Cast Air P2B495H — 4.95" OD Dual-Groove B-Section Motor Pulley, Hub Mount
The Cast Air P2B495H is a 4.95" outside diameter motor pulley with two B-section belt grooves and a hub-mount bore configuration. It is the largest of the Cast Air hub-mount dual-B-groove motor pulleys in the small-to-mid range lineup, sitting above the 4.45"/4.55" pulleys and below the larger fixed-bore pulleys (6.25" and up) used on high-horsepower compressors. The hub-mount design means you order a separately matched hub (LX, SD, or SK series) for your motor shaft size — the pulley body itself has no machined bore.
At 4.95" OD, this is the motor pulley to use when you need to run the pump at a higher speed for a given motor RPM — maximizing CFM output within the motor's power rating. Compared to the 3.55" P2B355H, the P2B495H runs the pump approximately 39% faster for the same motor speed. That translates to proportionally more CFM output, but also more load on the motor. The compressor must be properly matched: if the motor is sized for this drive ratio, it will handle it. If someone has installed a larger motor pulley than the original spec, the motor will run hotter and draw more current — potentially tripping breakers or shortening motor life.
Pulley Specifications
- Part Number: P2B495H
- Outside Diameter: 4.95"
- 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 required)
- Material: Cast iron
- Price: $66.41 (hub sold separately)
Selecting the Correct Hub
The P2B495H requires a separately ordered hub matched to your motor shaft diameter. Cast Air hubs:
- LX58: 5/8" shaft
- LX78: 7/8" shaft
- LX100: 1" shaft
- LX118: 1-1/8" shaft
- LX138: 1-3/8" shaft (LX taper-lock)
- SD138: 1-3/8" shaft (SD taper-lock)
- SD158: 1-5/8" shaft (SD taper-lock)
- SK158: 1-5/8" shaft (SK taper-lock)
- SK178: 1-7/8" shaft (SK taper-lock)
A 4.95" motor pulley is typically used on compressors with 1 HP to 5 HP motors. Motors in that range commonly use 7/8" (LX78), 1" (LX100), or 1-1/8" (LX118) shafts. Measure with calipers — do not assume. If you are replacing an existing hub-mount pulley, the hub markings will identify the hub series and shaft size already installed.
Understanding the Drive Ratio at 4.95" OD
This pulley produces the highest pump speed of the Cast Air hub-mount 2B lineup:
- At 1750 RPM motor speed with a 10" pump pulley: pump runs at approximately 866 RPM
- At 1750 RPM motor speed with a 12" pump pulley: pump runs at approximately 722 RPM
- Compared to 3.55" (P2B355H): approximately 39% higher pump speed
- Compared to 3.95" (P2B395H): approximately 25% higher pump speed
If your compressor was designed with a 4.95" motor pulley, the pump, motor, valves, and unloader system are all sized to handle those speeds and loads. Replace like-for-like unless you have a specific engineering reason to change the drive ratio — and the data to back it up.
When Shops Install Larger Motor Pulleys (and When Not To)
Shops sometimes ask about installing a larger motor pulley to increase compressor output without buying a bigger machine. Here is the reality:
- Going larger increases CFM, but also increases motor amps: If the motor is not rated for the additional load, you will see breaker trips, overheating, and shortened motor life
- Pump valve stress increases: Higher RPM means more valve cycles per minute — pumps running above their rated RPM wear valve seats, reeds, and rings faster
- The P2B495H is a replacement part: If your compressor came with a 4.95" motor pulley, this is the correct replacement. If it came with a smaller pulley and you are trying to upsize the drive, call us and we will give you an honest assessment of whether the motor and pump can handle it
Dual B-Belt Drive Service Notes
- Always use matched belt pairs: Both B-belts must be replaced together with a factory-matched pair. Mixing ages or brands results in unequal loading and early failure of the tighter belt.
- Break-in retensioning: New belts stretch during the first operating hours. Check and adjust tension after the first 4-8 hours of operation.
- Alignment check: Use a straightedge across the pulley faces after installation to verify the motor pulley and pump pulley are in the same plane. Misalignment by 1/8" or more will cause edge wear and shorten belt life significantly.
- Hub torque sequence: Follow the Cast Air hub installation instructions for tightening sequence and torque spec. Improper hub installation creates runout that causes vibration and premature bearing failure.
Where the P2B495H Fits in the Full Lineup
- P2B335-7/8: 3.35" OD, 7/8" fixed bore — $38.50 (smallest, slowest pump speed)
- P2B355H: 3.55" OD, hub mount — $38.50
- P2B395H: 3.95" OD, hub mount — $38.50
- P2B445H: 4.45" OD, hub mount
- P2B455H: 4.55" OD, hub mount — $64.49
- P2B495H (this pulley): 4.95" OD, hub mount — $66.41 (largest hub-mount, highest pump speed)
- P2B625-13/8 and larger: Fixed-bore pulleys for high-horsepower, large-frame compressors
Technical Specifications
- Part Number: P2B495H
- Outside Diameter: 4.95"
- Bore: Hub mount (hub ordered separately)
- Number of Grooves: 2
- Groove Profile: B-section
- Material: Cast iron
- Price: $66.41 (hub not included)
Why Buy From Air Compressor Factory Direct?
The P2B495H is the top of the hub-mount 2B pulley range, and ordering it incorrectly — wrong hub, wrong size — means a compressor that either will not assemble or runs out of spec. We stock the full Cast Air hub lineup and can pull up the original specification for your compressor model to confirm the motor pulley OD and hub series before you order. One phone call, one order, one shipment. That is how it should work.
- Free shipping on qualifying orders
- Free tech support: Call 866-217-0063 — confirm the correct hub for your motor shaft and verify the 4.95" OD matches your original spec
- Full manufacturer warranty on all Cast Air parts
- Honest guidance: If a larger pulley is not appropriate for your motor, we will tell you — not just take your order
Call 866-217-0063 for quick answers and help!
