Schlage A508-640 - Spacer, A Series Orbit Knobs

The A508-640 is a spacer for Schlage A Series knob locks built with the Orbit knob. It is a service part rather than a complete lockset, so it is what you order when the lock body and cylinder are still sound and you only need to make good one component that is worn, missing, or damaged after a rebuild. A locksmith or maintenance tech pulls the knob and trim, fits the spacer, and puts the same lock back on the door.

Orbit only. Schlage specifies the A508 against the A Series Orbit knob, which is the round ball knob in that line, and the other A Series knob designs take their own parts. Look at the knob on the door before you order: if it is not the ball shape, this is not the spacer for it and you want the one specified for the design you actually have.

Match it. Many Schlage A Series service parts are made finish specific, and the number after the dash in A508-640 is the finish code, not a size or a variation. That is the detail people get wrong on parts orders: they treat the base number as the whole part number and end up with a component that does not match the trim already on the door. Read the finish code off the hardware you are repairing and order the A508 in that same code.

Genuine Schlage. The A508-640 is a certified Schlage part, which is the point of buying it rather than a generic equivalent: a spacer sits inside the assembled lock, and a part built to Schlage's own tolerances goes back together with the original knob and rose without shimming or forcing. For anyone servicing a run of A Series locks, that is the difference between a repair that holds and one that comes back.

Commercial. Schlage classes the A508 as commercial door hardware, so it belongs to the A Series knob locks specified on commercial openings, offices, schools, multifamily common areas, and the like, not to Schlage's residential knob families. If the lock you are repairing came off a residential door, confirm it is actually an A Series before ordering this spacer.