Everyone has a theory about digging one way or another This summer I spent most of my time running a jd 450d with grausers on a pipeline job. I always dig over my drive motors. This way whenever I move I'm always going forward there are other reason too but I would like to hear everyones oppinion!
:usa I like to run with my idler in the front, i know im always going backwards but the side with the idler is somewhat longer and adds needed support. More so now im working in heavy material and need it and two is wear on the drive motor sprockets, but everyone has their ideas my last super.:Banghead would kick you off the job for running production or an attatchment over the drive motor. I just like to run that way for confort and if i got forbid there is a slope or base colapse i have the long side in front. Theres my take.:usa
I don't have any problem digging over tram motors on 50 ton and smaller hoes, With the bigger machines 100-200+ ton your working material that can do some real damage, 20-30 ton rock rolling out of a bucket will wreck any thing it hits, I've also heard of rocks being pushed in front of the teeth while digging in close and damaging motors. smaller hoes don't have that kind of power. In your situation a winch tractor could kick a good sized rock loose and possibly do some damage if it struck a motor. Ive seen some of the terrain your working up there (bs don't get it). I'm thinking of headin' up there when the weather breaks, hear there's a couple big spreads planned. Be safe, Gregg
Welcome to Heavy Equipment Forums 5seriescat! :drinkup
The Caterpillar operators manual recommends that the drive sprockets be in the rear when digging. I can visualize a few different reasons for that,one being that if you are pulling the bucket towards you all of the strain is on the sprocket and final drive gears/chain and it is a dead pull,there is no give or at least very little of the force is transferred to the idler which tends to cushion the effect of the force on the track chain. Also if you happen to be up against something solid with a track such as a stump,ledge or something that will not move I don't know how much force that the final drive housing is designed to take as you pull on whatever you happen to be digging and the drive housing is the only thing holding you back. I always made a mental note of where the drive sprockets were when traveling over uneven ground as well,especially if your tracks are loose as having the bottom of your tracks taught increases your chances of keeping the tracks on the machine whereas traveling with the sprockets forward tends to bunch up the loose track under the machine making it more likely to throw a track if there is that possibility on rough ground. As far as traveling "forward" remember that "forward" to most all tracked machines such as a bulldozer finds the drive sprockets in the rear. I have developed the discipline of always keeping the sprockets behind me and I never have to look at anything when it is time to travel the machine,I can concentrate on other things. I cannot imagine that Caterpillar would make the point if it were just to develop good habits for the operator.Ron G
over the sprockets i have always been told not to dig over the sprockets, it make sense to me because of wear on the under carrige. yhis is interesting because i thought it was standard prcedure to dig over the idlers?:beatsme
My 0.02. Hi, Folks. I tend to like the sprockets to the rear when I'm digging on the flat but I dig over the sprockets when I'm digging back up a hill simply because of that 'bunching' effect on the track chain if the sprockets were leading the way up the hill. Even on the flat, you get that 'bunching' of the track with the sprockets at the rear, which you don't get if you're digging over your sprockets. However, I tend to think that other factors more or less balance that out - on the flat. Having said that, I very seldom ever climb a hill with an excavator - or anything else on tracks - with the sprockets uphill, regardless of whether I'm digging or just travelling. Dozing downhill with a dozer or track loader is an exception. You could waste an awful lot of time turning around for each trip back up for the next push in that situation. Just my 0.02.
On the subject of digging over the drive motors, a good rule of thumb is not to do it. There are instances where you will do it, but it is best to keep the drive end away from the work. The force of digging should be on the idlers, where the track frame is made for the stress. When digging, you are pulling track tight along the bottom, not bunching it up under the sprocket. Also, as mentioned is the impact, both from falling or dragged material, but the fact that as you lift, nearly all of the machine weight is concentrated on the digging end. This stresses the drive housing unnessisarily. The prime exception to this is digging on an slope. Any time you are on a slope of any steepness, your drive end should be pointed down. This is true whether going up the slope or going down it. As far as the travel direction while digging, the wear on excavator tracks is not like the wear on dozer tracks. on a dozer, wear is increased in reverse, but on an excavator, while it will increase wear, the majority of wear on the excavator track comes while sitting and digging, with the twisting and turning side loads the tracks causing a lot of internal wear. I am sure there are exceptions, but in 20 years I have never seen a set of excavator tracks wear out the bushings, like a dozer does. Instead, they wear out the pins internally from the twisting and turning. Also, as posted above, I have known many pipeline companies that will fire you for digging over the track motors, unless they are on the downhill end of a pretty steep slope.
