The Castair 184DM is an adjustable belt tensioner motor base with the motor pre-mounted — a complete base-plus-motor assembly for 5 HP air compressor applications. This is the "mounted" version of the 184D base: the 5 HP, 184T-frame motor comes already bolted to the adjustable tensioner base, so you receive a ready-to-install assembly rather than two separate components. At $141.75, it costs $40 more than the base alone (184D at $101.64), reflecting the value of having the motor-to-base alignment already done at the factory.
Product Specifications
- Part Number: 184DM (5HP)
- Motor Frame: 184T (5 HP class)
- Configuration: Motor pre-mounted to adjustable belt tensioner base
- Includes: Adjustable tensioner base + 5 HP 184T motor assembly
- Price: $141.75
What the Pre-Mounted Configuration Means in Practice
When you order the 184DM, you receive the motor already secured to the tensioner base with proper alignment. This matters because motor-to-pump alignment on a belt-driven compressor directly affects belt wear, noise, and bearing loads. Getting that alignment right during installation on a loose base requires a dial indicator or at minimum careful measurement — it is a step that gets done correctly at the factory on the 184DM and is a common source of problems when skipped in the field.
Belt Tension Adjustment on the 184DM
- Same dual-bolt adjustable design as the 184D base
- Adjustment slot allows motor to slide along mounting axis for belt tensioning
- Lock bolts secure position after tensioning
- No need to remove the belt guard for routine tension checks and adjustments
184D vs. 184DM vs. 184Dx2M
- 184D ($101.64): Adjustable tensioner base only. You supply and mount the motor. Right choice when you have an existing motor and need only the base.
- 184DM ($141.75): Base with motor pre-mounted. Complete assembly for 5 HP single-compressor installations. Right choice for new builds or full motor-plus-base replacement.
- 184Dx2M: Pair of 184D bases, mounted, for duplex 5 HP installations. If you are building a duplex system with two 5 HP pumps sharing one tank, this is the component that handles both motor mounts.
5 HP Motor Specs (184T Frame)
The motor on the 184DM is a 5 HP unit in the 184T NEMA frame. Castair offers 5 HP motors in both single-phase and three-phase configurations:
- 5 HP single-phase (5-184-1): 208/230V, 1.15 SF, 24A at 208V / 22A at 230V, 1725 RPM, 1-1/8" shaft, 80 lbs
- 5 HP three-phase (5-184-3): 208/230/460V, 1.15 SF, 15/14/7A, 1725 RPM, 1-1/8" shaft, 65 lbs
Confirm with us which phase/voltage motor is included with the 184DM when ordering, as this matches your power supply requirements.
What's in the Box
- 1x Castair 184DM assembly: 5 HP motor pre-mounted on adjustable 184D belt tensioner base
- Mounting hardware
Note: Belts, pulleys, and belt guard not included. See Castair P2B-series pulleys for 1-1/8" shaft sizing and 2BG/3BG belt guard sizing for 5 HP pump applications.
When Does a Shop Need This vs. Ordering Separately
The 184DM makes sense when you are doing a complete motor and base replacement — if the base is damaged or worn along with the motor, you want both replaced with proper alignment. If your base is in good condition and only the motor failed, order a 184T-frame motor separately and mount it to your existing base. Call us at 866-217-0063 if you are not sure which approach is right for your situation.
Why Buy From Air Compressor Factory Direct?
We specialize in industrial air compressor components and can confirm the correct motor configuration (single-phase vs. three-phase) for your installation before you order. Free shipping, free technical support at 866-217-0063, and full manufacturer warranty on all Castair assemblies.
Call 866-217-0063 for quick answers and help!
