Unraveling the mysteries of … MV WINCHES

by Steve Turchet,
'Tech Tips'

There’s a saying about lawyers, guns and money: “It’s usually better to have them and not need them than to need them and not have them.” This could also apply to having a winch on your military vehicle; though many MVers would probably agree that winches on most common collectable MVs can be lumped into two basic categories. The first are just cool decorations, and while they are usually functional they are rarely if ever used. The second category applies to folks who do use their winches for actual work or recovery situations.

But, no matter how or if a winch is used, their operation and maintenance is often misunderstood and improperly performed. Note: For those who insist on correct terminology, be warned that I was brought up to call wire rope cable, so the terms will be used interchangeably.

TO WINCH OR NOT TO WINCH...
For many MVers, a winch is only a necessary accessory like the door-mounted spare tire on M37s. It is practical because it adds value and interest to a vehicle, but it’s “correct” only in the sense that, while many common military vehicles may have been equipped with winches, they probably weren’t.

As a general rule for cargo trucks — such as WWII Dodge WCs, Chevrolet G-506s, GMC CCKWs, and M-series vehicles such as Dodge M37s, Kaiser M715s, and the various deuce-and-a-halfs of all eras — only about one in 10 were equipped with winches during their military careers. On the other hand, some vehicles, such as the Ford GTB Burma Jeep, were usually fitted with winches. Furthermore, winches were a universal item on DUKWs. Then, of course, there are wreckers, bomb-service trucks and recovery vehicles that always had winches... sometimes two or three of them.

Winches were rarely installed on half-ton WWII Dodges, and almost never on carryalls, panel trucks and ambulances. There were a few exceptions for special duties and environments, but if you find an ambulance with a winch, it was almost always installed by a civilian owner. In regard to military jeeps with winches, either conventional or capstan, they were very ... very ... rare.

Just as one can take pride in owning an M-37 without a door-mounted spare, one can also be proud of an MV without a winch. Of course there’s nothing wrong with adding a winch to your vehicle, but don’t feel obligated just because “everybody else” seems to have one. If your vehicle’s data plate doesn’t include a winch diagram, it’s a pretty safe bet that the winch was added later.

IF YOU HAVE ONE, KNOW HOW TO USE IT
If one does have a winch on their MV, they may need or want to use it, so it should be kept mission-capable just like the vehicle itself. However, one should understand the limitations of a winch: most notably, it’s not a miracle device that will always get you out of trouble so you can drive where you probably shouldn’t.

One should also be aware that there are a few pieces of common MV equipment that can be as dangerous as a winch in the hands of an inexperienced or careless operator.

Obviously there isn’t space to go into detail about mounting, maintaining and operating winches on every type of common MV — buy a manual — but most types of front-mounted PTO (Power Take-Off) winches operate about the same. What applies to the mounting, maintenance and operation of one will more or less apply to all, including DUKWs with their rear-mounted winch.

Some military vehicle winches have a drag brake that keeps
the drum from over-running and backlashing the wire rope-
like line on a fishing reel. This brake should be adjusted just
loose enough so the wire rope can be pulled out by hand.

DISSECTING THE WINCH
The three main parts of a Power Take-Off (“PTO”) winch system are the winch itself, the winch drive shaft (which may be a single long shaft or two or three shorter shafts) and the Power Take-Off unit. The PTO is usually mounted on the main transmission, though sometimes on the transfer-case, as with the M211. It is generally controlled by a single lever, which is often attached to the PTO unit, but in some cases uses a linkage.

Some small civilian winch PTOs are single-speed, meaning that when engaged, whether in forward or reverse, they turn the winch at only one speed... though speed can be varied by speeding up or slowing the engine. However, on most common U.S. MVs, the PTO is a two-speed unit. High Range is used primarily to spool the cable (or wire rope) when not under load, while Low Range is generally used for doing the actual winch work.

The purpose of the winch drive shaft should be obvious — to transmit engine power from the PTO to the winch — and though it requires maintenance and adjustment, let’s first look at the winch itself. Most winches may look like simple steam-age devices, but they require proper maintenance for safe use and long life.

