Cast Air P2B355H — 3.55" OD Dual-Groove B-Section Motor Pulley, Hub Mount
The Cast Air P2B355H is a 3.55" outside diameter motor pulley with two B-section belt grooves and a hub-mount bore configuration. Unlike fixed-bore pulleys, the P2B355H does not have a machined bore — it accepts a separate hub (ordered for your specific motor shaft size) that locks into the pulley and clamps onto the shaft. This design lets the same pulley body fit multiple shaft diameters depending on which hub you order. It is one step up in diameter from the P2B335-7/8 in the Cast Air lineup, producing slightly higher pump speed from the same motor.
Hub pulleys are the right choice when: you need a diameter that is not available in a fixed-bore version for your shaft size, when you want the flexibility to reuse the pulley body if you change motors, or when the original equipment used a hub mount. For a 3.55" dual B-groove motor pulley, the P2B355H paired with the appropriate hub is the Cast Air part for the job.
Pulley Specifications
- Part Number: P2B355H
- Outside Diameter: 3.55"
- 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 recommended)
- Material: Cast iron
- Price: $38.50 (hub sold separately)
Selecting the Correct Hub
The P2B355H requires a separately ordered hub. The hub matches your motor shaft size. Cast Air offers the following hubs:
- 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 before ordering. The hub bore must match the shaft exactly. A hub that is 1/8" too large will not hold the pulley concentric with the shaft.
Why Hub-Mount Pulleys Exist
- Flexibility: One pulley body, multiple shaft sizes — order the pulley once and pair it with the correct hub for whatever motor you have
- Availability: Some OD/shaft combinations are not practical to stock as fixed-bore pulleys. Hub mounts expand the available combinations significantly.
- Replaceability: If a hub wears or a keyway strips, you replace the hub, not the entire pulley — lower cost on the next service
- Larger shafts: Fixed-bore pulleys have practical bore size limits. For shafts larger than 1-3/8", hub mounts are typically the only option.
Pump Speed at 3.55" OD
The 3.55" OD is the second-smallest motor pulley in the Cast Air 2B lineup. As a reference point:
- At 1750 RPM motor speed with a 10" pump pulley: pump runs at approximately 621 RPM
- Compared to the 3.35" P2B335-7/8: the 3.55" pulley increases pump speed by about 6%, slightly increasing CFM output and motor load
- Replace with the same OD as the original unless you have a specific reason to change the drive ratio
Dual B-Belt Drive Requirements
- Use matched belt pairs: When this pulley drives two B-belts, both belts must be replaced as a matched set. Mixing belt ages or brands creates uneven load distribution and accelerated wear on the tighter belt.
- Pump pulley must also be dual-groove: The 2B motor pulley pairs with a 2B pump pulley. If the pump pulley has only one groove, you cannot run two belts.
- Check belt tension on both belts independently: After installation, verify both belts are tensioned equally. An uneven drive creates lateral load on both the motor shaft and pump shaft bearings.
2B-Groove Hub Motor Pulley Lineup
- P2B355H (this pulley): 3.55" OD, hub mount — $38.50
- P2B395H: 3.95" OD, hub mount — $38.50
- P2B445H: 4.45" OD, hub mount (nearest official listing to P2B455H)
- P2B495H: 4.95" OD, hub mount — $66.41
Technical Specifications
- Part Number: P2B355H
- Outside Diameter: 3.55"
- Bore: Hub mount (hub ordered separately)
- Number of Grooves: 2
- Groove Profile: B-section
- Material: Cast iron
- Price: $38.50 (hub not included)
Why Buy From Air Compressor Factory Direct?
Hub-mount pulleys require getting two parts right: the pulley OD and the hub bore. We stock both the P2B355H and the full range of LX, SD, and SK hubs. When you call us, we will confirm both parts in one conversation and make sure you have everything you need to complete the installation without a second order.
- Free shipping on qualifying orders
- Free tech support: Call 866-217-0063 — we will help you select the correct hub for your motor shaft size
- Full manufacturer warranty on all Cast Air parts
- Honest guidance: We will confirm both the pulley and hub before you order
Call 866-217-0063 for quick answers and help!