Bunching it up. Hi, Jerry. May I suggest that you have another think about the bunching effect. When digging with the sprockets to the rear, as you dig, you are trying to pull the excavator toward the bucket as well as pulling the bucket toward the excavator. This will pull all the slack off the top of the track, over the front idler, down underneath and bunch it just ahead of the sprocket. Now I'm NOT saying that this means you should dig with your sprockets under the bucket. Far from it. IF the tracks are correctly adjusted, there oughtn't be a LOT of slack to be pulled down like that anyway. However, this same effect is why I always dig with the sprocket downhill when working up or down a slope, simply 'cos the effect is magnified on a slope. When doing this, if you are digging downhill, you are digging over your idlers anyway. It's only when digging uphill that you are working over your sprockets. Have a happy holiday season.
i dig main line here in michigan and i aways dig with the drives in the rear. The larger comp. :usa :notworthy make you dig with drives in the rear. if you do not do this you asked to run a dozer on the oppisite side of the job. then your hoe seat is replace by the new guy. the main line guys here are very picky about there operators running there hoes.
Back when i was knee high to a grasshopper i was always told not to dig over the sprockets because they could break.I always try to dig over the idler but their is some times when you can't.When i was a kid we were on a job and their was a old Cat 215 with a broken sprocket and the old guy said that's why you don't dig over the sprockets... glen:usa
bouncing affect i can definitely say that i have experienced a bouncing effect but i cant say that i have ever associated it with weather or not i was digging over the idlers or sprockets most probably already know but when the bouncing happens i throw a little material under my tracks, or i put my bucket down and move the tracks from side to side Ive found it helps a lot. at the company i work for digging over your sprockets is frowned upon greatly, there is situations were you definitely have to. one of the quotes above was cool it mentioned not digging over sprockets with machines that are over 100k lbs
I think I weighed in on this topic somewhere else but my mind is probably still going south. I find the idea of someone, even a manufacturer telling me that I'll ruin the final drives by digging over them to be completely ludicrous. I've only seen busted gears in finals from shock loading in such applications as pioneering roads in the mountains or shovel logging and I haven't seen that in more than ten years. Any salesman or repair person that tells me that will guarantee the next machine on my claim will be someone elses. If you think you can shock load the casing enough to break it by running into something I'll have to say I've never seen it happen since the Japanese started putting excavators in this country. That started about 1984. There might be something to the claim on old Cat linear final drives and I have seen problems in the old Case backhoes but again that was years ago. As to the statement that track bushings never wear out on excavators I'll have to say I wish that were true. Those machines must run on flat ground and have a truck for any move over a few hundred feet. Yes I will agree the tracks wear the insides more than the outsides, but in this area when the idler blocks get past the ends of the track frames we cut a link out of each side, install new sprockets and run the machine until there is nothing left. The best advise I have heard comes from Deas and backs up what I have been telling owners and operators for years. Make sure the sprockets are always on the down hill side of the machine. When you walk up hill with the sprockets forward you pull the chain tight over the top of the track frame and pull the front idler against the recoil spring. When you compress the recoil, the idler is pulled back into the track frame and you get slack on the sprocket and have a big chance of jumping the teeth. Now you really shock load the gears in the final. You will also point load the sprocket teeth against the track bushings and the reverse rotate wear on both will be magnified. I do like the statement on the big machines as they are generally working a high face. I have worked on 100 ton face shovels and never seen it happen but the comment just makes good common sense.
Where abouts in PA are you looking to head for the winter? I'm curious to hear what kind of work you're hearing coming up up here. :usa As far as digging over the final drives. I truely believe it is better overal for the machine to dig over the idlers, same goes for traveling a long(er) distance, keep the finals in the rear. I would think that having the idlers in the front would allow the track adjusters to absorb some of the pressure placed on the tracks from digging, whereas the other end is a rigid connection. But what do I know:beatsme
You didn't happen to be on that pipeline job in Berwick and up in Dallas, were you ??
Learning from older operators that invented dirt,this stems back to the days of chain drive and flat pads.The reasoning was that while digging, any spoils that were generated to the head of the tracks would not interfere with the chain drive and jump the track.Nowadays, the geometry of the house in relation to the front idlers has direct bearing on lifting and digging capacities.Our foremans will watch this like a hawk when it comes time for a rate change within our union.If an operator digs over the sprockets,his rate will not change and he will go back to doing other things.I will agree that there might be instances when it is unavoidable,but as long as the tracks are properly adjusted and maintained,there should be no isssues of digging over the idlers.Another thing to consider during pipe operations,is that if you were to keep your sprokets forward,the initial surge of moving back could possibly cause a trench failure at the head of the trench into your work area.Hope everyone had a great Christmas. IUOE Local 825:usa
I'll keep this in mind, I was accepted into the local union yesterday. Sounds like the supers are pretty picky.
