Bodine Gearmotor - Motor Constants - 12Motor constants are needed to calculate permanent magnet DC (PMDC) or brushless DC (BLDC or EC) motor specifications and ratings, or to match the motor properly to an amplifier. The motor constants are required in order to predict the PMDC or BLDC motor’s performance with changing variables, such as different input voltages or different loads. (See below PDF link for Bodine stock PMDC and BLDC motor constants.) This application note explains what the constants are, how they are derived and how to use them.

Common Motor Constants:

The most commonly used motor constants are Torque Constant (Kt), Voltage Constant (Ke), Electrical Time Constant (Te), Mechanical Time Constant (Tm), and Thermal Resistance (Rth). Typical values for these constants are derived by using measured values of No Load Speed, No Load Current, Stall Torque, Circuit Resistance, Circuit Inductance, and Armature Inertia with the following equations:

Torque Constant (Kt) — describes the proportional relationship between torque and current. Kt is usually expressed in the units Oz-in./Amp. See page 2 for additional information about torque constants.

Bodine Electric - Motor Constants - 03.26.2015

Voltage Constant, or Back EMF Constant (Ke) — is the Torque Constant expressed in different units, usually Volts/Krpm, in order to describe the proportional relationship between motor speed and generated output voltage when the motor is back driven as a generator in units of Volts/1000 rpm. See page 2 for additional information about voltage constants.

Bodine Electric - Motor Constants - 2

Electrical Time Constant (Te) — is the time required for a motor to reach 63.2% of its stall current after applying a test voltage with the motor shaft locked. It is usually expressed in milliseconds. Applied Voltage equals Rated Current multiplied by Circuit Resistance:

Bodine Electric - Motor Constants - 11

Mechanical Time Constant (Tm) — is the time required for an unloaded motor to reach 63.2% of its no load speed after applying its rated voltage. It is usually expressed in milliseconds.

bodine-gearmotor-motor-time-constants-5

Thermal Resistance (Rth) — is useful for predicting the ultimate temperature rise under different loading conditions in order to determine a maximum continuous torque rating. It is usually expressed in the units °C/Watt.

Bodine Electric - Motor Constants - 6

Using Performance Data to Calculate Kt and Ke

This speed/torque graph demonstrates how the linear equation of the current is used to calculate the Torque Constant (Kt) by using the slope “m.” The Voltage Constant (Ke) can then be calculated.

Using Performance Data to Calculate Kt and Ke

This speed/torque graph demonstrates how the linear equation of the current is used to calculate the Torque Constant (Kt) by using the slope “m.” The Voltage Constant (Ke) can then be calculated.

Bodine Electric - Motor Constants - 8

Bodine Electric - Motor Constants - 9

To download this information as a PDF, click here. To download the Motor Constants for Standard Bodine Gearmotors, click here.

To download Chapter 8, or any other section of the Bodine Small Motors Handbook, click here.

Copyright Bodine Electric Company © 04/2015. All rights reserved.

Posted by: Sarah Prais | April 10, 2015

Quiet Gearmotors for Medical Equipment

Bodine Electric_Mammography Machine - Medical EquipmentGearmotors in mammography equipment are used to raise and lower the scanner to accommodate the patient’s height. The primary design objective is smooth and quiet operation. Our team of design engineers addressed four aspects of the gearmotor design that contribute to quiet operation.

Worm Gearing
Bodine recommended a right-angle gearmotor with worm gearing. The sliding tooth action of worm gearing is generally quieter than the rolling action of spur and helical gearing. A second advantage for the application was that worm gears lock in place when there is no power to the gearmotor.

Machined Parts
By machining all mating surfaces of the motor and gearhousing, Bodine insured that the worm and helix gears, the motor armature and the motor end shield are precisely aligned. Better gear alignment translates into less noise. Unlike many gearmotors on the market today, all Bodine gearmotors feature machined surfaces throughout.

Ball Bearings Bodine Electric - Mammography Equipment - 2
Our engineers recommended ball bearings to minimize thrust loads on the driveshaft. Thrust loads can make the driveshaft shift back and forth within the gearbox. Ball bearings are pressed onto the driveshaft, locking it in place.

Quieter Brush and Commutator Components
Bodine engineers took several steps to reduce brush noise as much as possible. Special commutators were designed to prevent vibration and to ensure smooth brush contact. The brush holders were locked into the gearmotor endshield to prevent any “chatter”. Brush material and brush shape were optimized to minimize noise.

Bodine Electric engineers bring 110 years of application engineering and problem solving experience to a wide range of applications in industries as diverse as medical, packaging, industrial automation, and solar powered outdoors equipment. We look forward to working with you on your next FHP gearmotor design challenge.

Bodine Electric - Mammography Equipment - 3

Bodine Gearmotor Worm Gear Set PMDC Gearmotor

 

To learn more about Bodine Gearmotor Solutions in Medical Applications, click here.

Copyright Bodine Electric Company © 04/2015. All rights reserved.

Posted by: Edmund Glueck | March 18, 2015

Bodine Electric Gearmotors and Speed Controls

Bodine Gearmotors & Speed ControlsFrom our recent photo shoot: Bodine type 42R-GB/H, Hollow Shaft, AC 3-phase, Inverter Duty gearmotor, our type 24A4-P, 24VDC and 42A-FX, PMDC gearmotors. System matched to our selection of AC and PMDC motor speed controls – offered as chassis boards, NEMA-1 or NEMA-4. When a gearmotor and control are purchased as a set, enjoy our extended 2-year system warranty.

Posted by: Edmund Glueck | February 13, 2015

Bodine Gearmotors are Designed for Uptime!

Our team of MEs and EEs has the experience and knowhow to work on challenging applications across a wide range of industries. We are proudly celebrating 110 Years of “Quality in Motion” in 2015.

Our team of MEs and EEs have the experience and knowhow to work on challenging applications across a wide range of industries. We are proudly celebrating 110 Years of "Quality in Motion" in 2015.

Posted by: Sarah Prais | February 4, 2015

Model 2999 New Rugged AC Motor Speed Control

Bodine-gearmotor-AC-inverter-speed-control_01-2015

Bodine expands its extensive line of AC, PMDC, and BLDC speed controls with the new Model 2999. Featuring an industrial-grade NEMA-4X/IP-65 watertight aluminum die-cast enclosure, the model 2999 drives 230 VAC, 50 or 60 Hz, inverter-duty, 3-phase gearmotors rated up to 1 HP (746 W). It operates from single-phase 115 or 230 VAC, and it is GFCI compatible. The PWM output provides high motor efficiency and low noise. This control is ideal for applications that require adjustable speed, reversing, and stand-alone operation.

  • User-friendly, easy to set up design
  • Built- in on/off, reversing, and start/stop switches
  • Provides up to 200% starting torque
  • Drives 230 VAC, 50 or 60 Hz, inverter-duty, 3-phase gearmotors up to 1HP (746 W).
  • Extended 2-Year System Warranty – When a Bodine gearmotor and control are purchased together

To download the product brochure, click here.
To download the installation, operating, and mounting instructions, click here.

 Copyright Bodine Electric Company © 02/2015. All rights reserved.

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