The Schlage 48108613 is an OEM chassis for the Schlage ND Series Grade 1 cylindrical lock, documented in the Schlage ND Series Service Manual. It is a field replacement chassis - the internal mechanical carrier that determines the locking function of the installed lock. When the chassis on an ND Series installation fails, the lock either stops operating correctly in one direction, stops holding the latch in the correct state, or fails entirely. This part restores function without replacing the complete lock, trim, and cylinder assembly.

Before ordering, confirm the specific ND function installed on the door by referencing the Schlage ND Series Service Manual or the original project specification. Different ND functions use different chassis. The 48108613 is the correct chassis for a specific function in the ND Series catalog, and ordering the wrong chassis results in incorrect lock behavior after installation.

What the ND Series Chassis Is and Why It Fails

The chassis is the mechanical core of the ND Series cylindrical lock. Every functional behavior of the lock - whether the outside lever can retract the latch, whether the inside push button locks the outside lever, whether closing the door releases the button, whether the lever is always free for egress - is controlled by the chassis. The trim (lever, rose, cylinder) connects to the chassis. The latch mounts to the chassis. The chassis converts lever rotation into latch movement and manages the functional relationships between inside and outside control.

Chassis failure in the ND Series typically shows up as one of several symptoms. The outside lever starts operating when it shouldn't, or stops operating when it should. The push button stops releasing when the inside lever is turned. The lock holds correctly in one direction but not the other. These symptoms point to internal wear in the chassis - specifically the interaction between the latch cam, the push button mechanism, and the lever engagement components.

The ND Series is built to outlast Grade 1 requirements significantly. Allegion tests the ND chassis to 3,100 in-lb of abusive lever torque - more than 2.5 times the Grade 1 standard - and to 16 million cycles with nearly zero droop or wobble in the lever. But on the highest-traffic doors in institutional buildings, even that cycle life eventually runs out, or physical damage from forced entry, vandalism, or abusive use accelerates wear beyond the normal service schedule.

Schlage Cylinder Locks: How to Confirm the Right Chassis

The ND Series has 24 mechanical functions, and each function uses its own chassis. Before ordering the 48108613, confirm it is the correct chassis for the installed function. The function is typically visible on the original project submittal, the lock specification sheet for the building, or the Schlage label on the inside of the trim assembly.

If the function isn't documented, the ND Series Service Manual provides exploded views of each chassis and trim assembly with part number charts for replacement purposes. The service manual is available as a catalog reference on the SecurityParts product page for this chassis. Cross-reference the 48108613 against the service manual diagram to confirm it matches the installed function before placing the order.

Schlage ND Series Chassis Replacement: What the Platform Supports

Every ND Series chassis supports the same physical installation footprint. The ND uses the standard ANSI 161 cylindrical door preparation, meaning all ND Series chassis are interchangeable within the same door prep without any door modification. Standard door thickness for the ND Series is 1-5/8" to 2-1/8" (41 mm to 54 mm). Spacer kits handle thinner doors from 1-3/8" up, and extended configurations reach up to 6" door thickness for specialty applications.

The chassis construction uses zinc and steel components plated for corrosion resistance. The latch is stainless steel with 1/2" throw. The latch is adjustable at the chassis level for both flat and beveled door edge installations.

For the complete Schlage ND Series chassis and parts catalog, SecurityParts stocks OEM service components.