Marines hauled a 30,000-lb. Light Armored Vehicle (LAV) with a lightweight synthetic winch rope mounted to an LAV Recovery vehicle in a User Jury at the Detroit Arsenal in September. (U.S. Army TARDEC photo.)
TARDEC Communications Staff
Wire winch cables currently mounted in recovery vehicles weigh around 200 lbs., require four to six people wearing protective gloves to move it to disabled vehicles and are coated with a messy lubricant.
A 25-lb. synthetic winch rope can be toted to the same disabled vehicle by one person in about 30 seconds, and the gloves are optional.
Marines at Camp Pendleton, CA, recently conducted field user evaluations to test the performance of the lightweight synthetic winch rope, which could represent a major shift in a business based for decades in chains and cables. Members of the U.S. Marine Corps' (USMC's) 1st Light Armored Reconnaissance battalion conducted the evaluation with the Light Armored Vehicle Recovery (LAV-R) variant and its new winch; the Marines responded positively to the winch rope's light weight, ease of use, and readiness for fielding.
Members of a USMC LAV-R crew tried out the new rope during a User Jury at the Detroit Arsenal last fall and found it more effective to use in recovery missions. "It's a lot lighter and easier to handle," observed Gunnery Sgt. Chris Manning. "You don't have to worry about frays or kinks, you don't have to worry about keeping the dirt off it."
Another user from the fall trial commented: "The winch will help recovery operations save three-quarters of the time and manpower. We're very impressed and the equipment was proven successful." One of the Camp Pendleton users commented: "I learned a lot about the equipment and feel very confident that the new modifications done to the [LAV] Recovery will greatly increase mission capabilities in the fleet."
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While the Marines may be first adopters of the rope if the tests are successful, the U.S. Army Tank Automotive Research, Development and Engineering Center's (TARDEC's) Towing and Recovery Team plans to recommend the new equipment to the Army for recovery vehicles operating in the field.
Pulling Its Weight
Because the synthetic rope requires only one or two crew members for set-up, fewer people would be exposed to enemy fire during a vehicle rescue in combat areas.
"The legacy wire cable takes five guys about seven minutes to prepare a vehicle for towing. With the synthetic rope, one Marine took 27.5 seconds with the same length of rope — about 165 feet," commented Mark Weaver, Project Manager-LAV Sustainment. "The regular cable has to be rolled back onto the drum [after rescuing a vehicle]. One man could throw the synthetic rope in the back of the vehicle and drive away — like a hose or an electric cord — if they have to leave quickly."
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The LAV-R winch performance specification document states that the system must be strong enough to recover a vehicle mired up to the middle of its wheels and weighing up to 38,000 lbs., but Weaver says the engineering team designed the winch and rope to pull up to 60,000 pounds (using a snatch block to achieve a 2:1 mechanical advantage).
"We know the new rope with the same diameter will withstand the force and we're confident it can function beyond the capacity of the current cable," Weaver noted.
During the User Jury at the Detroit Arsenal, Marines proved the rope's sturdiness by pulling a 30,000-lb. LAV with the wheels locked.
In addition to the ease-of-use and strength benefits, the synthetic rope also offers a unique safety advantage: It will not unwind and whip if it breaks, as a wire cable does.
"Wire cables are wrapped over themselves five or six times, and the energy spins out if the cable snaps," Weaver explained. "A broken wire spinning like that could cut right through your hand. Our rope just drops if it's broken. There are no spun tendencies in the synthetic rope and no similar risk of physical damage."
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The synthetic rope is made from a material called Dyneema® — an advanced fiber rope based on an ultra-high molecular weight polyethylene and manufactured by industry partner Samson, a high-performance rope and cordage company.
TARDEC Engineers Emily Neville, Celeste Kozinski, Alan Cichosz and Stephanie Frederick worked with private industry partners on the team that converted a commercial winch for military use and integrated it, along with a generator, for vehicle mounting.
"Until we prove that it works in a military environment, people will be apprehensive about using synthetic rope because they don't want to be the first to try it," Neville stated. "This is the first program that will be fielded with a synthetic winch rope. We have some self-recovery winches out there with synthetic extension ropes, but this is our first 'real' recovery winch with synthetic rope."
TARDEC engineers and industry partners adapted the winch to military requirements. The more rugged hardware and hydraulics, along with modified electronics, give the winch the required 30,000-lb. rating.
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"The newer winch technology adjusts the system pressure to increase capability on the higher rope layers," Neville pointed out. "Typical drum winches only provide their maximum rated pull capability on the first layer, with the pull decreasing significantly on each successive layer. This winch system design reduces that effect by having a lower hydraulic pressure on the first layer, and increased pressure on the other layers so that those layers pull more than they ordinarily would."
The Camp Pendleton demonstrations involved LAV variants being dragged out of different recovery situations. After reviewing the user feedback and validation results, the USMC will determine whether to continue with initial production and then fielding. Neville indicated that, given positive test results, her team would advocate synthetic winch ropes for Army vehicles and joint platforms.