Apparatus Mounted Winches

The winch motor is typically either electric or hydraulic.  The motor provides the pull force multiplied through a transmission.

The drum is made up of components that correspond with either a wire rope or synthetic rope that should be specified when ordering a winch.  Usually, the drum is manufactured for use with either wire or synthetic rope, not both.  If synthetic rope is used on a drum manufactured for wire rope, it can crush the drum because it winds tighter on the drum causing cracking or forcing the flanges (sides) off the drum. Only recently, one manufacturer is now producing a drum that can be used for both types of winch rope.

The braking system for the wire rope equipped winch is housed within the drum.  If a synthetic rope is stored on this type of drum, the heat created from the drum brake can melt the synthetic rope.  The braking system for winches for synthetic rope is located on the outside of the drum, thus eliminating the chance of melting the synthetic rope.

A winch is geared for hauling or pulling an object on a relatively horizontal or near horizontal plane. Anything pulled above or below 45 degrees from horizontal considered hoisting.  Hoisting requires a different type of braking device than is used in a winch.  A winch is not a hoist, and you should never use it as such.  If you have any intention of needing to hoist, consult with your apparatus manufacturer and specify a hoist rather than a winch.

Do not specify a winch for any purpose that involves lifting people.  The safety factors required for lifting people are much higher than those applied to winches, which are designed for pulling objects.  If you need to lift people, do it with an aerial apparatus designed for that purpose.

The Working Load Limit (WLL) is the greatest force that the winch is capable of pulling.  The WLL is determined by the rating of the wire or synthetic rope that the winch drum carries.   All winch ratings are determined by the tension developed by the first layer of rope on the drum.  The first layer is the only layer that will provide a pull equal to the working load limit.  The capacity of a winch decreases as more layers are wrapped on top of each other around the drum. Each subsequent layer drops in maximum tension by approximately 10%.

Since the WLL is determined by the rating of the wire or synthetic rope on the drum, it is important to consider the factors that may reduce the capability of the rope.  Wire rope can be damaged by pinching, fraying, kinking, or corrosion.  There can be defects in swages, or damage can be caused by hazards at the scene.  The same is true for synthetic rope.  It is therefore prudent to limit your pulls to a value significantly less than the WLL of the winch.  Industry experts suggest that it is good to maintain a 4:1 safety factor in every pull.  Using this factor, a 9000 lb winch should be limited to a 2250 lb pull.

Before selecting a winch size, you need to establish what you want to do with your winch.  A 4500 lb vehicle can be held on a 30° embankment with the 2250 lbs of pull from a 9000 lb winch while keeping the 4:1 safety factor.  A 12000 lb winch could safely hold a 6000 lb vehicle on that same embankment.  Figure out what you are willing to do on a scene with your apparatus and select the winch capacity accordingly.  Jobs beyond the capability of your winch can be tackled by calling a towing service.

If your apparatus will be operating off-road in remote areas, you may wish to consider a winch with strength to assist in self-recovery.  The forces required for this are impossible to calculate.  The geometry is simple for a vehicle that is rolling if you know the weight and the grade, but if the apparatus is mired in mud, sand, or snow, the forces can’t be calculated with any certainty.  In this case, bigger is better.

• Drains batteries if engine is not running
• Easier to install as a portable unit
• Limited run time to avoid over-heating

• Comes in higher capacity ratings (9000 to 30,000 lbs)
• No duty cycle limit

Wire rope is currently the more common selection for winch rope.  Abrasion resistance and insensitivity to high heat make it the better choice if it will be used around sharp objects or flames.  The following are characteristics of wire rope:

• When winching there must be no less than five (5) wraps of wire rope on the drum prior to starting a pulling operation.
• It typically has a Roller Fairlead
• Most portable winches with wire rope will have a steel Hawse Fairlead
• Wire rope is a heavier type of winch rope
• Wire rope stores energy, so if it breaks, the ends will fly in both directions towards the winch and toward the object being pulled
• Metal wire has memory, once damaged it must be replaced
• Not very flexible
• Has good abrasion resistance
• It is resistant to heat
• It is more difficult and cumbersome to re-spool
• Most likely to “bird-nest” when re-spooling
• Damage from exposure to ultraviolet rays is not an issue

Synthetic rope is growing in popularity as it is much easier to handle than wire rope and is safer if it fails.  The following are characteristics of synthetic rope:

• When using in an operation no fewer than ten (10) wraps must be on the drum to start
• Utilizes a Hawse type of Polished Aluminum Fairlead
• Weighs less than wire rope
• Does not store energy, safer when it breaks
• Synthetic rope does not have memory so it has greater resistance to damage
• More flexible
• Not as heat resistant as wire rope. It melts at approximately 200° F
• Has poor abrasion resistance – must use a protective sleeve on rough surfaces
• It is easier to re-spool
• Less likely to “bird-nest”
• With some brands, ultraviolet light may be an issue (check the manufacturer)
• More expensive than wire rope

Protecting yourself and those around you is the first and foremost concern while winching.  Winches that have been overloaded, set-up improperly or coupled with unreliable accessories are prone to failure.  All personnel attending a winch pull should be in full PPE with leather or rescue gloves.

At hook strap is a length of webbing with a loop sewn into one end.  The loop is placed on the hook.  It is an essential component for handling of a wire or synthetic rope.  The strap is used to hold the hook and keep your fingers from being placed inside the hook and away from the fairleads as the winch rope is deployed or re-spooled back on the winch drum.  Always use the hook strap and retain the one supplied with the winch.

In order to objectively determine the amount of force placed on the winch rope, industry experts recommend the use of a dynamometer or load-gauge in the system where the line is returned from the snatch block back to the apparatus. This device provides the exact amount of tension in pounds of force on the system. The user can pre-determine where the appropriate limit is with the winch and observe it during the operation. This ensures never getting close to the limit of the rope or winch when a 4:1 safety factor is used.