{"product_id":"castair-replacement-motor-pulley-7-8-fixed-bore-shaft-3-35-od-2b-grooves-p2b335-7-8","title":"Castair Replacement Motor Pulley 7\/8\" Fixed Bore Shaft 3.35\" OD. 2B Grooves P2B335-7\/8","description":"\u003ch2\u003eCast Air P2B335-7\/8 — 3.35\" OD Dual-Groove B-Section Motor Pulley, 7\/8\" Fixed Bore\u003c\/h2\u003e\n\n\u003cp\u003eThe Cast Air P2B335-7\/8 is a 3.35\" outside diameter motor pulley with two B-section belt grooves and a 7\/8\" fixed bore. It mounts directly onto a 7\/8\" motor shaft and drives a dual B-belt setup to the compressor pump. Dual-groove pulleys are used on compressors where a single belt cannot transmit the required torque reliably — the two belts share the load, which reduces slippage under peak demand and extends belt service life. This is the smallest OD in the Cast Air dual-B-groove motor pulley lineup, which makes it appropriate for applications where you need to run the pump at a lower speed relative to motor RPM.\u003c\/p\u003e\n\n\u003cp\u003ePulley diameter controls pump RPM. A smaller motor pulley produces a lower pump speed for a given motor speed. If your compressor is correctly specified with a 3.35\" motor pulley and you are replacing a worn or damaged unit, match the 3.35\" OD exactly. Do not substitute a larger diameter unless you are intentionally increasing pump speed — and if you are doing that, you need to verify that the pump and motor can handle the increased load and speed.\u003c\/p\u003e\n\n\u003ch3\u003ePulley Specifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e P2B335-7\/8\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOutside Diameter:\u003c\/strong\u003e 3.35\"\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBore Size:\u003c\/strong\u003e 7\/8\" fixed bore\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Grooves:\u003c\/strong\u003e 2\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGroove Profile:\u003c\/strong\u003e B-section\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBelt compatibility:\u003c\/strong\u003e Two B-section V-belts (matched pair recommended)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMounting:\u003c\/strong\u003e Fixed bore — mounts directly on 7\/8\" motor shaft with key and setscrew\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Cast iron\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $38.50\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy Two Belt Grooves?\u003c\/h3\u003e\n\u003cp\u003eSingle-belt drives work fine for low-to-moderate torque applications. When the compressor gets larger — higher displacement, higher pressure, larger motor — the torque demand on the belt drive exceeds what a single B-belt can reliably transmit. Dual-belt drives solve this by splitting the load between two belts:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHigher torque capacity:\u003c\/strong\u003e Two B-belts can transmit roughly twice the torque of a single B-belt at the same pulley diameter\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReduced slippage:\u003c\/strong\u003e Less chance of belt slip under startup load spikes, which is when most belt damage occurs\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLonger belt life:\u003c\/strong\u003e Each belt runs cooler and with lower unit stress than a single belt doing all the work\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUse matched belt pairs:\u003c\/strong\u003e When replacing belts on a dual-groove drive, replace both belts at the same time with a matched pair. Mismatched belts (different brands, different ages) will have slightly different lengths and one belt will carry more load than the other, causing uneven wear and premature failure.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003ePulley Diameter and Pump Speed\u003c\/h3\u003e\n\u003cp\u003eThe 3.35\" OD is the smallest motor pulley in the Cast Air 2B lineup. Here is how it compares to others in the series, and what that means for pump RPM:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSmaller motor pulley = slower pump:\u003c\/strong\u003e A 3.35\" motor pulley driving a 10\" pump pulley on a 1750 RPM motor results in a pump speed of approximately 586 RPM\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLarger motor pulleys produce higher pump speed:\u003c\/strong\u003e A 4.95\" motor pulley in the same configuration would produce 866 RPM at the pump\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReplace with the same OD:\u003c\/strong\u003e If you are replacing a worn pulley, the 3.35\" OD is the specification that the compressor was designed around. Match it exactly.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIf you are tuning the drive ratio:\u003c\/strong\u003e Any change in pulley diameter changes pump speed, output CFM, and motor load. Calculate the new pump RPM and verify it is within the pump manufacturer's specified operating range before making the change.