Mainstream Engineering Corp v. Pad Depot Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Mainstream Engineering Corporation (Florida)
  • Defendant: Pad Depot, Inc. (Florida)
  • Plaintiff's Counsel: Law Office of Michael W. O'Neill
• Case Identification: 5:26-cv-00523, M.D. Fla., 07/28/2026
• Venue Allegations: Venue is based on Defendant's residence, alleged acts of infringement, and a regular and established place of business within the Middle District of Florida.
• Core Dispute: Plaintiff alleges that Defendant's generator mounting pads infringe four utility patents and three design patents related to pads for securing outdoor equipment against high winds.
• Technical Context: The technology concerns mounting pads for outdoor equipment, such as HVAC units and standby generators, designed to be lightweight for transport but heavy enough after on-site preparation to provide stability in hurricane-force winds.
• Key Procedural History: The complaint states that Plaintiff sent Defendant a cease and desist letter on March 25, 2026, putting Defendant on notice of the asserted patents, and received a response from Defendant's counsel on April 16, 2026.

Case Timeline

Date	Event
2018-01-19	Earliest Priority Date for '896, '148, '149, '921, D'858, and D'859 Patents
2022-02-11	Priority Date for D'425 Patent
2022-07-12	U.S. Patent No. 11,384,896 Issues
2022-10-04	U.S. Patent No. 11,460,148 Issues
2022-10-04	U.S. Patent No. 11,460,149 Issues
2023-05-16	U.S. Patent No. 11,649,921 Issues
2023-12-12	U.S. Design Patent No. D1,007,425 Issues
2024-01-30	U.S. Design Patent No. D1,012,858 Issues
2024-01-30	U.S. Design Patent No. D1,012,859 Issues
2026-03-25	Cease and Desist Letter Sent to Defendant
2026-04-16	Defendant's Counsel Responds to Letter
2026-07-28	Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 11,384,896 - "Mounting pad and method for deterring theft and securing outdoor equipment and appliances against high winds"

• Patent Identification: U.S. Patent No. 11,384,896, "Mounting pad and method for deterring theft and securing outdoor equipment and appliances against high winds," issued July 12, 2022.

The Invention Explained

• Problem Addressed: The patent describes a conflict between the need for outdoor equipment pads to be heavy enough to resist tipping in high winds, and the desire for them to be lightweight for easy transportation and installation '896 Patent, col. 1:25-44 Prefabricated solid concrete pads are heavy and difficult to handle, while lightweight plastic pads may not provide sufficient anchoring weight '896 Patent, col. 1:45-53
• The Patented Solution: The invention is a lightweight, hollow plastic shell that can be transported easily and then filled on-site with a material like water, often mixed with a gelling agent, to achieve the necessary weight for stability '896 Patent, abstract '896 Patent, col. 3:30-44 The pad features threaded inserts on its top surface, allowing equipment to be securely fastened to it '896 Patent, col. 4:62-67
• Technical Importance: This design provides a practical solution for installers by combining the transportability of a light object with the on-site stability of a heavy one, addressing both logistical challenges and regulatory requirements for wind resistance '896 Patent, col. 1:57-64

Key Claims at a Glance

• The complaint asserts independent claim 3 Compl. ¶34
• Essential elements of claim 3 include:
  • An equipment pad for securing a standby generator.
  • A surface having a plurality of threaded inserts positioned to align with openings in the generator's base.
  • A bottom surface.
  • A plurality of side surfaces connecting the top and bottom surfaces to form an internal hollow region.
• The complaint reserves the right to assert additional claims Compl. ¶34

U.S. Patent No. 11,460,148 - "Mounting pad and method for deterring theft and securing outdoor equipment and appliances against high winds"

• Patent Identification: U.S. Patent No. 11,460,148, "Mounting pad and method for deterring theft and securing outdoor equipment and appliances against high winds," issued October 4, 2022.

