Prosecution Insights
Last updated: April 19, 2026
Application No. 18/334,576

Spring Applied, Hydraulically Released Service Brake System

Non-Final OA §103
Filed
Jun 14, 2023
Examiner
AUNG, SAN M
Art Unit
3616
Tech Center
3600 — Transportation & Electronic Commerce
Assignee
Caterpillar Inc.
OA Round
1 (Non-Final)
78%
Grant Probability
Favorable
1-2
OA Rounds
3y 1m
To Grant
98%
With Interview

Examiner Intelligence

Grants 78% — above average
78%
Career Allow Rate
845 granted / 1089 resolved
+25.6% vs TC avg
Strong +21% interview lift
Without
With
+20.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
43 currently pending
Career history
1132
Total Applications
across all art units

Statute-Specific Performance

§101
0.4%
-39.6% vs TC avg
§103
52.6%
+12.6% vs TC avg
§102
31.4%
-8.6% vs TC avg
§112
12.7%
-27.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1089 resolved cases

Office Action

§103
DETAILED ACTION 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 . Claim Rejections - 35 USC § 103 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 (i.e., changing from AIA to pre-AIA ) 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. 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claim(s) 1-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Horsch (US – 5,601,160) and further in view of Bennett (US – 3,893,549). As per claim 1, Horsch discloses Hydraulically Actuated Brake Assembly For An Off-highway Implement comprising: at least one brake assembly (20, Fig: 2) including a brake actuator (32, Fig: 2) and a brake spring (58, Fig: 2), the brake actuator being movable in a brake application direction and in a brake disengagement direction opposite the brake application direction (brake apply, Col: 6, Ln: 65 - Col: 7, Ln: 14, Fig: 2, brake release, Col: 8, Ln: 39-58, Fig: 2), the brake actuator having a first pressure chamber (50, Fig: 2) and a second pressure chamber (60, Fig: 2) with the first and second pressure chambers being fluidly isolated from each other (Fig: 2), the first and second pressure chambers being arranged such that pressurized fluid introduced into the first and second pressure chambers respectively applies a first and a second hydraulic force on the brake actuator in the brake disengagement direction counter to the spring force (Col: 7, Ln: 45-50, Fig: 2); a first pressurized fluid supply (via line 416, Fig: 2, 8) in communication with the first pressure chamber (50, Fig: 2) for providing pressurized fluid to generate the first hydraulic force (Fig: 2); a second pressurized fluid supply (via line 426, Fig: 2) in communication with the second pressure chamber (60, Fig: 2) for providing pressurized fluid to generate the second hydraulic force (Fig: 2); wherein the first pressurized fluid supply and the first pressure chamber and the second pressurized fluid supply and the second pressure chamber are configured such that each of the first and second hydraulic forces can offset the spring force and move the brake actuator to a disengaged position (brake apply and release procedure, Col: 6, Ln: 65 - Col: 7, Ln: 14, Fig: 2, Col: 8, Ln: 39-58, Fig: 2). Horsch discloses all the structural elements of the claimed invention but fails to explicitly disclose the brake spring being arranged to apply a spring force on the brake actuator in the brake application direction. Bennett discloses Brake Apply and Release Mechanism comprising: the brake spring (70, The force in spring 70 has moved piston 66 rightwardly as seen in FIG. 2 against push rod 74, which has in turn engaged piston 50 so that a compressive brake apply force is exerted through the pistons and the push rod against the brake pad assembly 44 to mechanically hold the brake in the actuated condition, Col: 4, Ln: 4-10, Fig: 2) being arranged to apply a spring force on the brake actuator (piston 95, Fig: 2) in the brake application direction (The force exerted by spring 70 is sufficient to hold the brake actuated with enough braking force to meet the parking requirements of the vehicle, Col: 5, Ln: 12-15, Fig: 2). It would have been obvious to one having ordinary skill in the art before the effective filing date to modify the Hydraulically Actuated Brake Assembly For An Off-highway Implement of the Horsch to make the brake spring being arranged to apply a spring force on the brake actuator in the brake application direction as taught by Bennett in order to provide the wheel brake acts as an automatic parking brake and fail-safe service brake and braking system especially intended for heavy duty materials handling vehicles that eliminates the need for redundant circuit service brake systems. As per claim 2, Horsch discloses wherein the first