DC Motors Used in Electric Hoists, Reels and Winches

For many decades, DC motors1 have been utilized in electric hoists, reels and winches in the construction, marine, mining, trucking and milling/metalforming industries, among others. While the type, configuration and size of the motors is application dependent, in general, permanent magnet, explosion proof and wound field motor are used in these applications. Permanent magnet DC motors (PMDC)2 are used in hose reels for fire trucks, fuel delivery trucks and lawn care utility vehicles, as well as stage and marine winches. Explosion proof DC motors3 are used in hazardous environments and in applications that include hose-retracting reels in airport fueling operations, crane hoists, and motor-driven cable reels. Wound field DC motors4 (series, shunt or compound) are used in industrial environments for coil feeding reels in the milling/metalforming, crane hoists, motor-driven cable reels, and elevator hoist motors. In variable speed applications where a rectified DC or Silicon Controlled Rectifier (SCR) controller is used, the DC motor will be SCR rated. 5

Permanent Magnet DC Motors

For battery-powered and low-torque6 applications up to 10 HP,7 permanent magnet DC (PMDC) motors8 are commonly used for hoisting, hose reeling and winching operations. Due to the motor’s permanent magnetic field, PMDC motors exhibit a higher efficiency than wound field motors, and have a quiet operation in a compact, direct-drive design with high start up/locked rotor torque.9 PMDC motors are most suited for intermittent or light-to-moderate duty. Some PMDC motors used in these applications are Silicon Controlled Rectifier (SCR) rated.10 Custom PMDC motor designs are common for these applications and generally include special windings for greater capacities, brushless models, and protective coatings for corrosive, washdown or weather-proofing environments.

Explosion Proof DC Motors

Explosion proof DC motors11 are a class of electric motors constructed with a sealed design to both contain an explosion if it occurs within the motor and prevent the release of explosive gases or vapors to the surrounding environment. They are used in hazardous locations (Class I environments with flammable gases and vapors; Class II environments with combustible dust).12 Explosion proof DC motors used in hoists, reels and winches can be either permanent magnet or wound field motors. They are constructed with parts, materials and methods that give them a more robust construction. They are bulkier and heavier than open-enclosure motors. In addition, the motors’ brush and commutator assemblies are sealed from the outside environment so that any arcing that may occur cannot escape into and ignite dust, fumes and gases in the surrounding environment. They are also manufactured to be flametight. It is worth noting that there is a trend to replace brushed PMDC motors with brushless motors13 (BLDC), which do not have brushes and thereby eliminate a potential ignition source in a hazardous environment.

Wound Field DC Motors

While PMDC motors are used in hoist, reel and winch applications up to 10 HP, wound field DC motors14 are commonly used in industrial applications above this range and up to several hundred horsepower (HP), in both the standard and explosion proof types. They are typically used in coil winding (reel drives) in the milling/metalforming industry, crane/elevator hoists, winches and motor-driven cable reels. When used in crane applications, these motors will be rated for crane duty.15

In general, wound field DC motors are mainly the series- or shunt-wound types; however, compound DC motors, which are a combination series & shunt wound motors, are also used to provide specific torque speed characteristics as required by an application. Series DC motors are used in hoisting or winching operations because of their characteristic very high starting torque.16 While series DC motors consume more power than PMDC motors to produce their electromagnetic field, they’re powerful, efficient at high speeds and produce the most torque; hence, they are used for heavy duty winches.17 Shunt DC motors are used in constant speed applications, 18 such as reel drives. 19

While hose reels are generally low HP applications and use direct-drive, PMDC motors, cable reels are moderate-to-high HP applications that use a wound field motor & magnetic clutch drive system. Motor-driven cable reels are used in a wide variety of crane, material handling, and milling equipment including shore container cranes, pallet loaders, shuttle conveyors, transfer cars, among others. It should be noted that the type of motor used in cable reels depends on the application and can be an AC or DC motor. 20

Coil feeding equipment in the milling/metalforming industry use wound field DC motors in reel drives to unwind (pay off) metal coil reels and rewind (take up) the coil reels after the milling/metalforming operation has been performed. In the past, the speed of unwind/rewind motors was manually adjusted via an air clutch. This method caused more wear and tear on the machinery and increased energy costs. Currently, variable speed drives (VFD) with speed feedback power a DC motor to automatically maintain the line speed. This control methodology results in a smoother and more controlled payoff. 21 There is a trend in the control of coil feeding equipment to employ AC motors with flux vector control. 22 However, due to the very large, legacy population23 of wound field DC motors currently in use, AC motors represent only small part of this industrial application.

  1. Ohio Electric Motors. D.C. Motors. Ohio Electric Motors, 2011.
  2. Ohio Electric Motors. Permanent Magnet DC Motors. Ohio Electric Motors, 2011.
  3. Ohio Electric Motors. Explosion Proof DC Motors. Ohio Electric Motors, 2011.
  4. Ohio Electric Motors. Wound Field DC Motors. Ohio Electric Motors, 2011.
  5. Ohio Electric Motors. SCR Rated DC Motors. Ohio Electric Motors, 2011.
  6. Dale R. Patrick and Stephen W. Fardo. Rotating Electrical Machines And Power Systems. The Fairmont Press, Inc., 1997. Page 239.
  7. Richard C. Dorf, editor. Systems, Controls, Embedded Systems, Energy, and Machines. CRC Press, 2006. Page 8-21.
  8. Ohio Electric Motors. Permanent Magnet DC Motors. Ohio Electric Motors, 2011.
  9. Alan Hendrickson and Colin Buckhurst. Mechanical Design for the Stage. Taylor & Francis, 2008. Page 159.
  10. Ohio Electric Motors. SCR-Rated DC Motors. Ohio Electric Motors, 2011.
  11. Ohio Electric Motors. Explosion Proof DC Motors. Ohio Electric Motors, 2011.
  12. Ohio Electric Motors. Explosion Proof DC Motors. Ohio Electric Motors, 2011.
  13. Ohio Electric Motors. Brushless DC Motors: Low Maintenance and High Efficiency. Ohio Electric Motors, 2011.
  14. Ohio Electric Motors. Wound Field DC Motors. Ohio Electric Motors, 2011.
  15. M.V. Deshpande. Electric Motors: Application And Control. PHI Learning Pvt. Ltd., 2010. Page 186.
  16. Barbara Renner. Hands On Water and Wastewater Equipment Maintenance. CRC Press, 1998. Page 52.
  17. Interocean Systems. Winch Design. Interociean Systems, Inc., 2012.
  18. Robert J. Alonzo. Electrical Codes, Standards, Recommended Practices and Regulations: An Examination of Relevant Safety Considerations. Elsevier, 2010. Page 217.
  19. Eswar. Handbook of Electrical Motor Control Systems. Tata McGraw-Hill Education, 1990. Page 59.
  20. Sonich Industrial. Motor Driven Cable Reels. Sonich Industrial, 2012.
  21. Henry Ericsson Theis. Handbook of Metalforming Processes. CRC Press, 1999. Page 245.
  22. Mike Tooley. Plant and Process Engineering. Elsevier, 2009. Page 301.
  23. Bob Simon. DC motors: Why are they still used?. PlantServices.com, 2004-2012.
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