Dozer selection for scraper work.

[Olly]

Hi all,
I would really appreciate some help choosing the correct dozer for the work I have scheduled. I have a job that is big enough to justify purchasing a machine (my first). Hope to have a machine on the job site end of Dec 2018.
The job is a small subdivision in steep, clay country. The desire is to tow a scraper (scoop) to form the access ways – the bigger the capacity the better.

Two reasons for posting. I would love some help and insight. Also, having put in a bit of time to understand a little about the machinery I would like to share what I (think!) I’ve learnt.
Let me start by saying I would like a D6T. For the sake of economy/available funds I have had to lower my expectations and had leveled my sights at a D5M sized machine. After a little more research, I thought I had settled on a Komatsu D41P/E-6.

As a bit of background, attached is an excel sheet which lists the machine specs for the various machines I had been collating info on.
My requirements for the job:
1) A cab / AC is a must
2) Relatively low hours machine ~<= 4000 hours
3) Cost <= 75,000 US landed in NZ.
4) (V)PAT blade – I don’t intend to do any land clearing.
5) Capable of towing a ~9 yd scraper. I could go for a smaller dozer, but I would like to maximize the capability of the machine I am purchasing for future, potential work (no sense going to small..?).

In terms of sizing the correct Dozer for a 9 yd scraper (I feels as though I am working the problem backwards…:/) the only concrete input I have is a page out of the Caterpillar performance handbook. I have pasted the snippet below for reference.
http://i63.tinypic.com/2z52hdw.jpg

The snippet lists the estimated hourly production for a D5B with a R568 scraper in tow and indicates that the D5B (105 hp / 11700 kg) is capable of pulling a 9yd struck load.
As further confirmation, there is a vid of a D5M (110 net hp / 11700 kg) pulling an Ashland I-950 (

). For my inexperienced eye, it seems to be doing ok..?
There is a spreadsheet sheet linked below in which I have populated a list of Dozers and their relative spes. Most of the information comes from Richie Specs with a few corrections where I have found anomalies.
The info is by no means validated / correct, but the best I have, to date!
Apologies! I'm unable to share the excel file on the forum. I have uploaded the file to
http://s000.tinyupload.com/?file_id=76156979637997659244
Below is a link to a screen shot for reference..
http://i63.tinypic.com/sdefsj.png

In sheet 2 of the spreadsheet I have been populating the specs for different scrapers. The list of scrapers is not yet complete, but there are a fair few to go of.
Based on the D5B (105 hp) / R568 combination and D5M / I-950 I have several dozer options in that hp range:
D5B (105 hp)
D5M (121 hp).
D5K (~104)
Komatsu D41P/E-6 (110 hp)
Komatsu D39XP/EX-22 (105 hp)
JD 750. etc

For those kind enough to take a peek you will find a number of dozers listed in the sheet (hopefully others will find this info useful too!).
What is missing here, and where I am stuck, is on the weight of the respective dozers and how I can translate this to drawbar pull or similar.

Pricing is tilting me in favour of the Komatsu. For a D5M I can expect the machine to have an additional 50%-100% hours and to be, on average, 2-6 years older than the komatsu.
Now, my problem, how does the weight of the machine and ground pressure factor into the capacity of the machine to push, or in my case to pull a 9 yd struck scraper up hill?
I note that Komatsu also have a D39PX-22. The XP machines (LGP) seem to be very popular. Further, if I was to purchase a D39PX-22 I would not need to import the machine which would help speed things up. The D41P-6 are not so prevalent.

Below is a quick comparison (hp / weight / ground pressure) for the D39/D41 and the D5M/D5B/D6D?. I have included both the D39EX and D39PX in the line up. The cat D5M/D5B appear to be more than capable of pulling an I-950 scraper (what about the lighter D6D?)
http://i64.tinypic.com/efs22x.png
I note, according to the manuals for the Komatsu the drawbar pull vs speed is almost identical for the D41/D39. I have started to look at calcs for drawbar pull, but sadly my noodle of a brain has taken me about as far as it can. Am I going to notice the output of the D41 vs the D39 due to vehicle mass in soft material / clay?

Please excuse the length of post. For anyone who has made it to the end of this old epistle, thanks. I would be very grateful for you input!!

