US 11505231

US Patent 11505231, titled "Removable seat attachment for a stroller," was filed on July 29, 2022, and issued on November 22, 2022. The inventor is Mark Zehfuss. The original assignee was Baby Jogger LLC, with the current assignee being Baby Jogger II LLC.

Abstract:
The patent describes stroller systems with removable seats. An example stroller includes rear wheels, front wheels, a handle, and a frame with support portions for the rear and front wheels, connected by a folding mechanism. A main stroller seat support is positioned at a first vertical position near the handle. A front seat attachment is designed to attach to the front wheel support portion at a second vertical position, substantially lower than the first. This front seat attachment is configured to support a front stroller seat primarily over the front wheels, ensuring the stroller system's center of gravity remains between the front and rear wheels.

Plain-Language Overview of Independent Claims:

• Claim 1 (System Claim): This claim describes a stroller system with a main frame, including front and rear wheels, a handle, and a folding mechanism. The frame has a primary seat support near the handle at a higher vertical position. The key feature is a separate front seat attachment that connects to the front wheel support at a lower vertical position. This attachment is specifically designed to hold an additional front stroller seat mainly over the front wheels, ensuring the stroller's balance (center of gravity) is maintained between all wheels.
• Claim 13 (Method Claim): This claim outlines a method for converting a single stroller into a double stroller. It involves starting with a standard stroller (as described in Claim 1) and then attaching a front seat attachment to the front wheel support. This attachment is placed at a lower vertical position than the original seat, and it supports an additional front stroller seat primarily over the front wheels, thus keeping the stroller balanced.
• Claim 14 (System Claim): Similar to Claim 1, this claim describes a stroller system with a frame, wheels, handle, and folding mechanism, where a primary seat support is at a higher vertical position. The distinction here is the inclusion of a "removable seat attachment adapter" that can be decoupled from the front wheel support at a lower vertical position. This adapter is designed to support an additional front stroller seat largely over the front wheels, maintaining the stroller's center of gravity between the front and rear wheels.
• Claim 15 (Method Claim): This claim describes a method for converting a single stroller to a double stroller using a removable seat attachment adapter. It involves providing a stroller with the basic frame and seat setup, then "removably coupling" the adapter to the front wheel support at a lower vertical position. This adapter, in turn, supports an additional front stroller seat over the front wheels to ensure the system's balance.

USPTO and CAFC 2026 Dockets:
The patent is currently active. Publicly available information indicates that there is ongoing litigation related to this patent family, including:

• A PTAB case (IPR2025-01095) was filed, but not instituted (procedural).
• US cases have been filed in the Massachusetts District Court (1:24-cv-11582) and the Delaware District Court (1:24-cv-00725, 1:24-cv-00723).
• The first worldwide family litigation was filed in 2024.

As of April 26, 2026, a search for "CAFC 2026 dockets US11505231" did not yield any specific dockets or cases currently pending before the Court of Appeals for the Federal Circuit for the year 2026.