Winch Capacity (Rated Line Pull)
The first important consideration is winch manufacturer’s line pull rating. This is a combination of the mechanical capacity of the winch and the tensile strength of the line on the drum. The important part to remember is that, unless otherwise indicated, rated capacity is based on the first layer of winch cable (the one closest to the drum). Typically, there are three or four layers and that first one has the “lowest” gear ratio and the most pull.
How much pull is enough? The rule-of-thumb minimum is to take your GVW (that’s Gross Vehicle Weight, not curb weight) and multiply it by 1.5.
More line on the drum allows you to reach out farther but that’s often a mixed blessing. To start, as mentioned earlier, your winch’s maximum rated pull is on the first layer of line, so to get maximum pull, you have to spool out lots of cable. The other consideration is that more line on a drum is easier to get snarled up, jammed and kinked. For those reasons, many winchers prefer less line on the winch but carry an extra 50-foot length, with eyes splice in, to use as an extension. This is an especially viable solution if you have synthetic rope instead of wire rope on your winch. Having around 100 feet on the drum and a 50 foot extension is an ideal compromise for most people.
If line speed is a patience–testing issue for people, that’s mostly when spooling-in after a recovery. Many winches are extremely fast unloaded but all will slow down dramatically under a load. Most are in the 2-5 feet-per-minute range under load, regardless of unloaded speed. Decide your own level of patience when respooling but bear in mind that a winch that’s extremely fast under a load is likely to require lots of electrical power to deliver that performance.
Winch motors come in a variety of horsepower ratings and winch drivetrains with a variety of ratios. Just as with the vehicle drivetrain, low gears (high numerically) bring high torque multiplication and low speed and high gears (low numerically) bring high line speeds and low torque multiplication. To have a fast winch with lots of pull, you need a powerful motor combined with tall gears. Simple physics tells us this winch would have higher amperage draw for its load rating than a winch with lower gears. Bottom line, compare loaded and unloaded line speeds with amp draw to find a winch that matches up to your Jeep’s current or projected ability to deliver electricity, then consider line speed.
An Example of Cable Layer vs. Line Speed and Pull: Line speed and rated pull is effected by the layer of cable.
It similar to how tire diameter effects axle ratios. The first layer (the shortest “tire” that offers the lowest overall ratio and lowest speed) is the most powerful than the last layer (the tallest “tires” for the highest ratio and highest speed).
Line Pull and Speed vs. Layer: MileMarker 10,500 pound unit, low gear.
Three basic types of drivetrains have stood the test of time and remain on the market, spur gear, worm gear and planetary. Since the drivetrain has an effect on winch operation, we’ll list the types and the various features that will effect your choices.
Spur Gear: This type of winch uses a pair of spur gears; the big one on the motor shaft and the smaller on the winch shaft. Spur gear winches are fast but have fairly low amperage draw for their line speed because of low internal gear friction. They do need a strong brake to hold the load. The only spur gear winch still on the market is the legendary Warn 8274-50, the basic design of which dates back to the 1960s.
Worm gears go back farther than spur gear winches but the types used on light 4x4s today are not totally worm gear drivetrains. The worn gear is connected to the motor via spur gears. The motor lies under or alongside the gear housing and the spur gears offer some extra gear reduction. The worm gear winch is very good at load holding, with only a minimal brake needed, and is good at lowering a load under power. Their drivetrains are usually very robust as well and these last two features account for their popularity on tow trucks. On the downside, because of lots of gear reduction, they are far slower than either the spur or planetary winches, especially unloaded. The only worm gear winches on the recreational 4x4 market today come from Ramsey, Superwinch and Pierce.
Planetary Gear: These use a small planetary gear, similar to what’s used in automatic transmissions. Their best features are compact size, low weight and low cost. They are in the middle between the spur and worm gear types for drivetrain friction and amp draw. Their primary downside is that most use a brake inside the center of the drum that can get very hot when spooling out under load. Most winches on the market today are planetary types.
Electric winches come with two types of winch motors, permanent magnet (PM) and series wound (SW). PM motors, generally seen on the lower priced winches, draw some 10-15 percent fewer amps than the heavier-duty series wound motors but they are less tolerant of abuse and heat. They also tend to lose power in extremely cold weather. For the occasional wincher, or the careful wincher, the PM motors are perfectly fine. For heavy duty or cold weather use, SW are the best choice.