 

[nowing75]

Is it common there to pull pans with dozers? Don’t see it much in the us,or at leased not around indiana. It would seam to me to be to slow unless your not moving the dirt to far.

 

[Olly]

Hi nowing75. the bulk of the dirt will be moved less than 80 meters depending on the access way / site.
The only alternative that I'm aware of is a dozer, excavator and a truck. Or a dozer, scraper and an MFD tractor.. The latter (dozer, scraper and a tractor unit) would be ideal for me (one man operator) but I cant stretch that far at the moment.

 

[R.D.G013]

I used to work for an outfit up Tauranga way back in the 70s > 90s and we used IH TD 15 C s and towed Onions scoops had two with 8/11 yds and had one 6/8 with hungry sides which made it about 9 yds heaped. The 8/11 could move more dirt in a day on good going but when it came to steep country or soft going the 9yd one would just about shift as much as it was quicker loading, quicker back up the hills and didn't get. stuck as much in the soft going and you could go more places with it. Some times it doesn't pay to get to greedy unless the going is real favourable. I remember another firm came and hired one of the 8/11s to tow behind a D 8 H to work in some soft material, D8 would normally tow a 25yd or more but couldn't handle it in the soft going. We also had a D6 D later on with a Cat 70 size scoop behind it, was good in good going but limited to where you could go in the soft or when it got steep.

 

[Olly]

I received an email from Ashland below
"I see the smaller dozer [D39] is around 100 hp and the suitable scraper is the 950XL2 scraper. This scraper is 9.5 cu.yds [heaped]. And is 87.5” (222cm) width of cut. It requires two hydraulic remotes to operate the scraper. One remote controls the blade elevation and the second Hyd. Controls the front apron and the ejector wall."

I spoke with another company here in NZ that sells second hand machinery. The owner told me that to be effective (not getting pushed around on a grade / not scrabbling on the flat / and to be capable of loading) the dozer needs to be twice the weight of the pan. The Ashland 950 XL / I-950 is around 3628 kg (8000 pds). For a 6.858 m^3 (7.5 yd load - struck) assuming 1600 kg/m^3 for sand / clay / limestone that suggests the I-950/950 XL would need ~ 24,000kg machine.

For the D5B / R56H combination (self loading) that is listed in the cat performance handbook;
The D5B weighs in at 11700kg
and the R56H (dry) ~ 8900kg (https://www.heavyequipmentforums.com/threads/rome-r56h-scraper.72135/)
+ 6.9 m^3 load at 1700kg/m^3 = 20,630kg.
The load to tractor weight ratio of 11700/20,630 is closer to 0.56 - certainly a long way from the factor of 2 mentioned above. Is the info in the cat performance handbook practical? or purely theoretical?

 

[Olly]

Thanks R.D! I was just searching for the hp/weight for the TD 15c (140hp / 14968kg).
I couldn't find a weight on the 6/8 vickers-onion, but assuming it weighs a couple of ton (i read somewhere the onions were quite light?) that's close to a 12 ton load (1600*6.1+2000) behind the TD.
You mention running a Cat 70 behind the D6D (140hp?/9235kg), what do you think of pulling a small scoop (like the 6/8 onion) behind a D41/D39 or similar in steeper going? Still trying to get my head round it all!

 

[R.D.G013]

Are you sure he was talking about the loaded weight and not the empty weight coz a 24,000KG dozer on a 9 yd scoop could end up pulling it in half. Twice the empty weight would be more like it, that would make the dozer around 8,000 kg or so. From memory the 6/8 was around 6 ton and the 8/11 went around the 8 1/2tom empty. It can also depend on how good your grousers are and the width of them as to how much traction you are going to get. There is an out fit in the USA that uses D 10 & 11 s towing scoops made out of 651 scraper bowls. Think the stuff in the cat book is from field studies so it should be reasonably practical. Over on FB is a site called NZ Road Transport & Contracting there is a bloke there called Merv Pepper from Coromandel way who is still into scoops and things. A friend of mine in TGA was running D 7H LGP with Kokudu scoops behind them not sure what size they were but they are another manufacturer of hyd scoops.

