Prosecution Insights
Last updated: April 19, 2026
Application No. 18/967,800

POSITIVE DISPLACEMENT PUMP SYSTEM

Final Rejection §103
Filed
Dec 04, 2024
Examiner
DAVIS, MARY ALICE
Art Unit
3746
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Rolls-Royce
OA Round
2 (Final)
77%
Grant Probability
Favorable
3-4
OA Rounds
2y 10m
To Grant
99%
With Interview

Examiner Intelligence

Grants 77% — above average
77%
Career Allow Rate
718 granted / 929 resolved
+7.3% vs TC avg
Strong +32% interview lift
Without
With
+32.3%
Interview Lift
resolved cases with interview
Typical timeline
2y 10m
Avg Prosecution
26 currently pending
Career history
955
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
36.4%
-3.6% vs TC avg
§102
27.4%
-12.6% vs TC avg
§112
26.6%
-13.4% vs TC avg
Black line = Tech Center average estimate • Based on career data from 929 resolved cases

Office Action

§103
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . DETAILED ACTION In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. CLAIM INTERPRETATION The presence of claim limitations that are preceded by the phrases “wherein” often raises a question as to the limiting effect of the claim limitations (see MPEP §2111.04). The Examiner has interpreted the limitations following the phrase “wherein” as positively being claimed (i.e. the claim limitations are required and/or the claim limitations following the “wherein clause” limits the structure), where “wherein” is being used as a transitional phrase. Specification The amendment to the specification received on January 20, 2026 is acceptable. The specification objections are hereby withdrawn. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, 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. Patentability shall not be negated by the manner in which the invention was made. Claims 1, 2, and 11 are rejected under 35 U.S.C. 103 as being unpatentable over MUIZELAAR (US Patent Publication US 2016/0281712 A1) in view of DAWN (U.S. Patent Publication US 2021/0215257A1). Regarding claim 1, MUIZELAAR discloses: a positive displacement pump system (300) (see Figures 6 and 7) comprising: a first positive displacement pump (314) comprising a rotatable element (334, 332); a second positive displacement pump (320) comprising a rotatable element (342, 340); and an electric motor (344, 346, 355) (see Figure 6, ¶0050, where a stator with a coil that interacts with a rotor (354) with a magnetic coil (355) is considered to be an electric motor due to electricity is able to energize the motor (see ¶0051)) comprising a stator (344, 346) and a rotor (354, 355), the rotor being coupled to the rotatable elements of the first positive displacement pump and the second positive displacement pump to provide drive thereto (see Figure 6, ¶0049-¶0051); wherein the rotor is supported for rotation by the rotatable elements of the first positive displacement pump and the second positive displacement pump (see Figure 6); and wherein the rotatable elements of the first positive displacement pump and the second positive displacement pump each comprise pump shafts (326, 327) which are coupled to a rotor shaft (354) of the rotor (see Figure 6). MUIZELAAR fails to disclose the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; wherein the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by an external coupling; and wherein the external coupling is a flexible coupling. Regarding claim 1, DAWN teaches: that the shaft can be split one or more times along its length, with these parts coupled by flexible couplings, such as spring beam couplings, bellows couplings, or magnetic couplings, for example in order to facilitate manufacture or maintenance of the pump, to accommodate static or dynamic misalignment of the components, or to reduce vibration or limit shock loads (¶0141). It would have been obvious to a person having ordinary skill in the art at the time of the invention was made to have the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; wherein the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by an external coupling; and wherein the external coupling is a flexible coupling in the positive displacement pump system of MUIZELAAR, since applying a known technique (i.e. splitting a shaft in multiple locations along its length and coupling the shaft sections with a flexible coupling, thereby the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; wherein the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by an external coupling; and wherein the external coupling is a flexible coupling), as taught by DAWN, to a known device (i.e. the positive displacement pump of MUIZELAAR) would have yielded predicable results. The results are predictable and provide the improvement of facilitating manufacturing or maintenance of the pump, accommodating static or dynamic misalignment of the components, or reducing vibration or limit shock loads, which is taught by DAWN in ¶0141. PNG media_image1.png 558 665 media_image1.png Greyscale Regarding claim 2, MUIZELAAR discloses: the electric motor is supported solely by the rotatable elements of the first positive displacement pump and the second positive displacement pump (see Figure 6). Regarding claim 11, MUIZELAAR discloses: the first positive displacement pump, the second positive displacement pump and the electric motor are disposed within a common housing (see Figures 6 and 7 that show a common housing). Claims 1, 4, 5, and 13-16 are rejected under 35 U.S.C. 103 as being unpatentable over YATES (U.S. Patent Publication US 2005/0232784 A1) in view of MUIZELAAR and in view of DAWN. Regarding claim 1, YATES discloses: a positive displacement pump system (see Abstract and Figures 2-4) comprising: a first positive displacement pump (10; 11, 12) comprising a rotatable element (11, 12); a second positive displacement pump (13, 14, 15) comprising a rotatable element (14, 15); and wherein the