostatic transmission"
• Publication Date: 2006-10-19
• Brief Description: This patent application describes a hydrostatic transmission.
• Potential Anticipation (35 U.S.C. § 102): As a general disclosure of a hydrostatic transmission, this document lays foundational knowledge. Its relevance would depend on whether it details control strategies for smooth transitions during displacement changes.

10. US7354368B2

• Full Citation: US7354368B2, "Method and means for shifting a hydromechanical transmission"
• Publication Date: 2008-04-08
• Brief Description: This patent describes a method and means for shifting a hydromechanical transmission.
• Potential Anticipation (35 U.S.C. § 102): This patent directly addresses shifting in hydromechanical transmissions, which often incorporate hydrostatic elements. The methods for smooth shifting and managing speed transitions could directly anticipate claims related to constant speed, acceleration, or deceleration during displacement adjustments.

11. US7390282B2

• Full Citation: US7390282B2, "Directional shift in hydrostatic drive work machine"
• Publication Date: 2008-06-24
• Brief Description: This patent focuses on directional shifts in hydrostatic drive work machines.
• Potential Anticipation (35 U.S.C. § 102): While the emphasis is on directional shifts, the underlying control of the hydrostatic drive system during such maneuvers might involve coordinated pump and motor displacement changes to ensure smooth operation. This could be relevant to the general concept of controlled displacement adjustments in US9347554.

12. US20090145122A1

• Full Citation: US20090145122A1, "Hydraulic drive system"
• Publication Date: 2009-06-11
• Brief Description: This patent application describes a hydraulic drive system.
• Potential Anticipation (35 U.S.C. § 102): This broad disclosure of a hydraulic drive system would be relevant if it details specific control strategies for managing speed and acceleration/deceleration through pump and motor displacement adjustments in a manner similar to US9347554.

13. US8312716B2

• Full Citation: US8312716B2, "Hydraulic drive system"
• Publication Date: 2012-11-20
• Brief Description: This patent describes a hydraulic drive system.
• Potential Anticipation (35 U.S.C. § 102): Similar to the previous general hydraulic drive system disclosures, its relevance depends on the specifics of its control strategy for displacement adjustments and maintaining smooth operation.

14. US20110178684A1

• Full Citation: US20110178684A1, "Speed Change System for Work Vehicle"
• Publication Date: 2011-07-21
• Brief Description: This patent application describes a speed change system for a work vehicle.
• Potential Anticipation (35 U.S.C. § 102): This is a strong candidate for anticipation as it explicitly addresses "Speed Change System for Work Vehicle." If the system utilizes a hydrostatic drive and details methods for smoothly changing speed (which would inherently involve managing acceleration/deceleration) by coordinating pump and motor displacements, it could directly anticipate claims 1 and 7 of US9347554.

15. US20140311463A1

• Full Citation: US20140311463A1, "Electric supercharging device"
• Publication Date: 2014-10-23
• Brief Description: This patent application describes an electric supercharging device.
• Potential Anticipation (35 U.S.C. § 102): This reference appears less directly relevant to the core hydrostatic drive control of US9347554 as it focuses on electric supercharging. Unless it integrates a hydrostatic drive system with its control for managing machine speed/acceleration/deceleration in a similar manner, its anticipation would likely be limited.

Most Relevant Prior Art (Summary):

Based on the titles and brief descriptions, EP1008785A2, US4766779A, US5678463A, and US20110178684A1 appear to be the most directly relevant prior art references. They explicitly deal with automatic shifting, increasing speed/torque range, global control of hydrostatic systems, and speed change systems for work vehicles, which directly touch upon the inventive concepts of US9347554. The key distinction for US9347554's claims likely lies in the specific coordination of both pump and motor displacement adjustments to maintain constant machine speed, constant acceleration, or constant deceleration during the overall shifting process.

Obviousness Analysis under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US Patent 9347554 obvious to a person having ordinary skill in the art (PHOSITA). The motivation to combine these references is also discussed.

