Quick question for you seasoned dozer hands. I spent last week at the training grounds doing safety and orientation week. I spent one day on dozers and we were instructed to decelerate completely before changing directions, then throttling back up once the change of direction has been made. We were on Deere 650H's, a D6RXL with diff steer, and a D8R with diff steer. I always throttled down as instructed, just curious if you can change directions without doing so and not cause any harm to the machine.
I don't see why you would need to. But don't take my word.
The only thing I do realize is that the machine will jolt in the direction you're changing to, just not sure if it's hard on anything mechanically. I noticed when running the 8 and the 6, I'd throttle down while pulling the machine into neutral, coast it a little, then roll into the change while throttling up. Seemed pretty efficient with the diff steer, I guess my biggest question is with the hystat style. It's almost human nature to slow down engine RPMs before changing direction, but if you're doing high production work I can see where it could cost you some time to bring her all the way down, change direction, then throttle back up. I would like to put this out there that I'm not asking this question on a laziness standpoint of having to throttle down, just seeing how others run. Maybe there is a preference to decelerating before switching directions when you compare between hystat dozers, diff steer, and traditional clutch/brake style.
The jolt could be hard on parts of the machine I guess. By the way, you don't live far from me.
Keepin it real in Lynnwood. You wanna see some interesting operating, head down 99 just north of 180th, they're digging out some contaminated soils or something right alongside 99. I watched them a bit yesterday, 2 Kobelco 200's hogging out a bunch of dirt in some real gumbo. I saw today one of the guys got enough gonads to head down to the bottom of the cut and wade around in the mud a little, it's real soup. Check it out if you're close, big 'ol hole.
They are always doing something to 99, it is a piece of junk. They need to demo it. Haven't been to seattle in a month though. I do go into renton now and then and get to see the custom cranes down there for light rail, the new renton project is nice also, Cat 320 on every corner and about 5 tower cranes in a block.
Shifting ? On the Powershift transmissions, if you shift(Change direction) under full or 1/2 throttle,without decelerating, you will accelerate the wear on the 1st gear Forward and 1st gear Reverse clutch pack. Don't know about the later Hystats , but it's got to be similar to street racing . Sitting at the light , racing the engine , dumping the clutch, or holding the brake on automatics, to beat the other guy, just to the next light.
I don't think a "Hystat" (HydroStatic?) would need to throttle down. Cascade Scraper, it is almost 1AM go to bed.
Using the decelerator. Hi, CascadeScaper, There is only one reason for not using the decelerator - you HATE either yourself or the person who is paying the repairs bills for that machine - or both. The decelerator is there for a reason, 'ackshully' two reasons. The first is to reduce the shock loads of speed and especially direction changes. Even with a torque converter in the drive train of a powershift transmission, there is still a shock load factor because almost all powershift transmissions have a torque divider in them which splits the power from the engine and sends approximately 30-40% direct to the transmission and the other 60-70% through the torque converter. It is this 30-40% of engine power delivered direct to the transmission that gives powershift transmissions their 'snap', the almost instant response, BUT it is also this same feature that can cause mostly long term problems if the decelerator is not used pretty religiously. The one exception that I can think of at the moment is if you happen to be travelling uphill and you want to change direction. Then I sometimes flick the trans control lever into neutral, pause a second or two and then select the other direction. The pause is to allow the machine to start travelling in the other direction by itself before re-engaging the transmission, thereby reducing the shock. The second reason for the existence of the decelerator is to make the machine more controllable, by giving the operator the ability to control engine revs, ground speed and power output to suit the prevailing conditions. So, if you own a powershift machine and you like repair bills and downtime, or if you want to make happy shareholders in the manufacturing company, (LOL) don't bother using the decelerator for making your transmission changes. Hope this helps.
Thanks guys. Kinda what I figured, but thought I'd ask. Like I said, I would have to train myself to not use the declerator when changing direction, it's second nature for me to throttle down, but I was curious if things were done fifferently and/or more effectively otherwise. I don't run dozer very often, hopefully that'll change in the future. The 8 hours I spent on various dozers at the grounds was the longest consecutive hours I've ever spent on a dozer, just never have the need to run one. However, I did get pretty good at feeling with the machine when I need to reduce engine RPM to keep from spinning the track under load. We were doing slot dozing excercies, naturally with a full blade on the 650H's headed up the ramp to the pile at the end of the pass, you could get a little more on the blade than those machines can handle. Took me a little bit, but I could just about feel before the tracks would cut loose so I'd drop the revs a little, lose a little bit of the load, and keep on chuggin without spinning the tracks.
I have always stabbed the deaccelerator with any direction/shift change.I see many that don't,the majority probably and I have heard that it is not neccessary but it is contrary to any reasoning I can muster on the subject. I grew up and learned on the older mechanical driven equipment but even if I had not I try to run equipment with respect as if I owned it and that is one consideration that any machine deserves. The John Deere dozers seemed to have been designed with abuse in mind as they take forever to change directions as they gradually engage the power train after having changed from one to the other.In fact a full throttle reversal does not seem to change the time needed to acomplish the change in direction whether you use the deaccelerator or not but JD seemed to take all that into consideration when they designed their transmissions. It has been my observation that the other brands which shift faster are not so gentle and benefit more from slowing the engine when shifting. If any operator spends much time on the older equipment with worn front idler shims and loose tracks that the sprockets have to wind up the slack before the machine moves and then it jerks your neck each time you change directions you tend to rethink your environment after a while with your own comfort in mind and one of the possibilities that comes to the forefront is maybe if that sprocket was not turning so fast when it finally engages the track chain it might not whip my neck so much when it finally does start moving again.Even worn out bottom rollers will create some slack in the track chain to say nothing of contributing to a bumpy ride and after hours in the saddle these things can wear on you.Ron G
hystats. Hi, [-Agent-]. All the hydrostatic drive machines that I have ever had anything to do with seemed to be designed to run on constant full revs and the operator is supposed to use the infinite variability of the transmission to control any shock loading. There also seems to be a delay system built into most of them to cater for changes of direction. Having said that, on most of them, it is possible to give both you and the machine quite a shock by travelling at high speed and suddenly slamming the trans control straight through to neutral. On most hystats, this applies the automatic brake instantly which usually causes either a severe dent in the windscreen or trauma level whiplash, depending on which direction you were travelling in at the time. Hope this helps.