SHOCK of moving??????????? Hi, 385 Diggin' Doug. Quote: "Another thing to consider during pipe operations,is that if you were to keep your sprokets forward,the initial surge of moving back could possibly cause a trench failure at the head of the trench into your work area." Unquote. Please? I don't understand the difference in 'initial surge' between having the sprockets at the front and having them at the rear. I have always thought that the object of the exercise was to ease the travel control levers into the travel position to avoid 'surge' as much as possible. Grabbing them and 'reefing' them through to full travel speed/power is not only likely to produce a 'surge' for the machine but also for the operator's neck. And anyway, just how much 'surge' is there in going from a standing start to the blistering pace of a couple of miles per hour in a second or two? Please correct me if I am wrong but I was always under the impression that, just like a normal crawler tractor, an excavator's sprockets are actually slightly above the plane of the rollers and idlers anyway so that they don't transfer any load directly to the ground - unless you lift the front of the tracks off the ground one way or another. Personally, I don't care about any formen/supervisors watching me when I'm digging. If I happen to be digging on a hill, either up the hill or down it, I will be keeping my drive motors and sprockets downhill - unless instructed specifically to do other wise and then I would be inclined to ask for those instructions in writing for the CYA principle.
I guess that everything on your side{including previous posts} are always taken to the extreme.I do not recall mentioning the ""reefing"" process.To understand is to listen.In my 33 years of operating,I have noticed that the guys who dig over the sprokets go into "panic mode" when moving the travel control levers to set up for another stick.Therefore causing a quick forward / reversing motion that could cause a surge to be placed upon the face of the trench being excavated.I can probally guess that you have been running hoes for over a great period of time doing extreme pipe work and have amassed a knowledge base matched by no other.I can respect that.We work in type C most of the time and sometimes get into B.Working C will bite you every time if you are not on your game.Just like you,I have never been told that I have been doing something wrong or unproductive.I go and do my job to the best of my ability.If I or my observations do not measure up to your 'standards' ,oh well. Foremans are Foremans.When they forget where they came from it makes life hard on everyone. IUOE Local 825 :usa
Yes I was on the job in Dallas up there I was on a 270d in the big swamp that was the wettest one I was ever in. I was on 30' mats it was like beeing on mashed potatoes another operator came very close to loosing a 270c I have pics of that wow. before I even dug I could burry the stick all the way to the boom there was no bottom it was a peet bog I matted through there 3 times, then I cleaned it up with a long stick cat 322 and pulled the mats what a mess, on our boardwalk we had mats up to 8 deep and they just kept sinking,we floated the pipe in it was cool to watch. When I got done there I went to Berwick on a 450d when that was done I went to southern virginia and now I'm laid off only by choice!! In about a month I'm heading to Louisianna
Congrats on your becoming Union :drinkup :usa How did you get in?Supers are Supers.When they forget where they came from it makes life hard on everyone.Wish you the best with your Union experience. IUOE Local 825:usa
Does 542 keep you with one contractor on these pipe jobs?What's coming up in Louisianna ? IUOE Local 825
No I usually find my own work (only union) 542 has work if I want it but I really dont care for building trades or road work. Here are some pics of the Dallas Pa job please keep in mind both hoes are on 30' mats but the other hoe did not take enough mats in with him and he got it trouble as you can see another hoe brought him alot more mats and we got a sideboom with a winch to get him out.
Nice pics ! What a mess ! What did you guys bring through there ?
24" gas line
the most obvious thing that comes to my mind is...it's apparent the manufacturers want you digging with the sprockets behind you. the levers that run the tracks when you're in that position, you push your levers ahead, the machine moves ahead, pull them back, the machine backs up. and if you had your choosies, why would you want to drag that dirt, etc, up into your drive sprockets?
Digging with Big Face~Shovels would recommend The Sprockets at the back as its good to travel the machine into the material with the bucket down. This helps the fill factor when the face is small. Also I wouldn't recommend the Finals at the front on a RH120 BH as they stick out and can be knocked off very easy (Seen this happen) Ross
No kidding, I was up in that Saddle Ridge development working when you guys were putting down the mats. You know that house down by the 2 detention basins by the swamp. I did that house. I did talk to the operator putting down the mats, but he was from Virginia I think. He drove a Ford pick-up I remember. I took a ride through there one day and I did see one of the hoes sitting in the swamp. Looked like he slid off of the mats. My buddy is a union mechanic/welder and he was on that job. His name is Chris Derwin. He is a big guy, about 6'4" and drove a red Ford service truck. Another guy I know, Tommy Shaffer was up there working too.