A winch is basically a worm gear driving a shaft, but the drum that holds the cable (or wire rope) is usually not part of, nor is connected directly to, the drive shaft. Instead, the drum is free to rotate on the shaft like a spool of thread on a pencil, and is usually connected to the shaft by a sliding dog-clutch controlled by an external lever. By disengaging this clutch, the drum can be free-spooled, such as when pulling out cable by hand. Some winches have a drag brake that keeps the drum from over-running and backlashing the cable like line on a fishing reel.

The military seems to have been of two different minds at various times about whether the dog-clutch should be left engaged or disengaged when the winch wasn’t in use. Leaving it disengaged is best from a safety standpoint: that way if the PTO lever is accidentally engaged the winch won’t start spooling out cable (or pull off the vehicle’s bumper if winding in). About the only reason to leave the clutch engaged is to keep a show-quality tension on the chain. However, if the drag brake is properly adjusted, it should keep the chain tight by itself.

A worm gear tends to hold its position under load, meaning that the worm resists being turned by the gear instead of vice-versa. However, many winches are also equipped with an automatic brake. This may be an external-contracting band type, or it might be a wet-pack clutch inside the winch gear case. Generally, the band type automatically disengages when the winch is under power and clamps down again when power is removed. While band type brakes are usually external, the clutch pack types generally run in the gear case oil, so the correct type of oil and the oil level should always be maintained. Band type brakes need to be adjusted from time to time (depending upon how often the winch is used), and the lining material wears and will eventually have to be replaced. Wet-pack brakes will also eventually wear out.

Most types of front-mounted PTO (power take-
off) winches on common collector U.S. military
vehicles operate about the same.

Most winches may look like simple steam-age
devices, but they require proper maintenance
for safe use and long life. A winch is basically a
worm gear driving a shaft, but the drum which
holds the cable (or wire rope) is usually not part
of, nor is connected directly to, the driven shaft.
Instead, the drum is free to rotate on the shaft
like a spool of thread on a pencil, and is usually
connected to the shaft by a sliding dog-clutch
controlled by an external lever.

BECOME FAMILIAR
Imagine that you have just purchased an MV (always a good thing to imagine) and the vehicle came with a winch. Assume that the winch system is in good condition and ready to use... except for checking the gear case oil level and lubrication points. Let’s familiarize ourselves with its workings so that adjustments and service procedures will make more sense.

First, check the gear case oil level. On most winches this is done by removing a threaded plug on top of the case. As with the recommended position of the sliding clutch, the military seems to have changed its mind several times as to the correct oil level in winches ... anywhere from up to the filler neck to an inch below. It’s probably a good idea to leave a little room for expansion, but the oil level should always be high enough to cover the worm and at least half of the driven gear. If the oil seal on the worm shaft leaks it should be replaced. Most such seals may be found by number at bearing supply houses. For most vehicles, the winch uses the same 90 weight gear oil as the transmission, transfer-case and differentials ... though of course check your manual. The PTO unit usually shares oil with the transmission or transfer-case.

Lubing the drive shaft universal joints and carrier bearings is obvious, and look for grease fittings on the winch itself. There is often a fitting on the end of the drum shaft, and sometimes on the outside ends of the drum. A few drops of oil should be put on the sliding clutch mechanism, control lever pivot pin and detent from time to time to keep them free and operating smoothly. Likewise, oil the PTO lever or linkage in the vehicle’s cab, and the lever safety latch. The military once advised pouring used engine oil on the wire rope to keep it from rusting, but then changed its mind because the oil rotted the fiber core. While some show vehicles have canvas winch covers, it’s doubtful if many such items were actually used, or lasted very long during military service.

Operating a PTO winch is always safest with two people; one in the vehicle’s cab, and the other up front on the ground at the winch. Of course, there may be times when one has to operate a winch alone. If so, one should be twice as careful. I don’t like wearing gloves while using winches — at least when winding in cable, even though the cable (or wire rope) is often rusty, greasy, and full of snags. Gloves often give people a false sense of security about their hands; and gloves can be caught in a sliding clutch or rotating drum, or snagged on the cable when it’s winding in. I would rather have a cut on my finger than lose a finger. Long sleeves are also a potential hazard, and just rolling them up is no guarantee that they won’t slide down at the wrong moment.

Always stay clear of the winch line when it’s under load. Wire rope often stretches under load, and if it or the hook or the chain should break, it will come snapping back with more than sufficient force to rip your head off. And, unless you want to risk being a soprano for the rest of your days, never straddle or step over the line when it’s under load.

