Premium Replacement The 91-171874-12 (C) Bobbin Case Opener (also known as a hook opener or position finger) is a critical timing component for the Pfaff 481, 483, 487, and 563 industrial series. This "C-class" version is specifically engineered for heavy-duty applications, featuring the reinforced geometry and clearance required to handle thicker threads and larger needle sizes.

As a high-quality generic replacement, it performs the vital task of momentarily pulling the bobbin case basket away from the rotation of the hook, creating the physical gap (the "thread path") necessary for the needle thread to pass smoothly around the hook without snagging.

Key Features & Performance
Heavy-Duty "C" Specification: Designed with a more robust profile to withstand the higher torque and thicker thread gauges (up to T-90 / V-92) typical of heavy garment and upholstery production.

Precision Timing Profile: The "finger" is milled to microscopic tolerances to ensure it engages and releases the bobbin case basket at the exact millisecond required during the hook's rotation.