Digging over the sprockets. Hi, 385Diggin' Doug. Re the 'reefing' terminology, you mentioned a 'surge' at commencement of travel. In my experience, if the travel controls are operated smoothly, there is no surge. However, I have noticed that a 'surge' or jerky commenement of movement often results from pulling the travel controls too quickly into the 'operate' area of their movement, either forward or reverse. Hence, 'reefing'. I have not noticed that guys who dig over the sprockets tend to go into 'panic mode' when moving the travel levers any more than those who dig over the idlers. However, if you have, so be it. The simple fact that I have not noticed it does not mean that it doesn't happen, only that I haven't noticed it. I would hesitate to say that my knowledge base is matched by NO other. There are a couple of tricks that my original instructor showed me that I have not mastered yet, probably at least partly because my hearing was never as good as his at the time he was teaching me and is worse now. And nobody has to measure up - or down - to my standards. Other's standards are their business. I simply asked about the 'surging' because I believe that, if it occurs, it is most likely to be caused by operator technique, no matter which direction the machine is travelling in and I hadn't noticed it being worse when working with the sprockets facing the digging area. Being a resident of a backward country like DownUnder, I have never heard of 'type c' and 'type b'. Most of us down here are a bit simple and so the powers that be haven't got that technical with us yet. If it's under 5 feet deep, it doesn't need batters or benches, although it may need shoring or boxing. If it's over 5 feet deep, it needs to be battered or stepped on a 1:1 ratio and, if stepped, may still need shoring or boxing. Some contractors also station a 'cockatoo' or lookout beside a trench whenever there are men working in it, especially if the ground looks a bit 'suss'. Foremen and supervisors who forget where they came from can make life hard - always assuming that they came up through the ranks. These days, we are getting a few DownUnder who DON'T have that background but rather are university 'edumacated'. Most of them are worse, sometimes a LOT worse. As for university-bred engineers???????????????????????????????? Hope this clears the air a bit.
Congratulations, CascadeScaper Hi, CascadeScaper. Congratulations on your acceptance into your local. That might open a few doors for you, huh?
Yes it does and thank you for your professional response and input! The typing of soils comes from OSHA guidlines which are based upon the soils' composition.(Competent persons in excavation 29 CFR 1926 Subpart P)Their classifications are Stable Rock,Type A,B & C. A good foreman who will tell a worker to do something have better make damn sure he can do it himself first.They don't teach that in any book or class.A lot of their ideas work on paper,and I tell them what they can do with that paper.Have a Happy & Prosperus New Year .
Best wishes backatchyer. Hi, 385Diggin' Doug. I'm pleased that the air is cleared now and the best wishes backatchyer.
Deas and Doug, thanks guys! I was accepted as an apprentice, not a bad way to start. I figure I'd rather be the best apprentice than the worst journeyman. My dad wanted me to try to get on as a journeyman, but I figure I'd rather start off as an apprentice.
Be patient and don't rush it.Good things come to those who wait.Learn as much as you can when you can.Make sure you take as many OSHA courses as you can or whatever they offer.You have time on your side.If you stick with it,you will be in good shape in your later years.
The only stupid question . . . . . . . Hi, CascadeScaper. Look to learn the small lessons as well as the big ones. If you have any questions that you can't get answers for at your local, bring 'em back here. If the answers that you get at your local don't make sense, bring 'em back here. I won't be able to help with union-related issues as I'm not familiar with your U.S. union system, but I'm sure there are a number of members here who can help. Best of luck, Buddy.
my 2 cents. i try never to dig over the drives because i have had the pleasure of replaceing them for the cost of $6,500 each. it undoubtably puts more stress on them and i whould rather keep the expensive stuff as far away from the buisness end as possible. the other reason i recomend it is if you ever need to back up in a hurry to avoid a accident or if your hole decides it wants you in it you may end up forgeting you are backwords makeing things worse. if a building starts comeing down on you while dissmantleing it backing up 5 feet may save your life. in a panic situation you will not think to hit the pedals of push the sticks opposit.
Thanks guys, I appreciate it!
:usa I think that most companies frown on operators who continiously dig over their drive motors. I think if you're not going to dig over the idlers just for the mechanical reasons, that you would do so for the comfort. The long side of the track takes away alot of the shock from digging heavy materials or with an oversized bucket, as i normally do. Keep your best foot forward .
Welcome aboard 385digging_doug. What part of the keystone state do you hail from?:usa :drinkup Would it be right to assume that you run a 385?:notworthy
I always try to work over my idlers, but can not do it all the time due to the fact of the attachments we have on our machines all the time. We have shears and grapples on our machines, and being in the scrap business we can’t always get the machine turned around in some of the tight roads we have in the yard, but if I know I got a lot of heavy lifting in in the area I’m working I make sure I get turned around before I go down the road to work. But also on the other hand sometimes it don’t always work out. A lot of times I start out over the idlers picking things up or cleaning up the burners and have to pick up working over the idler or at a 45 degree angle and then swing over the finale drive reached out all the way to drop and stack material. Other times I make a heavy lift over the idler and have to swing over the finial drive and then walk the machine closer to the truck. So it don’t always work out in my situation, but I always try to keep the idler in front of me.
Well some boss's say over the idlers others say over the drive motors, well as long as I'm in the seat it's over the drive motors. I always try to dig the same way that way when something happens You dont have to think which way your heading. Last spring I was working near a job by Kinsley construction they were moving a causway in the susquehanna river in Harrisburg I watched there hoe operator he never knew which way he was digging he would travel and go the wrong way a few times well on day sure enough he did this and flopped a new 330c in the river water in the engine they had to drag it out! One of the reasons I dig over my drive motors is we work hills alot almost all of our new hoes have grauser pads and when your on a hill you want your drive motors down hill!
yes you do, with the drive motors behind you, and idlers in front of you, when you push your levers ahead, the machine moves ahead, pull the levers back, the machine backs up. to me, that just seems a natural motion, one that the manufacturers intended for some reason or another. that is unless somebody has changed the valving on all the machines you've been running.
