|Hyster W8K w/Young Arch|
The winch business has seen massive consolidation in recent years. There are now 2 survivors. Allied systems of Sherwood Oregon, has acquired the Hyster, Lufkin, and Lantec names in winches. Paccar, better known for Kenworth trucks, owns Carco, Braden and Gearmatic.
Of these names, Carco and Hyster are the best known for dozer winches, although now the Hyster winch name is no more as it appears that Allied bought the winch product line but not the name, but I am featuring a Hyster winch here just the same.
Fifty years ago, just about every dozer had a winch on it. People were used to working with cable, and if they didn't have a 'towing' winch, then they had a smaller double drum that was used for control cables. Pull behind scrapers, and rippers used these cables.
Now days dragging logs with a dozer is the exception and not the rule, and dozers often aren't even present on logging operations. Hydraulics have replaced control cables for lifting rippers and managing scrapers. All of this had made the market for winches on the backs of dozers shrink radically. It is a rare day when you see one.
All of this does not mean that the classic towing winch on the back of a dozer is the same as it was 50 years ago, though in truth it is not a lot different. The Changes are evolutionary. Our first Hyster winch was purchased new about 1952. It was a D4N model for as you might guess a D4 Cat. Fifty years later we got our second Hyster winch and it is a W8K for a Fiat Allis HD16B. Though different in size, the basics are still very much the same. They both bolt on the back of the dozer and are powered off the dozer PTO. Within the winch there are monstrously heavy gears and a massive gear reduction which finally turns the drum that holds the cable.
The winch of 50 years ago featured an internal expanding drum brake with brake shoes expanded by a cam. You set the brake by pulling a long manual lever with ratchet teeth to hold the lever. Shifting was accomplished with another long lever which slid some gears around inside the winch to achieve forward, neutral and reverse.
The W8K winch is known as a power shift winch. It features a single lever control which really activates a hydraulic spool valve inside the winch. The lever has 4 positions, Centered is the normal position. The brake is set and the drum doesn't move. Pulling the lever back feathers in the clutch to activate the wind up direction and releases the brake. Pushing the lever forward sets the unwind clutch and releases the brake. Pusing the lever 'over center' forward releases the brake but does not activate the power unwind clutch. This is not the same as 'free spool' as you can pull the cable off with the machine, but all the gear train has to turn meaning that you cannot pull it by hand. Winches with a 'free spool' feature, have a mechanical disconnect allowing the drum to turn free of the gear train.
The beauty of the powershift winch is that it doesn't take 3 hands to run it. One lever working through a remote cable activates a spool valve and hydraulics do the work. Indeed this class of winch requires that there be a remote mounted hydraulic pump on the dozer to provide oil pressure for the control purposes. It takes a fairly small pump (like a power steering pump) and works at low pressure (a few hundred pounds pressure), and uses the lubrication oil from the winch for control oil. Compared to the old manual shift jobbies, the power shift is a joy to use. The 'inching' works nicely and if you want to wind up the winch a few inches or slack it a little even under heavy load, you can, just by gently moving the control lever. The Older manually shifted Carco winches got part way there by using an external band brake. As is typical of a band brake that is dead ended on one end they only work one way. With these winches you could wind 'through the brake'---i.e. wind up the winch with the brake set, but there was no graceful way to release the brake. When you released the brake, the load dropped. You could of course reset the brake and catch the dropping load if you were quick, but the sight was not pretty if you were trying to gracefully lower a heavy load. The powershift, adapted by both Carco and Hyster resolved these issues.
The Hyster W8K shown here has a Young integral arch on top of it for logging. The elevation gives you some lift to get the logs or what ever you are towing off the ground and the fairlead (the combination of rollers) lets you pull off to the side without 'burning' the cable over the side of the drum.The downside, or should I say the 'upside' is that if you pull too hard, the extra leverage from the elevation pulling location can lift the front of the dozer off the ground providing reduced traction and other unhappy consequences such as getting sun in your eyes even if the sun is directly overhead.
Even though winches don't change very fast, Allied has now replaced the W8k with a W8L winch. The 8 stands of 80,000 pounds of 'pull', and is a size typical for use on a D7 class machine. D8 and larger dozers usually get a 120,000 lb line pull winch, while smaller dozers get smaller winches. The W8L of Allied has 2 significant changes. First in keeping with the times they switched from a manual spool valve to an electric one. This means that instead of a control cable and a lever, you have an electric wire and a joystick for a control. That makes things a lot simpler. The other change is long the same lines. They put an accumulator inside the winch and moved the hydraulic pump in the winch as well making the winch totally self contained except for the control wire and joystick. The reason for the accumulator, or alternatively the reason for the engine mounted hydraulic pump, is that the PTO in a dozer is not a 'live pto' It is transmission driven so when the converter is stalled, or in a manual drive, when the master clutch is released,the PTO does not turn, which would mean that there would be times when the controls wouldn't work. The accumulator in hydraulic talk is a spring loaded pressure chamber----When the pump is working, it pumps up the chamber and compresses the spring which maintains pressure in the control circuit when the pump is not turning. This in turn implies that the hydraulic controls are the more complex closed center system as opposed to the classic open center system.
The future is already here, at least at Carco. Having made the winch completely self contained except for an electric wire running to a joystick, there isn't much more you can do for the controls, however, getting rid of the PTO mechanical connection has something going for it. As I noted above PTO's on dozers are not 'live'. Farm tractors got live PTO's more than 50 years ago, but the idea of putting a live PTO on a dozer never took. Likewise, as a winch maker you have to adapter to the various torque characteristics of the PTO's and deal with mechanical incompatibilities. Likewise newer dozers, have very robust hydraulic systems. It should be no surprise then to see that the latest and greatest winches are hydraulic drive. To integrate the winch to a machine you only need to figure out how to bolt it on the machine and route a couple hydraulic lines to the dozer hydraulic system, and an electric wire to the operator compartment. Since the hydraulic systems are almost universally 'live' in that they operate whenever the engine is running, so does the winch.
Indeed loggers figured out some years ago that hydraulic winches were the way to go. The buy them and mount them on log loaders which also have robust hydraulic systems, and they don't even need the dozer to bolt it on. A PTO winch had to be in a particular place on the back of a dozer because of the PTO and had to be of a particular size and gear ratio to match the PTO. By contract a hydraulic winch only needs to be solidly mounted to something and have a couple hydraulic lines and a control wire run to it or if you are using the hydraulics for control as well, you don't even need the control wire. this flexibility in use opens up a whole new world as to how these winches can be used.