hydraulic force is variable by the first pressurized fluid supply and the second hydraulic force is variable by the second pressurized fluid supply (Service brake valve 412 is responsive to manual operation of brake pedal 402L while service brake valve 414 is responsive to operation of brake pedal 402R. Each valve 412 and 414 is preferably configured as a three position valve including an intermediary metering position that serves to modulate the fluid pressure being applied to each brake assembly 20, Col: 15, Ln: 30-37, Fig: 1, 8). As per claim 3, Horsch discloses a service brake input device that controls the first and second pressurized fluid supplies to vary the first and second hydraulic forces (As will be appreciated, the position of each valve 412 and 414 controls the fluid flow to the cavity 50 of each brake assembly 20 thereby influencing the service brake function of the implement 10. That is, when the service brake is to be applied, the operator operates either and/or both brake pedals 402L, 402R to shift the respective valves 412, 414 to the left, as shown in FIG. 8, thereby allowing pressurized fluid into the brake cavity 50 with sufficient pressure to overcome the effectiveness of the spring release mechanism serving to hold the service brake in a released position, Col: 15, Ln: 38-49, Fig: 2, 8). As per claim 4, Horsch discloses wherein the first pressurized fluid supply (Fig: 8) communicates with the first pressure chamber (50) via a first fluid supply line (416, Fig: 2) and the second pressurized fluid supply (Fig: 8) communicates with the second pressure chamber (60) via a second supply line (426, Fig: 2). As per claim 5, Horsch discloses wherein the brake actuator (32, Fig: 2) engages with a braking apparatus that is configured to apply a braking force (via brake piston 46, 48, Col: 6, Ln: 65 – Col: 7, Ln: 14, Fig: 2). As per claim 6, Horsch discloses wherein the braking apparatus (32) includes multiple brake plates arranged to compress multiple brake discs (28, 30, Fig: 2). As per claim 7, Horsch discloses wherein the brake actuator (32, Fig: 2) is supported in a brake housing (22, Fig: 2) and is movable relative to the brake housing in the brake disengagement direction and the brake application direction (Fig: 2). As per claim 8, Bennett further discloses wherein the first (56, Fig: 2) and second (68, Fig: 2) pressure chambers are arranged on a side of the brake actuator opposite the spring (70, Fig: 2). It would have been obvious to one having ordinary skill in the art before the effective filing date to modify the Hydraulically Actuated Brake Assembly For An Off-highway Implement of the Horsch to make the first and second pressure chambers are arranged on a side of the brake actuator opposite the spring as taught by Bennett in order to provide the wheel brake acts as an automatic parking brake and fail-safe service brake. As per claim 9, Horsch discloses Hydraulically Actuated Brake Assembly For An Off-highway Implement comprising: a brake actuator (32, Fig: 1) that is movable in a brake application direction and in a brake disengagement direction opposite the brake application direction (brake apply, Col: 6, Ln: 65 - Col: 7, Ln: 14, Fig: 2, brake release, Col: 8, Ln: 39-58, Fig: 2), the brake actuator having a first pressure chamber (50, Fig: 2) and a second pressure chamber (60, Fig: 2) with the first and second pressure chambers being fluidly isolated from each other (Fig: 2); and wherein the first and second pressure chambers are arranged such that pressurized fluid introduced into the first and second pressure chambers respectively applies a first and a second hydraulic force on the brake actuator in the brake disengagement direction counter to the spring force (Col: 7, Ln: 45-50, Fig: 2). Horsch discloses all the structural elements of the claimed invention but fails to explicitly disclose a brake spring arranged to apply a spring force on the brake actuator in the brake application direction. Bennett discloses Brake Apply and Release Mechanism comprising: a brake spring (70, The force in spring 70 has moved piston 66 rightwardly as seen in FIG. 2 against push rod 74, which has in turn engaged piston 50 so that a compressive brake apply force is exerted through the pistons and the push rod against the brake pad assembly 44 to mechanically hold the brake in the actuated condition, Col: 4, Ln: 4-10, Fig: 2) arranged to apply a spring force on the brake actuator (piston 95, Fig: 2) in the brake application direction (The force exerted by spring 70 is sufficient to hold the brake actuated with enough braking force to meet the parking requirements of the vehicle, Col: 5, Ln: 12-15, Fig: 2). It would have