The Castair Replacement Motor Hub with 1-3/8" Shaft (LX138) is the motor hub for Cast Air compressor units that use a larger 1-3/8" diameter motor shaft. This is the largest shaft size in the standard LX series, typically found on higher-horsepower Cast Air compressor models where a bigger motor — and therefore a larger output shaft — drives the pump assembly. Verify your shaft diameter with calipers before ordering. A 1-3/8" shaft measures 1.375" in decimal — this hub is machined specifically for that size.
What the Motor Hub Does
On a belt-driven compressor, the motor hub is the component that mounts to the motor shaft and carries the drive sheave (pulley) that transfers power to the compressor pump via V-belt. On direct-drive configurations, it may serve as the coupling interface. Either way, it's a high-stress part — it takes the full torque load every time the motor starts under load. When the hub bore wears loose on the shaft, or the hub itself cracks from fatigue, the symptoms show up as vibration, belt alignment problems, and eventually a compressor that won't run correctly.
Key Features
- 1-3/8" Shaft Bore: Fits motor output shafts measuring 1.375" in diameter — the largest standard size in the LX series
- Cast Air OEM Part: Manufactured to Cast Air's specifications for correct fit on compatible compressor models
- Precision Machined Bore: Proper tolerance fit prevents shaft slop and keeps the drive assembly running concentric
- Direct Replacement: No machining or modification required for compatible Cast Air units
Technical Specifications
- Part Number: LX138
- Shaft Diameter: 1-3/8" (1.375")
- Component Type: Replacement Motor Hub
- Manufacturer: Cast Air
- Price: $19.25
Note: Manufacturer's product page was unavailable at time of writing. Confirm compatibility with your specific Cast Air unit before ordering.
When You Need This Part
- Motor hub shows cracking, bore wear, or visible damage
- Compressor produces unusual vibration or noise, particularly at startup under load
- Belt keeps going out of alignment despite correct tension and sheave alignment
- Motor replacement requires a hub matched to the new motor's shaft size
- Preventive maintenance on a high-hour compressor before the hub fails in service
LX Series Hub Lineup
- LX58 — 5/8" shaft
- LX78 — 7/8" shaft
- LX100 — 1" shaft
- LX118 — 1-1/8" shaft
- LX138 — 1-3/8" shaft (this part)
Why Buy From OEM Diagnostic Tools?
We stock the complete Cast Air LX motor hub series. When your compressor goes down, you don't have time to chase parts across three vendors. We've been sourcing Cast Air replacement components for shops and industrial customers since 2016. Free shipping on qualifying orders. Call us with your compressor model and we'll confirm the right hub before you order.
Call 866-217-0063 for quick answers and help!