The best way to learn about operating a winch is to rewind the cable on the drum. Winches usually fall into two categories in respect to their cables: those that were seldom used, so their neatly-spooled cables will look like a long coil spring when unwound, and winches that were used a lot, so their cables are stretched and will resist being wound back on the drum in any semblance of neatness. These kinds of cables are also usually full of snags. New wire rope will also often resist being wound in neatly, and the procedure we’re covering now could also be followed if one is installing new line. If you’re working alone be prepared for some fast moves, and leave your vehicle’s cab door open. You might also consider rigging a temporary ignition switch, such as a toggle with jumper wires, so you can kill the engine from in front of the vehicle. I installed such a switch as a permanent feature on the front of a GTB Burma Jeep that I used for salvaging equipment out of mine shafts in Arizona, and I still have ten fingers to prove that it worked.

Anyway, with your vehicle warmed up and idling, unhook the winch chain. There should always be a short length of chain at the front of the winch line, and the hook is attached to that. About three or four feet is the average length, and it’s considered poor practice to have any of it wrapped on the winch drum. If you’re doing this the safe way with two people, then your trusted friend is in the cab at the controls, and your fingers — and possibly your life — is in his or her hands while you’re out front on the ground. (You may want to trade positions at times to get the full experience.) My youngest son was my “cab-man” at seven-years-old, and I trusted him a lot more than many so-called adults. If you have a friend who tends to daydream, find another person for this duty.

After unhooking the chain, disengage the sliding clutch (though it should have already been disengaged) and try to pull out the cable by hand, walking away toward your winching point. This may or may not work, depending upon the type of winch, its condition, and/or if it has a drag brake. If the drum will free-spool, then walk away, pulling the cable into the field, across the yard or down the driveway, until it’s fully unwound and stretched out.

An alternate method is to hook the cable to something — preferably not your porch rail — then slowly back up, pulling out the cable. Use caution as you get near the end of what’s left on the winch drum so there won’t be a sudden jerk.

If you have to power-out the line, you should either have a cab-man or be very fast on your feet, because when you get all the cable off the drum it’s going to start reeling back in the other way if you don’t shut the winch down immediately. To power out, engage the sliding clutch on the winch — with the PTO in neutral, of course — then get in the vehicle, step on the engine clutch, engage the PTO lever in the Reverse or Out position, and gently let out the engine clutch. Then jump out and run to the front of the vehicle to pull the cable toward whatever you’re hooking it to. Then, of course, you will have to run madly back to the vehicle to disengage the PTO.

If this is the first time you’ve tried your winch, be alert for three things: 1) The data plate on the dashboard might not be correct for the vehicle, and instead of spooling out cable you’re actually winding it in. (Remember, you can’t see the winch from inside the cab.) 2) A previous owner might have wound the cable backwards on the drum, which does the same thing. 3) If when letting out the clutch, you hear unpleasant noises or the engine stalls, stop at once and find out what’s wrong. Do not assume that something is just a little rusty and try to break it loose by applying more gas!

The normal load on an engine to power-out a winch is very slight — it should barely hesitate at idle when you let out the clutch — and the only normal sound should be a grumbling whine, with sometimes a little vibration from the PTO and winch drive shaft. If the engine stalls or threatens to, put in the clutch and shift the PTO back into neutral. While it’s possible that the winch is merely stuck from rust or disuse, there are other, more serious reasons why a winch won’t budge, and you can usually avoid destroying a winch by finding out why it won’t turn instead of trying to force it to.

For example, I once bought a GMC M211 from a contractor. Whether done by accident, or by someone with a grudge against his boss, a half-inch nut had been dropped into the gear case through the oil filler hole and had jammed between the worm and drum shaft gear. (The shaft gear is often made of bronze, while the worm is usually steel.)

The first time I tried to power-out, the engine stalled. The smart thing to do would have been to stop immediately and find out why. Was the PTO jammed? Unlikely, but possible. Was a carrier bearing frozen on the winch drive shaft? Possible. Were the winch drum shaft bushings frozen? Possible. What I should have done was put a pipe wrench on the winch drive shaft with the PTO in neutral and tried to turn it. Then I would have found that it turned in one direction but jammed when going the other way. Elementary, Watson. Something is caught in the worm.