been obvious to one having ordinary skill in the art before the effective filing date to modify the Hydraulically Actuated Brake Assembly For An Off-highway Implement of the Horsch to make the brake spring arranged to apply a spring force on the brake actuator in the brake application direction as taught by Bennett in order to provide the wheel brake acts as an automatic parking brake and fail-safe service brake. As per claim 10, Horsch discloses wherein the brake actuator (32) is supported in a brake housing (22, Fig: 2) and is movable relative to the brake housing in the brake disengagement direction and the brake application direction (Fig: 2). As per claim 11, Bennett further discloses wherein the first (56, Fig: 2) and second (68, Fig: 2) pressure chambers are arranged on a side of the brake actuator opposite the spring (70, Fig: 2). It would have been obvious to one having ordinary skill in the art before the effective filing date to modify the Hydraulically Actuated Brake Assembly For An Off-highway Implement of the Horsch to make the first and second pressure chambers are arranged on a side of the brake actuator opposite the spring as taught by Bennett in order to provide the wheel brake acts as an automatic parking brake and fail-safe service brake. As per claim 12, Horsch discloses wherein the brake actuator (32, Fig: 2) engages with a braking apparatus that is configured to apply a braking force (via brake piston 46, 48, Col: 6, Ln: 65 – Col: 7, Ln: 14, Fig: 2). As per claim 13, Horsch discloses wherein the braking apparatus includes multiple brake plates arranged to compress multiple brake discs (28, 30, Fig: 2). As per claim 14, Horsch discloses Hydraulically Actuated Brake Assembly For An Off-highway Implement comprising: a mobile machine (Fig: 1) comprising: a frame (12, Fig: 1); at least one traction device supported on the machine frame (The transmission 16 has drive shafts 18 extending in opposite directions therefrom for independently turning each drive wheel 14, Col: 6, Ln: 10-14, Fig: 1, 2); a service brake system (20, fig: 2) for a applying a braking force on the at least one traction device (Fig: 2, 8), the service brake system comprising: at least one brake assembly (20, Fig: 2) including a brake actuator (32, Fig: ) and the brake actuator (32) being movable in a brake application direction and in a brake disengagement direction opposite the brake application direction (brake apply, Col: 6, Ln: 65 - Col: 7, Ln: 14, Fig: 2, brake release, Col: 8, Ln: 39-58, Fig: 2), the brake actuator having a first pressure chamber (50, Fig: 2) and a second pressure chamber (60, Fig: 2) with the first and second pressure chambers being fluidly isolated from each other (Fig: 2), the first and second pressure chambers being arranged such that pressurized fluid introduced into the first and second pressure chambers respectively applies a first and a second hydraulic force on the brake actuator in the brake disengagement direction counter to the spring force (Col: 7, Ln: 45-50, Fig: 2); a first pressurized fluid supply (via line 416, Fig: 2, 8)in communication with the first pressure chamber (50, Fig: 2) for providing pressurized fluid to generate the first hydraulic force (Fig: 2); a second pressurized fluid supply (426, Fig: 2) in communication with the second pressure chamber (60, Fig: 2) for providing pressurized fluid to generate the second hydraulic force (Fig: 2); wherein the first pressurized fluid supply (416) and the first pressure chamber (50, Fig: 2) and the second pressurized fluid supply (426) and the second pressure chamber (60, Fig: 2) are configured such that each of the first and second hydraulic forces can offset the spring force and move the brake actuator to a disengaged position (brake apply and release procedure, Col: 6, Ln: 65 - Col: 7, Ln: 14, Fig: 2, Col: 8, Ln: 39-58, Fig: 2 ). Horsch discloses all the structural elements of the claimed invention but fails to explicitly disclose a brake spring, and the brake spring being arranged to apply a spring force on the brake actuator in the brake application direction. Bennett discloses Brake Apply and Release Mechanism comprising: a brake spring (70, The force in spring 70 has moved piston 66 rightwardly as seen in FIG. 2 against push rod 74, which has in turn engaged piston 50 so that a compressive brake apply force is exerted through the pistons and the push rod against the brake pad assembly 44 to mechanically hold the brake in the actuated condition, Col: 4, Ln: 4-10, Fig: 2) and the brake spring being arranged to apply a spring force on the brake actuator ((piston 95, Fig: 2) in the brake application direction (The force exerted by spring 70 is sufficient