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFixed Bore vs. Hub Pulleys\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFixed bore (this pulley):\u003c\/strong\u003e Machined to 7\/8\". Mounts directly on the motor shaft. No additional parts required beyond a matching key.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHub pulleys:\u003c\/strong\u003e Require a separate hub ordered for the specific shaft size. See the P2B355H, P2B395H, P2B445H, and P2B495H for hub-style pulleys in the dual B-groove lineup.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFor 7\/8\" shafts:\u003c\/strong\u003e The P2B335-7\/8 is the direct, no-hub option at 3.35\" OD. If you need a different OD with a 7\/8\" shaft, a hub-style pulley with an LX78 hub is the path to other diameters.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eBelt Guard Compatibility\u003c\/h3\u003e\n\u003cp\u003eDual-groove pulleys in the Cast Air lineup are used with specific belt guards. For reference:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e2BG guard (24x16x5):\u003c\/strong\u003e A2, A3, A4, A8 models\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e3BG guard (32x20x5):\u003c\/strong\u003e C1, D3, G11 models\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4BG guard (40x20x5):\u003c\/strong\u003e C2 model\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4BG7 guard (40x20x7):\u003c\/strong\u003e C3, G30 models\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e5BG guard (48x32x7.5):\u003c\/strong\u003e C3U, C4U models\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e2B-Groove Motor Pulley Lineup Comparison\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B335-7\/8 (this pulley):\u003c\/strong\u003e 3.35\" OD, 7\/8\" fixed bore — $38.50\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B355H:\u003c\/strong\u003e 3.55\" OD, hub shaft — $38.50\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B395H:\u003c\/strong\u003e 3.95\" OD, hub shaft — $38.50\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B445H \/ P2B455H:\u003c\/strong\u003e 4.45\"-4.55\" OD, hub shaft\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B495H:\u003c\/strong\u003e 4.95\" OD, hub shaft — $66.41\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B625-13\/8:\u003c\/strong\u003e 6.25\" OD, 1-3\/8\" fixed bore\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B675-13\/8:\u003c\/strong\u003e 6.75\" OD, 1-3\/8\" fixed bore\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B725-11\/8:\u003c\/strong\u003e 7.25\" OD, 1-1\/8\" fixed bore\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B80-13\/8:\u003c\/strong\u003e 8.0\" OD, 1-3\/8\" fixed bore\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eP2B875-13\/8:\u003c\/strong\u003e 8.75\" OD, 1-3\/8\" fixed bore\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e P2B335-7\/8\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOutside Diameter:\u003c\/strong\u003e 3.35\"\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBore:\u003c\/strong\u003e 7\/8\" fixed bore\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Grooves:\u003c\/strong\u003e 2\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGroove Profile:\u003c\/strong\u003e B-section\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBore Type:\u003c\/strong\u003e Fixed (no hub required)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Cast iron\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $38.50\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h3\u003e\n\u003cp\u003eDual-groove pulleys are not a part you want to get wrong — if the OD is off, your pump speed changes; if the bore is wrong, the pulley does not go on the shaft. We stock the full Cast Air motor pulley lineup. Call us with your compressor model number and we will confirm the correct pulley before you order.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e on qualifying orders\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree tech support:\u003c\/strong\u003e Call 866-217-0063 — we will confirm the OD and bore against your compressor model\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\u003eHonest guidance:\u003c\/strong\u003e We will tell you if there is a better match for your specific application\u003c\/li\u003e\n\u003c\/ul\u003e\n\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":53342573265109,"sku":"P2B335-7\/8","price":71.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/MOTOR-PULLEYS-300x248.jpg?v=1772652762","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-replacement-motor-pulley-7-8-fixed-bore-shaft-3-35-od-2b-grooves-p2b335-7-8","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}