rotatable elements of the first positive displacement pump and the second positive displacement pump each comprise pump shafts (see Figure 3 that shows pump shafts that are hollow for both the first positive displacement pump and the second positive displacement pump) which are coupled to a shaft (see Figure 3 that shows that they are coupled to a hollow shaft that (17) extends into); the pump shafts of the first positive displacement pump and the second positive displacement pump are connected by respective intermediate shafts (17, 19) extending therebetween (see Figure 3 that shows intermediate shafts between the pump shafts); and the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by an external coupling (see Figure 3 that shows a circular external coupling between (11) and (17)). the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; wherein the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by an external coupling; and wherein the external coupling is a flexible coupling YATES fails to disclose an electric motor comprising a stator and a rotor, the rotor being coupled to the rotatable elements of the first positive displacement pump and the second positive displacement pump to provide drive thereto (YATES discloses that the rotatable elements of the first positive displacement pump and the second positive displacement pump are connected to the gear box of the engine); wherein the rotor is supported for rotation by the rotatable elements of the first positive displacement pump and the second positive displacement pump; wherein the rotatable elements of the first positive displacement pump and the second positive displacement pump each comprise pump shafts which are coupled to a rotor shaft of the rotor; the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; and wherein the external coupling is a flexible coupling (YATES shows a rigid coupling). Regarding claim 1, MUIZELAAR teaches: a positive displacement pump system (300) (see Figures 6 and 7) comprising: a first positive displacement pump (314) comprising a rotatable element (334, 332); a second positive displacement pump (320) comprising a rotatable element (342, 340); and an electric motor (344, 346, 355) (see Figure 6, ¶0050, where a stator with a coil that interacts with a rotor (354) with a magnetic coil (355) is considered to be an electric motor due to electricity is able to energize the motor (see ¶0051)) comprising a stator (344, 346) and a rotor (354, 355), the rotor being coupled to the rotatable elements of the first positive displacement pump and the second positive displacement pump to provide drive thereto (see Figure 6, ¶0049-¶0051); wherein the rotor is supported for rotation by the rotatable elements of the first positive displacement pump and the second positive displacement pump (see Figure 6, that shows the electric motor is between the first positive displacement pump and the second positive displacement pumps, and therefore the rotatable elements of the first positive displacement pump and the second positive displacement pump support the rotor for rotation); and wherein the rotatable elements of the first positive displacement pump and the second positive displacement pump each comprise pump shafts (326, 327) which are coupled to a rotor shaft (354) of the rotor (see Figure 6). It would have been obvious to a person having ordinary skill in the art at the time of the invention was made to have an electric motor comprising a stator and a rotor, the rotor being coupled to the rotatable elements of the first positive displacement pump and the second positive displacement pump to provide drive thereto; wherein the rotor is supported for rotation by the rotatable elements of the first positive displacement pump and the second positive displacement pump; and wherein the rotatable elements of the first positive displacement pump and the second positive displacement pump each comprise pump shafts which are coupled to a rotor shaft of the rotor in the positive displacement pump system of YATES, in order to operate the positive displacement pump system of YATES by an electric motor versus operation by the engine. Utilizing different power sources for operations of the positive displacement pump system requires only routine skill in the art and produces predictable results (i.e. an electric motor is able to independently operate the positive displacement pump system from the engine, as well as, prevents an engine failure if there is a failure in the positive displacement pump system (see ¶0031 of YATES that discloses that weak couplings are used in order to prevent damage to the engine gear box if the pump has a serious jam or seizure). The Examiner would like to note that YATES utilizes very similar components to the current application, where the only difference is the connectivity to an electric motor versus connecting to the engine gear box. MUIZELAAR teaches that it is well-known to place an electric motor between the first positive displacement pump and the second positive displacement pump that are used to support the rotor of the electric motor, where adding an electric motor between the first positive displacement pump and the second positive displacement pump and connecting of the rotor to the pump shafts would require only routine skill in the art and produces predictable results (i.e. the ability to control the positive displacement pump system with an electric motor). The modified positive displacement pump system of YATES/ MUIZELAAR fails to disclose the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; and wherein the external coupling is a flexible coupling. Regarding claim 1, DAWN teaches: that the shaft can be split one or more times along its length, with these parts coupled by flexible couplings, such as spring beam couplings, bellows couplings, or magnetic couplings, for example in order to facilitate manufacture