Ive never seen planetary failure from digging over the finals, although i dont recommend doint it because of the unneccesary weight and pressure u put on the finals. thats why your not suppose travel while carrying any additional weight other than the machine itself. and if u do its a good idea to bring the object in close then set it down and move back and repick it. plus theres always the risk of slamming a large rock or pice of concrete into the final wich could shatter it. but the main cause for planetary failure on small to meduim excavators ive seen stems from operators not practicing a technique of leveling hard humps of ground out before they track over it wich puts the dry pins in a severe bind especially on machines with wider shoes. the next thing that happens is that the rails get latteral slack in them prematuerly from all the flexation wich could easily cause the track to fall off. operators often try and compensate by adjusting the track out. the problem is that with such a long track frame u cant get the track tight enuff to take out the lateral slack and u end up putting the seal and bearing between the motor and the planetary in a hellacious bind. it starts making metal very quickly. the metal will actullay clump togethor inside the planetary and basically pack like silt forcing the cohesive gear oil out of the center of the clump until it becomes dry and a large chunk flakes off into the gears. with no room for expansion in the planetary, the gears shatter. although a a disadvantge of working off the front idlers is that if the operator consistantly uses the track as a back stop to force large rocks or concrete into the bucket it can spread the idler yokes over time and also cause the track to be misguided and fall off.
Over the years I have repaired a number of punctured hydraulic lines.
I live in Northampton County by Nazareth.I work for a Union company out of Burlington County NJ.I run our 385 when needed mostly doing deep or extreme pipe work.I also do most of our Grader work when needed.Kinda get involved in everything.Nice change of pace at times.Where are you from and who do you work for?
I meant to get to this when that question came up, but I got otherwise occupied, and then forgot. The regulations Diggin' Doug refers to are available online. Here's the link to the bit about soil classification: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10931
lol without knowing yer soil classifications then u dont know what yer benching or sloping requirements are. but dont worry OSHA will always let u know. for some of u guys who would like to know more u can buy National center for construction education and research (NCCER) modules on many different aspects or machines of the excavation industry. if u buy the below grade construction module u will know what the term ANGLE OF REPOSE means. the modules are about $15 to $20 a piece i think and pretty easy to read.
Angle of repose is the natrual fall of dirt 1 1/3 to 1:usa
We do happen to know one or two things about soils down ere.....Just our soil classification jargon is a lot different ....so us poor colonial descendents of convicts can understand them: http://www.clw.csiro.au/aclep/asc/asc.htm Geologically speaking, Australia, and in particular, Western Australia are some of the earliest formed and most exposed bit of the earth....so our dirt is pretty well worn out...as such what remains may have huge local variance of composition (its grains of Felspar, quartz, mica, iron and so on) The Australian Clasification provides a guide for determining the soil characteristics rather than labelling a type A, B etc....oil may be oil but I really have to tell you that out here sand is not sand....we have seven classifications of sand locally ranging from crap that compacts well to useless crap that your kids can't even build a sand castle with. The important thing is not to make an assumption based on a classification label but to gain an understanding of the characteristics and the very very localised variances. Over in Deas part of Down Under, and under the old classification he would quite often have 4 to 5 soil types on one small site in an area known as the Hinterlands where a 2 billion year old mountain range has decomposed and washed to the coastal plain. Recently here, a gentleman of US origin, and working as a consultant for a large Australian construction company came to help out with some Acid Suphate soils in the Perth Basin. He watched an excavator take a bucket of clay in the site and up end the bucket, shake like nothin on earth and the muck refuse to come out of the bucket.....he remarked "You've got Gumbo"
I did read somewhere, think it was a Cat publication going back a bit that when lifting or digging heavy materials always do it over the idlers that way the load is transfered from the ground to the trackpad, tracklink/rail then to the idler, the pin&bush take virtualy no vertical load plus the idler is supported on both sides. Digging over the sprockets the load goes from the link ,to the pin, to the bush,then to the sprocket, if the pins/bushes are getting thin I guess broken or cracked bushes would be the result. Just my 2cents worth.
I'm originally from Bloomsburg, but now live with my fiance' in Chester County. I work for Allen Myers, which, at the moment has me working in Richmond, VA. This is why it took me 20 days to reply to your post:cool2 How is the 385 to run? you enjoy it?:drinkup
The 385 is one awsome machine :notworthy I have given others there test and the Cat's come out on top in my book.I do enjoy running it as well as enjoy everything else we do.However,it is parked right now and I am running a grader for Tilcon.It is a good change of pace. How long have you been with AAM and what do you primarily do ?.When you work out of state like this do they give you per diem or take care of your expenses?I would be curious as to what their pay rate and benefits are like now.Back in the early 90's I took two weeks of my vacation and worked for them in Bristol @ Merck.Myself and everybody else on that job had issues with the formeman Dave Terrelle and I wound up leaving.Keep in touch.
