just looking for feedback on what different factors cause duck walking and if anybody knows any good techniques to deal with it?
Duck walking ??? Could you explain what the scraper is doing. Loaded or empty or both.
pull up and restart your cut. you can also keep your apron low to minimize the depth of the duck walk. gl
Not sure, but im gonna guess that he's meaning the hop/bounce that they do at speed, like on the haul road. If thats the case then it's caused by the fact that the tires are six feet tall and have 30k plus pounds of weight on them...not a whole lot you can do about it. Maybe take it to the local tire shop and have them try to balance them
Baby wipes work wonders to prevent duck walking, the cheap TP in jobsite Honey Buckets is problematic at best.
Best thing is to stop it right away, slow down if it's in the fill and raise up if in the cut. When the rear tires hit the first mound they cause it again and again like perpetual motion. It's frustrating, the only way to take it out is split your mark( straddle the bumps ) Some materials are worse than others, we used to run railroad iron drags in front of the rear tires to knock down the initial bump before the tires hit it.
Some scraper bowls have an automatic cushion ride system that works through the hydraulic accumulators to stabilize the machine. That or a cushion hitch may help prevent the duck-walk.
You can't use a cushion hitch in the cut or fill which is generally when the phenomenon presents itself.
I think all the sand is making it worse cuz i usually dont have a prob with it. Does using the diff lock while cutting help? Also i think if i turn the cab about half a pass over, then back it seems to stop it. I'm just asking to see if that makes any sense, or is it just in my head?
i like to use diff lock almost every load, but no, it doesnt affect the duck walk. dont load fast and shallow. if youre taking a thin cut, stay off the rear engine until you start to bog or lose traction (timing). if you start to duck walk soon after you begin to cut, pull out, wait till rear wheels pass, then restart cutting. and like mentioned above, dont keep your apron much higher than you need it. welcome to dirt world
I spent forty years in heavy and highway industry and never heard of duck walking. In the midwest of USA we always called it hop or bounce. Dpete and Shanes advice is spot on. Nige; you should see some of the idiots that I have seen in the cut and on the fill with the cushion hitch up. It is enough to bring tears to your eyes. There are ways to cure them of doing it, if you know what I mean Changing tire pressure can sometimes make a difference in the severity of the duck-walk.
One could always get unruly scraper operators back into line when you were triple-pushing 657s with 3 x D9G's. A few hard hits up the rear worked wonders..... I recall way back when cushion hitches were first introduced. To the old-school scraper operators it was a sign of the world going soft.
Even though this probably won't add much to the thread I'll still put in my $0.02. I've spent right around 5000 hrs on a Challenger with a JD 1810E pan cleaning drainage ditches in farm fields and know what duck walking is. I've found it caused by two things, one being more common. Hard packed sticky topsoil is the worst I feel. Ground that wants to come up in big slabs and leave holes for the tires to bounce through. Second could be more so referred to a washboarding but for the most part completely preventable is speed. Like ScraperX said slow, shallow, tight apron controls depth of cut to help prevent the slabbing. I know this might be controversial but if you're trying to cut final grade having a partial load in bowl helps. I do a lot of jobs start to finish with the scraper and when you're working by the hour if the last loads are not full loads it doesn't matter.
Yair . . . The first 627 I ran was a brand new stiff hitch. When the fleet of cushion hitches arrived no one wanted "old stiffy" but I didn't mind . . . no way could I run with the cushion hitches though with giving myself and the machine a beating. I poked along and did my own thing mostly self loading, the fellers were good and set the cut up with good rills for me to grab. If I was in the right place at the right time I got a bunt up the ass or could maybe grab a hook occasionally. I might have done a few less loads a day but the old girl paid her way. Cheers.
