At the heart of the Cloud Street Winch lies a sprag type clutch which effectively disengages the hydraulic motor during rewind. This allows the hydraulic fluid in the system to deaerate and return to equilibrium during this phase. This is only one of the reasons we were able to achieve such a large reduction in the volume of oil needed in our winch. Other competitors incorporate clutches only in their ‘heavy duty’ versions. Their ‘light duty’ versions push hydraulic fluid through the system during both payout and rewind phases, leading to excess heat build up and unnecessary aeration of the fluid. This, in turn, necessitates using much more hydraulic fluid as can be seen by the large tanks being used. Furthermore, on closer inspection of the clutches being used, one finds that the rated torque for our clutches is nearly twice the capacity of our competitors. The technically inclined might ponder that if the towline exits the spool approximately 12” (1ft) from the centerline, and most paraglider manufactures recommend the highest towing tension to be in the neighborhood of 90 DaN (~220lbs), we would end up with at least 220 Ft-lbs of torque being transmitted to the clutch/shaft. Indeed this number will be larger as the outside radius of the spool initially is significantly larger due to the line stack. It becomes noteworthy then that the clutch used in our competitors winches falls significantly short in rated capacity at 150 Ft-lbs while ours far exceeds this number at 284 Ft-lbs, nearly twice the capacity! Nevertheless, some choose to install underrated clutches because it is significantly cheaper to do so. Good for budget, not good for longevity.
The hydraulic components chosen for the Cloud Street Winch are also top quality. Only custom built, Charr-lynn hydraulic motors are used. These motors are second to none. We custom order every motor from the Charr-lynn factory with the tightest tolerances available along with high pressure, high temperature viton seals. Other competitors use lesser quality as well as generic versions of the same motors because they are significantly cheaper. What is not told however is that the tolerances in these motors is significantly looser, which leads to quite a bit more heat build up in the hydraulic fluid due to internal leakage. Again, for the technically inclined, we use hydraulic fluid as the medium for transmitting and dissipating the energy being used to apply tension to the towline. Here is the break down of what happens: 1.) We put work or energy into the system by pressurizing the fluid via the turning of the spool with a given towline force 2.) We then take that pressurized fluid and reduce the pressure back to atmospheric conditions through means of a pressure reducing valve 3.) Instead of putting that energy to useful work, such as turning something else or moving something, all of the energy is relieved and effectively wasted, consequently all the wasted energy then turns directly into heat. This is where the majority of the heat in these hydraulic tow rigs is generated. The rest of the heat being generated is within the hydraulic motor and peripherals. Using a loosely built cheap hydraulic motor allows for internal leakage and more fiction which significantly increases heat build up within the fluid even before reaching the relief valve! The use of custom built hydraulic motors is yet another reason why we are able to use less hydraulic fluid in our system and still maintain reliability for the long run. Not cheap but well worth the benefits we have realized by choosing this path.
As for cooling the oil, we have developed two options. One for normal use and one for heavy duty use. Both options are more than adequate in the intended use environment. The heavy duty version incorporates a fan cooled hydraulic radiator with a thermoswitch to automatically control the fan. It is powered either through a accessory plug or trailer hitch plug at the rear. No matter which option you choose, each are incorporated into the design of the winch and are mounted on the winch itself. Our competitors have chosen to mount the cooling components loosely on the control lines and it is left up to the user to find a safe place to put the radiator in the bed, trunk or back seat I suppose…and not damage the components in the process.
The rewind drive components also contribute to the reliability of the CSW. One significant factor of the smooth payout behavior of the CSW can be attributed to the fast and very tight rewind of the towline as well as the towline itself. We use 1200 lb test Spectra on our winches where our competitors use 1000lb test. Not only does the 1200lb line last significantly longer, from experience we have found that it stacks better during rewind and feels much smoother upon payout. The high rewind tension also improves the payout behavior and can be attributed to the superb rewind system incorporated in the CSW. The clutches we use for rewind are fitted with needle bearings rather than a simple bushing to allow for further longevity. The bushings in our competitors winches are sensitive to chain tension and see significantly more wear than one with proper needle bearing support. While our competitors get away with using this cheaper version of a clutch, we just don’t feel it is worth leaving someone in the desert with a mile of line hanging over sage brush because of a clutch failure.
Furthermore, an adjustable Lovejoy chain tensioner is used on the CSW to maintain chain tension and prevent derailments from chain stretch and expansion due to heating. With these components coupled together, we are able to maintain high chain tensions without any detrimental wear to the clutch, providing a smooth and worry free rewind. Next, only industrial grade Honda motors are installed on the CSW. We have monkeyed with the Briggs and Stratton motors and determined that they are just not up to par with our principles. The Honda is hands down the best motor available and is THE most reliable engine available.
