The Castair 213DM is an adjustable belt tensioner motor base with the 7.5-10 HP motor pre-mounted — a complete base-plus-motor assembly for compressor installations using the 213T NEMA frame. The "M" designation means mounted: the motor is already bolted to the adjustable tensioner base, aligned at the factory, and ready to install on your compressor pump. If you are replacing both the motor and the base on a 7.5 HP three-phase Castair system, the 213DM saves installation time and eliminates field alignment guesswork.
Product Specifications
- Part Number: 213DM
- Motor Frame: 213T (7.5 HP class — specifically for the 7-213-3 three-phase motor)
- Configuration: Motor pre-mounted on adjustable belt tensioner base
- Compatible Application: 7.5 HP three-phase Castair compressor systems with 213T-frame motors
- Duplex installation: Order two 213DM units for duplex builds
What Pre-Mounted Means for Your Installation
Motor-to-pump alignment on a belt-driven compressor determines belt life, noise level, and bearing wear. A misaligned motor causes uneven belt wear, premature bearing failure on both the motor and pump crankshaft, and increased noise. The 213DM arrives with the motor positioned correctly relative to the tensioner base — the alignment work is already done. In the field, you mount the assembly, install the belt, adjust tension using the slotted tensioner, and you're running.
The 213T Frame Motor
The motor included in the 213DM assembly is the 7-213-3 three-phase motor: 7.5 HP, 208/230/460V, 1.15 service factor, 213T frame, 1725 RPM, 1-3/8 inch shaft, 130 lbs. This is a three-phase motor — if your installation requires single-phase power, you need the 215T-frame motor (7-215-1) and the 215D/215DM base instead.
213DM vs. 213D: Which to Order
- 213D ($138.91 — base only): Order when your existing motor is serviceable and only the base needs replacement, or when you prefer to source the motor separately
- 213DM (contact for price — base + motor): Order when replacing both motor and base, or for new builds where you want factory-aligned assembly. Eliminates the field alignment step.
Duplex Installations with the 213DM
For duplex 7.5 HP systems (two pumps sharing one tank), order two 213DM units. The Castair duplex Right From The Start kit RFS001D covers 10 HP duplex and includes oil, vibration pads, ball valves, flex hoses, and filter elements for the duplex build. Alternating controls (pressure switch or magnetic starter alternating panel) are required separately for duplex operation.
What's in the Box
- 1x 213DM assembly: 7.5 HP 213T-frame motor pre-mounted on Castair adjustable 213D belt tensioner base
- Mounting hardware
Note: Belts, pulleys, belt guard, and tank not included. Confirm motor voltage (three-phase only — 208/230/460V) matches your power supply before ordering.
Why Buy From Air Compressor Factory Direct?
We specialize in industrial air compressor components and can confirm the correct motor and base configuration for your installation. 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!