Nice thing about diff steer, no brake in neutral. When I was running the 8, coming back off my pile, which was probably 7-8 feet tall at it's peak, you gotta shift quick otherwise you'll start rolling backwards pretty darn quick. I didn't touch the brakes either, that'd whiplash worse than anything I've ever felt. I never used the brakes until the end of the day pulling all the equipment out to the road. I was in the 8 and the road was sloped slightly. I thought I'd try to roll the machine into place as it was a short distance instead of lugging it down in first gear. Big mistake, barely touched the brake pedal going about half the speed of first gear and it threw me forward pretty good. I just looked down at my instructor, shook my head, he was laughing at me, everyone had a good laugh at my expense. Ron, I hear you with the JD's, I think that's what I'm feeling. It just seems slow to get going, I figure that's why I'm asking if there is a faster way. But, if it's the same whether you decelerate or not, the answer is incredibly obvious.
My machines decelarate and stop on direction changes, I give one warning if I see it a second time they're off the machine. Had to put a bevel gear and pinion in a D8K for ram assing direction changes
Sense Of Humor??????????????? Hi, DPete. Did your sense of humor disappear into the black hole in your check book? LOL. Yeah, I know it's not funny having to put a bevel gear and pinion into any dozer, never mind when it's as big as a D8, and even less so when it need not have been necessary. From what I can gather, the D10 and D11 R series had a bit of a weakness in the transmission that would result in a broken shaft if there was persistant shifting without coming to a complete stop and engine at idle before shifting. I've heard a few reports of them being sidelined with this problem. Stick to your policy, Mate. I'd have a very similar one myself.
The D4 Hystat I run, all the travel functions are electric, so you only need the decel just to make a nice smooth transition, but I still use it if I am pushing down hill and I don't want my head to go through the front window when going into reverse. The D3 3 speed I ran previously, the torque converter took alot of the shock out of it, but my Dad always warned me not to shift unless it was almost idling.
personaly i decel when changing directions, just seems to me thats the best way, but i run a machine that others run also, i know that they dont decel when changing directions. when it was new the trany shifted smooth, now there is a long pause, and its just not the same, hard to explain. i dont know if im right but i think its from not deceling, ide like to see some more responses on this too. deas the machine im talking about is a 11r just like you said, i think it gets shifted alot without decelled or stopped, im anxious to see how long the trany holds up.
As a rule, you should decelerate any piece of machinery before changing directions, whether it heavy equipment, a truck, car or even hand tool. You put undo stress on numerous parts which will eventually lead to premature failure. In this case, in addition to the transmissions that already have been mentioned, you have splines on the input shaft, splines to the drive sprockets, the drive sprockets themselves and the track components that will all be exposed to unnecessary shocks. Repeated over an over, this practice will accelerate wear and require parts to be replaced earlier than if they had been treated more gently. As computers become more and more prevalent in machines, I wouldn't be surprised if they don't install a program in the machines that automatically decelerates them during shifts, or at least cushions the direction change. My F-350 has a built in delay in the transmission when shifting from forward to reverse.
Well Our D8R has 13,800 hrs of no decel shifts. No transmission or final drive work. No odd oil samples. I was always told they have modulator valves to absorb the shock. Cat has had these since the 60s. Our old D6D has had no failures from no decel and our D5 96j had a transmission out a 16,000 hours for seals. My grandfather never deceled or 41B Fiatallis either. But it ate final drives, although this was common to all of them. Its most efficient to run the Machine WFO. Every decel drops efficiency and production. Just personal observation. Not disareeing, just stating personal opinion.
you know...........never mind...I am not even going to respond to the question...if you have even a little mechanical knowledge you know the answer.
On the bigger JD dozer they don't have a true decelerator they have a hand throttle. They do have a "decelerator", but its more or less a brake. None of the other operator or I ever idled down for direction changes, but I was sure to not do it very quickly on purpose just in case.
My Dad's old D-3B had the decel on the gear selector, you had to twist it, that was very odd, one day the cable snapped, talk about panicking.
I'm with you. Ben, I was reading the whole thread thinking I was on my own till I got to your post. I don't use the decelerator a 100% of the time, only when I need to. A lot of times I will just touch the break as I pass through neutral, it stops the snatching and you don't loose your power. For me, it all depends on what I am doing and what the conditions and material are like. I don't like the delay that you get when you decel fully. I have been running dozers pretty much full time for over 35 years and in all that time I can only think of one transmission that went on me, it was on a rented D4H and I had only been on it for 2 or 3 months, so I don't think I take all the blame for that. With a lot of the D3 and D4B models you did not have a decel pedal to use but they had powershift transmissions and I never had a transmission give up on one of them either. The 941, 951, 955 and 977 had powershift tranmissions and I personaly never saw one with a decel pedal. I suppose it could and probably will be said that the tracks on those models are slicker and their is less resistance there. Just my opinion, for what it is worth
Ya, by the time the got the trans out of course it needed PM hell it was $29K by the time they got done with me. Of course they had to pull the steering clutches to get the cross shaft out, naturally they needed some discs and springs la de da de da. took the mechanic a frikkin day to pre load the cross shaft bearings. naturally the trans pump was worn had to have that @ $1800. End of rant
Always decel, and as far as production and efficiency the diffenence in a day from decel and WOT might be only one single push. According to some of the post about not deceling is I have a ? for you. When you run a loader do you just keep mashing the "accel" pedal at all times and then just switch dir. or do let off the gas and then make your dir. change. DPete, If I catch someone not deceling they get no warning. They are told not to do it when hired. Not deceling and riding the brake are my two biggest pet peaves.
Ill respond to that like this.... Do you take a transmission out of a 980 and put it in a D8? No totally different animals. I let off when doing directional changes in loaders yes. But were comparing apples to oranges here. T the modulation and sequencing valve work differently in these two types of machines.
So tell me what you do with a wheel dozer then?
