It seems i read a thread a while back regarding operating tricks for excavators. If i remember correctly, the statement came up that it was wise to "jump turn" the excavator whenever possible (i may have read that completely backwards). Am i correct in saying the jump turn involves bucket down on the ground to assist the turntable spin movement in making a turn, in lieu of just spinning the tracks? I feel like a complete moron for asking the question, but could the jump turn cause additional stresses on the turntable (and reduce turntable life) versus the other option? What's the consensus?
I always use the bucket and swing to help turn the tracks, our machines have the 36" track and they just don't turn very good if the ground is soft. I just use the bucket to help out on the turning.
Is this the one you're talking about? Becoming a Hydraulic Excavator Operator: Tips
If I'm making slight turning adjustments in tight quarters and jockeying around a little, I won't jump turn. However, if I want to make a 90 degree turn, I ALWAYS jump turn. It's faster, easier on the undercarriage, and you look like a badass doing it, seems like a lot of guys don't jump turn. Style points!:drinkup There is a bit of a learning curve to be able to do it quickly and smoothly. A guy could learn how to jump turn quickly, but if you slam the machine back to the ground or take 10 seconds to complete the turn, you've accomplished nothing. It's all about practice, just like anything else. I can do 45 degree jump turns smoothly in about 3 seconds with the tracks headed in the direction I want to go by the time they hit the ground.
I always do it, easier on undercarriage.:bash
Compare the stress of picking the undercarriage partway off the ground with that of digging a bucketful out at full reach. Which do you suppose stresses the turntable more?
I usually do it to keep from tearing up the ground so much. I have never been able to quantify whether or not it is hard on the swing bearing or undercarriage. I have never seen where it broke anything or caused anything to break. Basically it looks to me like it is a personal preference. I do know that it impresses customers when done right and makes an operator look pretty ham fisted when done wrong in front of someone who knows what it should look like.
I jump-turn quite often. It can be harmful to the machine if not done correctly. I've seen guys pick the machine 3ft in the air and move which is hard on the stick and boom. I just pick it up a few inches and then turn. When doing this manuever, make sure that your bucket is placed so that your stick is at least vertical or slightly outward. If the stick is crowded in, the cylinder on the boom is extended and when the tracks are picked up in the air, the rod could be bent.
O.K. I'll be the first to agree that its not a good idea to "jump Turn" every time you turn the machine, here's why; Yes it puts undue stress on the T.T. bearing. Extra stress on the swing drive gearing as well. Don't forget turning the machine with ALL its weight on the final drives, when the finals would only have a fraction of the machines weight on them during a normal turn (or the idlers for that matter) Also, correct me if I'm wrong, most 2 pump machines use 1 pump for each track UNLESS an implement is activated, in which case the straight travel valve redirects 1 pump's flow to the track valves and one's to the implement valve line-up, so really your'e only getting half the flow to the track motors when jumping. I agree there are situations when jumping is an awesome tool to straddle a ditch or something and should be used in those situations. I also see alot of guys here doing it with a hammer on, point straight down, no way thats good on the hammer. Just my opinion, would be interested to hear what the Cat rep thought on this..............Derek.
we have a 690e with 7k hrs on it, has had a packwheel on it for the last 4k hrs. no play in the bearing yet, and it's on the rear sprockets 9-12 hrs a day
Depends on the machine and the conditions I'm in some machines won't turn without some help.
I was always told anything bigger than a 350 you always jump turn anything sharp. Now if you can make a long sweeping turn then go for it. The larger excavators ive run it was alomost impossible to turn them without having some help from the bucket. You dont want to rip the track off an 1100 and have to get off and explain why you were to lazy to take the time to use the bucket. My 2 cents:usa
It would only be on hard ground like concrete i wouldnt bother jumping. Most of the time I jump, all things considered its easier on the machine. You wouldn't have any choice if the ground is real soft, you gotta jump. Might be kinda obvious but dont dig the teeth in when doing it or you will really torque the dipper, place the bottom of the bucket on the ground with the dipper vertical and raise yourself up a few inchs.
another thing I like to do is use the swing of the house to help turn the tracks (with the bucket in the air). Its done by swinging the house the opposite direction you are tryng to turn the tracks, so basically the tracks are rotating underneath the house. This eases up strain on the track motors because its not trying to twist the entire weight of the machine, just twisting against the friction on the ground. This only really works well when on something flat and hard, or when cresting over a small ridge in a perpendicular fashion. And looks just as badass as a jump turn!!
it also help to pull the crowd in towards you as you swing the house during a jump turn.
I just love jump turns, NOT. Had an operator on my 320 (7454 hrs) not long ago:Banghead he liked to do JUMP TURNS, I now have the swing assembly out of that 320 replacing the pinion gear, the $1,100 gear should be here next week!!!!! I always use the swing to help turn, but never lift the tracks off the ground, if you have to lift the tracks you need to do something different if at all possible. It will save your boss (or you) a very large repair bill (1100.00 + downtime + labor to install = ) I know that sometimes it has to be done, but most times just using the swing will get the job done and is a lot easier on the machine. Badass=$$$$$$$$$$$$$$$ :IMO (from experience)
Lots of times we have to climb onto RR tracks then turn and straddle them. Jump turn is the only way to do it. Most of the time we have to stand them up pretty high to get it done. If we don't do it this way,we stand a pretty good chance at rolling the rail over, if you do that, it SEVERLY upsets the trackmen that have to reset,and respike that piece of rail. However,I can see both sides of this discussion having valid points.:IMO
We work in soft ground all winter and the "jump turn" is much quicker and seemingly easier on the final drives. I always try to dig with my sprockets to the rear, so I find myself having to jump turn a 360 which can be accomplished with almost one move if done right(which takes some seat time). ZAXIS
The Blade Runner has oversized drive motors for dozing and I still jump turn. Just enough down presure that the bucket stays put. Less ground damage and seams to be easier on the machine.
The swing gears are the weakest part of a machine. For those of you that "level" with the edge of the bucket IMHO that is hard on the machine I think the same with jump turns. Don't get me wrong, there is a time a place for everything. But as a rule I don't do it. Final drives are designed to "track" the machine. I understand some of the older machines have weak drive motors, but most of the newer machines have no trouble turning with the tracks alone. As with any rule there are exceptions, the RR track example, the deep mud. I also have a complaint about leveling aspect. If excvators were designed to level with the bucket side to side, manufacturers would have but cutting edges on the edges of the buckets. From my experience we had to separate the house from the undercarriage on a 1500 Insley to replace the rotac. NOT Fun let alone costly.
it'd be my guess, there was more damage to that pinion from somebody "batting" dirt back into an excavation vs. jump turning,...our 200 hitachi had 9300 hrs on it when we got rid of it, no problems, our 690 deere is right at 8k hrs right now, no problems....and both of them spent the last 5k hrs of their career with a pack wheel on them, for the most part front idlers off the ground sitting on the rear sprockets. on a jump turn, if there isn't any sudden jolt, it hasn't been my experience that it creates probs with the swing pinion or gearbox
We work in the woods a lot with our machines. I jump turn when I have to. When tracking through a lot rock and stumps I think its easier on the UC. Most of the time were running mowers on our machines so moving rocks and big stumps is out of the question.
I think if jump turns were necessary dozers would have booms and buckets
thats completely apples and oranges.... on a dozer, the tracks provide the working means. on an excavator, the tracks are just to move it from one spot to another... they have nothing to do with any real earthmoving.
Jump turns have their place in certain conditions and look good when done by an experienced operator. I can't envisage any problems provided it's done smoothly........C ya........Ray