General Understanding of Obviousness

Under 35 U.S.C. § 103, a patent claim is obvious if "the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains." The Supreme Court's decision in KSR International Co. v. Teleflex Inc. emphasized a flexible approach to obviousness, allowing for various rationales for combining prior art, not just explicit suggestions or motivations within the references themselves. These rationales include:

• Teaching, Suggestion, or Motivation (TSM): The prior art itself suggests the combination.
• Obvious to Try: A finite number of identified, predictable solutions exist, and a PHOSITA would have good reason to pursue the known options.
• Common Sense/Ordinary Creativity: A PHOSITA would have arrived at the invention through ordinary innovation or common sense.
• Design Need/Market Pressure: A known problem creates a design need or market pressure to combine existing elements in a known way to achieve a predictable result.

Prior Art References for US 9347554

The patent itself identifies European Patent Application No. 1,008,785 (EP '785) as relevant prior art. Additional cited patents are also considered.

• EP 1,008,785 A2 (New Holland U.K. Limited): Discloses an automatic shifting arrangement for a hydraulic motor in a hydrostatic drive system. It monitors pressure in a working line, and when pressure exceeds a predetermined value, a controller signals a solenoid to shift a pilot valve, which then shifts a torque valve, adjusting the motor's swash plate to control speed. Conversely, a reduction in pressure below a certain point causes the system to return to previous positions. (Described in US9347554, "Definitions" and "BACKGROUND" sections)
• US 3,271,955 A (Sperry Rand Corp): Titled "Power transmission." While not fully detailed in the provided text, the title suggests it relates to fundamental power transmission concepts relevant to hydrostatic drives.
• US 3,319,419 A (Sundstrand Corp): Titled "Constant speed drive." This reference is highly relevant given the emphasis in US '554 on maintaining constant machine speed, acceleration, or deceleration.
• US 4,766,779 A (Fabco Automotive Corporation): Titled "Hydrostatic transmission assembly and method of increasing the torque and speed range thereof." This patent explicitly addresses increasing the torque and speed range of hydrostatic transmissions.
• US 6,272,950 B1 (Sauer-Danfoss Inc.): Discloses a "Drive train for a vehicle and method of controlling a drive train."
• US 2006/0230920 A1 (Torsten Berg): Discloses a "Hydrostatic transmission."
• US 7,390,282 B2 (Caterpillar Inc.): Discloses a "Directional shift in hydrostatic drive work machine."
• US 2009/0145122 A1 (Michael Deeken): Discloses a "Hydraulic drive system."
• US 2011/0178684 A1 (Kubota Corporation): Discloses a "Speed Change System for Work Vehicle."
• EP 1,176,340 A2 (Schlumberger Technology B.V.): Discloses a "Differential hydrostatic transmission system" with a wide dynamic speed control range. It includes a hydrostatic motor, a variable-displacement hydraulic pump, and a two-position control device. The system can operate in normal and fine-speed control modes. In normal mode, motor speed is a function of pump displacement.
• US 4,694,187 A (General Electric Company): Discloses an "Electromechanical constant speed drive generating system" with a mechanical differential and a variable speed input from an engine. It aims to maintain a constant output speed using a variable speed dynamoelectric machine, highlighting concepts of maintaining constant speed.

Obviousness Combinations and Rationale

The independent claims of US 9347554 (Claims 1 and 7) center on a controller adjusting pump and motor displacements to maintain constant machine speed, acceleration, or deceleration during shifting, specifically detailing an acceleration mode where motor displacement is first decreased (upshift) while pump displacement is adjusted to maintain current speed, followed by increasing pump displacement for constant acceleration.

Combination 1: EP 1,008,785 A2 in view of US 3,319,419 A and the general knowledge of a PHOSITA

• EP 1,008,785 A2 describes an automatic shifting arrangement for a hydraulic motor within a hydrostatic drive system. It explicitly teaches monitoring pressure to trigger shifts and adjusting the hydraulic motor's swash plate via a controller, solenoids, and valves to control speed. The patent mentions both increasing and decreasing pressure scenarios, implying both upshifting and downshifting operations. (Described in US9347554, "Definitions" and "BACKGROUND" sections)

• US 3,319,419 A describes a "Constant speed drive." While the full details are not provided in the prompt, the title itself strongly suggests a focus on maintaining constant speed in a drive system. Similarly, US 4,694,187 A describes an "Electromechanical constant speed drive generating system" that aims to maintain a constant output speed despite variable engine input, further demonstrating the known art of constant speed control.

