The Schlage S00031721097-KIT is the OEM unassembled chassis kit for the Schlage ND Series ND50 and ND53 cylindrical lock functions. It ships unassembled with no finished parts-no rose, no lever, no escutcheon, no strike. This is the raw internal chassis mechanism for the ND50 entrance/office and ND53 entrance lock with inside indicator functions, packaged for field assembly and installation by a locksmith or qualified installer. When the chassis on an existing ND50 or ND53 installation fails-the latch no longer retracts on lever operation, the inside push-button mechanism strips, or the latch prong alignment breaks-this kit replaces the internal chassis without touching the trim, lever, or cylinder.

The unassembled format and no-finished-parts designation means this kit can be stocked as a universal replacement for any ND50 or ND53 installation regardless of the installed finish, lever style, or trim configuration. The chassis does not carry a finish coating. Assembly is required before installation.

Schlage Cylindrical Lock Chassis: ND50 vs ND53 Function Difference

The ND50 and ND53 share a single chassis because both functions use the same internal lock mechanism. The functional difference between the two is entirely in the trim, not the chassis.

ND50 (ANSI F82 Entrance/Office Lock): The push-button from inside locks the outside lever until the button is released by turning the inside lever or by key from outside. The inside lever is always free for immediate egress. This is the standard entrance/office function used in corporate offices, medical suites, government offices, and institutional corridor doors where inside control of outside access is required.

ND53 (ANSI F109 Entrance Lock with Inside Indicator): Functionally identical to the ND50 but adds the IND IS (Inside Indicator)-a "Locked/Unlocked" display visible from inside the room. The indicator mechanism (47710918, sold separately) and the indicator sign mount in the trim and connect to the chassis slide to display lock state. The chassis for ND53 is the same as ND50-only the trim assembly differs. This is why the S00031721097-KIT covers both functions from a single part number.

Schlage ND Series Chassis Installation: Handing and Door Compatibility

From the Schlage ND50/53 installation instructions (Allegion document 015922): the chassis installs on the inside of the door with the slide opening aligned toward the latch. The slide opening interfaces with the latch bar and latch prong-this is the mechanical link between the chassis and the latch bolt. When correctly aligned, lever operation transmits through the chassis to retract the latch.

The chassis is reversible for handling. If the slide opening does not align with the latch on initial positioning, the chassis handling can be changed per the installation instruction before securing. The anti-rotation plate then installs on the outside of the door, with the plate tab aligned to the indent on the hub.

Standard door thickness for this chassis is 1-3/4". For thinner doors, spacer kits are required: 48029970 for 1-3/8" to 1-1/2" doors, 48029971 for 1-1/2" to 1-5/8" doors, and 48029972 for 1-5/8" to 1-11/16" doors. The chassis is not compatible with door thicknesses below 1-3/8" without a spacer kit.

Schlage Commercial Cylindrical Lock Chassis: ND Series Grade 1 Platform

The ND50/53 chassis meets ANSI/BHMA A156.2, Series 4000, Grade 1. The ND Series platform is UL listed for 3-hour fire door assemblies on up to 4'x10' single doors and 8'x8' pairs under UL10C positive pressure, and 90-minute rating on 8'x10' pairs with 3/4" latch. The chassis is ADA compliant and meets the Buy American Act (BAA).

The ND Series also includes electrified function variants (ND50EU, ND50EL) that use a separate electrified chassis-the S00033868134-KIT covers the ND12/80EL electrified chassis. The S00031721097-KIT is the mechanical chassis for the standard non-electrified ND50 and ND53 functions. Confirm the function is mechanical before ordering.

For the complete Schlage ND Series parts catalog including chassis kits, indicator mechanisms, spacer kits, and latches, SecurityParts stocks OEM parts.