Not only is it much easier on the machine, but it's also a whole lot more comfortable for the operator. Being "smooth" on a dozer will make the day so much more pleasant. I actually use the decelerator when I'm pushing. With fuel prices so high, I only use the power I need at the given time... If I need a little more power, I'll let up on the decelerator. My D6D doesn't burn fuel like the big machines, but it will burn through $300 per day pretty easily.
Apples to oranges. Hi, Ben46A and LDK. Before I start, I'll tell you that I am very definitely with the great majority of people in this thread in that I believe decelerating is the way to go. Having said that, I do not necessarily subscribe to the idea that it has to be a full-blown 'back to idle' with all dozer models and I often only give the pedal a quick kick down and back up again as I make the change. I have however seen enough evidence to make me think that there is a lot of value in coming right back to idle and fully stopped with the D10 and D11 'R' series machines. Now to the Cat track loaders, which are the only ones with which I have much experience, and the decelator-less smaller dozers. I think that comparing these machines to the larger powershift dozers is also like comparing apples to oranges. As I understand it, any Cat machine that does not have a decelator pedal has a different split ratio of power through the torque converter and that which is sent direct to the transmission. I can remember seeing figures some years ago showing the difference between dozers and track loaders. Dozers were shown as being 65% to the torque converter and 35% direct to the transmission while loaders had a 70%-30% split. The loaders had the higher ratio to the torque converter to reduce the shock loads because they didn't have a decelerator pedal. I think that this arrangement also applies to the smaller powershift dozers that don't have a decelerator pedal but I am not sure. I do know that the first powershift D4D's did not have a decelerator pedal but they were at least an option on powershift D4E's. Having said this, I will also tell you that I pretty much always cut the hand throttle back on a powershift Cat track loader - 941, 951, 955, 977, 983 - both when approaching a truck and when changing direction. Maybe the machine doesn't need it but I sure do appreciate it at the end of a long day. Hope this helps.
I think I'm as smooth as the next guy, maybe even as smooth as silk on direction changes and I barely touch the decel pedal. As far as using the decel pedal when dozing, I only ever do that if I'm in rock or edging round something. It irritates the **** out of me to listen to an operator playing with the decelerator all day. Likewise I never cut the revs down on the hand throttle and would not want anyone working for me that did, I figure that the machine is made by the manufacturer to run at full throttle. Wouldn't pay for us all to be the same I suppose?
HI Deas, I will freely admit thet you are obviously more mechanicly minded than I am and when I see a post from you I allways read it because I merit your opinion but I honestly have not left a trail of destruction in my wake over the years. I have and do tend to use the decelerator more on the 9, 10 and 11 but it is more a touch than a press. The strange thing for me is I actually hate being on a dozer that doesn't have that damned pedal. Russell
We got hystat Liebherrs for many years. They are made to work on full throttle, but they are also designed so that the operator desides how bad his/her day is gone be.. You just move your lever slowly down to neutral, speed goes slowly down close to zero, and just pass neutral quickly and it starts to move the other way. They also got a delay in the system that responded when u where brutal. But the ride would be very bad. Going from full speed forward to full reverse is not something u do more than once! The pressure relief system was only designed not to kill your finals, u would still be very close to the windscreen... Regarding decel, i always say to my students to decel and stop completely before shifting. If you want to survive in that machine for years, u got to have habits not destroying your body. In our Komatsu's(65/85) i let it travel down on low trottle, before shifting to neutral, let it ride to stop, then the other way, then throttle up. When the clutches connects, then its metal to metal, ride can be a hell if u slams it in the other direction. Engine and transmission got so much power and mass is not so big, so the change in direction can be rather brutal. (of course downhill/uphill change demands another prosedure..) But i can also see that a D9/10/11 will operate in another manner. I bet the converter is constructed in another way than the smaller ones. That big mass moving and a change in direction; somethings going to give way. And i bet the converter or gearbox is doing that, before building up max force in the other direction. I don't know if those got a lock-up converter, but my experience with those is that they opens when u change gear/direction and loocks up again when the converter wheels got nearly the same speed.(often 90% and more) And that can take some time and produse some heat.... If there is a system like that in the big ones, shifting at full speed would be no problem. U would produse heat peaks when changing direction, but that may not be a problem.(Bet there is some oil in those beasts) Bet we got to have some inputs/advice from a CAT mechanics that know how the trans is constructed and made to be operated here...
I've always been told to decel down, usually at the same time you go into neutral. Then into the other direction. I usually decel down when going from 1st to 3rd, just a lil to ease the change. Makes things go smoother, same when downshifting, I will decel shift to the lower gear and get out of the pedel, therefore you downshift and dont' really change speeds cause you have already lowered your speed with the decel. Out of the two dozers I've grown up on and around neither have had any transmission troubles, one has approx. 25,000 hours and the other about 22,000(Dresser TD-15C's). using the hill or pile and gravity to aid in changing directions always works good too. Trbo
when the company i work for got the 11r the trainer or field rep or whatever he was said decel on direction changes, didnt give any reasons just said decel. it only takes one full throttle direction change and you know the best way to do it, decel.
I agree to some extent on the direct drives, powershifts, and torque converter machines. We have a 650GTC and have been on other dozers like this and its natural to decal to half to three quarter throttle and then back into gear. But on the hystat machines like the 650J's like someone said they have parameters built in the comput. Even on the 544J/K and 672D/G's you can go full speed in 4th or whatever gear and go the opposite direction and the machine does the rest. The transmission is constantly changing to the conditions to prevent possible damage. That is one of the selling points Deere pushes when costumers are visiting there proving grounds.
Lets see some hard facts on this topic. I will look and see what I find maybe some others can do the same. I just cant imagine manufacturers not suggesting you use the decel on direction changes. It certainly doesnt slow production down so I wont even entertain that thought, it is just plain ridiculous to suggest that. I feel the same way about operators that change directions in b-hoes and front end loaders with out coming to a complete stop. Use the brake, it is there for a reason. LAZY LAZY LAZY
There are a couple different issues being discussed here that I can see, decelerating during upshifting and decelerating during reversing, completely separate issues. The original question related to reversing, and I'll stand by my original post in saying to decelerate when reversing, even though some machines may be manufactured to shift under power. If this unknown, then it would be safer and cause less damage to decelerate, but ideally the operator should follow the manufacturer's recommendations for the particular machine he's operating.