The Invention Explained

• Problem Addressed: Similar to the '896 Patent, the invention addresses the need for a mounting pad that is easily transportable but provides sufficient weight to secure equipment against wind-driven tipping '148 Patent, col. 1:25-33 It notes that modern, taller equipment has "exacerbated the wind-driven tipping issue" '148 Patent, col. 1:11-12
• The Patented Solution: The patent describes a pad with a top surface featuring a "plurality of receivers" for fasteners '148 Patent, abstract These receivers are positioned in specific patterns (e.g., quadrilateral) to accommodate different equipment footprints, and are described as having a lower surface at a depth less than the pad's overall thickness '148 Patent, col. 11:8-16
• Technical Importance: This approach offers a versatile mounting platform capable of securing various equipment models with different mounting hole configurations, thereby increasing its utility for installers '148 Patent, col. 8:49-53

Key Claims at a Glance

• The complaint asserts independent claim 12 Compl. ¶49
• Essential elements of claim 12 include:
  • A pad for securing equipment via fasteners.
  • A top surface, a bottom surface, and a side surface defining a distance between them.
  • The top surface has a plurality of receivers for fasteners, with each receiver having a lower surface at a depth less than the distance between the top and bottom pad surfaces.
  • The plurality of receivers consists of a set of four receivers in a quadrilateral pattern.
• The complaint reserves the right to assert additional claims Compl. ¶49

U.S. Patent No. 11,460,149

• Patent Identification: U.S. Patent No. 11,460,149, issued October 4, 2022.
• Technology Synopsis: This patent discloses an equipment mounting pad with sets of receivers that contain inserts. The invention focuses on the arrangement of these receiver-and-insert combinations into specific patterns (e.g., triangular, trapezoidal, quadrilateral) that are associated with distinct equipment models, providing a versatile mounting interface '149 Patent, col. 9:35-65
• Asserted Claims: Independent claim 3 is asserted Compl. ¶64
• Accused Features: The NEXTPAD® and Oval Pad are alleged to have receivers with inserts arranged in a quadrilateral pattern to secure a generator Compl. ¶¶66-67

U.S. Patent No. 11,649,921

• Patent Identification: U.S. Patent No. 11,649,921, issued May 16, 2023.
• Technology Synopsis: This patent describes a hollow equipment pad with a top surface containing a plurality of receivers. These receivers, in turn, contain threaded inserts specifically formed to receive fasteners, ensuring alignment with the mounting openings on a standby generator to securely fasten it to the pad '921 Patent, col. 9:21-44
• Asserted Claims: Independent claim 1 is asserted Compl. ¶79
• Accused Features: The complaint alleges the accused pads have a top surface with receivers containing threaded inserts that align with generator mounting openings Compl. ¶¶81-82

U.S. Design Patent Nos. D1,007,425, D1,012,858, and D1,012,859

• Patent Identification: D'425 Patent issued December 12, 2023; D'858 Patent issued January 30, 2024; and D'859 Patent issued January 30, 2024.
• Technology Synopsis: These patents protect the ornamental design for a support member. The claimed design, defined by the solid lines in the patent figures, includes the overall rectilinear/rounded-rectangular shape of the pad, beveled edges, and small circular features on the top surface Compl. ¶97 Compl. ¶112 Compl. ¶127
• Asserted Claims: The single claim of each design patent is asserted Compl. ¶93 Compl. ¶108 Compl. ¶123
• Accused Features: The overall appearance of the NEXTPAD® and Oval Pad products are alleged to be substantially the same as the claimed designs in the view of an ordinary observer Compl. ¶96 Compl. ¶111 Compl. ¶126

