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More to Winches Than You Might Think

Issue 9 and Volume 16.

Many rescue rigs have winches installed as a matter of customization, not actual usefulness. It is important that rescuers have a good understanding of winches and their safe use for rescue operations. They should understand the grades of winches, power systems, and internal gearing.

Grades of Winches

Industrial-grade winches are designed for everyday use, such as towing and rescue service. Industrial-grade winches have greater duty cycles and are constructed with more rugged materials. These winches meet SAE J706 standards.

Commercial-grade winches are installed on vehicles typically for self recovery or used to trailer equipment. Power is usually supplied by an electrical system.

Utility-grade winches are intermittent-duty-cycle winches used for recreational purposes. Power is usually supplied by an electrical system.

Power Systems

Electric winches run on power supplied by the vehicle’s electrical system, often producing high current draws. Generally a minimum of 90 amps of alternator output is recommended for powering a winch.

Another method of powering winches is hydraulically. In this case, power is supplied from hydraulic pumps, which are, in turn, supplied from PTOs or are belt-driven. Prolonged use can be tolerated.

Internal Gearing

In winches that use a planetary gear, a central gear drive is used, around which two or more gears rotate. This allows faster line speed and quieter operation.

On winches that employ a worm gear, a cylindrical worm drives a round worm gear. The worm gear, in turn, rotates the drum of a winch. Greater strength and easier repair are advantages of this unit.

Line Pull vs. Wire Rope Length

Rescuers usually assume that the winch’s capacity remains the same regardless of the amount of wire rope being used. This is an incorrect assumption, usually leading to failure of the object (resistance) to be moved.

All winches have a rated working capacity, as supplied by the manufacturer. It is based on the winch’s capacity in the specific configuration. Planetary-driven winches will lose capacity when their drum diameters are enlarged by wrapped wire rope. A winch can exert the greatest force only when pulling by the first layer of wire rope on the drum. Each additional layer of wire rope added to the drum will decrease the line pull capacity of the winch. It is important to know where the maximum load will occur during the line pull.

Rescuers should consider the amount of line pull needed when the operation begins and ends. For safety, five wraps of wire rope must be left on the drum. One technique that can be used to regain lost line pull capacity is to introduce a snatch block. The snatch block will decrease the amount of wire rope on the winch drum; thus, the lost line pull is regained.

For example, a rescue truck is equipped with an 8,000-pound winch and 100 feet of 3⁄8-inch wire rope. If you use 50 feet of wire rope for a rescue and leave two layers of wire rope on the winch drum, the line pull would be 6,700 pounds. If only 15 feet of wire rope were used, leaving three layers of wire rope on the winch drum, the line pull would be 5,700 pounds. Remember to not exceed the working load limit of the wire rope itself.

BILLY LEACH JR. has been actively involved in emergency services since 1976, combining career and volunteer experience. He serves as the developer and senior presenter for BIG RIG RESCUE™. Also, he is a member of the N.C. Emergency Management USAR Task Force 7, sponsored by Ash-Rand Rescue & EMS. He conducts training in vehicle rescue and has presented at various symposia, conferences, rescue schools, and regional fire/rescue training seminars. He is the coauthor of Big Rig Rescue, on the topic of heavy truck anatomy and extrication.


Winch Maintenance

Daily:

  1. Inspect the winch thoroughly to determine that no parts are broken, damaged, or missing. Repair or replace as necessary only as specified by the manufacturer.
  2. Inspect winch mounting for missing or loose mounting bolts. Tighten as necessary.
  3. Inspect the wire rope’s entire length for damage and cleanliness. Rewind the wire rope onto the winch drum smoothly and evenly. Lubricate as necessary.

Monthly:

  1. Lubricate all winch components as suggested by the manufacturer. Use a high-quality general-purpose automotive grease or lithium extreme pressure NLGI Grade 2 grease with molybdenum disulfide in it. Clean the fitting before injecting grease. Inject only until clean grease exudes from the joint or vent.
  2. Check all fluid levels. Refill as necessary.

Annually:

  1. Check and adjust any linkages, brakes, and connections.
  2. Drain and refill any fluids with the manufacturer’s suggested materials.

Safe Winching Operations

  1. Always wear complete personal protective equipment during winching operations. Clear the area of spectators and unnecessary rescuers.
  2. Fully understand your winching components, capacities, and operating procedures.
  3. Position the winch squarely to the work area. Use snatch blocks to change direction of the pull. Anchors (deadmen) must be sufficiently strong.
  4. Set winch-equipped vehicle’s parking brakes and use wheel chocks for all tires.
  5. Don’t free-spool the winch when wire rope is under tension.
  6. Don’t wrap a wire rope around anything on which you are pulling to produce a choker.
  7. Don’t tie a knot in the wire rope.
  8. Load hooks properly, with the open tip away from people.
  9. Take up any wire rope slack slowly. Check and double check all rigging every time.
  10. Responders should be located at a distance from the rigging greater than the distance between the two rigging points that are farthest apart and never within an angle produced by the rigging. Rigging that forms an angle is similar to a slingshot toy. The wire rope is similar to a stretched rubber band that possesses stored energy.
  11. Properly store, lubricate, and inspect all winch components according to the manufacturer’s suggestions.

 

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