Beats me why anyone would want to decelerate when changing to a higher gear, I could see doing it if you were changing down and the dozer is not under load? That pedal is getting more attention from me today than it does when I'm in the seat, I hope it don't rain again today so I can get out there tomorrow and forget about it again!!
Clear the issue. Hi, Folks. I'm with Steve on clarifying this issue. If you look at the original question, there is no place for discussion of hydrostatic drives in this discussion because they work in a totally different way. There is also no room for discussion of track loaders and small dozers without decelerator pedals simply because they don't have decelerator pedals. So back to the question : "decelerator question -------------------------------------------------------------------------------- Quick question for you seasoned dozer hands. I spent last week at the training grounds doing safety and orientation week. I spent one day on dozers and we were instructed to decelerate completely before changing directions, then throttling back up once the change of direction has been made. We were on Deere 650H's, a D6RXL with diff steer, and a D8R with diff steer. I always throttled down as instructed, just curious if you can change directions without doing so and not cause any harm to the machine." That is the question. A quote from some illiterate, ignorant twit who posted on page 1 - "The decelerator is there for a reason, 'ackshully' two reasons. The first is to reduce the shock loads of speed and especially direction changes. Even with a torque converter in the drive train of a powershift transmission, there is still a shock load factor because almost all powershift transmissions have a torque divider in them which splits the power from the engine and sends approximately 30-40% direct to the transmission and the other 60-70% through the torque converter. It is this 30-40% of engine power delivered direct to the transmission that gives powershift transmissions their 'snap', the almost instant response, BUT it is also this same feature that can cause mostly long term problems if the decelerator is not used pretty religiously." Now let's proceed from here. LDK, there is no telling when any prospective trans problems may show up, or even if they will occur at all. Like you, I had never had a powershift transmission fail on me - until late last year when a Cat D5B that I was operating started losing power through the second gear clutch. Now I'm still not sure 'cos the boss sold the dozer rather than repair it but I suspect that it was a valving or seal problem rather than a clutch pack problem. I threw the symptoms at an experienced Cat fitter and he agreed but also said that there was no way of knowing for sure without pressure testing and oil analysis, hence I'm still in the dark. But I still will continue to use the decelerator on direction shifts or downshifts, at least partly because I like the way my neck currently holds my head up high and straight.
You know Deas, back in the old days of the Direct Drive tractors this was a question that would of never occured. I miss those old machines, got to drive a old 93j D5 yesterday, sure brought back memories.
Decel When the Allis Chalmbers HD41 & 41B that was one of there selling points you did not have to decelerate the were made to shift from foward to reverse under full power! When you shifted there is a small pump on the end of the pinion that supplied oil to what they called a shift inhibit valve when you made a direction change with the lever as long as the pinion was turning so fast it would not shift it worked quite well. But you would soon find out that it shifted faster if you deceled that not (ie don't push out to the end of a high wall and throw it into reverse or you would most likley need clean pants) They did have some problems with the system mainly dirt when we would install a rebulit transmission after it we had ran it a bit and warmed up the oil one of the ways we would test the system to see if would shift properly was to rev up the machine in gear with both steering clutches released the drive shaft would spin and it would not shift for a min or so free wheeling like that we would do that several times and if it did not hang up in gear we knew it would work ok and it was alright to put the rest of the covering back on the machine and let the customer have it to use
I know getting off the beating path ! But you never know first poster might just have to run an old stick shift some day and will need more information. I started out on my first dozer it was a D6C 76a or 74a for stick shift i think ?to long ago.Usually ran the main trans in 2 or 3.Then shift the shuttle back and forth from forward to reverse. Making sure to hit the clutch release lever at just the right time,whith the other hand, to get the clutch to release,shift shuttle in which direction you wanted to go.With the "throttle left wide open". Pull clutch lever and away you went ,at the same time grabbing the dozer blade control and hitting the ground with a smooth quick load of dirt in front of the blade. Only thing ? To do this you needed the clutch brake to be working!!!!!!!! If it wasn't in good shape your would have to throttle down the dozer then usually grind it a little to get it to go in.Sometimes you might even have to shut it off to get it to go in if the brake was really out of adjustment,or wore out. Adjustment was the key and not riding the brake when shifting it. Then again if you was really an operator you could get everything just right lag it down hit the clutch and pop the shuttle and away you went. Anyway some of use on here i'm sure knows the procedure:drinkup:usa
Constructo, You hit the nail on the head, I know all about the clutch brake. We still have two of the old DD, we have a 47a and a 17a D7. These machines are geared alot slower but really if a person knows how to shift one of these machines as you have described the production is not that much slower than the powershift (slip-o-matics).
A page from a Cat brochure from the late '60's, explaining that in the interest of "extremely fast cycle times" that "rapid speed and directional changes can be made at full load with no need to decelerate, brake, or pause in neutral. And this is for a 983, no less. I remember reading similar things in Cat dozer literature over the years, about full power directional changes and modulating valves and such, but I always figured it must apply to machines that were in much better condition than what I was running. Every time I tried it with a powershift machine, Cat or otherwise, I was rewarded with a neck snapping jolt and audible protest from the machine. I personally decelerate everything to change direction, new or old, regardless of what the manufacturer claims. I have a 983, and while BSing one night over a few beers with a couple of older and wiser operators the subject came up as to the enormous quantity of fuel the machine burned during the course of a day's work. One of them asked me if I deceled to change direction, and when I said yes he replied "Well that's your problem right there, see that black cloud every time you snap the throttle open? That's where your fuel's goin'! Them machines was meant to run at rated rpm, not waste time and fuel revvin' up and slowin' down!" I told him I would try it next time I ran the machine, but my resolve only lasted one cycle- I couldn't stand the crashin' and bangin'. Decided I'd rather burn the fuel rather than tear the machine apart.
Made it a bit bigger, too hard to read that tiny print. I do realize that the 983 is a track loader and not a dozer, but to me the principle is the same.
