Demax USA Inc v. Mayflower Auto Equipments Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Demax USA Inc. (Texas)
  • Defendant: Mayflower Auto Equipments Inc. (California)
  • Plaintiff’s Counsel: Ni, Wang & Massand, PLLC
• Case Identification: 4:26-cv-00177, E.D. Tex., 02/18/2026
• Venue Allegations: Plaintiff alleges venue is proper in the Eastern District of Texas because Defendant maintains a regular and established place of business in the district from which it imports and distributes the accused products.
• Core Dispute: Plaintiff alleges that Defendant’s swing arm style tire changers, which feature double assist arms, infringe a patent related to a tire changer apparatus designed to prevent damage to wheel rims during operation.
• Technical Context: The technology relates to automated tire changing equipment used in automotive repair, where mechanical arms assist in the process of mounting and dismounting tires from wheel rims.
• Key Procedural History: The patent-in-suit claims priority from a 2007 Chinese patent application via a PCT international application. The complaint alleges Defendant had actual notice of the patent prior to the lawsuit's filing.

Case Timeline

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

U.S. Patent No. 8,528,620 - "Swing Arm Style Tire Changer"

The Invention Explained

• Problem Addressed: Conventional swing arm tire changers can suffer from low structural rigidity Compl., Ex. A, ’620 Patent, col. 1:29-32 During the high-force operation of dismounting a tire, the main swing arm and its supporting upright stem can deform, causing the dismounting head to physically contact and damage the wheel rim Compl., Ex. A, ’620 Patent, col. 1:32-37
• The Patented Solution: The invention adds a "first auxiliary arm unit" that is connected to the main swing arm and includes a tire-pressing wheel Compl., Ex. A, ’620 Patent, col. 2:56-61 While the main dismounting head applies a downward force on one part of the tire, the auxiliary arm’s wheel applies a downward force on another part of the tire, receiving an equal and opposite upward reaction force from the tire Compl., Ex. A, ’620 Patent, col. 2:61-col. 3:4 The patent teaches that this upward force on the auxiliary arm effectively offsets the downward force on the main arm, stabilizing the entire structure and preventing the deformation that leads to rim damage Compl., Ex. A, ’620 Patent, col. 3:1-4 The apparatus also includes a second auxiliary arm for additional functions Compl., Ex. A, ’620 Patent, abstract
• Technical Importance: This approach seeks to improve the reliability and precision of tire changing machines by using a force-cancellation principle to maintain structural integrity, thereby protecting expensive wheel rims from damage during servicing.

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claims 2-5, 7, 9, and 12 Compl. ¶13
• Independent Claim 1:
  • a base;
  • a workbench rotatably supported by said base;
  • an upright stem upwardly extended from said base;
  • a swing arm having a first end portion mounted on said upright stem for rotating about said upright stem;
  • a tire changer arm movably mounted on a second end portion of said swing arm;
  • a tire changer head provided on said tire changer arm;
  • a first auxiliary arm unit connected to said swing arm and comprising a tire-pressing wheel;
  • a second auxiliary arm unit connected to said upright stem; and
  • a tire-pressing head mounted to said second auxiliary arm unit.

III. The Accused Instrumentality

Product Identification

The accused products are identified as "swing arm style tire changers," specifically including the "3.0 HP Heavy Duty New Double Assist Arms Tire Changer Wheel Changers Machine 988" and "Tire Changer model: 560/950 with Mayflower Tire Changer Double Assist Arm Model 232" Compl. ¶13

Functionality and Market Context

The complaint alleges these are "swing arm style tire changers" that Defendant makes, uses, sells, offers for sale, and/or imports into the United States Compl. ¶13 They are sold through Defendant's website and its Amazon.com storefront Compl. ¶4 The complaint characterizes the machines by their "Double Assist Arms," which are the basis for the infringement allegations Compl. ¶13 The complaint does not provide further technical detail on the operation of the accused products. No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint references a claim chart attached as Exhibit B purporting to show how the accused products infringe Compl. ¶16 However, this exhibit was not provided with the complaint. The analysis below is therefore based on the narrative infringement theory presented in the complaint.

The central infringement allegation is that the accused products, which are marketed as having "Double Assist Arms," embody the patented combination of a primary swing arm with both a "first auxiliary arm unit" and a "second auxiliary arm unit" as recited in claim 1 of the ’620 Patent Compl. ¶13 Compl. ¶15 The plaintiff’s theory appears to be that one of the accused "Assist Arms" constitutes the claimed "first auxiliary arm unit connected to said swing arm" and the other constitutes the "second auxiliary arm unit connected to said upright stem."

Identified Points of Contention

• Structural Questions: A likely point of dispute will be the precise connection points and structural relationships of the "Double Assist Arms" on the accused products. The infringement analysis will depend on whether one assist arm is "connected to said swing arm" and the other is "connected to said upright stem," as strictly required by claim 1.
• Functional Questions: The patent specification heavily emphasizes the force-offsetting function of the first auxiliary arm to prevent deformation of the swing arm Compl., Ex. A, ’620 Patent, col. 2:61-col. 3:4 A key question will be whether the accused products’ assist arms perform this specific function, or if they serve other purposes, such as merely pressing down the tire bead without providing the claimed structural stabilization benefit. The complaint provides no detail on this point.

V. Key Claim Terms for Construction

The Term: "a first auxiliary arm unit connected to said swing arm"

Context and Importance

This term is critical because it describes the structural element that purportedly provides the patent's key innovation: preventing deformation of the main swing arm by offsetting operational forces. The defendant will likely argue for a narrow construction of "connected to said swing arm" that is limited by the specification, while the plaintiff will argue for a broader interpretation. The outcome of this construction could be dispositive of infringement.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: Claim 1 uses the general term "connected," which could be argued to encompass any form of direct or indirect mechanical linkage between the first auxiliary arm and the main swing arm Compl., Ex. A, ’620 Patent, col. 6:35-36
• Evidence for a Narrower Interpretation: The specification discloses a specific embodiment where the first auxiliary arm unit is "pivotally and rotatably supported through the connecting arm unit 16" which is mounted onto the swing arm 10 Compl., Ex. A, ’620 Patent, col. 3:45-50 A defendant may argue that the term "connected" should be limited to this disclosed pivotal connection, which is necessary to achieve the described force-offsetting benefit.

VI. Other Allegations

Indirect Infringement

The complaint makes a conclusory allegation of indirect infringement Compl. ¶15 but does not plead specific facts to support the required elements of knowledge and intent, such as referencing user manuals, marketing materials, or other evidence of encouraging infringement.

Willful Infringement

The complaint alleges willful infringement based on the assertion that Defendant had "actual notice of the '620 Patent and the infringement alleged herein at least as early as December 30, 2025" Compl. ¶17, which is prior to the complaint's filing date of February 18, 2026 Compl. p. 1 The basis for this alleged notice is not specified.

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

This dispute appears to center on the structure and function of the "assist arms" common in modern tire changers. The case will likely turn on the following key questions for the court:

1. Claim Construction: A core issue will be one of definitional scope: how will the court construe the term "connected to said swing arm"? Will the term be given its plain and ordinary meaning, or will it be limited by the specification to a structure that necessarily provides the force-offsetting function described as the invention's primary advantage?

2. Evidentiary Proof of Infringement: A central factual question will be one of technical correspondence: does discovery show that the accused "Double Assist Arms" machines have a structure that maps onto the distinct claim limitations of a "first auxiliary arm unit connected to said swing arm" and a "second auxiliary arm unit connected to said upright stem"? The complaint’s lack of technical detail makes this a primary issue to be resolved.