QL4-21

Tue, 6 Jan 2026 07:00:07 GMT

SkyLoc QL4-21 Caged Floating Receptacle

Three-Piece Assembly | Radial Float Design | 4140 High-Strength Steel

Technical Overview

The QL4-21 caged floating receptacle is a precision three-piece assembly engineered for structural applications requiring radial float capability. The assembly consists of the QL4-NUT (threaded insert with 1/4-28 UNF-3B two-lead thread), QL4C-CAGE (17-7 PH stainless steel spring cage), and QL4-BASE (mounting base). This design allows controlled radial movement to accommodate hole misalignment and panel tolerances while maintaining secure fastening capability. Manufactured from 4140 steel heat treated to 180-200 KSI with cadmium plating per AMS QQ-P-416 Type II, Class 2 and dry film lubricant, this receptacle provides exceptional strength and corrosion resistance for demanding aerospace and industrial installations.

Specifications

Assembly Components:	QL4-NUT, QL4C-CAGE, QL4-BASE
Thread Size:	1/4-28 UNF-3B (2-Lead Thread)
Receptacle Type:	Caged Floating with Radial Float Capability
Nut & Base Material:	4140 Steel (ASTM A29)
Cage Material:	17-7 PH Stainless Steel (ASTM A564)
Heat Treatment:	180-200 KSI per AMS 2759 (nut & base), TH1050 (cage)
Finish:	Cadmium Plate per AMS QQ-P-416 Type II, Class 2 with Dry Film Lubricant (nut & base), Passivated per AMS 2700 (cage)
Float Capability:	Radial float for hole misalignment accommodation
Compatible Systems:	QL4S Series Quarter-Turn Studs
Equivalent Part Number:	CA21021 Series
Compliance:	AS9100D Certified, CAGE Code 435Z0

Applications

Aerospace: Structural panels requiring hole misalignment tolerance, engine cowlings, access doors where radial float compensates for assembly tolerances
Motorsport: Body panels, chassis components, applications requiring quick-release capability with tolerance accommodation
Industrial: Equipment enclosures, machinery panels, installations requiring radial movement to accommodate thermal expansion or structural flexing
Marine: Deck hardware, structural assemblies in corrosive environments requiring float capability
Defense: Military aircraft structural panels, ground support equipment requiring MIL-SPEC corrosion protection with radial float

QL4-21 Assembly Components

Component	Part Number	Description
Nut	QL4-NUT	Threaded insert with 1/4-28 UNF-3B two-lead thread, 4140 steel, cadmium plated with dry film lube
Cage	QL4C-CAGE	Spring cage for radial float, 17-7 PH stainless steel, passivated
Base	QL4-BASE	Mounting base, 4140 steel, cadmium plated with dry film lube

Complete System Components

Component	Part Number	Description
Stud	QL4S Series	Quarter-turn studs compatible with 1/4-28 two-lead thread receptacles
Receptacle	QL4-21	Caged floating receptacle assembly (this product)
Retainer	QL4S-RET Series	Spring retainers for loose panel applications
Grommet	QL4G Series	Load distribution and panel protection

Key Features

Radial Float Design: Spring cage allows controlled radial movement to accommodate hole misalignment and assembly tolerances
Three-Piece Construction: Modular design with nut, cage, and base components for reliable performance and serviceability
High-Strength Materials: 4140 steel heat treated to 180-200 KSI provides superior load capacity for structural applications
Corrosion Protection: Cadmium plating per AMS QQ-P-416 Type II, Class 2 with dry film lubricant for harsh environment durability
Two-Lead Thread: 1/4-28 UNF-3B dual-start thread enables 180-degree rotation for rapid quarter-turn fastening
Industry Standard Interchange: Compatible with CA21021 series receptacles

📏 Selection Guide: Use QL4-21 caged floating receptacles in applications requiring radial float to accommodate hole misalignment, structural movement, or thermal expansion. The three-piece assembly provides reliable quarter-turn fastening while allowing controlled radial movement. Individual components (QL4-NUT, QL4C-CAGE, QL4-BASE) are available separately for service and replacement - contact sales for component ordering information.

Quality & Compliance

Manufactured by Skybolt Aerospace Fasteners under AS9100D certification at our Leesburg, Florida facility (CAGE Code: 435Z0). All QL4-21 receptacle assemblies are 100% inspected to drawing specifications and include full material traceability. Materials conform to ASTM A29 for 4140 alloy steel and ASTM A564 for 17-7 PH stainless steel. Heat treatment meets AMS 2759 requirements for 180-200 KSI ultimate tensile strength. Cadmium plating on nut and base components meets AMS QQ-P-416 Type II, Class 2 requirements with dry film lubricant for enhanced performance in aerospace and military applications.

Tridair® is a registered trademark of Howmet Aerospace, Inc. or its subsidiaries. Skybolt products are compatible alternatives and are not manufactured by or affiliated with Howmet Aerospace.

Visit SkyLoc® EXT Receptacles to see additional products in this category.

Skybolt - SkyLoc® Structural Fasteners / SkyLoc® External Thread (EXT) Series / SkyLoc® EXT Receptacles