A few more ideas that have been pondered for discussion: 1) Go into the cut at a much slower pace. Load the bowl about 1/4 - 1/3 full, once this weight is on the back tires, then ramp up the speed to lock in a large load. 2) Investigate welding "Skid Shoes" onto your scraper. This would enable you to hit the cut at your desired higher speeds, and help stabilize the bowl, and wheels from duck walking.
i have learned that like mentioned, start digging with only your front motor until you get some dirt in there then floor em both, when dumping you have to be fast opening your lip and crowding out your dirt right away, matching your rpms to your ground speed, keep her rapped up. i use my tranny lock almost every time, locked in 2nd using front motor only. if ur moving too fast the initial blob that falls out when you open your lip, your back tires will go over it then there will be a gap before your back tires climb onto the dirt your crowding out. dump as deep as your biggest rock, one side hits a rock wile your dumping that starts a duckwalk , try to dump downhill, most important always split your tracks, if a duckwalk starts stop it asap, dont spread the disease! what scraper do you run?
I can't answer for the original poster, but in the other thread he said he was running a 623 self loader. Don't know if he runs another one too.
right now I am operating a 623. I run 627 and 637 as well, so i know what ur saying. My duck walking issue is happening when the dirt to dry or too wet. normally I like to cut in second but if I cut in first it's not so bad. dragging haul roads is the worst, is way too slow for that and still duck walks. And when the Phil starts to get bad if I even try to drag it smooth it just duck walks bad. I know I probably sound like a rookie but I'm really not, I'm just used to jobs where the right amount of water is importantand I never have a problem with duck walking
Yes know all about it and yes there is a solution they are call skid pads everyone of our scrapers have one of 2 designs on them! the one is a solid skid pad that is a foot or 2 behind the blade at the outside edge of the stinger bit that has shims that are adjustable! they get adjusted if the operator is not to lazy according to blade wear and or dirt type! The other is a hydraulic skid pad with a 6 inch cylinder on it with valves and tanks on them to control flow and extension! Jerry
Id like to know more about the skid pads. Tried searching but no results on scrapers came up. U got any pics of them, or a link i can check out?
I would have to look might have some of the hydraulic but we haven't found a way to put them on Deere pans there isn't enough room! Not sure I have any of the bolt on! Deere made some at one time but don't know if they still do but don't see that they would work very well!! I will see if I have any pics
These are our own design so don't think you find anything on web
Yair . . . I have been following this thread with interest. My memory must be shot because I can never remember this phenomenon ever being an issue. Are we are talking what I know as "woo boys" or maybe "washboards" or "corrugations" . . . a series of cyclic undulations similar to what can occur with a dozer grading heavy clay? I honestly can't ever remember that being uncontrollable in the cut and in the fill I think it was mainly a function of speed when spreading nice material such as gravel. To get an even spread we used to put the arm around both levers and force it out beneath the lip. I would be really interested to see a picture of those skid pads still learn'n the phenomenon is obviously caused by material of which I have no knowledge. Cheers.
Here is the only pictures I could find on my computer! These are the hydraulic ones and how they work is at the back of the floor of this finish scraper is the pivot of the skid pad and then it sticks behind the floor about 24" and the cylinder on the rod side is just plumbed into the main tube on the scraper for exhaust we don't need it for what we are doing the top one has a one way adjustable flow control valve and then is plumbed into a tank that can hold compressed air! Ok so how it works it the tank is half full or so of hyd oil and then compressed air on top so that when the scraper is lifted up the air pushes the hyd oil into the cylinder and extends it out, when the scraper is let down the flow control valve only lets so much oil back into the tank but is adjustable to be slower or faster depending on soil conditions or operators liking! So when the scraper wants to gouge in the pad will let it dig in but at a controlled rate not all at once. For example my understanding would be on duck walking if the scraper is going to fast tire pressure overcome the the bit pull down just a bit on whatever will give just a bit be it tire squat or whatever and then it pops it back out and does this at a fairly fast rate of speed side to side hence the term duck walking or wash boards! so then when the tires start squatting in this case the skid pad is more solid and only lets it dig at a more controlled rate and don't let it gouge! Not sure if you can understand that or not!
