Ives 3SP1 4-1/2" x 4-1/2" Full Mortise Spring Hinge - Three Knuckle - Standard Weight

The Ives 3SP1 is the 4-1/2 x 4-1/2 full mortise spring hinge in Ives's standard weight range, built for medium weight commercial and residential doors where automatic closing is required by code or application.

Spring hinges are often specified on fire-rated door assemblies. NFPA 80 and most building codes require fire-rated doors to be self-closing. A surface-mounted door closer accomplishes this and is the more common specification on high-traffic commercial openings. Spring hinges accomplish the same self-closing function with no visible hardware on the door face or frame, which is why they're used on light commercial and residential fire doors where a surface closer would be over-specified or visually undesirable.

Three spring hinges are typically required per fire-rated door. Two spring hinges may be sufficient on lighter non-fire-rated doors; confirm the requirement with your local building authority or the door assembly listing before specifying. For all Ives and commercial spring hinges, browse our spring hinges catalog. For all commercial door hinges, view our door hinges catalog.

Three Knuckle vs. Five Knuckle

Standard commercial ball bearing hinges use five knuckles: five cylindrical barrel segments that interlock and stack to form the hinge barrel. Spring hinges use three knuckles because the spring mechanism occupies the barrel space. The spring housing takes the place of the two middle knuckles found on five-knuckle hinges. On an installed door, three-knuckle spring hinges are visually identifiable from the barrel profile and are slightly more compact in barrel length than a five-knuckle hinge of the same height.

The three-knuckle design is the universal standard for spring hinges. When replacing existing spring hinges, confirm the existing hinges are three-knuckle and the same leaf size (4-1/2 x 4-1/2 in this case) before ordering.

Spring Tension Adjustment

The 3SP1 spring tension is adjustable after installation. The spring tension pin can be repositioned to increase or decrease the closing force. Higher tension closes the door faster and more firmly. Lower tension gives a slower, gentler close. On fire-rated doors, the spring tension must be set high enough to reliably latch the door on every close. On non-fire-rated doors where a quieter or slower close is preferred, tension can be reduced accordingly.

Ives 3SP1 Full Specifications

• SKU: 3SP1 4.5X4.5 652

• Also known as: Ives 3SP1, 3SP1 spring hinge, ives 3sp1 4.5x4.5, ives spring hinge 4.5, 3SP1 US26D

• Series: Ives 3SP1

• Type: Full mortise, three-knuckle, spring hinge

• Weight class: Standard weight

• Gauge: 0.134"

• Application: Automatic self-closing; medium weight doors

• Size: 4-1/2" x 4-1/2" (114 x 114 mm)

• Material: Steel standard; Stainless Steel also available

• Finish shown: 652 (US26D) Satin Chrome, Steel base

• Spring: Adjustable tension via spring pin

• Packaging: Sold individually; wood and machine screws included

• ANSI: A156.1 A8112 (Steel); A5112 (Stainless Steel); A2112 (Brass)

• Fire door use: Yes, with three hinges per door per code requirements

• Resources: Ives Full Catalog in Resources section

3SP1 Available Sizes

The Ives 3SP1 spring hinge is available in 4-1/2 x 4 and 4-1/2 x 4-1/2. The related products section on this page includes both sizes. The 4-1/2 x 4 is specified when the door or frame has less hinge space. The 4-1/2 x 4-1/2 (this product) is the standard commercial size for most medium-weight door applications. Confirm the existing hinge space on the door and frame before selecting between the two sizes.