D-Flange Mount
D-Flange mount electric motors — also referred to as NEMA D-Flange or B5 motors — feature a precision-machined flange with rear-mounted bolt holes for direct coupling to pumps, gearboxes, and mechanical drives.
Unlike C-Face mounts, where bolts thread into the face of the motor, D-Flange bolts pass through from the driven equipment side, giving clean access and rigid alignment when space is limited.
Designed for OEM integration and process equipment, D-Flange motors deliver vibration-free performance and are available in ODP, TEFC, and Explosion-Proof (TEXP) enclosures from 1 HP to 200 HP.
What Is a D-Flange Motor?
A D-Flange motor has a flat machined mounting flange with through-holes on the bolt circle, allowing the unit to bolt from the driven equipment side into a gearbox or pump housing.
This rear-bolt configuration keeps the motor face smooth, reduces contamination, and simplifies replacement or service.
✅ Key Advantages
Rear-bolt (through-hole) mounting for clean installation
True NEMA D-Flange dimensions for interchangeability
Perfect alignment for close-coupled pumps and gearboxes
Compact design for tight OEM assemblies
Works horizontally or vertically depending on frame design
Compatible with VFD speed control and soft starters
Typical Specifications (D-Flange Motors)
Specification Typical Range / Option
Mounting Type D-Flange (NEMA B5)
Horsepower Range 1 – 200 HP
Speed (RPM) 900 / 1200 / 1800 / 3600
Enclosures ODP, TEFC, TEXP
Frame Sizes 56D – 449TD
Voltage Options 208 / 230 / 460 / 575 V (3-Phase)
Materials Cast Iron, Stainless Steel, Fabricated Steel
Service Factor 1.15 (Standard)
All D-Flange motors conform to NEMA MG 1 dimensional standards for B5 mounting and are fully compatible with standard pump adapters and gear reducers.
Common Applications for D-Flange Motors
Close-coupled centrifugal and vertical inline pumps
Gearboxes and mechanical drives
Compressors and blowers
Agitators and mixers
Process and OEM machinery
Equipment requiring sealed or compact flange interfaces
D-Flange motors are preferred wherever rear-mount access or limited front-clearance demands a low-profile, precision-fit installation.
Enclosure and Frame Options
Frame Materials:
Cast Iron – Vibration damping and mechanical rigidity.
Stainless Steel – Corrosion resistance for sanitary or chemical duty.
Fabricated Steel – Lightweight, customizable for OEM builds.
Mounting & Compatibility
Interchangeable with C-Face via adapter rings or conversion kits
Compatible with pump brackets, gear reducers, and brake modules
Available in footed, footless, or flange-only configurations
Suitable for horizontal or vertical installations
Standard or inverter-duty windings for VFD operation
Request a Quote or Spec Sheet
Looking for a D-Flange mount electric motor for your pump, gearbox, or process equipment?
Our team can specify the correct frame size, flange pattern, enclosure, and voltage for your system.
Request a Quote or Request Spec Sheet to receive detailed specifications, pricing, and availability from Brook Crompton, US Electric, and Worldwide Electric.