Yes as said before hydros are designed to run WOT with no decel on direction change. For example the Case K series are all designed with electronically controlled hydros. Therefore when the shift is made the machine will gradually slow down and make the shift on its own, no need to decel. Think of a skid steer, do you decel when you change direction??? No, you ram the levers the other way and keep going, skid steers run on hydros as well, that is the beuty of them, less operator input.
Powershift Transmission Failure ? Hello Deas Plant, Operator Error, ever hear that ? No matter if you run a machine all season or just one shift, if something breaks thats the old song. Personally I know of several Powershift transmission failures,over the years. A D8-46A, D8K-77V ,D10N. Also a Cat 16G grader . Now why did they ? Symtoms were transmision slippage. I complained, they pulled transmission filters, and found metal particles. The D8K I had run all season. We were in real rugged hilly terrain, pipeline work. Steep grades, pulling equipment up hills and letting equipment downhills and, ripping in pits. Now in the pits some guys used the transmission as a brake when changing direction. Never coming to a complete stop with the foot brake. But that was a slow roll, not a high speed roll, like coasting down a steep grade in neutral ,at quiting time , in a hurry to park. Anyway, the feedback from the mechanic was 1st gear clutch pack wore, not destroyed , but worn heavy. I always used the decel to slow down. If ripping downhill, touch the brake and reverse. Just a slight roll. But other Cats were in worse condition, so we were told to stop completely, to change direction. Not use the transmission as a brake when changing direction. Even a slight roll. That was company policy. The other Cat transmision failures, The D8-46A and the D10N, the tranny started slipping, just like an auto or pickup. The D8 was hauled off to the shop, after they pulled the tranny filter and seen heavy metal contamination. Never seen or heard about that later. The D10N, tranny filter was pulled , heavy metal contamination. The problem was called in, was told to still run it. 5 days later complete failure. Took 3 week to rebuild. Another outfit that summer ,had a D10N tranny problem, and stopped,parked it, and called for a replacement exchange unit, and were up and running in 3 days. The Cat 16G 3rd Forward gear was slipping badly, and 5 th reverse. various operators were told to run it, they all tried and laughed, couldn't do any real work, finally the dense equipment super had to haul it off. He thought it was another problem or the Operators fault. Anyway, back to my original post. 1st gear clutch pack problem was direct feedback from the mechanic and shop foreman. So to answer the original ? of does any harm come to the machine ? I say yes. So after reading the other responses, just wonder what the job circumstances are. Flat level ground or steep hillside work.
The 983 I cited as an example is a powershift, same as a D8H or K, not a hydrostatic
Passionate about Pedals... Wow, with the amount of excitement stirred up over a simple pedal, I'd hate for anyone to ask a question involving a lever... We'd all be stuck in here until our fingertips were bleeding! www.petersfamilytrucking.com
Dozers and track loaders. Hi, DieselDave. If you take a wander back to post #29 in this thread, I have posted some information on the differences between the track loader powershift trans and the dozer version. As I understand it, the loader and dozer transmissions had some differences, the chief one being the proportions of the power split to torque converter and direct to the transmission. The loaders were made for a 'softer' shift uinder full power. However, like you, I prefer to throttle back before making a direction shift with a powershift track loader, 'cos I value my neck and back at least as much as the health and longevity of the machine. The original publicity blurb for Cat powershift transmissions claimed that you could shift any which way under full load, full power and full speed. And you could. But, as I remember, it didn't take long for that claim to disappear from their advertising. Maybe I'm just 'natcherly' cynical and/or suspicious but I can't help thinking that there might have been a reason why that claim was dropped. Can anybody help me here? Am I being overly suspicious or cynical? LOL. Northart, say Sir, it seems to me I have heard that cry somewhere before. "GARD-DAMM ARP-RAYTERRRS" And why would you spend $500 or a grand fixing it NOW when you can spend 10 to 20 times that much later and complain louder about the useless 'sunnza' whodunnit? LOL. D6peg and Construct-O, you didn't even need the clutch brake working at all - IF you came to a complete stop before moving the shuttle lever/Johnson bar to the opposite direction - just so long as you didn't roll at all before you had completed the shift. Like you, I didn't think there was all that much difference in shifting times if you got it right with the direct drive BUT there sure was a noticeable difference in the amount of effort required. Where the clutch brake really came into its own was engaging a gear from neutral after you had disengaged the master clutch. I did hear once or twice that toothpaste in the gearbox helped here - polished the teeth as they bashed against each other while you were trying to get the gears stopped to select one. LOL. And D6peg, the first dozers that I ran didn't have the luxury of a shuttle lever/Johnson bar. Cat 20 and 22 and a 2T D4. THEN, I graduated to a 3T D7 with cable angle blade. petersfamilytru, wanna start a thread on the park brake lever on a 46A D8? LOL.
Song Hello Deas, So you heard that song to. LOL . I always told'em, well if they were never used, then they would never break down. Bring worn out equipment on the job, and then expect it to last the job. How about, when the clutch brake is worn out, "grind me up a pound" was the saying.
"You ram the levers the otherway and keep going" Well maybe you do but I know I slowly let off and change direction. Even when I turn aggresively on a skid steer I let off the lever smoothly. I have a 550H and I will tell you you if you change direction by just ramming the lever back it jolts the he#* out of the machine. I did it once and I will NEVER do it again. I saw a guy in a 650 h simply ram the lever back after pushing forward and deciding to back up and he found him self against the dash board. It is a simple physics. Equipment being ran in a smooth manner is one of the many signs of a good operator.