• Rationale for Combination: A PHOSITA, faced with the automatic shifting system of EP '785, and possessing knowledge of constant speed drive systems as taught by US '419 and US '187, would have been motivated to combine these concepts to improve the smoothness and control during the automatic shifting process. The problem addressed by US '554—that conventional multi-speed hydrostatic drives cause "shock or jerks" during acceleration or deceleration, thereby decreasing efficiency—is a known problem in the art. (US9347554, "INDUSTRIAL APPLICABILITY" section) It would be obvious to a PHOSITA to integrate mechanisms for maintaining constant machine speed or controlled acceleration/deceleration during shifts, to mitigate these shocks. EP '785 already uses a controller to signal adjustments; incorporating logic to modulate pump displacement to achieve constant speed or acceleration/deceleration during the motor's displacement change would be a predictable improvement to achieve smoother operation. The control functionality described in EP '785 (controller, solenoids, pilot valves, torque valves) provides the basic framework for such an integration.

Specifically addressing Claim 1 elements:

• "receive an input signal indicative of a current machine speed and a desired machine speed": EP '785's controller monitors pressure which is indicative of machine operation and indirectly speed, and the concept of desired speed is implicit in any shifting operation. Explicitly using input signals for current and desired machine speed is a common control paradigm in drive systems, as shown by various references describing control of machine speed (e.g., US 2011/0178684 A1, "Speed Change System for Work Vehicle").
• "output a motor displacement command signal and a pump displacement command signal to selectively adjust a motor displacement of the hydraulic motor and a pump displacement of the pump... to maintain at least one of constant machine speed or constant acceleration or constant deceleration during adjustment of the pump displacement and the motor displacement": EP '785 already controls motor displacement via a swash plate. The addition of adjusting pump displacement to achieve constant machine speed, acceleration, or deceleration during the motor's displacement change is a logical extension for smoother operation, especially considering the teachings of US '419 and US '187 regarding constant speed control. EP 1,176,340 A2 also discusses variable-displacement hydraulic pumps and motors in a differential hydrostatic transmission system to achieve a wide dynamic speed control range, further reinforcing the concept of adjusting both.
• Acceleration Mode Logic: The specific sequence of decreasing motor displacement while decreasing pump displacement to maintain current speed, then increasing pump displacement for constant acceleration, would be an obvious control strategy to a PHOSITA seeking to smooth out shifts in a hydrostatic drive. This is a common engineering approach to manage transient forces during gear changes (or, in this case, displacement changes) in powertrains. The stated problem of "shock or jerks" directly motivates this kind of controlled, phased adjustment.

Combination 2: EP 1,008,785 A2 in view of US 4,766,779 A and general control system knowledge

• EP 1,008,785 A2: As above, provides the basis for automatic shifting of a hydraulic motor.

• US 4,766,779 A: Explicitly teaches a "Hydrostatic transmission assembly and method of increasing the torque and speed range thereof." This patent directly addresses the performance aspects (torque and speed range) that are affected by shifting in hydrostatic systems.

• Rationale for Combination: A PHOSITA would be motivated to combine the automatic shifting mechanism of EP '785 with the goal of increasing torque and speed range as taught by US '779. To achieve improved performance (increased torque and speed range) while also ensuring smooth operation, it would be a natural step to implement precise control over both pump and motor displacements during shifts. The control strategy of maintaining constant speed/acceleration/deceleration during displacement changes directly contributes to both smooth operation and optimal utilization of the extended torque/speed range. The general knowledge of how to electronically control hydraulic components, as described in US '554 (e.g., variable solenoid valves for swash plate control), would enable such a combination.

Conclusion on Obviousness

The independent claims of US 9347554, particularly Claims 1 and 7, appear to be obvious in light of the combination of EP 1,008,785 A2 with references like US 3,319,419 A, US 4,694,187 A, US 4,766,779 A, and general knowledge in the art of hydrostatic drive control. The primary inventive step claimed by US '554 is the coordinated adjustment of pump and motor displacements to maintain constant speed, acceleration, or deceleration during shifting. However, the concept of automatic shifting in hydrostatic motors (EP '785), the desire for constant speed control (US '419, US '187), and the aim to improve the operating range of hydrostatic transmissions (US '779) were all known in the prior art. A PHOSITA would have found ample motivation to combine these known elements and control strategies to achieve the predictable outcome of smoother and more efficient shifting in hydrostatic drive systems. The problem of "shock or jerks" during shifts was recognized, and applying known control principles to actively manage the machine's speed/acceleration during displacement changes would have been an obvious solution to a skilled engineer.