But, no, I had to give it gas and try again. Crash! A completely shattered winch drum gear. Maybe the drive shaft shear pin would have saved the winch, but someone had replaced it with a bolt.
Anyhow, if there are no nasty noises or stalled engines — and you’re working alone — you’ll have to jump down and pull out the line as it unreels. And then make a fast re-entry to disengage the PTO at the end.

Okay, one way or another you’ve gotten the wire rope off the drum and all stretched out. If it’s badly rusted and/or full of snags and frayed spots you may want to replace it. Wire rope comes in many grades intended for different uses. At the low-end is “plow cable.” It’s cheap, but you don’t want it on a winch. Fiber-core wire rope is best for most winches. Of course, you will buy wire rope with a breaking strength that exceeds the capacity of your winch. (Read your manual.)

The wire rope usually attaches to the drum with a clamp or a wedge, which should be simple to figure out. Be aware that on some winches it’s easy to wind the cable on backwards.

To wind the line neatly and tightly, there must be tension on it, and someone (likely yourself) will have to be standing in front of the vehicle guiding it in. This is the most dangerous part of a winching operation, and if you’re doing it alone then, again, I advise rigging a kill-switch so you can shut off the engine from out front on the ground. Use low speed on the PTO as well as the lowest engine speed you can get. Ideally, the wire rope should be fully stretched out in a straight line and attached to an object of sufficient weight to drag and keep it under tension.

Sometimes a cinder block is all it takes, though sometimes a jeep is better if the cable is new or sprung into unwilling coils. Be aware that whatever object you attach to the line is eventually going to come very close, sandwiching you between it and your vehicle’s bumper. No one would be nutty enough to try winding in line to a tree by letting the vehicle pull itself along and staying three steps ahead of it ...or would they?

Three steps IS a good distance to keep from the bumper while guiding the wire rope onto the drum. After you have done this once or twice you should have a pretty good idea of how to operate your winch in situations where it’s needed.

The three main parts of a PTO winch system are
the winch itself, the winch drive shaft (which
may be a single long shaft or two or three shorter
shafts) and the power take-off unit. The PTO is
usually mounted on the main transmission,
though sometimes on the transfer-case.

An automatic winch brake should only be
adjusted if the winch fails to hold under load
when power to it has been removed... such as
when stepping on the engine clutch. The brake
should be tightened by small degrees until it will
hold the winch drum under load with power
removed. Over-tightening this brake will put an
unnecessary strain on the drive system and winch
gears, and will also wear out the lining material.

The safety collar on a winch drive shaft allows
the drive shaft to be short enough so it can be
removed without demounting the winch or the
PTO. It also prevents the shaft from sliding out
of the winch yoke and falling off if the shear pin
breaks. Since some provision has to be made for
vehicle frame flex, the safety collar should be
adjusted with about 1/2 inch of clearance.

MAINTENANCE AND ADJUSTMENT
Let’s move on to the maintenance and adjustment of winches. We have already covered basic lubrication, but there’s one point in the system that’s often neglected, and this is the yoke collar on the winch drive shaft in conjunction with the shear pin. I’ve given an example of what can happen if the shear pin is replaced with something that won’t break before either the winch or the wire rope does. Correct shear pins for specific winches are often hard to find. In most cases a soft grade-2 bolt will do, and if appearance is a factor, a little grinder work and drilling a hole for a cotter pin will make it look correct.

The use of grade-5 bolts is risky — sometimes they are just as effective as shear pins on larger winches, but there’s a wide variance in the strength of most commercial fasteners, and many grade-5 bolts are a lot stronger than they need to be. Likewise, most clevis pins (a tempting substitute) are at least grade-5 in strength, and may prove to be stronger than your wire rope or winch gear.

One may want to experiment, using a winch line pull that approximates your winch’s capacity, which is always rated at the first wrap of cable around the drum... read your manual. Beginning with the softest pin you can find, work up the hardness scale until you get something that seems to consistently shear at about the right strain.