 

[Olly]

Hi R.D.G013, An empty pan would make more for more realistic numbers. As you say, I would only need an 8 ton dozer. The chap I was speaking too, however, felt the D41 (~12000kg) would be too small. He was recommending a D51 - a bit too rich for me.
When I started looking at scrapers a rep recommended something with a dolly. Would a scrapper like the RP-90CS solve the problem? In the little digging I have done, I've only seen dolly wheeled scrapers behind bulldozers.. Not sure why..
Thank you for the contact. I will pop Merv a message too. Cheers!

 

[R.D.G013]

I have never used one like them, only ever dolly wheel scrapers, but they would provide more weight on the dozer which could be an advantage , where as a dolly wheel scraper carries all its weight on its own 4 wheels. There are some videos on youtube of some dozers with direct hitch scoops working and they seem to go all right, might put a bit of extra wear on the sprockets and final drives in the process.

 

[John C.]

Interesting sounding project. I don't know much of anything about that type of operation but do know a bit about some of the dozers. The D5B would be pretty old and might require a lot of expensive work before you can put it to work pulling pans. The D5M model had a lot of electrical and electronic problems that required pulling the transmission. Speed sensors and electric harness issues ran rampant in those machines. The high drive undercarriage is expensive to replace but the weight, size and high cab configuration would indicate to me a better fit for pulling pans that the other machines. The K model Cats are oval track units and even though the horsepower you state seems like enough according to your calculations I would have to wonder what they actually put on the ground. The K models are all hydrostatic drives and I suspect they might get hot on long hard pulls. Horsepower is probably not the best indicator of how the machine will pull. I like looking at the range of torque the engine can maintain when determining pulling power.

On Komatsu machines the PX models were all LGP units here in the states. EX models were standard gauge and track pad widths. Komatsu might also have a mid width unit now. The D39 model Komatsu dozers used to just be the Dresser TD9 units that were renamed after Komatsu finished the purchase. They were a torque converter machine with a power shift transmission. That might be different now but is a point you should find out about before purchase.

As far as drawbar pull goes I like to think that the weight of the machine will determine the actual draw bar pull. A twenty thousand pound machine in a pull on flat ground is going to break traction and spin when trying to get a load moving that weighs the same. The other side of that issue is handling that weight when you start to head down hill. You are going to be able to drop the pan to slow down but that will eat up time and carries a risk of jack knife if you don't catch it in time.

Keep us up to date on how your project progresses.

 

[Karaya]

I like CEG's charts for specs: https://dev.constructionequipmentguide.com/charts/crawler-dozers

Don't know if they're any better than Ritchie Bros. though.

This is an article on how to calculate drawbar pull: https://auto.howstuffworks.com/auto-parts/towing/equipment/tow-bars/drawbar-pull1.htm

 

[DMiller]

The most common smallish scrapers in the US are now the all wheel drive tracked AG tractors pulling reasonably sized scraper pans on a tongue hitch. Have gained popularity and notoriety as to less expensive easier to maintain and not as operation specific while easier to move site to site as the old dozer/pan set ups.
https://www.forconstructionpros.com...47320/pull-scraper-and-tractor-selection-tips

 

[Olly]

Hi All. Thank you kindly for your replies / the help!
@DMiller, I was looking at the AG tractors initially, and while cheaper to run, for many of the sites I will still need to form the access-ways / pads etc. I’m not sure I can get away without either a dozer or an excavator. I could purchase an MFD tractor and scraper and hire an excavator (and load the scraper directly). Less machinery would however be better, especially as I will be operating solo. After ‘this job’ I could possibly purchase an tractor and use s dozer for the initial cuts / loosely forming the access ways and pads.

Thanks John C for the overview. That was very helpful. I spent a bit of time looking for a good cond D5M / K series dozer earlier in the year. I’m grateful for the insight. With regards to the Komatsu dozers, the EX machines are rather scarce. I was considering whether I could simply run some narrower tracks on the PX if it became necessary to improve traction / reduce wear. I had a chat with a different Komatsu NZ rep in the upper north island, however. He was recommending a Komatsu D51 for this type of work (scraper work) - again, a bit rich for me. He had never heard of anyone using the D41P-6 / D39 (hydrostatic) for pulling scrapers. From the little he knew, he was advising against it.