We use pull pans and so that's what ours were designed for! Havnt ever run a self propelled so don't know if it would work on them or not but don't know why not!
i ran alot of b,c,d and e models and never had an issue with duck walking till the series 2 e. i dont know how they are balanced different or what but they naturally swing or rock side to side just driving in the lower gears, the g models are the worst, dont know about the elevating scrapers, given the added height i imagine could be worse. if your cutting edges are even and your back tires are even, dont give up hope, try to feel your back tires when your dumping, somehow they are getting uneven starting the duckwalk, if your in the same tracks of another scraper your doomed already. take a load lock the trany in second rap it way up dump your load about a foot deep, if you crowd your dirt out in one continuous motion it wont duckwalk.
From your description, it seems they are designed to work with the pull pans that lower the rear end in order to cut. I do not see this working on self propelled rigs since the rear is fixed, and they raise and lower at the front. It does sound innovative on your type of pull pans though.
I've seen skid pads work successfully on pull pans that have a fixed rear as well. I have never encountered them being used on a self propelled scraper, but I think it would be worth the effort in trying! Think of the productivity gained without duck-walking into the cut, and hitting it at a high speed...
With Pull scrapers, duck walking typically happens in light cuts at higher speeds. Its the side to side rocking motion of the blade in the cut. This is often confused with power hop, with creates more of a washboard cut in similar conditions (usually light grade work). Slowing down a bit should cure it, but if speed is key, check your routers for wear. If they are new, add metal or drop to the lower position (on Deere scrapers). Tire pressures on both the tractor and pan can affect this too so make sure they are set at the manufacturers recommended pressures. Last, if all else fails, mounting fixed skid plates under the frog should fix it - no need to get fancy.
My opinion on what starts duckwalking: when dumping is when one of the rear tires raises on the dumped material before the other and if the speed of the machine is constant, it puts the machine in a perpetual state of "wave" because of the weight of the machine that doesnt go away until both rear wheels are traveling on the same level at the same time for enough distance to get balanced. when cutting, the opposite is true: it's when one side of the cutting edge hits the cut before the other or when the material you are cutting is softer or harder on one edge of the cut. If I start duckwalking when I start dumping, I slow way down and lower the can so I'm half dumping, half grading. Of course you have to be very careful with the crowd so you're not putting too much pressure on the apron. If you're running by yourself (or without a motor grader cleaning up) and not worried about what's behind you for the other guys and i start duckwalking sometimes I'll just slow down a little and ride it out and let it duckwalk until I'm empty, then when I return to the fill with the next load I'll split the last one in half, keep the apron closed and lower the can and start grading at a slow speed (like 1st or 2nd gear and taking out the high spots) with the can until it's grading smooth then open the apron and crowd the material out really, really slow. On a side note, 9 times out of 10, I run with the cushion hitch ON in the fill. If I have to take out duckwalk tracks, I turn it OFF. I know it's supposed to be OFF in both the cut and the fill but that's how I roll. If the machine starts to duckwalk almost immediately after you start cutting, slowing down and laying off the rear engine until it's cutting smooth again almost always helps. If it's near the end of the load before it's starts doing that, I'll just finish the load and split that cut in half the next time. So does lifting up and traveling forward until the rear wheels are past it and trying again. Just try a few different things until you find what works best for you. stripping and placing topsoil is the worst because generally it loads and dumps in clumps so no matter what you do, you'll fight this phenomenon all day.
Shanek, #2 is covered by the router bits. Many times a scraper will duck walk easier when the router bits are worn out or new inserts have been welde in too high or at the incorrect angle. This makes it easier to penetrate the ground.
Duck walking with pull pans happen when your spreading material that's inconsistent or when out of material, then soon as your wheels hit a rock or a hole it cause the bit to lift up or dig in. We add metal floats that chain on ahead of the rear wheels and that helps with selfp propelled or pull pans. Our finish scraper has skids. Also keeping a lot of dirt in front of the bit helps.
I've spent over 6000 hrs running a pull pan. If you're having trouble with bounce, you need to go back to scraper school.