I belive you are commenting on my post, of deceling while going from 1st to 3rd? It takes longer to write it out then it ever does to actually do it. When I said on my post about deceling to up shift its not a full decel or even half a decel. Maybe I'm wrong. But when I do it its more of a motion, just a lil down so when you do shift it doesn't jump up to speed as quick, I never slow it down, just don't let it speed up as fast as its able to. Do this alot when team pushing trees or grading a long drive way etc. get moving and then shift up, just using the pedel to ease the speed up(say instead of going from 3 mph to 6 right now, I go 3, to 4 to 5 to 6, quick but not BAM and there). I guess its kinda hard to explain. I am sure if you saw me doing it you would see there is really not much difference, just slowing the rate of exceleration. Trbo
Hi Deas, I do remember you mentioning the difference between machines with decel pedals and those without. The 983 has a torque converter and no power divider, I suppose that it makes for a softer transition but it's still mighty sudden at WOT I just posted that brochure because it was the only example I could find offhand of a manufacturer recommending full power directional changes. I also remember them making similar claims for the dozers, just couldn't find an example to post. I remember the same as you- those claims didn't last long
I learned quickly to use the decelerator on any powershift transmission, particularly my 8230 Terex. That pedal was added for several reasons, the least of which is to keep you from walking in circles for 2 hours after you get out of the machine (think about having your right foot stuck to the floor for 10 hrs a day while pushing!). As Deas said the full power shifts advertising F to R went away quickly from the CAT literature. I think they figured out that to shift under power through the speed ranges, both up and down was good, however not so good from F to R or R to F, (they probably experienced the same pain in the head and neck area that the operators did when using WOT during direction changes:Banghead), this is particularly true of the Allison in the Terex’s, not using the decel on that machine will quickly cost you about $20K in transmission repairs, not to mention the cussing and aggravation of having to remove the Transmission from that miserable (insert any color/brand of machine here), If that damn (insert any color/brand of machine here) had hooves and teeth it would bite and kick worse than a horse!:deadhorse. I love horses, not!!!
On Beating Machines To Death - And Yourself Too. Hi, Folks. It seems to me that some of you are remembering that machines can 'bite' back when you operate them roughly. I heard a LOT of talk when I was a li'l tacker about how rough dozers were on the operators and how they ruined your back and how they were 'man-killers'. It didn't stop me wanting to get into operating dozers more than anything I could think of. I started on stick shift machines and graduated to powershift machines and not once did I ever try to beat a machine up with the transmission controls or any other part of the machine. I figured out very early that if a machine broke it could be fixed with spare parts or some 'electric glue'. Fixing broken humans is a little more complicated. Today, I have a very good relationship with my back and neck and all my innards are in their original places. Comes from treating both the machine and myself with all due respect.
Deas, I'm in top form too, still putting in a steady 75 to 80 hours a week.
I'm with you on this Deas. The first "big" dozer I drove was a 17A-D7. No decelerator in sight, just a hand throttle, set then forget. I also remember the Cat information brochures when powershifts were first introduced, with modulating valves to take care of high speed direction and range changes. For some obscure reason I used to use the decelerator for changes and continued with that since my first powershift in 1968. Around that time I drove a TD20 series B that used to decelerate atumatically between changes. Some here may remember these as they had a lovely growl from the turbo each forward to reverse change. Over the years, I also drove dozers with automatic braking between direction changes. From memory, one was a komatsu 355. The most responsive dozer I ever drove was a Fiat Allis HD-41B. Bulk power for its size from a 1710 cummins, but alas the rest of it was very weak........C ya.........Ray
Decelerator pedal. Having spent 40 odd yrs on dozers I have allways used the D pedal specially when making direction changes, makes for a much smoother shift. Some makes seem to have a softer shift than others Cat & Komatsu probably being the smoothest Ive come across. The torquedivider is used in the D6 thru D11 only all the rest being TQ only, Komatsu are TQ only with a lockup clutch in larger models to give better fuel economy. Allis Chalmers used a modulating clutch ahead of the TQ which disengaged all power to the tranny when passing thru neutral when making direction changes on the 16,21,31&41 . IH on the TD 15B,20B,25B &TD30 used a system operated from the trans clutch pressure to decelerate the engine revs when passing thru neutral. I do remember the HOWL that a 20B used to make as I did 2yrs on one back in the late 60s. Case would have to be the worst for abrupt shifts as there is nothing soft about their trannys plus 10 hrs holding your foot on an accelerator pedal on a Case and you know what an aching leg feels like.
Looks like a good discussion here. Deas, I agree that you will be treated as you treat your tractor. Decel is definatly in order, though not clear down to idle. More important than the decel though is that you have stopped moving in one direction BEFORE you drop the shifter in the opposite gear. Compare this: Full throttle shift when dozer is stationary results in smooth engagement of trans, due to modulation. Shifting reverse while still moving forward(or vice-versa) results in neck snapping jolt at anything much over an idle. This varies some from one machine to another, but the general idea is the same. I think this is probably the explanation for LDK and others being able to run with no decel, they stop betwen directions. I will usually go to neutral, then as machine comes to a stop, engage the lever the other direction, and I am USUALLY at about 1/2 to 3/4 revs when engaging, but feel no shock as I have come to a stop first. With that said, its hard to be perfect all the time, and on occasion, gears get engaged before motion has stopped, and that is rewarded by a resounding snap of the neck. Someone mentioned loaders above, and I will touch on that as well. I have had Cat trainers say that it is best to run loaders, especially large(980 and up) at full throttle, and use the neutraliser pedal to STOP and engage the other direction. If stopped completely, this is a very smooth shift, not even inducing spillage from the fullest of buckets. It only results in a jolt if pedal is released BEFORE you have stopped moving. The engine is much happier for this treatment, as it doesn't overfuel to get back up to speed while lugging. Boom up cycle is much improved, as power is still applied, and there is a lot less fuel washing down cylinder walls, contaminating the oil. I have watched many 988 loader operators who decel to shift directions, but do not brake to a stop with the neutraliser before engaging the other gear, and they think they are being "easy" when they are really jerking the machine harder with this shift at near idle than I do at wide open throttle. These thoughts apply mainly in production work. In a light duty use, I only use as much throttle as needed to get the work done. The shifting is the same though.
Decelerating?? Never had a Cat wrench or book tell me to decel from forward to reverse and reverse to forward. It's a full powershift and valves allow it. Up shifting under load is really a no no to decel. Done it for um-teen rears and never paid for a trans by this kind of shifting. Just my experience through the years. Talking about 6's, 7's, and 9's that I use too own.