I did find a few more examples for dozer/scraper sizing specifically for the Komatsu dozers / onion boxes– links below.
“cat 40 [cat 40 requirements: D4 [43, 67] Kw (net)] behind a D31, seen that a few times, they seem to handle them alright”
https://www.heavyequipmentforums.com/threads/cat-70-and-a-d6n.34210/

“[The Onion] 06-8 is a damn good little scoop, guy I know near me tows one behind a D41A-3 [93 hp / 9800kg] and it loads it in under a minute.”
http://www.ceforum.co.uk/archive/index.php/t-1265.htm

Alot of [Onion] 06/8s made it here and were converted to hyd. Guy near me tows behind a komatsu D41A-3 [Gross Power 93 hp, 69.4 kw] and it works real well, loads 8yd in under a minute. And it is a light scraper to tow too.
http://www.ceforum.co.uk/archive/index.php/t-1265.html>

Hi all! I'm looking for a Cat 60 scraper or an Onions 9/11 open bowl for my D6C
http://www.classicmachinery.net/forum/viewtopic.php?t=1253

As far as dozer selection goes, I’m starting to wonder if I would be better advised to fall back on the tried and tested - where I began the search! Unfortunately, there aren’t many of the earlier Cats on the market here in NZ at the moment either, at least not with a 3 way blade.
Back where I started 6-12 months ago. Ha! Not sure if you can call a circle progress. I’m getting in some miles though all the same..

Thanks for the links Karaya . I will most certainly check your links out! Where I had struggled earlier was translating the more common calcs for conventional wheeled vehicles to tracked.

 

[DMiller]

Cool video, gives great credit to the old 6's, strong machines and dependable.

 

[StanRUS]

Cool video, gives great credit to the old 6's, strong machines and dependable.

Frogging the scraper; brings back memories. We still have D6, Cat60 carry-all.

 

[Olly]

I've been scouring for a D6C / D6D. There appears to be a D6D with cab in good condition - $70,000.
https://www.trademe.co.nz/business-...97.htm?rsqid=839bed015cb148f8a94a1d7036a903ba
Unfortunatly it is a bull blade. Not cheap. If it had a 3-way, I'd be tempted to buy it and be done with it! Its overpriced, but I don't anticipate I'd lose too much money when it came time to sell it.
As far as a D6D/D6C with 3-way and powershift goes, I haven't seen anything yet. Not sure about importing a machine that old either (late model D6C). Concerned I’ll be paying top dollar for something on its last legs if I purchase here in NZ.

Looking again at the Komatsu’s, I came across a thread where someone was talking about putting an ashland behind a hydrostatic Deere 750C [110hp / 11,810 kg].
https://www.heavyequipmentforums.com/threads/ashland-pull-scraper-john-deere-dozer.71015/

@John C. you noted that I should have be looking at the torque range that the engine can sustain when pulling rather than weight / hp? Unfortunately, the only info I have been able to find on the D41/D39 are the attached spec sheets... Not sure quite sure what I am looking for!
You also mentioned that the D39 "were a torque converter machine with a power shift transmission [and that this] is a point ..should find out about before purchase". Were you recommending to steer clear of the hydrostat due to over temping? As far as environmental temps, mid summer, here in NZ we are typically in the 25-27 deg c. I don’t know if that changes things at all? Are there ‘simpler’ mods that can be done to improve the cooling? I note talk of a similar mod for the later model D6C in one of the forums here. Are there other aspects I should be considering?

In terms of traction alone the D6D (which sounds like it is more than up for the job) is around the 9200 kg mark while the D41P-6 (D41E-6) is around the 11080 (10510) kg mark. What I don’t understand is how to factor in the relative ground pressures and the respective ground contact areas of the different machines. The D41P/E-6 machines are certainly heavier than the D6D, but the ground pressure for the Komatsu P/E is less than half that of the D6. Based on the 2*pan rule, the D41 would be ok on face value.

 

[John C.]

For torque specs you will need to look specifically at the engine by itself. Find out what is used in each and then check the specs by the horsepower rating as there will be several different tunings. You can have an engine with 100 horsepower but only 40 foot pounds of torque compared to the same 100 horsepower engine with 75 foot pounds of torque. The second might be able to pull your scraper in second gear while the first would only work in first gear.