to hold the brake actuated with enough braking force to meet the parking requirements of the vehicle, Col: 5, Ln: 12-15, Fig: 2). It would have been obvious to one having ordinary skill in the art before the effective filing date to modify the Hydraulically Actuated Brake Assembly For An Off-highway Implement of the Horsch to make the brake spring being arranged to apply a spring force on the brake actuator in the brake application direction as taught by Bennett in order to provide the wheel brake acts as an automatic parking brake and fail-safe service brake and braking system especially intended for heavy duty materials handling vehicles that eliminates the need for redundant circuit service brake systems. As per claim 15, Horsch discloses wherein the first hydraulic force is variable by the first pressurized fluid supply and the second hydraulic force is variable by the second pressurized fluid supply (Service brake valve 412 is responsive to manual operation of brake pedal 402L while service brake valve 414 is responsive to operation of brake pedal 402R. Each valve 412 and 414 is preferably configured as a three position valve including an intermediary metering position that serves to modulate the fluid pressure being applied to each brake assembly 20, Col: 15, Ln: 30-37, Fig: 1, 8). As per claim 16, Horsch discloses a service brake input device that controls the first and second pressurized fluid supplies to vary the first and second hydraulic forces (As will be appreciated, the position of each valve 412 and 414 controls the fluid flow to the cavity 50 of each brake assembly 20 thereby influencing the service brake function of the implement 10. That is, when the service brake is to be applied, the operator operates either and/or both brake pedals 402L, 402R to shift the respective valves 412, 414 to the left, as shown in FIG. 8, thereby allowing pressurized fluid into the brake cavity 50 with sufficient pressure to overcome the effectiveness of the spring release mechanism serving to hold the service brake in a released position, Col: 15, Ln: 38-49, Fig: 2, 8). As per claim 17, Horsch discloses wherein the brake actuator (32) engages with a braking apparatus (via brake piston 46, 48, Fig: 2) that is configured to apply a braking force to the at least one traction element (Col: 6, Ln: 65 – Col: 7, Ln: 14, Fig: 2). As per claim 18, Horsch discloses wherein the braking apparatus includes multiple brake plates (28, 30, Fig: 2) arranged to compress multiple brake discs that are connected to the at least one traction element (Fig: 2). As per claim 19, Horsch discloses a parking brake system that includes a parking brake input device that directs the first and second pressurized fluid supplies (piston 48 acts as a park brake piston that is resiliently biased toward an engaging position with piston 46 by a plurality of equally spaced springs 58, Col: 7, Ln: 39=50, Fig: 2). As per claim 20, Bennett further discloses wherein the first (56, Fig: 2) and second (68, Fig: 2) pressure chambers are arranged on a side of the brake actuator opposite the spring (70, Fig: 2). It would have been obvious to one having ordinary skill in the art before the effective filing date to modify the Hydraulically Actuated Brake Assembly For An Off-highway Implement of the Horsch to make the first and second pressure chambers are arranged on a side of the brake actuator opposite the spring as taught by Bennett in order to provide the wheel brake acts as an automatic parking brake and fail-safe service brake. Conclusion The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. A: Middelhoven et al. (US – 5,050,939), B: Middelhoven et al. (US – 4,893,879), C: Engle (US – 4,018,140), D: Engle (US – 3,954,304), E: Engle (US – 3,833,095), and F: DAVIS et al. (US – 2023/0150458 A1). Any inquiry concerning this communication or earlier communications from the examiner should be directed to SAN M AUNG whose telephone number is (571)270-5792. The examiner can normally be reached 9:00 AM - 5:30 PM. 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, Robert Siconolfi can be reached at 571-272-7124. 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. /SAN M AUNG/Examiner, Art Unit 3616 /Robert A. Siconolfi/Supervisory Patent Examiner, Art Unit 3616
Read full office action

Prosecution Timeline

Jun 14, 2023
Application Filed
Nov 25, 2025
Non-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

1-2
Expected OA Rounds
78%
Grant Probability
98%
With Interview (+20.7%)
3y 1m
Median Time to Grant
Low
PTA Risk
Based on 1089 resolved cases by this examiner. Grant probability derived from career allow rate.

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