Decelerating was never an issue with a D6B but that was a long time ago. The first automatic dozers that we had were D6C dozers and Cat strongly suggested we use the decelerators when shifting. After repairing drive components on a few of them, using the decel when shifting became mandatory for our operators. When I retired, we still used the decelerator on all our dozers when shifting from forward to reverse and vice versa, from the D5 to the 11's, no exceptions. We didn't require the engine to be completely throttled down but using it was a must. We kept it pretty simple (KISS) - No decelerator, no job. Besides, when you get used to using it, it becomes automatic. I can't imagine many Cat mechanics telling anyone that shifting from forward to reverse at full throttle causes no undue stress or wear on drive components, old or new dozers. From my experience, a few pennys of prevention is worth megabucks in repairs!
Welcome to Heavy Equipment Forums Dirtman52! :drinkup
I guess i tend to agree with the majority here. It seems to me that the D-pedal was put in the machine for a reason. Would you shift your pick up from fwd to rev at full throttle? Niether would I. We have few operators that shift without using the D-pedal, they look like rags in a dryer in there. If it was my equipment, I would send walking. The only excuse I can see for not using it is pure lasiness
False assumptions tor Whatever reason you want to pin on me for not always using the decelerator, please don't assume I'm lazy. I am the wrong side of 52 and have been running dozer's for a living since leaving school at 15 years of age and to date have never been called lazy by anyone that knows or works with me. I am known by some for getting the job done as fast as I can and having no tolerance for slackers, which category do come under?
Going nuts... I've been operating a cat since I was a kid and the last few days have been torture. Everytime I step on the decellerator, I think of all these comments. I've never before wondered if I was doing the right thing, the wrong thing, or the worst thing... I just stepped on the damn peddle! I need a twelve step program to de-program myself of all this information!
The first step is acceptance or so I've heard. I always thought it was time for a beer. Eleven more beers after the first and you have it, a twelve step program. hic George
I'm halfway through the 12 steps right now!
I didn't meen to offend anyone, but that is what I was always told was the main reason for not using the D-pedal. I can remember my Grandfather, running a old 977 with lever steer , He would shuffle his feet between the 2 pedals to get to it.When I started running it, I got lots of butt chewings for not getting my feet in there quick enough. Lazy was thrown at more than once. It didn't take me long to learn to get them on the pedal.Same went for our old A/C HD 19with the hand clutch and hand throttle.Its there for a reason so use it,Heard that speech alot, nnot only to me, but to anyone else that dared run his babies!
On Lazy Or Not Clued in. Hi, Knucklehead98. I once had the dubious privilege of running lever-steer 955's, both H and K series (That 955K was English-built AND powershift with lever-steer. ODD!) and an old 977H lever-steer. Quote: "I didn't meen to offend anyone, but that is what I was always told was the main reason for not using the D-pedal. I can remember my Grandfather, running a old 977 with lever steer , He would shuffle his feet between the 2 pedals to get to it." Unquote. To get to what? Yes, there were TWO pedals, both steering brake pedals, on those lever-steer machines. There was no decelerator pedal, only a hand throttle, unless somebody had gone to an awful lot of trouble to put in a decelerator, and where would they put it 'cos you already had a steering brake pedal under each foot? The pedal-steer machines did have a third pedal but it was 'brake-only' and activated both brakes without dis-engaging the steering clutches. I almost always cut the revs on the hand throttle with Cat powershift track loaders before changing direction but that is just me and my neck is in pretty good shape. So were all those transmissions when I left them. Quote: "Same went for our old A/C HD 19with the hand clutch and hand throttle." Unquote. All I can say is that if your grandfather insisted on cutting the revs with the hand throttle on a stick-shift machine with a hand clutch before making a direction change, he would be about the only person I have ever heard of who did it. I always thought that was why those machines had a hand clutch, to make it easier to engage it smoothly and it was 'over-center' so that it would engage AND dis-engage more postively. Or have I spent 43 years not being clued in? Am I allowed to be a little suspicious of your knowledge base?
Our 977H had D-pedals on either side of the center consol, it was a trick to try and squeeze your foot between the brake pedals and the console to get to the pedal. As for the 19, it actually has a D-pedal, but all the parts aren't there,so we use the hand throttle. Everyone that I have seen run this machine uses it the same way. As my dad always said, you have to have arms like a monkey to run that darn thing! Pretty much the same for the old '77
http://www.machinerytrader.com/list...6257201&GUID=36FA018551FC432E826D35A2EF11AB5A Found a picture of the D-pedals on a 977-H They are between the console and the brake pedals
Ha Ha! ointlaugh
As far as the John Deere H series and J series dozers, you would not have to use the decel pedal. When you shift from one direction to the other the Transmission controller would ramp down the current to the PCP controls of the transmission pumps until the machine stopped and then increase the current until the pumps were in full swash in the other direction. With the multifunction valves in the circuit it would not cause any damage to the machine. The only reason you would want to decel is if you were bored and needed to exercise your foot. The later J series has a switch on the front console that allows you to decel the transmission only without lowering the engine speed. This will keep your hydrualic speed to you blade the same as you slow down the tractor at the end of a cut.
Thank you for asking this question. When I first read it I was sure of the answer and expected a short sharp swift response. ( Its there use it ) It just goes to show what a broad cross section of responsible, sometimes vocal experienced members there are on this forum and I thank you all for your valuable, experienced responses. It has been educational, informative and at times amusing. For anybody who hasn't read the whole thread, I hope you find the time its worth it. From an operator who started on a little Track Marshall, 6 months seat time on a powershift D6 (76? vintage) 18months on an 8K and couple of months on a high drive 6H. :notworthy:notworthy:notworthy
D-pedals on a 977H Hi, Knucklehead98. Thank you for posting that link. My edumakayshun has just been enlarged. The only 977H I ever ran didn't have that feature. Probably better for my knees and ankles without it too. LOL. Re the HD19 with the incomplete decelerator linkage: Why not fix the d****d thing so you don't need to be an octopus to run it?
We very rarely use the 19 anymore. In fact I don't think it even got started last year. I need to go get some pics of it though. The canopy on it is supported my cables, was wondering if this was a common thing or not.There is also a long story behind that tractor.If He ( its name is Rusty)could only talk!!!!!!!!!!!