Doug, I'm curious to know whose 385 you run. Is it that R&R you mentioned? The only R&R I know of is in Chester NJ that Trackhoe71 works for, you said that's not them. You said they are in Burlington County do you mean "RNR"?
Make sense to me.
an experienced operator once said to me if you dig over your idlers the track is tensioned on top and better to dig over motors cos tensioned underneath. if anybody can expand on that, its you lot! not my opinion by the way, just my 2 pence worth.
one more quick question. Doug I have yet to take a pic of a 385. Where is yours located I would love to get a pic.
If I can put my two cents in. 1. You dig over the idlers as less wear on the drive sprokets due to the chain sliding up and down,2. The drive reductions can weigh, depending upon size of machine from several hundred to over 1000# each. If they are behind you the machine WILL be much more stable. 3. The direction of the drive pedals is correct. Push back and the machine goes back, forward and the machine goes forward. and 4.It is MUCH safer for the operator. Unfortunely have been involved with accident investigation over the years. If a tree, log, pipe, pole, ect falls into the front of the cab and hits those travel levers, it will push them backwards. Gearbox to the rear and the machine will pull away from the object, Gearbox to the front and the machine will move forward into whatever has fallen into the front of the cab,,driving it DIRECTLY INTO THE OPERATOR'S CHEST!! Not a guess, but fact. My two cents.
very close X2 saw it done with a railway sleeper one night. Exactly how it didn't become a fatality is still quite beyond me. Saw a pic today of an exc with a 24" cast iron pipe through the cab screen. He was lucky, saw it coming and got up on the seat. BUT, was over his track motors so the machine kept tracking onto the pipe. Luckly he had the presence of mind to turn the key off.
If you watch the machine as you dig, it rocks towards the bucket as you put a load on it. Look at the final drive sprocket, it is actually elevated above the bottom rollers to keep the weight off of it. If you dig into your finals you are rocking the weight of the machine on the bearings in the final drive and you will greatly reduce the life of the bearings.
never never. dig over unles avoidable. my cat salesman also has said in the very past drives are figured into counter weight of machine
Jack Deere, the drive sproket and idler sproket are BOTH slightly elevated in most excavators, not to protect them but to GREATLY smooth out the ride during travel. Mr. Hoeman, your Cat Salesman does not know what he is talking about ( What salesman does?). Per SAE J 1097, the lift charts must be calculated for 75% of stability and or 87% hydraulic capacity in the WORST conditon, which on an excavator is over the rear, for both safety and to avoid ambulence chasing lawyers. You will note this applies to the over end specification unless specifically noted different. To do differently would be dangerous and misleading.
pipe in cab Sorry about the quality, I took a pic of the pic I was shown yesterday. The story goes that he was carrying the pipe to put it in the scrap skip. There was a length of pipe with a small piece of pipe beyond the joint. While tracking ( you all seem to say walking !) the vibration shook the small piece out of the joint which resulted in the pipe becoming unbalanced and ........ The machine is/was a 210 Volvo.
Rob Thats tragic. Its probably just as well the pic is not too clear. You can tell what happened, but we are spared the gory detail. Maybe others can learn from this horrible mistake. This just goes to show that even a "simple" task should be thought through to see all the possible outcomes before proceeding. I am generally very carefull, and this gives me one more thing to think about when carrying things, even a short distance. I nearly had a similar incident many years ago while clearing trees on a D-8K dozer. A 6" or so branch from a pile next to the one I was pushing whipped around my blade, and happened to be lined up perfectly with the back side of my decel pedal. I was creeping through at an idle in first gear, but when the branch pushed the pedal up, the tractor sped up. When it sped up, another branch was aimed square at me in the seat. I first tried to push down harder on the pedal, then realized what happened, and had the presence of mind to shift quickly to reverse. Had I panicked, it could have been ugly.
Sorry JDOFMEMI,I didn't make it clear ..... the operator got away with it :beatsme He saw it coming and managed to get himself up on the seat, and saved his legs. The point was he was over his track motors ( not illegal ) and as a result the machine tracked on to the pipe more, pushing it further into the cab. Luckly he managed to get to the key and turn it off.
JDOFMEMI Thanks for the pictures and I am glad that the operator survived. I pray that at LEAST ONE life is saved due to this post. I have some that I will not post who were not so luck! Have a good one.
I remember an old Cat training film featuring 200 series machines where it said work over the idlers. If I remember correctly (it was a long time ago) they mentioned stability as well as wear on the undercarriage. There is no load moment indicator like on a crane to shut you down on an excavator, so if you are getting close to tipping capacity it couldn't hurt to have the weight behind you. Just my .02.