III. The Accused Instrumentality

Product Identification

• The NEXTPAD® and Oval Pad generator pads Compl. ¶28

Functionality and Market Context

• The complaint alleges that the accused products are equipment pads used to secure standby generators Compl. ¶¶36-37 They are marketed and sold to third parties through a commercial website Compl. ¶29 A screenshot from the website shows the "NextPad 4"" and "NextPad 3"" for sale, described as pads for Generac generators Compl. ¶29
• Functionally, the pads are alleged to have a top surface, a bottom surface, and side surfaces that form an internal hollow region Compl. ¶36 This region is allegedly for a foam insert Compl. ¶36 The top surface includes receivers with threaded inserts that align with the mounting holes on a generator, allowing it to be secured with fasteners Compl. ¶28 Compl. ¶36 The complaint provides a photograph of a cross-section of an accused pad, labeling the top, bottom, and side surfaces and showing a porous internal material Compl. p. 14, Image 5

IV. Analysis of Infringement Allegations

11,384,896 Infringement Allegations

Claim Element (from Independent Claim 3)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
An equipment pad securing at least one standby generator, wherein the standby generator has a base that has a plurality of openings for a plurality of fasteners to pass individually through one of the plurality of opening to secure the standby generator to the equipment pad, the equipment pad comprising:	The NEXTPAD® is an equipment pad to secure a standby generator.	¶36	col. 10:18-21
a surface having a plurality of threaded inserts that are positioned on the surface to align with the plurality of openings on the base of the standby generator in order for one of the plurality of fasteners to pass through one of the plurality of openings and thread into one of the plurality of threaded inserts in order to secure the standby generator on to the surface of the equipment pad;	The NEXTPAD® has a top surface with multiple threaded inserts that align with the openings on the base of the standby generator in order for fasteners to pass through the openings and thread into the inserts and secure the generator to the pad.	¶36	col. 10:22-37
a bottom surface; and	Axiomatically, the NEXTPAD® necessarily has a bottom surface.	¶36	col. 10:38
a plurality of side surfaces attached to the top surface and bottom surface and forming an internal hollow region encapsulated by the top, bottom, and side surfaces.	The side surfaces of the NEXTPAD® attached the top and bottom surfaces and form an internal hollow region for a foam insert to be placed therein.	¶36	col. 10:39-44

• Identified Points of Contention:
  • Scope Questions: Claim 3 requires an "internal hollow region." The patent specification heavily focuses on this region being filled on-site with a liquid or gel to add weight '896 Patent, col. 3:30-44 The complaint alleges the accused product's hollow region is for a "foam insert" Compl. ¶36 This raises the question of whether a pad constructed with a pre-installed foam core meets the "hollow region" limitation as contemplated by the patent.
  • Technical Questions: The complaint provides a photo of fasteners being inserted into the accused pad Compl. p. 13, Image 3 A technical question will be whether the evidence demonstrates that these are "threaded inserts" as required by the claim, and not another type of fastening mechanism, such as a thread-forming screw into plastic.

11,460,148 Infringement Allegations

Claim Element (from Independent Claim 12)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A pad for securing an equipment via fasteners comprising:	The NEXTPAD® is an equipment pad to secure a standby generator using fasteners.	¶51	col. 11:1-2
a top surface, a bottom surface, and a side surface attached to the top surface and the bottom surface, the side surface defining a distance between the top surface and the bottom surface;	The NEXTPAD® has a top surface, a bottom surface, and side surfaces defining a distance between the top and bottom surfaces.	¶51	col. 11:3-7
said top surface having a plurality of receivers for receiving fasteners positioned thereon, the receivers having a lower surface at a depth less than the distance between the top surface and the bottom surface, wherein the plurality of receivers consists of a set of four receivers in a quadrilateral pattern.	The NEXTPAD® has receivers in its top surface to receive fasteners, and the receivers are in a quadrilateral pattern. The receivers' lower surfaces are less than the distance between the top and bottom surfaces because the receiver is essentially a blind hole.	¶51	col. 11:8-16

• Identified Points of Contention:
  • Scope Questions: A central dispute may arise over the meaning of the term "receiver." The complaint alleges the accused product's "blind hole" structure satisfies this limitation Compl. ¶51 The court may need to determine if "receiver" simply means any recess for a fastener, or if the patent's context implies a more complex structure, potentially one that includes an insert '148 Patent, col. 8:54-63
  • Technical Questions: The complaint includes a photograph of a broken piece of the accused product showing a hole that does not pass through the entire pad Compl. p. 27, Image 3 A key evidentiary question will be whether this photograph, and any other evidence presented, is sufficient to prove that the accused "receivers" have a "lower surface at a depth less than the distance between the top surface and the bottom surface" as required by the claim.