Being the person who has to fix dozers, I definitley prefer them to use the decal pedal. I was in a mine in a 3rd world county where the operators NEVER used the decal pedal. They had issues with track links breaking, master bolts breaking and coming loose, sprocket segments had to be welded as the segments came loose sometimes, occaisional broken axles shafts. Transmission 1st gear usualy wore out before the hours were up. Sometimes the final drive bolts would loosen and final drive would start coming off. The operators were extremely bad and abused the machines, so maybe things wont be as bad with normal operators. (such as in Canada,US Australia etc). Once we got a good dirt boss in and we clamped down on not using the decal pedal, these problems were reduced noticably. It doesnt need a full return to idle or anything, just a bit of a drop in load/engine power will go a long way. Things are especialy bad with this in some of the new dozers with bidirectional autoshift buttons. The operator will travel flat out in reverse in 2nd , the when he changes to forward, the trans switches to 1st fwd and the machine will nearly wheel stand.
Hi guys im new here i have a 955k and the guy i bought it from had a bungie cord that he hooked to the throttle which could be why im reworking a final drive where is the decelerator located can i get one from another loader and put it in mine thanks james
In over 8 years of operation of a D8 46A12,000 ish dozer, in all kinds of work, sometimes deceling and sometimes not. Even with final pinion seals leaking, engine rear seal leaking at one point in time. Never once did the transmission, bevel gears, finals need any kind of work. And this guy I worked for rarely ever changed any of the fluids. If I would never say a thing about changing oil it would have never been done. Reason 1 for wanting my own machine is I can run it how I want to and not hear "come to a complete stop and decelerate each and everytime" or what ever it is they can think up, like locking out 3rd gear. If you ever want to watch and see SHOCK LOADING, go watch a brand new very large CNC machining center, I personally don't see how they last so long and hold accuracy with the unbelievable rapid direction changes, and alot of them run 24/7, and don't need much for work even into the 12 year range.
955K Decelerator Pdal. Hi, Fabman72. Welcome to the forum. I have never seen a 955K or L with a decelerator pedal, only a hand throttle just inboard of the powershift control lever. As I understand it, they had a different power-splitting arrangement in the torque divider, sending 70% of the power through the torque converter and only 30% direct to the transmission. Most of the larger Cat dozer had a 65/35% split which made them slightly 'snappier' to operate but also slightly more susceptible to damage from not decelerating. Personally, I used to throttle down and back up with pretty much every change unless I knew that the weight of the machine was going to be working with the change in direction to lessen the shock if I just paused for a second or so in neutral before selecting the opposite direction. Dozer575, you operate your mental D8H any way you like. I'm not paying your imaginary parts bill. Hi, Knucklehead. Yes, it was fairly common practice in days gone by to put some lengths of cable into the tops and bottom of pipe legs for a canopy, especially if the dozer happened to be working in rock and the canopy was basically only for weather protection. The cable sections allowed the canopy to move around without the legs snapping due to movement and fatigue. Most such canopies only had a canvas top laced to the top frame. I'd love to see some photos of that old girl. I've always had a bit of a soft spot for the A-C dozers. I think I could spare the time to read the story sometime too, if you want to tell it.
Gee Dozer575 Im not sure about not slowing up between directions. If a machine will last "x" long its bound to last "x+1" if you can minamize the shock loading. Whist it is new it might not be so bad but once there is a little bit of wear things can get nasty pretty quick. At the end of the day if the decel wasnt required they wouldnt put it in there. As for 3rd gear, its supposed to be used for emergincies only, and trust me when you have to pay for your own track gear you soon learn to travel very slowly. Personly I never use 3rd in ours and never walk it backwards or faster than one third throttle in second. On small machines you can get away with walking them fairly quickly but as they get heavier the wear rate goes through the roof. Just my 2cents. Cheers
Being a wheel loader operator and not a dozer operator, why do dozers use a decelarator instead of an accelerator? Rn'R.
Rocksn'Roses, I guess dozers spend a lot more time at WOT or a consistant rev, whereas on a loader you are varying the revs all the time. Thats my thought on it, but I have done a lot more on a dozer than a loader so someone else may have a better answer for you. Cheers.
Last year I asked on old "catskinner" (I think that's the term you fellers use) this question and he didn't really know why either. That was the only reason we could think of it's just that I thought perhaps you would have more control pushing on short runs and perhaps finish work with an accelerator. Rn'R.
decelerator this board has answered more questions for me than all the "operators" in my area have answered in the 20 plus years i have been playing with equipment. i changed the throttle on my komatsu 10 years ago so it would return to idle when changing directions. did it because i and the other "operator" had heart problems. if heart gave out it would return to idle. dont know what would have stopped a d75s running max throttle. always wondered if it was best for machine. thanks guys and gals. keep up the great work.
Sensible move. Hi, Jughead. That is one very sensible move. Congratulations on recognising a problem and devising a solution for it. Now all you have to do if you do have a heart attack is try to get your foot off the loud pedal. It's good to hear of somebody doing a little thinking about their situation. Hi, Nextdoor. Dozer575 makes the comparison between a large CNC machine and a D8 or larger dozer. I have yet to see the CNC machine whose moving mass weighed in excess of 40 tons. Does that tell you anything about where this person is coming from? Personally, I don't know what he's on but I don't want a kilo of it. He has been posting some rather weird, way out and just plain stupid stuff on various forums under various names for some years now and most people on those forums would like for him to just disappear and leave the rest of us in peace to enjoy our machinery. One of the wonders of this bloke though, is that he HAS posted the occasional good piece over the years, Trouble being there is an awful lot of 'Dynamic Lifter' in between the good posts. Just my 0.02.
decelerator loud petal is next to shift lever one has to turn loose to shift trans
Ah I see, point taken. cheers
Even more sensible Hi, Jughead. That sounds even more sensible. Great idea. I hope you never NEED it.
as far as i know of you dont have to decelerate in the series3 and the new T models if you listen carfully when you change direction without decelerating you will hear the engine beeing "clutched"out and then throttle a little down before the transmission take over and you will drive backwards without ANY shocks at all and another thing is that every time your engine will have to thottle up it will use more fuel than if it just run full throttle but in some cases you will have to decel