Do the locomotion of motors

"Come on, do the locomotion, I know you'll get to like it if you give it a chance. Do the locomotion, a chugga-chugga motion like a railroad train." -Grand Funk RailroadMotors, of various types, have provided profound changes in everyday life for over a century. Throughout recent years, however, they have undergone changes to more efficiently and effectively complete tasks in less time.


Trends in Electric Servo Motors


  • Smaller size, lower cost

  • Increased standardization

  • Increased acceleration rates

  • Metric motor mounting

'Come on, do the locomotion, I know you'll get to like it if you give it a chance. Do the locomotion, a chugga-chugga motion like a railroad train.' -Grand Funk Railroad

Motors, of various types, have provided profound changes in everyday life for over a century. Throughout recent years, however, they have undergone changes to more efficiently and effectively complete tasks in less time.

Electric servo motors, in particular, whose applications range from robotics, semiconductor equipment, packaging, food and beverage, to printing, don't just chugga-chugga along, they improve productivity and breathe life into a myriad of processes.

Control Engineering surveyed 1,500 readers, in part, to examine what electric servo motor types are used and for what applications; determine the importance of selected features in the purchase decision; and qualify respondents' involvement in recommending, specifying, and/or purchasing electric servo motors. Two hundred sixty-two completed the survey for a 17% overall response rate.

Seven of ten, 70%, respondents recommend, specify, and/or purchase electric servo motors. Forty-eight percent recommend, specify, and/or buy these motors for in-plant requirements, and 27% do so for OEM use.

How are these motors being applied?

Fifty-nine percent of respondents' company total electric servo motor applications were for new projects. Twenty-five percent were for replacement applications, while 16% were for retrofit.

Standards, smaller sizes

Servo motors have undergone various changes, none more noticeable than the size.

'There are several unique new demands being put on servos, one area is standardization, and the second is size,' says John Mazurkiewicz, Baldor Electric (Fort Smith, Ark.) product manager.

'Many newer machines must be reduced in machine size and therefore motor and control size. In several applications, 1-2 hp vector motors in positioning applications, with typical diameters of approximately seven inches, have been replaced by smaller brushless servo motor equivalents, measuring under five inches square,' adds Mr. Mazurkiewicz.

Seven of ten, 70%, respondents felt the 'physical size versus power' of the electric servo motor was important to their applications.

Electric servo motors with a power range of up to 5 kW were the most frequently used at 85% and purchased type in the last 12 months, at 81%. The 5-10 kW were used by just 39% and purchased type in the last 12 months at 31%. (See table.)

New smaller size, lower cost servo motors, and lower cost servo drives have supplanted step motor systems in many traditional stepper applications, such as semiconductor manufacturing and medical devices, states Ken Wyman, vice president of API Motion (Amherst, N.Y.). This is not to imply stepper systems are going away anytime soon, he adds.

Size and power range were important factors to respondents. As for type of servo motor wanted, it's notable that the brushed dc motor was preferred by 65%. A brushless type was preferred by 16% of respondents, while the rest had no preference.

Distributions of Electric Servo Motor Power/Size Ratings

In use

Bought in last 12 months

Up to 5 kW



5-10 kW



11-20 kW



21-30 kW



Over 30 kW



Source: 2000 Control Engineering Electric Servo Motor Study
Values add to more than 100% due to multiple responses.

Price, EMI/RFI

On average, pricing, standard sizes, and EMI/RFI protection were the leading functional features respondents wanted in electric servo motors. On the performance end, high output torque, high torque at low speeds, and software for setup/tuning were the leading features respondents wanted.

Motors with up to 3,000 rpm speed capability were most in demand with an 80% response. Thirty-five percent required 3,001-4,000 rpm speed capabilities.

Similar to other areas in society affected by global trends, e-commerce is one factor bringing a new element to motion control.

According to Laura Elliott, Omron Electronics (Schaumburg, Ill.) product marketing manager, although there is still a human element needed to specify and configure a system, e-commerce will become an important tool when purchasing servo systems.

Other trends customers will see in the industry include more intelligent drives. The survey further notes, more than six out of ten (61%) respondents use, or expect to use, electric servo motors and controls in an integrated package.

Also, 'there is a strong trend for metric servo motors in many different applications. This is due to product availability and standardization efforts of NEMA and IEC,' says Baldor's Mr. Mazurkiewicz.

The servo motor market looks stable for the next year. Twenty-three percent of respondents anticipate an increase in their purchase of electric servo motors in the next 12 months. Most, 40%, felt their level of purchases would remain at about the same level as the past 12 months.