or maintenance of the pump, to accommodate static or dynamic misalignment of the components, or to reduce vibration or limit shock loads (¶0141). It would have been obvious to a person having ordinary skill in the art at the time of the invention was made to have the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; and the external coupling is a flexible coupling in the modified positive displacement pump system of YATES/MUIZELAAR, since applying a known technique (i.e. splitting a shaft in multiple locations along its length and coupling the shaft sections with a flexible coupling, thereby the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by respective intermediate drive shafts extending therebetween; wherein the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are connected by an external coupling; and wherein the external coupling is a flexible coupling), as taught by DAWN, to a known device (i.e. the modified positive displacement pump system of YATES /MUIZELAAR) would have yielded predicable results. The results are predictable and provide the improvement of facilitating manufacturing or maintenance of the pump, accommodating static or dynamic misalignment of the components, or reducing vibration or limit shock loads, which is taught by DAWN in ¶0141. Regarding claim 4, YATES discloses: the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft are hollow and the intermediate drive shafts are received within the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft (see Figure 3 of YATES and the discussion above of the modified positive displacement pump system of YATES /MUIZELAAR where MUIZELAAR discloses using a motor to connect between the first positive displacement pump and the second positive displacement pump and YATES discloses utilizing hollow shafts). Regarding claim 5, YATES discloses: the respective intermediate drive shaft are connected with the pump shafts of the first positive displacement pump and the second positive displacement pump and the rotor shaft by splined connections (27, 25) (see Figure 3 of YATES that discloses utilizing splined connections to connect shafts. The combination of YATES/ MUIZELAAR would have utilized the same splined connections to connect to the rotor of the motor). Regarding claim 13, YATES further discloses: at least one or both of the first positive displacement pump or the second positive displacement pump is a gear pump (see Figure 3) and the rotating element is a first gear of the gear pump (11, 14), the gear pump further comprising a second gear (12, 15) which meshes with and is driven by the first gear (see Figure 3, Abstract, and claim 13). Regarding claim 14, YATES further discloses: a gas turbine engine (see ¶0002 and ¶0003, claim 12) including a positive displacement pump system of claim 1. Regarding claim 15, YATES further discloses: the positive displacement pump system is part of a fuel or oil supply system (¶0001). Regarding claim 16, DAWN further teaches: the external coupling is a bellows coupling (¶0141). Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over the modified positive displacement pump system of MUIZELAAR/DAWN in view of BROOKES (U.S. Patent 10,174,760 B2). Regarding claim 12, the modified positive displacement pump system of MUIZELAAR/DAWN discloses the claimed invention as discussed above, however, fails to disclose the electric motor is at least partially immersed in a pumped liquid. Regarding claim 12, BROOKES teaches: the electric motor is at least partially immersed in a pumped liquid (Column 2, lines 40-45). It would have been obvious to a person having ordinary skill in the art at the time of the invention was made to have the electric motor is at least partially immersed in a pumped liquid in the modified positive displacement pump system of MUIZELAAR/DAWN, in order to cool the motor, as well as, avoiding a need for a seal (see Column 2, lines 40-45 of BROOKES). Response to Arguments The cancelation of claims 3 and 6, and the amendments to claims 4 and 5 have resolved the claim objections, which are hereby withdrawn. The amendment to add claim 16 directed to a bellows coupling would normally be a drawing objection, however, since 162 is in a box shape, this can be interpreted as a bellows coupling. Applicant has placed claims 3, 6, and 7 into claim 1. A new rejection is discussed above with a new secondary reference, DAWN (see above for details). The combination of claims 1, 3, 6, and 7 was not recited in the previous office action (due to claims 6 and 7 did not depend from claim 3), thereby the rejection is necessitated by amendment. The arguments are based on the combination of claims 3, 6, and 7, which the Examiner has put forth a new argument utilizing DAWN that teaches it is well-known to split shafts in multiple pieces, as well as, utilizing a flexible coupling between the pieces such as a bellows couplings in order to facilitate manufacture or maintenance of the pump, to accommodate static or dynamic misalignment of the components, or to reduce vibration or limit shock loads (see DAWN ¶0141). Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Communication Any inquiry concerning this communication or earlier communications from the examiner should be directed to MARY DAVIS whose telephone number is (571)272-9965. The examiner can normally be reached M-F, 8 am-4pm. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Essama Omgba can be reached at (469) 295-9278. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /Mary A Davis/ Primary Examiner, Art Unit 3746
Read full office action

Prosecution Timeline

Dec 04, 2024
Application Filed
Oct 30, 2025
Non-Final Rejection — §103
Jan 20, 2026
Response Filed
Mar 28, 2026
Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
77%
Grant Probability
99%
With Interview (+32.3%)
2y 10m
Median Time to Grant
Moderate
PTA Risk
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