Dimension - 2" x 0.5"
 
Spring Brake Shoes
What it is: The term "spring gear" is ambiguous and not explicitly covered in the web results. It could refer to a gear mechanism incorporating a spring (e.g., for tension or return functions) or a specific product like Yukon Gear’s differential spring kits. Alternatively, it might be a typo or colloquial term for a spring-loaded gear system in automotive or machinery applications.
Function: If related to differentials, it could be part of a spring kit that maintains pressure in a limited-slip differential (e.g., Yukon Gear’s kits for Dana 28–50). In other contexts, it might describe a gear with a spring to absorb shock or ensure engagement, such as in clock mechanisms or small machinery.