Pics of the CSW:
Some text from the $10,000 towmeup.com winch setups…..Hydraulic, but lots of this info can be applied to ours:
Operation is simplicity itself, which is what makes this winch design so reliable. A 12 1/2 gallon tank contains hydraulic fluid. This fluid flows to a hydraulic motor with a drum directly attached to the output shaft. 5500′ of 1100 # test Spectra line is wound on the drum, and the line routes through a pulley, up to the tracking head swivel, and then out to the pilot, who is attached to the line through a drogue parachute (held collapsed under line tension) a weak link, and a release system. When the pilot is ready to launch, the tow vehicle or vessel accelerates away from the pilot at a speed around 25 M.P.H. and the hydraulic fluid flows freely from the tank, through the motor and back to the tank through an oil cooler. There is no tension on the towline at this point. Once the pilot has their glider cleanly overhead, the tow technician rotates a knob on the winch control panel which causes a restriction in the fluid flow from the motor back to the tank. This in turn causes the hydraulic system pressure to rise, increasing the resistive torque on the motor and hence builds tension in the towline. As the tension rises, the pilot is gradually and smoothly pulled into the air. Once the pilot is safely airborne, the tow technician adjusts the hydraulic system pressure to a predetermined value, which will cause a constant tension on the towline. As the tow continues the pilot pulls line off the winch, while the vehicle moves forward, and consequently climbs smoothly away from the earth. Flying through a thermal or wind gradient has no effect on the tow tension because it is automatically controlled. Rather than getting big surges with every bump, or gust, the line simply spools off faster or slower, which affects the climb rate slightly, but allows nice smooth tows to altitude. Once the pilot has reached the altitude desired, the rewind motor is started up, the pilot releases, and the motor turns a hydraulic pump which rotates the drum in the opposite direction, causing the line to rewind. The parachute on the end of the line that was hooked to the pilot is no longer under tension, so it inflates causing tension on the towline to make a nice tidy rewind and preventing the line from landing in a less than opportune location. Simplicity itself, isn’t it.
This system doesn’t use a level wind because it is simply not needed. The winch drum is only 1.9″ wide and has a diameter of 28″. It can hold up to 6500 feet of line, and because it is so skinny, and the line is rewound under tension, it stacks very neatly and tightly on the drum. Once the pilot is safely off the ground the system tension is set, and essentially will remain unchanged during the flight. O/K, the technically minded will note that the torque on the system has to change as the line spools off the drum, and the effective line diameter is reduced. In theory it would require the operator to reduce system pressure as the torque increases with a decreasing line diameter. After extensive testing and simulations, we determined the final drum size for a very specific reason. It is the same reason we use a very high quality towline, manufactured specifically to our specifications. As the line length increases, the drag imposed on the line by moving through the air also increases. By sizing the components to compensate for this effect, we were able to perfectly balance the flight loads, drag, and torque loads so that once set, the system pressure never needs to be changed. Simplicity of operation and reliability were high on our list of design criteria, and you will be very happy with the results.
Pics of the towmeup.com setup:
A note from Stu, from towmeup.com:
One of my customers sent me a note asking if I could post a quick reply. I have a bit of a clue on hydraulic winches, in fact we just shipped our 168th one out last week. I definately prefer a hydraulic winch over a friction style payout system, but now that we have an Integrex on the shop floor, we’re looking at building the ball screw level wind / fairlead assembly. If I can solve that issue, we’ll likely put a smaller friction style system on the market. that said, it will never match the eprformance and ease of use of a hydraulic system.
As for your questions:
The greatest concern you should have must always be that you never want to have an uncontrolled increase in line tension.
Avoiding tangles is absolutely key to this. If you use a wide, narrow drum you absolutely must have some type of level wind. This is probably the hardest part on this style winch. You can do it cheaply, with a manually operated fairlead that you shove back and forth during the rewind, or use some type of level wind. I’ve seen all sorts of Rube Goldberg ways to do this. The only one I really like is a Flennor Ball reverser, and it’s worth more than most winches. Cheaping out on this area if you plan to run the tow autonomously will give you grief someday. A skinny drum works very well if you have enough power to rewind the line under high tension (this rules out any of the little electric starter motor systems) and you use a skinny drum. Our drums are 2″ across the inside of the flanges and the lowest point of the drum to the first guide pulley distance is 40″. 48″ would be ideal. Much less than 40″ and the line will ound up during the rewind, and fall over. this, or to low a line tension on rewind will cause havok on the next tow. As the line pays out under tension this fluffy section will be pulled down deeply into the core causing a line dig. Often the jam will break the line or the pilots weaklink. the wrost part is the friction caused by stufing the line through severl layers will melt the line in several areas and you might end up with 8 or more line breaks caused by the same event. In case you get a poor rewind, you should alwasy dump the line and wind it back on properly before the next tow. If you got the line dig and keep breaking the line, grab your scrap spectra and dump the line. As you rewind it, when you see a sketchy section just pull some of your spare line right up through the core of the sketchy area to double the strength. It will save a lot of hassles later on. If you’re lucky enough to have 2 winches in a boat like we do, it’s super simple. If not, you’d better avoid the issue in the first place.
Incidentally the drum core and diameter can easilly be sized so the torque generated balances out the tow and air loads and you never need to touch the line tension during the tow.