The only hydraulic winches on the market come from Mile Marker. They are simply a planetary winch with a hydraulic motor that’s powered by the vehicle power steering pump. The most serious difference is duty cycle. You can winch all day, every day with a hydraulic as long as the engine is running. On the other hand, the electric winch can give you five minutes of full power pulling with a dead engine, but seldom do electric winch-equipped Jeeps have the electrical system necessary for continuous use. If you do a lot of winching, such as with farm, ranch or commercial use, a hydraulic winch will do that job forever. For the occasional use most Jeepers subject a winch to, an electric is more than adequate. For high duty cycle electric winching, chose a robust worm gear winch.
You have two basic choices, wire rope and synthetic rope. Both will do the job and each have plusses and minuses. They both are rated for strength via diameter and the tensile strength of their materials. In the common 6,000-15,000 recreational 4x4 winch, cable diameters of 5/16, 3/8 and 7/16-inch are seen in both wire and synthetic ropes. Tensile strength, the point at which the rope breaks (a.k.a. “parts”) varies according to type, characteristics and diameter, but is higher than the pull rating of the winch. Their ratings have some reserve for a safety factor to account for wear and minor damage.
Wire rope is the traditional choice. It’s made up of strands of carbon steel wire, usually seven bundles of 19 strands (a.k.a. 7x19). Less common is 6x37, which is more flexible and resistant to fatigue but less resistant to abrasion than 7x19 because of the thinner wires. With just a few exceptions, 7x19 wire rope is what comes with winches from the factory.
On the plus side, wire rope is more resistant to abrasion than synthetic. It’s very heat resistant and relatively inexpensive. On the downside, it vulnerable to crushing when not properly respooled. It’s relatively heavy, with a 120 foot roll of 5/16 cable weighing about 28 pounds with a hook. Wire rope can be spliced but not easily or by novices. Individual wire strands routinely break and create small hooks that rend flesh, so gloves are vital. Wire rope can store large amounts of kinetic energy and can whip with deadly effect if something breaks loose.
Synthetic Winch Rope:
Synthetic winch ropes are the new kid on the block and there’s lots to talk about. As few premium winch packages come new with synthetic rope. Most winch manufacturer’s are offering a synthetic rope upgrade and you can buy the rope separately to upgrade most types of older winches.
On the plus side, synthetic is light; a 120 foot roll with a hook weighs about 5 pounds. Synthetic generally drops dead with minimal “snap” when something breaks. It’s often stronger than an equivalent diameter wire rope and has appendage-friendly surfaces. It floats and in an emergency you can tie a knot into it. Knots do weaken it but if you perform a long splice at a break, it’s as good as new. Splicing 12 strand rope is lots easier than wire rope.
Synthetic rope also has a few disadvantages. It’s more susceptible to chafing than wire rope. It has a high initial cost, though it’s superior performance makes it a good value overall. The most significant potential operational problem has to do with synthetic’s ability to withstand heat. The common planetary winch has a one-way brake built into the center of the winch drum. When spooling out under power, i.e. lowering the vehicle under a load, that brake will generate some serious heat. Winch manufacturers caution against this lowering practice and advise doing it only in short 20 foot increments with long cooling periods. Rope damage from heat can go unseen on that first layer and damage may start occurring at temperatures as low as 150 degrees.
There are several ways around the temperature dilemma. Some winch rope has a higher temperature resistance but comes with lower tensile strength, so you would have to use a larger diameter rope to maintain the same tensile strength. An interesting cure is to have enough of the high temp rope spliced onto a stronger rope to cover the first later of the drum. Larger diameter rope can be splices to smaller to compensate for the strength difference. An even easier solution is to place an insulating sheath of nylon over that first layer. The easiest solution is to follow the winch manufacturer’s recommendation and not power out in long stretches. Remember that most worm or spur gear winches do not have this problem.
We’ll leave the looks department to your good eyes but whatever mount you choose must be able to handle the pulling capacity of the winch. The weight of the winch and mount then becomes an issue. Too much weight may cause your front suspension to sag lower. In some cases stiffer front spring are necessary to carry the extra weight. How far the unit protrudes is part of the weight issue but also an approach angle issue. The farther it hangs out will multiply the load on the springs as well as reduce approach angle. A mount that seriously impairs your approach angle may be a net loss in the performance department, perhaps causing you to need the winch more.