Servo Motor Products

For more information on servo motors, circle the following numbers, or visit . For a broader listing of servo motor manufacturers, go to the Control Engineering Buyer's Guide at and look under categories for Motors, Special: servos; and under Servo Systems and Devices.

SL Series brushless motors

Charlottesville, Va. -GE Fanuc Automation has added three new SL Series brushless servo motors to its motion control product line. The models are rated at 2.5, 3.5, and 5 kW motor output power with continuous torque up to 140 lb-in. SL Series servos feature metric motor mounting, shaft oil seals, and MS connectors for all wiring interfaces to the motors as standard. The models are an extension of the SL V-Series servo motors and are supported by current SLconfig set-up software. It is said that the SL Series servo motors and amplifiers offer a cost-effective solution in applications requiring small size, high acceleration, and high speed. GE Fanuc Automation

Low-cost, high-torque motors

Rohnert Park, Calif. -Compumotor's BE Series brushless servo motors are said to produce up to 25% more torque than other equivalent size motors at a cost savings exceeding 20%. Available in sizes 23 and 34, the motors are able to solve applications requiring up to 42 lb-in. continuous torque. Increased torque is the result of an added number of magnetic poles on the rotor. The BE Series motors are also created using a bridged stator design. Open laminations of the stator are shaped into the body of the motor. This design reduces both material costs and time required to assemble the motor, says the manufacturer. Compumotor

Size, speed accentuate motors

Schaumburg, Ill. - W Series motors are compact, rugged, and available with different capabilities and options to suit a variety of different high-speed, positioning applications. Among the possible applications are winding control, part transfer, pick and place, feed control and cut-to-length. The motors feature slim profiles and cylindrical designs and have a range of 30 W to 5.5 kW. High resolution feedback on the motors allows for control at low rpm. Omron Electronics Inc.

Brushless motor range extended

Amherst, N.Y. -NEMA frame size 17 turbo servo brushless motors maximize torque density through the use of high strength neodymium magnets. The size 17 series offer continuous stall torque from 2.0 to 4.9 lb-in. in three models. A choice of windings accommodates drives with bus voltages ranging from below 75 to 325 V dc. Turbo servo motors are both UL recognized and CE compliant and are stocked as part of API Motion's MotionSelect program. API Motion

Unique design, small size motor

Fort Smith, Ark. - BSM50 Series is the smallest in Baldor's servo motor family. The motor is 2.1 inches square and can provide up to 48 lb-in. of peak torque. Designs are available to provide speeds up to 12,000 rpm. Features of the brushless servo motor family include 200 °C moisture resistant, multi-coated wire encapsulated for double protection and improved reliability; motor enclosure with shaft oil seal meets IP65 for durability; and continuous duty 155 °C operation that includes internal thermal switch for protection. Baldor brushless servo motors and drives are suited for applications such as robotics, semiconductor equipment and packaging. Baldor Electric Co.

XT motor delivers rapid acceleration

Radford, Va. -Kollmorgen has released a high-resolution sine encoder option for its Goldline XT brushless servo motor. Goldline XT motors offer a range of torque ratings, frame sizes, and speeds in a rugged package. Continuous torque ratings range from 1.29 to 48.0 Nm, with speeds up to 6,000 rpm. The motor's high torque-to-inertia ratio delivers rapid acceleration, while its low cogging torque ripple offers smooth machine operation. Typical applications are high-speed registration, film coating and web control. Kollmorgen

Brushless motors offer rugged design

Rockford, Ill. -PMA Series of brushless servo motors offer a voltage range of 240- 480 V ac, frame sizes from 70-190 mm, and a continuous rated torque range of 0.5-54 Nm. It is said that the servo motors are designed to deliver more torque while offering higher performance and efficiency for applications that include packaging, semi-conductor manufacturing, textiles, robotics, converting, document handling, and printing. The PMA2, PMA4, PMA5 and PMA6 motors offer 16 models; most are available with commutating encoder or SinCos encoder feedback devices, in addition to standard resolver primary feedback for integration with other control schemes. Pacific Scientific

Motor provides enhanced power

Hoffman Estates, Ill. -Indramat's line of high-performance, high-voltage MHD digital ac servo motors are designed for demanding applications such as high-production transfer lines, stand alone machine tools, converting, printing and packaging machines, and general factory automation. MHD servo motors are said to provide manufacturing machines with enhanced power. Available in six frame sizes, MHD motors offer continuous torque from 24-1,080 lb-in. and maximum torque from 60-2,035 lb-in. Peak speeds up to 7,000 rpm are available. Rexroth Indramat

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