Cast Air P2B455H — 4.55" OD Dual-Groove B-Section Motor Pulley, Hub Mount
The Cast Air P2B455H is a 4.55" outside diameter motor pulley with two B-section belt grooves and a hub-mount bore configuration. It requires a separately ordered hub (LX, SD, or SK series) matched to your motor shaft diameter. This pulley sits in the mid-range of the Cast Air 2B hub motor pulley lineup — larger than the 3.95" P2B395H and smaller than the 4.95" P2B495H — producing moderate-to-high pump speeds on 1750 RPM four-pole motors.
Important note on part number verification: The P2B455H (4.55" OD) is listed in our database at $64.49, but the closest current listing on the Cast Air website is the P2B445H at 4.45" OD. There is a 0.1" difference in outside diameter between these two part numbers, which produces a small but real difference in pump RPM. Before placing your order, please call us at 866-217-0063 so we can verify the exact part you need — whether that is the 4.55" unit, the 4.45" unit, or a different diameter entirely. We would rather spend two minutes confirming the right part than have you receive the wrong one.
Pulley Specifications (As Listed)
- Part Number: P2B455H
- Outside Diameter: 4.55"
- Bore Configuration: Hub mount (bore depends on hub selected)
- Number of Grooves: 2
- Groove Profile: B-section
- Belt compatibility: Two B-section V-belts (matched pair)
- Material: Cast iron
- Price: $64.49 (hub sold separately)
P2B455H vs. P2B445H — What the Difference Means
A 0.1" difference in pulley OD may seem trivial, but it produces a measurable difference in pump speed:
- P2B455H (4.55" OD): At 1750 RPM motor speed with a 10" pump pulley → pump runs at approximately 796 RPM
- P2B445H (4.45" OD): At 1750 RPM motor speed with a 10" pump pulley → pump runs at approximately 779 RPM
- Difference: About 17 RPM at the pump, or roughly 2.2% more pump speed with the 4.55" pulley
- On most applications this is within acceptable tolerance. On a compressor already running near motor capacity, the additional load from the higher RPM could cause nuisance tripping.
- If you are replacing a failed pulley: Check the OD of the original before ordering. If it measures 4.45", order the P2B445H. If it measures 4.55", the P2B455H is correct — but call us to confirm availability.
Selecting the Correct Hub
Hub-mount pulleys require a separately ordered hub. Cast Air hubs available:
- LX58: 5/8" shaft
- LX78: 7/8" shaft
- LX100: 1" shaft
- LX118: 1-1/8" shaft
- LX138: 1-3/8" shaft
- SD138: 1-3/8" shaft (SD taper-lock style)
- SD158: 1-5/8" shaft (SD taper-lock style)
- SK158: 1-5/8" shaft (SK taper-lock style)
- SK178: 1-7/8" shaft (SK taper-lock style)
Measure your motor shaft diameter with calipers. Do not assume — measure. The hub bore must match the shaft exactly. Call us if you are unsure which hub series (LX, SD, or SK) your application requires; the series used depends on which was originally installed and what is accessible for your compressor configuration.
Why This Size Motor Pulley?
At 4.55" OD, this pulley is used on compressors that need to run the pump at a moderate-to-high speed relative to motor RPM — typically mid-sized two-stage compressors where output CFM targets require higher pump RPM than smaller pulleys deliver. The dual B-section grooves handle the torque transmission requirements of larger compressors where a single B-belt would be insufficient. Applications in this range often include 5 HP to 10 HP compressors with two-stage pumps.
Dual B-Belt Drive Installation Notes
- Replace both belts simultaneously: Matched belt pairs only. Mixing a new belt with an old belt creates unequal tension and load distribution.
- Verify pulley alignment: Both pulley grooves on the motor side must align with the corresponding grooves on the pump pulley. Misalignment by even 1/8" causes belt edge wear and shortened belt life.
- Check tension on each belt: After initial installation, run the compressor for one hour and re-check tension. New belts stretch slightly during break-in and will need retensioning.
- Hub installation: Follow Cast Air hub installation instructions. The hub locking screw sequence matters — improper installation can leave the hub slightly off-center, creating runout.
2B Hub Motor Pulley Lineup
- P2B335-7/8: 3.35" OD, 7/8" fixed bore — $38.50
- P2B355H: 3.55" OD, hub mount — $38.50
- P2B395H: 3.95" OD, hub mount — $38.50
- P2B445H (nearest castair.net listing): 4.45" OD, hub mount
- P2B455H (this listing): 4.55" OD, hub mount — $64.49 (verify before ordering)
- P2B495H: 4.95" OD, hub mount — $66.41
Technical Specifications
- Part Number: P2B455H (verify — nearest castair.net listing is P2B445H at 4.45" OD)
- Outside Diameter: 4.55"
- Bore: Hub mount (hub ordered separately)
- Number of Grooves: 2
- Groove Profile: B-section
- Material: Cast iron
- Price: $64.49 (hub not included)
Why Buy From Air Compressor Factory Direct?
Because there is an open question on this specific part number — P2B455H vs. P2B445H — we want to talk to you before you complete your order. Our tech support team can pull up the Cast Air documentation, confirm which part is correct for your compressor, and make sure you get the right pulley and the right hub in a single shipment. That is faster and cheaper than ordering the wrong part and waiting for a return and reship.
- Free shipping on qualifying orders
- Free tech support: Call 866-217-0063 — we will verify P2B455H vs. P2B445H and confirm the right hub for your shaft
- Full manufacturer warranty on all Cast Air parts
- Honest guidance: If there is uncertainty on a part number, we will say so and help you resolve it
Call 866-217-0063 for quick answers and help!