LUBRICATION
As far as lubrication, the yoke collar should always be free to rotate on the winch drive shaft if the shear pin breaks, so coat the shaft lightly with grease within the yoke, and squirt some oil on the shear pin. On older MVs, especially those used around salt water, it’s very common for the yoke to be rusted onto the shaft, making the shear pin useless. If that’s the case, you will have to take it off — heat and/or a puller may be required — and polish and lube the shaft so the yoke is free to turn unless the shear pin is installed.

An easy way to check if the yoke is rusted or frozen is to remove the shear pin, and with the winch and PTO in neutral, try to turn the shaft by hand or with a wrench. The shaft should rotate without turning the winch.

While you’re underneath inspecting things, be aware that another important part of the winch drive shaft is often missing, or at least improperly adjusted, especially on vehicles where the winch has been added later. This is the safety collar. It serves two purposes: first, it allows the drive shaft to be short enough so it can be removed without demounting the winch or the PTO. Second, it prevents the shaft from sliding out of the yoke and falling off if the shear pin breaks. Since some provision has to be made for vehicle frame flex, the safety collar should be adjusted with about a half an inch of clearance.

Other adjustments occasionally required to keep a winch operating properly are the drag brake setting (if so-equipped) and the automatic brake adjustment. The drag brake should be kept just tight enough so the wire rope can be pulled out by hand without the drum over-running and backlashing. The automatic brake is relatively long-lived and trouble-free. It should only be adjusted if the winch fails to hold under load when power to it has been removed ... such as when stepping on the engine clutch. The brake should be tightened by small degrees until it will hold the winch drum under load with power removed. Over-tightening this brake will put an unnecessary strain on the drive system and winch gears, and will also wear out the lining material.

TIPS FOR INSTALLATION
So far we’ve been dealing with winches that were already on vehicles. What about installing a winch on your present MV? Again, that’s what manuals are for. However, here are some tips ...

If you want a genuine military winch for your G.I. jeep, you’re in for a lot of frustration. These winches are extremely rare and usually hideously expensive if you do find one. You may also fall victim to some sort of scam if you see one advertised on the web. There is nothing wrong with installing a modern electric winch on your jeep if you actually need a winch, and this can usually be done in such a way that removal for show is easy.

For most other common U.S. MVs, winches are generally available and reasonably priced. Most will be “used take-outs,” and some will have been abused. The safest way to buy a winch system is to look it over while it’s still mounted on a vehicle. Make sure it has all its parts... again, a manual will be handy. Put a pipe wrench on the winch drive shaft and make sure the winch turns. Look inside the gear case to check the condition of the gears. While the condition of the wire rope is relatively unimportant since it can easily be replaced, it’s logical to assume that if the line is heavily worn the winch was used a lot. If you must buy a winch sight-unseen, buy from a reputable source and get a refund or replacement guarantee in writing.

Another reason you should have a manual is to be sure you’re getting not only the right winch for your vehicle, but also all the parts necessary to install it. For many vehicles, special front bumpers and/or frame extensions are part of the package. It’s best to buy everything as a complete package. If you buy components from different sources you will probably end up paying a lot more.

The absolute best way to make sure you get everything is to take a winch system off a vehicle yourself. This has the added advantage of letting you experience what’s involved in installing the winch. While, again, a manual is imperative, there are some things about installing winches that you probably won’t find in manuals.

One of these is that many Canadian M37 type trucks used a different transmission than U.S. models, so the U.S. PTO won’t fit. Or vice-versa.

PTOs sometimes require shims ... if it howls, then it probably needs to be shimmed. PTO shims are often available at commercial truck and equipment suppliers, or may be made from sheet metal like cutting a gasket. Don’t be surprised if neither the special winch bumper(s), the frame extensions, or the winch itself seem to want to fit in the mounting holes of your vehicle. A heavy drift punch or alignment tool will usually be required. Be prepared to re-drill some holes.

Winches are heavy. Save your back by using a hoist or jack when lifting, moving, or positioning them ... especially since the winch will seldom fit on the first try.

Weight is also a factor on aged front springs. You might want to pile everything onto the front bumper first to see if you’ll have to add new leaves or have the springs re-arched.

Since installing winches on many MVs requires that part of the radiator grille be removed, it’s smart to protect the radiator with a piece of plywood.

And finally, while installing a winch is seldom fun — even if that winch is never used for anything but a cool decoration — it probably is better to have one and not need it than to need one and not have it.

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