I am a believer, Now. While I have always tried to work with the drive motors behind me, for various reasons, fear of damage to the motors, more counterbalance, pulling the track tight on the bottom instead the top, and a off-beat safety reason, I never put a lot of effort in it. If in the course of working if the drive motors happen to get in front of me unless I was digging in rock I did not care. Well the off-beat safety reason happened today. I was clearing trees from a pond dam. A lot of trees. They were close together, and ranged from 18" to 6", some dead, some live. I took out the dead ones first as I did not want any falling on my trackhoe. Careful not to push a tree over into another tree which could damage the top of a standing tree which could fall later. After 6 hours of work with just a few trees left, I squirreled around and started on a 18" tree. After a couple of root cuts I reached up a little and eased the tree over away from me. Then boom, the front window exploded, showering me with glass. I was looking at the jagged end of a branch that broke off and fell, it was aimed at my belly. It bounced off the trunk and came back through the window, part of it hit the drive levers and started driving the machine backwards. I did not flinch, I just put my heels of the pedals and kept going backwards till the branch fell out of the cab. I then picked it up with the thumb and tossed it on the fire and kept working. The fellow that owned the property was on the other side of the pond watching. After another hour of work I was finished. I pulled up to talk to the land owner. He asked if that sort of thing happened very often. I asked why? He replied that I did not blink, just kept on working like it was normal. It was 19 degrees and what he could not see under 3 layers of clothing was me shaking. Remember the off-beat safety reason I mentioned?. Years ago a man that I respect told me to keep the motors behind me so if any thing came through the window it would push me away and not pull me in. Tomorrow when I install the new window it will have a sticker on it for the operator to see, with one word on it. THINK The levers are coming off the pedals, too. Just in case i forget to, THINK. Needless to say I am now a true believer.
Also better to dig with sprockets at rear if something comes the front glass and hits the levers you will back out of it instead of going furher into it. The front idler system springs are there to absorb the external shock during digging also.
Well , i have finally found out why you should not dig over the drive motors . Watching the Volvo factory video on YouTube , it is explained why . As the sprockets sit directly on the pins and bushes , all the digging forces and grinding actions are applied straight to the pins and bushes which causes undue wear . When digging over the idlers , all the digging forces are spread directly to the chains via the idler flanges and track rollers . Simple really when you think about it .
Makes you think what would have happened if he had worn a seat belt?
Thanks,Iron Horse.I had not analyzed that far but that has to be the major reason for it. I read it in a Cat operators manual for a 215 and figured if it would apply to Cat excavators then it might be good for them all.Ron G
That is a very valid question. Its one I am not going to play with as I am the worlds worst when it comes to not wearing a seatbelt when operating machines. Thats despite having a friend ejected from and killed by a Cat 988 shovel many years ago. I would NEVER recommend an operator to not wear a seatbelt. What I do myself is my lookout. On edit. Thanks Iron Horse for that titbit of info.
That is one scary picture of that Volvo Rob, I bet he'd done a fair muck shift in his 'undercrackers' when that came tumbling through the window. I have never addded my thoughts to this digging over the motors debate, but my practice is to just dig over whatever is under me at the time. However if I'm laying pipes or working over the edge of something, then I like to get the machine the right way around for safety. I think all this debating digging over motors surely applies to the 20tonne plus machines on heavy applications, the average machine on a UK site is raced about everywhere with little time to worry if you are the right way around or not. I'm not saying it's best practice, but as we all know hirers are after productivity and would not take too kindly to messing about trying to be the 'right way around'. The one I get most annoyed at is the idiots who cannot reverse a Rubber Duck onto a low loader in the yard. Instead they drive them on steering axle first, and leave the operator with the problem! You should try reversing them off in the dark whilst carrying all the buckets with cables overhead.
may have alraedy been posted but w it has more to do with the finals acting as counter wieght when away from the work.
I've been looking at this thread for a while and keeping out as it seems like a discussion for operators, however I thought I'd stir the pot a little from my mechanic's point of view. I've been repairing machines for many years now and the number of collapsed excavator idlers I've replaced = lots, and the number of excavator final drives with failed hub-bearings (not counting failures due to no oil) = none, so the argument for putting less stress on the FDs doesn't really stand up. I would say that the weight of a FD and motor wouldn't be too different from the weight of an idler and recoil assembly, so the balance theory isn't too good either. Also, consider the situation that you are in bad ground and you are digging over your idlers. You then move along and you are now tracking hard in reverse. OH NO! Yell the purists. Mustn't do that!...Could this be a black mark for digging over the idlers? The only good argument I've heard is the one for moving the machine away if a branch comes into the cab. Lets all dig over the final drives and give those fragile idlers an easy life
A final drive motor asemmbly full of gears is alot heaver than a thin idler full of air. and also and maybe this is becuase Komatsu has so mutch power if you hit the idler with the bucket the recoil spring absorbs it the final has no such safty and you can actuly and it has happend snap a shaft or literly break the hub iin a final.
CMark, to say that because you've replaced more idlers than drive motors the idlers are fragile is like saying that because the drivers seat in a car always wears more than the passengers' it must be more fragile. If most digging is done over the idlers, they will take more punishment. If we all went to digging over the motors you'd never see an idler fail. Which would you rather replace? Idler bushes or motors/pins/bushes/final drives? Dragline, I've never noticed the idlers or sprockets to be raised on an excavator. What types are you talking about?
