Information from Kadee's website: #31 HO Scale 30-Series Plastic Couplers with Gearboxes - Long (25/64") Underset Shank HO-Scale MAGNE-MATIC This industry leading coupler features plastic standard coupler with metal knuckle, and #621 torsion centering spring and comes complete with #233 insulated draft gearbox and lid. The #31 Magne-Matic® Plastic Coupler is designed mostly for body mounting with limited space either above or below the mounting platform, with or without Draft Gear Box Lid and with Draft Gearbox Lid either on top or bottom. Note: The 30-Series Torsion Spring can be mounted either below or above the coupler shank, but must always be mounted between the Coupler Spring Lid and Draft Gearbox. The #141 Whisker® Metal Coupler mounted in a #252 Snap-together Gearbox is equivalent to the #31 Coupler. The Whisker® Coupler mounted in a #252 Snap-together Gear box makes for simple and easy assembly. It is not recommended to use a metal coupler directly on a metal surface or in a metal draft gearbox to avoid possible electrical crossover and shorting that may cause damage. Refer to our helpful Coupler Conversion Charts to determine the appropriate coupler to use on your model. 30-Series Coupler Instructions 30-Series Chart Two pair per package HO-Scale Package Includes: (2) Pair #31 Plastic Shank Couplers - Long Underset Shank (2) Pair #621 Torsion Centering Spring (2) Pair #233 Gearboxes & Lids (2) Pair #210 Washers (2) Pair #256 - 2-56 Screws (2) #622 Knuckle Springs #31 Plastic Coupler Features: Material - Metal Knuckle, Plastic Coupler Shank Shank Length - Long (25/64") (center hole to back of coupler head) Coupler Offset - Underset Knuckle Spring - #622 Centering System - Standard Shank Centering Spring - #621 Torsion Centering Spring Head - Standard Head Works With - #233 draft gearboxes #233 Plastic Draft Gearboxes & Lids Features: Material - Insulated Plastic Dimensions - 3/8"L x 5/16"W x 9/64"H Works With - NO.5®, #58, 20-Series Couplers #31 in a #233 gearbox on top. Mounting Specifications: Mounting Height - 29/64" Centerline - 25/64" Trip Pin Height - 1/32" Center Hole - 2-56 Insulated Screws are the most commonly used. (Screw length will vary) #31 in a #233 gearbox on bottom. Mounting Specifications: Mounting Height - 13/32" Centerline - 25/64" Trip Pin Height - 1/32" Center Hole - 2-56 Insulated Screws are the most commonly used. (Screw length will vary) Recommended Tools: #206 Insulated Multi-Purpose Coupler Height Gauge #231 Greas-em Dry Graphite Lubricant #237 Coupler Trip Pin Pliers #240 Double Headed Pin Vise #241 Dual Tool Manual Uncoupling Tool and Spring Pick #246 Tap (2-56) and Drills (#50 and #43) #1020 Coupler & Special Purpose Tweezers
