{"product_id":"castair-replacement-motor-pulley-hub-sd-shaft-6-15-od-3b-grooves","title":"Castair Replacement Motor Pulley Hub SD Shaft 6.15\" OD. 3B Grooves","description":"\u003cp\u003eThe Castair P3B615SD is a 3-groove (3B) replacement motor pulley with an SD-style taper-lock hub and 6.15\" outer diameter. Three grooves mean this pulley runs three matched B-section belts, significantly increasing power transmission capacity compared to 2-groove designs — appropriate for higher-HP compressor motors where two belts are not sufficient to handle the torque without slipping. The SD hub uses a taper-lock bushing (sold separately) so the same pulley can be adapted to different motor shaft diameters.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eNote: Cast Air did not provide a dedicated manufacturer product page for this pulley.\u003c\/strong\u003e Specifications are drawn from the product listing and standard 3B SD-hub pulley engineering conventions. Call us before ordering to confirm the correct SD bushing size for your motor shaft.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Three Grooves?\u003c\/h2\u003e\n\u003cp\u003eA 3B motor pulley is used when the motor power and torque exceed what two B-section belts can reliably transmit. On compressors in the 3-5 HP range — and on some heavy two-stage compressors — running three belts distributes the drive load, reduces per-belt tension, and eliminates belt slip during the loaded part of the compression cycle. The tradeoff is higher belt replacement cost, but in exchange you get better belt life (lower tension per belt), smoother power delivery, and a drive system that handles the motor's output without overdrivng individual belts.\u003c\/p\u003e\n\n\u003ch3\u003ePulley Specification Details\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGroove Profile:\u003c\/strong\u003e 3B (three B-section V-belt grooves)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHub Type:\u003c\/strong\u003e SD taper-lock (bushing required, sold separately)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Diameter (OD):\u003c\/strong\u003e 6.15\"\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Motor-side pulley for higher-HP belt-drive air compressors\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Cast Air belt-drive compressors using SD-hub motor pulleys and B-section belts\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e P3B615SD\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eSD Hub — How It Works\u003c\/h2\u003e\n\u003cp\u003eThe SD taper-lock system uses a standard SD bushing that slides into the pulley's tapered bore. The bushing is available in multiple shaft sizes, allowing the same pulley to mount on motors with different shaft diameters. Once installed, the taper draws the bushing tight against the pulley bore as the mounting screws are torqued, creating a concentric, vibration-resistant fit. When the motor needs to be replaced, back out the mounting screws, the taper releases, and the bushing can be transferred to the new motor or a new bushing can be ordered for a different shaft size.\u003c\/p\u003e\n\n\u003ch3\u003eSD vs. SK Taper-Lock Hubs\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSD hub:\u003c\/strong\u003e Larger flange diameter than SK. Used on larger OD pulleys and higher-torque applications. The SD bushing is a specific size — confirm your pulley is SD-series before ordering a bushing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSK hub:\u003c\/strong\u003e Smaller standard. Used on smaller to mid-size pulleys in the Cast Air lineup. Not interchangeable with SD.\u003c\/li\u003e\n\u003cli\u003eThe P3B615SD uses SD bushings — order accordingly. If you are not sure which bushing your application uses, call us with the pulley part number and motor shaft diameter and we will identify the correct bushing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhen Does a Shop Need the P3B615SD?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eOriginal 3-groove SD-hub motor pulley is worn, cracked, or damaged\u003c\/li\u003e\n\u003cli\u003eRebuilding a higher-HP Cast Air compressor that factory-shipped with a 3B SD-hub motor pulley\u003c\/li\u003e\n\u003cli\u003eMotor replacement on a 3-belt drive system where the pulley can be reused with a new bushing\u003c\/li\u003e\n\u003cli\u003eUpgrading from a 2-groove system because belts are slipping under load — requires matching 3-groove flywheel on the pump side\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e P3B615SD\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGroove Type:\u003c\/strong\u003e 3B (three B-section V-belt grooves)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHub Type:\u003c\/strong\u003e SD taper-lock (bushing sold separately)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Diameter:\u003c\/strong\u003e 6.15\"\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBelt Section:\u003c\/strong\u003e B-section (three matched belts)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $105.88\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Data:\u003c\/strong\u003e Product page not available — specifications from product listing data\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat Is Included\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1x Castair P3B615SD motor pulley (SD hub)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eSD bushing and three B-section matched belts are not included. Specify your motor shaft diameter when ordering to get the correct SD bushing. Belts must be ordered based on your drive center distance.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h2\u003e\n\u003cp\u003eGetting a 3-belt SD-hub drive system right requires matching components — correct bushing bore, correct belt section and length, correct flywheel groove count on the pump. We have been working with Cast Air compressor systems since 2016 and can help you source everything needed in one order. Free shipping, free tech support, full warranty.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCast Air specialist\u003c\/strong\u003e since 2016\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e on all orders\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree tech support\u003c\/strong\u003e — we help identify the correct SD bushing and belt set for your application\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull manufacturer warranty\u003c\/strong\u003e on all Cast Air parts\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSystem-level sourcing\u003c\/strong\u003e — pulley, bushing, and belts together\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342573953237,"sku":"P3B615SD","price":195.96,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/MOTOR-PULLEYS-300x248_8ee87bed-3803-4cef-a7af-1612b9be7999.jpg?v=1772652780","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-replacement-motor-pulley-hub-sd-shaft-6-15-od-3b-grooves","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}