So we're suggesting that the reason final drives rarely fail is because most operators are conciencious guys who take special care not to dig over them? Hmmm? I think you'll find the reason is because final drives have big expensive ball or roller bearings in them, swimming in lots of (hopefully )regularly changed gear oil, whereas idlers have a cheap pin and bronze bush which takes all the side force when turning. As for the myth of final drive weight, I've been working on a Cat 375 today so I did a little research. Weight of the idler and recoil assembly = 982kg, final drive assembly = 953kg. Can't say if this ratio applies to all machines but is is probably a reasonable indicator. A recoil spring requires far more to compress it than hitting the track with the bucket. You need to be pretty determined to compress those things using the machine's own hydraulics. Believe me, I've tried doing it when the recoil spring through bolt has broken and I've needed to get some slack in the track. All I'm saying is that in my opinion, it doesn't really matter. Operators can do far more good for an undercarriage by digging the tracks out every day, rather than sweating over which end the idlers are at.
Best thing is to keep the bucket off the tracks altogether and keep the tracks clean but we don't work in a perfect world. Generally I dig with the blade out front and the drives out back, so I hit the blade instead of the rubber track. Also makes it easier to remember which way you are facing when moving the machine. I will dig with blade out the back if I need extra penetration power or need to level the machine on a slope. Horses for courses but they all eat oats. And yes the story about the drives/idlers being counterweights is just that a story. Next time you are near an ex walk to the back of the machine and look at it, you should find a hefty piece of steel sitting there, it's name is counterweight. If you have to rely on the weight of the idlers/drives to counter the weight of the load you are overloading the machine and should stop doing that before you tip the thing over. Not an ex but a good demo of when a machine has reached it's limit http://www.skidsteersmackdown.com/season2/ go to the power lift vid
:notworthy never a truer word spoken
In general construction ( which a lot of us work in) the machine tends to work in its full envelope, ie every where in its circle. A lot of our work can be cross carriage, so we spread the wear evenly so to speak, let the rollers have their share of the work load, why should they have an easy time of it !!
Where in Lincolnshire are you from, Johnny? I was born in Holbeach
Lincolnshire Market Rasen area, inbetween Lincoln and Grimsby, funny you say Holbeach if you go into Holbeach from the A17 and straight through I did the concrete base for the petrol station sign several years ago for a company from caistor down the road from where I live. I also go to port sutton bridge a couple of days a month to do maintenance work on the port on the river.
http://www.youtube.com/watch?v=fagurRgXnFc&feature=related The manufacturers could be wrong , but I don't think so .
Very enjoyable, if the discussion proves anything it is that everybody has their own ideas, right or wrong. Anyplace I have worked the drive chains or hyd. drive was in the back whenever possible.
Iron Horse we have battled and disagreed in the past on many items for sure, but in this one I am with you! As the video states....Only dig over the idlers, My feelings exactly!!! I WILL know which way to push my pedals in a gosh-darn-it moment, because I will always have my pedals at front to remind me as a responsable operator that they might need to get me out a quick get out now moment!!!! I have seen the guessing game, and seen it have devistating endings!
Forgot to mention that on my micro there are hoses (covered in steel braids) running to the drive motors. Would be a pain if something where to damage them as they are somewhat exposed.
OK so now we've moved the goalposts and we're saying that we shouldn't work over the final drives, not because it's hard on the finals, but because it's hard on the bushes? Right?
For my two cents worth one should always dig in the direction of travel .As previously stated here people have had close calls with items entering the cab or working on bad ground where the instinctive action will be to track back away from any hazard ie pull the levers back this would be a automatic reactive response to any impending issues and for me this should be the paramount reason for the motors to be behind you .We can repair the tin and steel of an undercarriage a lot easier than we can the flesh and blood of an operator.Any other reason secondary and like splitting hairs even irrelevant. Stock
i was always told to dig with the drivesprokets in the front the reason for this is the idlers are on a piston and the pressure from build up can damage the seals also should anything happen the operator can push the track pedals forward and track backwards out of the problems.but everyone has a different way of doing stuff
Having broken the lower window with a railway sleeper while site clearing, luckily the breaking glass was enough to frighten me so much that I let go the levers before any further trauma occured, and seeing the picture of the Volvo with a large piece of pipe through the windscreen I would ask anybody who has that thought in their head as the best way of getting out of trouble to PLEASE give it some serious thought as to if it really is the best option. I dont believe it is.................but each to his own
I must agree with Rob;having had a few incidents myself now on the very rare occasion I get seat time when I pull or step on the near side of the pedals the excavator goes back.
I have read articles over the years in magazines that say to avoid digging over the drive sprockets and when traveling travel forward ( idlers in front ) not reverse it was said that their is much more wear when sprockets are in the front when digging and travelling . I had heard it so much over my 35 years of operating I thought it was a common rule not really a personal preferance .