I'm not sure of what you mean by traction. According to my performance manual the D6D weighs in at 31,500 pounds and the listed draw bar pull is 140 horsepower. The Komatsu D41 isn't quite 25,000 pounds and the horsepower shown in Ritchiespecs is only 127. A D39 weighs less than 22,000 pounds and only shows 105 horsepower.

The difference between torque converter machines and hystats first is operator comfort. Full power turns and rampable speeds are real nice. The snap turns you get on the 39s that I've been around get tiresome real quick. Second item concerns repairability. While both systems are expensive to fix, the hystat comes in at machine scrapping costs if you trash a component. The last point I can make is that neither machine was made for continuous pulling. There is a reason so many direct drive clutch machines were used in the ag industry opposed to torque converters. It's OK to push a couple of hundred feet with hydraulic oil or a torque converter but at the end of that push you get to back up with no load and the engine pushing air through the radiators at high idle. Your 50 foot pounds of torque engine goes from 50 to 5 in reverse. Latch onto that scraper and your minimum load is that of the empty scraper. You never unload the engine and drive train. You 50 foot pounds of torque machine only goes back to 35 or so foot pounds pulling the scraper.

Last point I can make is that you can't design what you want to do out of a book. The book can only gives you a ball park and I've seen many times it's not close. You also can't depend on advertising materials. They lie in order to sell machines. The best you can do to help yourself is go watch someone doing the job. Believe only half of what you see and none of what you are told.

 

[Olly]

Thank you John. The weight of the D6D I'd pulled of richiespecs was 20,359.7 lb. Your value makes a LOT more sense! Thank you for the correction.
By traction I was referring to the ability to pull a load without scrabbling / loss of traction. Very loosely, calculating the tractive effort, or soil thrust using Bekker's model:
https://en.wikipedia.org/wiki/Grouser
https://www.google.com/search?q=Off-Road+Vehicle+Locomotion+Using+Bekker's+Model&ie=utf-8&oe=utf-8&client=firefox-b

% Constants:
% H = soil thrust
% b = track width
% l = contact length
% c = coefficient of cohesion (a soil property)
% h = grouser height
% W = gross vehicle weight [kg]
% phi = angle of repose (a soil property)

%% D6D
% b = 700;
% l = 5430
% c = 65; % Mixture of inorganic silt and clay - compacted. http://www.geotechdata.info/parameter/cohesion.html
% h = 25;
% W = 11600;
% phi = 65; % value based on earth / clay: https://en.wikipedia.org/wiki/Angle_of_repose

%% D41
b = 406;
l = 3690
c = 65;
h = 25;
W = 14,061;
phi = 35;

%% Beckkers model for soil thrust
H = b*l*c*(1+(2*h)/b) + W*tan(phi)*(1+0.64*((h/b)*acot(h/b)))

%% Outputs:
% D6D: Soil thrust equals 2.6472e+08
% D41: Soil thrust equals 1.0937e+08
% Based on the above the soil thrust for the D6D is a factor 2.4204 greater.

Very grateful for this forum. Will take your advice John and do my best to avoid the books (as far as possible!). I was driving a tractor back in the day before moving into engineering. With a bit of luck I might get the chance to go back to digging holes - there's just something about moving dirt . Unfortunately I don't have any experience yet with the heavier machines. I should get someone else in.. But I figure if I take my time I'll (hopefully!) get there in the end.. .

Again, thanks for the correction. I couldn't understand why the D41 kept coming out on top - always a risk when pulling numbers from the web. I've put the search for Komatsu to the side for now and am focusing on the D6. Hopefully I will find something soon.
For those sifting through the specs for the various machines I have added a couple of updates to the sheet and linked it (https://ufile.io/b6qgc). Where available there are links within the sheet which will take you to the source data should you need it. You will just need to change the file extension to .xlsx to view. For those who don't have excel, there is a very nice freeware called LibreOffice Calc. I highly recommend it. Cheers!

 

[epirbalex]

There is or was up to yesterday lunchtime a D155-1 Komatsu set up for what you want , 1000 hrs on recon motor , tracks over 60% $54,000 including GST , scoop extra . BoP area . It would do what you want and some .

 

[Olly]

Hi epirbalex. I hadn't been looking at the older komatsu. They were not on my radar. Thanks for the reminder / recommendation .