V. Key Claim Terms for Construction

'896 Patent

• The Term: "internal hollow region"
• Context and Importance: The construction of this term is critical because the patent's inventive concept involves a lightweight, transportable shell that is made heavy on-site. The complaint alleges the accused pad contains a "foam insert" in its internal region Compl. ¶36 Practitioners may focus on this term to determine if a pad manufactured with a foam core falls within the scope of a claim for a pad with a "hollow region" intended to be filled.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The plain language of claim 3 itself does not specify the contents of the "internal hollow region" or when it must be filled. This may support an argument that any encapsulated internal space, regardless of its contents (or lack thereof), meets the limitation.
  • Evidence for a Narrower Interpretation: The specification repeatedly describes the purpose of the hollow region as being for on-site filling with water and a gelling agent to add weight '896 Patent, abstract '896 Patent, col. 3:30-44 This context suggests the term refers to a void intended to be filled by the end-user, which could be used to argue that a region designed to be occupied by a factory-installed foam insert is outside the claim's scope.

'148 Patent

• The Term: "receiver"
• Context and Importance: This term is foundational to the infringement allegation for the '148 patent. The complaint equates this term with a "blind hole" in the accused product Compl. ¶51 The definition of "receiver" will determine whether the mounting points on the accused pads meet this claim limitation.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent states that fastener devices can "engage the receivers 140" and that receivers can be provided with inserts, but does not explicitly state that an insert is a required component of every receiver '148 Patent, col. 8:50-51 '148 Patent, col. 8:58-63 This could support a construction where a "receiver" is any feature, including a simple recess, designed to accept a fastener.
  • Evidence for a Narrower Interpretation: The specification describes receivers being "formed to compliment the many types of fastener devices" and details how they can contain threaded inserts or be formed to accept thread-forming screws '148 Patent, col. 8:54-65 This may support an argument that a "receiver" is a specifically engineered feature, not merely a hole, that actively interfaces with a fastener.

VI. Other Allegations

• Indirect Infringement: The complaint alleges both induced and contributory infringement. For inducement, it points to Defendant's alleged acts of "encouraging, advertising, promoting, and instructing others to use" the accused pads Compl. ¶38 Compl. ¶53 For contributory infringement, it alleges the pads are especially made for infringement and are not staple articles of commerce suitable for substantial non-infringing use Compl. ¶40 Compl. ¶55
• Willful Infringement: The complaint alleges willful infringement based on Defendant's purported knowledge of the patents. This knowledge is alleged to stem from a pre-suit cease and desist letter sent on March 25, 2026, as well as from patent markings on Plaintiff's own "QwikPad®" product and website Compl. ¶31 The complaint asserts that Defendant continued its infringing activities despite this knowledge Compl. ¶41

VII. Analyst's Conclusion: Key Questions for the Case

This case presents several technical and legal questions for the court. The outcome may depend on the answers to the following:

• A core issue will be one of structural equivalency: Does the "internal hollow region" required by the '896 patent, which the specification describes as being fillable with a liquid or gel, read on the accused products' alleged internal structure containing a pre-installed "foam insert"?
• A second key issue will be one of definitional scope: Will the term "receiver" in the '148 patent be construed broadly to mean any recess or blind hole for a fastener, as the complaint alleges, or will it be given a narrower construction requiring a more specific structure, potentially including an insert, as may be suggested by the patent's detailed description?
• For the asserted design patents, a central question will be one of visual comparison: From the perspective of an ordinary observer familiar with prior art designs, is the overall ornamental appearance of the accused NEXTPAD® and Oval Pad substantially the same as the designs claimed in the D'425, D'858, and D'859 patents?