Access to the winch cable is both a cost and safety issue. Some winch mounts will have minimal drum access, making it more difficult to respool the cable. If you can’t do that properly, the cable may get damaged. Also, cable that is difficult to access increases the risk of hand injuries when respooling.
An electric winch is only as good as the power supplied to it. The first weak link of the OE system is the battery. Starting batteries do not like being deeply discharged and will die when used this way often. The upgrade depends on which type of battery you will use. A typical lead acid “wet” deep cycle battery can handle the discharges but may not have enough cold cranking amps to be a good starting battery. In the conventional wet battery realm, your answer is a marine battery. They are more robust and capable of both starting your Jeep and deep discharge cycles.
A better upgrade is a spiral cell battery, like the Optima Yellow Top or ProComp HDX off-road. These are specially built as dual purpose (starting and deep cycle) batteries that have good starting amperage but can be repeatedly discharged and charged safely. They also have low internal resistance and can discharge and recharge faster than a normal lead acid battery.
In all cases, buying the biggest, highest rated battery that will fit your application will extend winching capability. Select a winching battery based on the amp hour (AH) capacity. One amp hour is one amp
for 10 hours or 10 amps for 1/10th of an hour. Because the way batteries charge and discharge is not linear, as the preceding line might indicate, there are several different ways to rate AH. The most commonly seen is the C/20 rate, which is the number of amps the battery can put out for 20 hours before the battery voltage drops below 10.5 volts. A 55 amp hour battery measured under the C/20 protocol will put out 2.75 amps for 20 hours (55/20=2.75).
If you want to see approximately how a battery will perform under a winch load, divide the maximum winch draw, or any part thereof, into the amp-hour rating. A 55 amp-hour battery with a 400 amp load will drop to 10.5 volts in about 8 minutes (55/400= 0.137 hrs x 60= 8.22 minutes. That’s a perfect world scenario, and variable between different types of batteries, so actual performance would probably be lower, but it gives you a way to compare. If you use double batteries in parallel (positive terminal to positive, negative to negative), AH capacity is doubled. Keeping the voltage above 10.5 volts is conducive to long winch motor life.
Some owners install a second battery, isolated from the starting battery and just for the winch. That eliminates the danger of running the batteries flat winching and then needing a jump to start the engine. Battery isolators, solenoids, switches and other methods of connecting the batteries are available from various manufacturers. The key to these components is that they all match the amperage draw and the output of the alternator. That includes the electrical cable. Fine strand welding type cable is best for carrying a heavy current.
You can extend winching time by installing a higher output alternator. Alternators of 100-150 amps are suitable for winching but duty cycle is just as important as amps. The average OE alternator is rated for about a 60 percent duty cycle, give or take.
If you run any OE alternator, regardless of amp output, at maximum output for long periods, they overheat and go up in smoke. Many of the aftermarket, high output alternators are industrial rated and have duty cycles at or nearing 100 percent. Industrial alternators are available at up to 200 amps that fit many 4x4 engines. Those with external regulars are often 100 percent duty cycle units. Outputs over 150 amps require a look at the belt drive system. A given belt can drive only so many amps.
If you are installing a Mile Marker hydraulic, step one is to completely change the power steering fluid. Use a quality fluid like Royal Purple’s Max EZ synthetic and consider a oil cooler on the return line. On older rigs, consider having the power steering pump pressure tested. If it’s half worn out, you won’t get the maximum out of your hydraulic winch. Some Jeeps come with power steering pumps on the weak side to run a hydraulic winch. That includes virtually all the newer Jeeps. The older Jeeps (CJ and YJ to ‘90) with Saginaw P-series pumps are ideal. The ’91 and up TC style pump is marginal. You can upgrade most Jeeps to a Saginaw P-series pump via Super Pump kits from AGR and others.
Many winch manufacturers offer an accessory kit. It will, or should, contain a pair of gloves, a tree protector strap, a couple of shackles (a.k.a. clevis pins or D-rings), a length of choker chain and a snatch block. For wire rope winches, a roller fairlead helps prevent cable damage and for synthetic line, a hawse type fairlead, either aluminum, polyurethane or polished steel is vital to prevent rope damage.
Many people like the convenience of wireless controllers that allows the winch operator to be anywhere within line-of-sight inside a hundred feet or so. Solid state controllers, such as the Warn M.O.S.F.E.T., offer trouble free operation without worry of sticking or corroded solenoids.
Content provided by Jim Allen
©2007 Jim Allen