One thing to consider is the compounding effect of the line as it wraps over itself. the forces generated are intense. On our system the outward force is well over 17,800 pounds trying to pop the drum sides off. On poorly built systems you’ll see the sides blow off the drums, or the core of the drum witll just collapse. You clearly don’t want this to happen during a tow.
We use a Danfoss gerotor motor becasue it functions equally well as a pump (in the payout mode) or a motor in the rewind mode. Specifically a DS-80 with a 1″ keyed shaft. I like the solidity of a taperlock hub and a keyway to lock our drum directly to the output shaft of this motor.
On the rewind motor anything that gives the required flow rate and system pressure is good. Fluid flow = line speed, more flow, faster speed. Pressure = torque, more pressure = more line tension. A 2 stage pump gives you an easy way to get both with a lower HP rewind motor. A single stage pump is best since you can actually stationary tow with the winch just as well as you can payout tow, although the power required to drive this is fairly high. The formula to compute the power required to drive a single stage pump that’s reasonably efficient is is HP = GPM X PSI X .000583 That’s assuming an efficient pump. You might figure in 15% more for loss in efficiency. With a 2 stage pump you can get away with say 6.5HP running an 11 GPM pump. This gives around 11 GPM at low pressure and 2.5 GPM @ 3000 PSI.
In theory you need 1 gallon of fluid for evey GPM the pump can put out at 3000 PSI. That means you SHOULD have around 25 gallons of fluid. We’ve done extensive testing to see what the PRACTICAL minimums are and like to use around 12.5 gallons, with the provision that the fluid level in the tank is at or above the level of the winch motor and the suction side of the rewind pump so neither pump has to suck fluid up to it to prime. You DEFINATELY DON’T want to suck air into your Payout motor. Incidentally this is an area many builders get wrong. In their quest to shave weight, they reduce the fluid volume. What they really do is generate a very hot running system that will quickly lose the ability to generate or maintain system pressure reliably. Ever see the guys pouring water on their motors to try to cool them down? The problem with a payout winch is that all the normal hydraulics engineers are used to the standard high pressures normally found in a hydraulic system. You really don’t move a lot of fluid, and what you do is so highly pressurized it moves easily through small orifices. When we launch a pilot in Payout mode though, we are moving huge volumes of fluid at very low pressures. We suck fluid out of the tank, pullit up through the winch motor which works like a pump to pressurize the fluid. The fluid is then returned over a meter out circuit across a valve, back over an oil cooler and into the tank to flow back up through the pump, etc. the oil going back to the tank is always full of tiny bubbles. You need to size the hoses on the low pressure side especially to help reduce this faoming as much as practical. As the tow progresses the oil in the tank gets full of bubbles from the top, down. You need enough fluid so you are ALWAYS pulling fresh non-bubbly oil back into the suction lien to the pump. If you don’t have enough fluid, eventually you start to suck in tiny bubbles. this is a suction line, so the bubbles expand and then compress as they go back through the pump. You’ll hear the whine as cavitation sets in, and the rotors of your pump are being slowly eroded away, causing fluid leakage and making the motor very hot. If you can’t touch the pump you don’t have near enough fluid. It’s really that simple. Cutting the fluid volume is the WORST way to try to save weight.
I like to be able to go to 3000 PSI since the components are all readilly available. Anything more gets dangerous if you don’t know what you are doing, and going less means you need a bigger motor.
Fittings are sized to handle the flow requirements. This is where you need to be really careful. Our system uses several check valves to force fluid to go to specific places. All of these check valves on the low pressure side are not what a normal hydraulics engineer would choose. An engineer will look at your system and figure 16GPM is the maximum flow, and stuff in some check valves rated for that flow. In reality though, you’ll find that even 100 GPM 1 PSI cracking pressure check valves can’t handle the volume we need in the payout, which would be 16 GPM at 20 PSI as we start the tow. Interestingly a 200 PSI WOG swing check in 1 1/4″ size will work just fine. If you ever see more than 50 PSI on the return side, you’ve already got a big proiblem, so 200 PSI is more than adaquate. orientation of the valve is VERY important though. Gravity needs to work to help swing them closed.
If you go to www.TowMeUp.com you can download a winch operating manual. It will show you exactly how all the components of a hydraulic winch work, why you want to use them, and if your competent, it has all the information to build your own system.
You’ll likely find though as many otehrs have that it’s just as cheap to buy a finished, tested, completed system from us, as it is to buy all the materials and then have to make all the parts yourself. I’m kind of fortunate that we have a host of CNC tools available to us that I can use to make winch parts when the machines would otherwise sit idle. Most of the parts are now made on a Mazak Integrex that automatically loads raw stock into the machine and spits finished parts out the front door through a robot or parts catcher. The other components are made in house on a CNC plasma cutting table, a CNC vertical mill, and often welded up automatically with a welding robot. I’m really just the hand assembly guy that puts them together. the good part is that somebody has to go test them though
The Quantum Winch seems to be well liked and cheap:
Pay-Out Winch Features