Simpson Capstan Rope Winch
A Simpson Capstan Rope Winch is a great tool for hauling, dragging, or lifting heavy objects. It can turn a small chainsaw engine into a rope pulling machine -- useful for hunters, wood cutters, boat owners, ATV riders, and even rescue workers.
Advantages of a Winch Powered by a Chainsaw Engine.
A winch powered by a chainsaw engine offers many benefits when compared to both an electric or PTO style winch. PTO winches are always mounted on a vehicle and depend on its running condition for power. If a vehicle won't run, the winch won't work.
An electric winch that is mounted on a vehicle is not completely dependant on a vehicles running condition, but even this is limited if a pull lasts for very long. Electric winches can draw down battery reserves quickly, so if the vehicle is not running, its usefulness diminishes. Another problem with electric winches is that in long or hard pulls, the winch motor can heat up. When it does, pulling power decreases. A winch powered with a chainsaw engine is self-contained. It does not depend on a vehicle's engine or battery. It will run as long as there is fuel in its tank.
Portability is a Chainsaw Winch's Biggest Advantage
Another benefit to not having a vehicle mounted winch is portability. Most people can carry a chainsaw winch, so it can be taken where a vehicle can't go. This is the feature that makes a chainsaw winch the choice of many big game hunters. Truck mounted winches are not effective when trying to move a big game animal downed thousands of feet from a road or deep in a ravine. The same is true for wood cutters and other users who need to be able to pull objects that a vehicle can not approach.
Winches mounted on vehicles present another problem when the vehicle itself is the object of the pull. Since most winches are mounted on a vehicle's nose, most winches can only pull the vehicle forward. Unfortunately, the easiest way to extract a vehicle that is stuck in the mud or high-centered is often to pull it in the opposite direction of the way it went in or more simply said: backwards. This is not possible with winches mounted in a vehicle's front bumper. Again, the portability of a chainsaw winch makes it easy pull on a vehicle from whatever direction will free it the easiest.
Advantages of a Capstan Style Winch
A capstan or rope winch offers some real advantages when compared to a cable style winch. The first advantage is the rope itself. It's true, steel cable is super-strong, but for many pulling jobs, rope is strong enough and offers the benefit of being more flexible and easier to work with. It can also be knotted or tied -- a hard thing to do with steel cable.
Another problem with cable winches is the spool. Cable is pulled from its end, so it is necessary to collect it on a spool when pulling. While this may seem like a benefit, it does present a common problem. Not only is a pull limited by the length of cable the spool can collect, but cable rarely fills the drum evenly when being pulled in. It is common for cable to over-fill a portion of a spool, becoming too large to continue. And this often happens when only a portion of the cable is retrieved. A capstan winch is not limited by the capacity of a spool, nor its housing. A capstan does not pull from the end of the rope, nor does it collect the rope it retrieves.
Another benefit of the capstan design is that its pulling speed is constant and the winch's full pulling force is available all the time. On a cable winch, the spool will pull slower with more force when most of the cable is deployed and as the drum fills, its pulling speed increases and pulling force decreases. This is because the pulling ratio varies depending on how much cable is on the spool. As layers of cable stack up in the spool, the pulling ratio changes. With a capstan style winch, the capstan pulls only on the rope wrapped around it. Layers of rope don't stack up and change the pulling ratio.
There are other advantages of the capstan design. Because of its simplicity, it is never necessary to run a spool backwards or "free wheel" a spool of cable to let it out. It is also not necessary to run the winch to take up slack in the line. You just begin a pull from any portion of a rope you choose.
The capstan design also makes it easy to gently start or stop a pull. The friction of the rope wrapped around the capstan determines how much slippage occurs. So the number of wraps on the capstan and the rope tension being held behind it works like a clutch to control the force of the pull.
How We've Used A Simpson Winch at Madsen's
To illustrate the many uses of a capstan winch, when we were wiring our shop and warehouse, we helped the electrician pull bundles of wires through long runs of conduit with a Simpson winch. We chose to use a capstan winch over a cable winch because we felt we would have more control on the pulling force. With a capstan winch, the more tension placed on the rope around the capstan, the harder it pulls. This allowed us to gently pull bundles of wires without damaging them or the insulation around them.
How It Attaches to a Saw
A Simpson winch weighs only 9 lbs. and easily attaches to most any chain saw power head. It is powered by a short cutter-less 3/8" pitch drive chain. This is a common size found on most mid-size chain saws. To install it, remove the saw's bar and chain, install the furnished adapter and cutter-less chain, and you are ready to pull.
The winch's maximum pull is 2000 lbs. Naturally, the size of the saw's engine affects the power of the winch. A saw engine of about three cubic inches or 50cc works well.
The chain saw and winch combination shown weighs about 27 lbs.
Not All Rope Will Work with a Capstan Winch
It is important to know that only low-stretch Dacron or Polyester rope can be used with a Simpson capstan winch. The reason for this is rope made of Nylon, Polyurethane, Polypropylene, or some other "plastic" like fiber can melt from heat caused by the friction on the capstan. So if you are arborist, you can't use an old climbing rope with a capstan winch.
For this winch, we stock 300' spools of 5/16" double-braided Polyester rope that has 4,200lb. tensile strength. This is what most winch owners buy. Also available by special order is a 3/8" double-braided rope that has 5,600lb. tensile strength or 3/8" twisted Polyester rope that has 2900lb. tensile strength. All rope is availble in either 300' or 600' spools.
The Capstan Design Advantage
A capstan winch is not limited to the length of cable a drum will hold
Pulling power decreases on a cable winch as its drum fills, while a capstan winch remains constant
It is not necessary to run the winch to take up the slack in the winch line
It is not necessary to run the winch backward to let out cable
It is easy to "feather" the pulling power with tension applied to the rope around the capstan
The Benefits of Pulling With Rope
Rope is flexible and lightweight
Rope can be knotted and tied if it breaks
Rope is less dangerous if it breaks and snaps back