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 | D.Hunt
Join Date: Posts: 1 
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2001-12-28 34114
Why do the Kubota tractors weigh so much less than New Holland, Case, and John Deere? I am comparing tractors of the same power rating and it seems that the Kubota always has less weight. Please respond as the Dealer here has no idea. TIA
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| Bird Senter
Join Date: Jun 1999 Posts: 962 
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2001-12-28 34115
D. Hunt, there's been lots of discussion about that, but I'm not sure anyone has come up with a positive answer that they've checked for accuracy. One "theory" I've heard is that the others give a tractor "curb" weight; i.e., ready to use, while Kubota gives a "crated" weight that does not include tires wheels, ROPS, etc. that the dealer installs. And since I, too, have never weighed my tractor, I had no idea if there's anything to that theory. ....
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| JohnInCA
Join Date: Feb 2002 Posts: 13 Southern CA
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2001-12-30 34142
Take a good look at the two tractors, and it is fairly obvious that the NH weighs more. The transmission, axles, etc., are quite a bit larger on NH than the Kubota. ....
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 | cutter
Join Date: Feb 2000 Posts: 1307 The South Shore of Lake Ontario, New York 
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2001-12-31 34162
Yes the N/H does have larger castings etc..it is a bit larger machine. But don't forget the difference in build technics, the Kubota has a steel frame as a backbone and the others are built as a conventional tractor with castings bolted from one component to the next as the backbone. Which is better?? I don't know, but it explains a great deal of the weight difference along with the other item Bird mentioned. Personally, I like the idea of the steel girder frame running from front to back. ....
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| D.Hunt
Join Date: Posts: 1
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2001-12-31 34164
I think you should take a better look at the NH and John Deere. The ones I looked at all had a steel frame in addition to larger castings in the construction. I was worried about thr frame on the Kubota flexing under load as well as the lack of weight when doing any heavy work. I was tring to find out if Kabota expects you to add more weight to use a FEL than the other tractors require. In my opinion this would put more stress on the Kabota. ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2002-01-01 34178
Several years ago I asked the same question and was told that it was the policy of Kubota to publish their weights without the wheels and tires. The dealer said it had to do with shipping, imports, and insurance. That would sure make the difference, but I haven't any idea if it is true. I tend to take anything that a tractor salesman tells me with a large grain of salt. The more sincere he sounds, the more salt I use. While we're being suspicious, I have to say that I've never weighed any of my own tractors to compare their weight with the specs and haven't the slightest idea what they really do weigh.
Farm tractors tested at Nebraska with their famous ASAE tests which go a long way toward keeping the advertising department's creativity in check. Not so with compacts. The compact tractor industry's published specifications have a colorful history which cuts right across the brands. We've seen manufacturer's 3pt lift and FEL force figures vary 50% depending on who was measuring them and where. HP is the same way. Weight shouldn't surprise us at all. There are industry standards, but compliance varies.. I'd be reluctant to believe the published figures without some confirmation. ....
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| cutter
Join Date: Feb 2000 Posts: 1307 The South Shore of Lake Ontario, New York
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2002-01-01 34180
I have looked, I have owned all three. ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2002-01-02 34200
Roger with some of my customers, I have to take what they say with a grain of salt and some time more. Not that many salespeople do know what they are selling well enough, they just want to sell and with a smile away we go! Weight is on it's way down on all tractors. The question is how light can you go and still have enough traction to get the job done? the lighter the better as it will give you longer life and better fuel economy and less ground compaction. Lightness should enhance the tractors responsiveness to throttle position. Many tractors in the ag end have been over weight for years. The things we have seen from this is engine failure and complaints of sluggishness. People do not want to operate them as they need to be shifted more often. They will pull more but only to a point. Properly over weight and you can cut 2/3rds of the driveline life. A good salesperson should be able to relate different successes they have had that worked for other people just like you. ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2002-01-02 34201
Yep, Art I agree with you. Tractors were too heavy for way too long, and the weight was in the wrong places. I go back to the days when engines themselves were not considered to be "variable speed engines". You selected speed with gearing and ran the engine at the rated RPM. There have been lots of advances. I also think that you need enough weight for traction and balance and that is enough. As Cutter says, the materials can change the weight as well. I sure wouldn't rate any tractor on weight as pro or con without taking other things into consideration....just as I wouldn't take the published weight as gospel without using that grain of salt. Art, nothing against tractor salesman. I think I should have made a strong distinction between professional salesman with product knowledge - they are wonderful - and the salesman who are just there to sell product without knowing from experience. Too many of the latter and too few of the good ones. When I find a good salesman I listen carefully to what he has to say. But they are just so darn rare! Or am I falling into "oldfartism"? ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-01-03 34218
I'm guessing that 4wd allows tractors to be lighter. Before 4wd, power got to the ground only through the rear tires. There's only so much tire design can do for traction, and adding weight is the best way to utilize more power. Maybe the idea was that manufacturers just made 'chunky' tractors because owners would add more ballast anyway.
I've heard some people elsewhere who seem to treat ballast as something 'wholesome' (the more the better). The weights they claimed for their tractors were pretty incredible. There didn't seem to be the sense that there are ideal weights for given types of work or that more ballast may be worse than better. It's good to hear affirmation that excess weight wears things out.
4wd solves some of the traction problem, and so there should be less need for heavy tractors. However, I'm guessing that weight and weight distribution seldom is very good for a 4wd tractor, because 4wd is still thought of as an option. I imagine that most tractors actually are designed as 2wd machines.
I wonder how long it took before manufacturers started designing front-ends to accommodate loaders? Maybe eventually manufacturers will drop the pretense that 4wd is an option and perhaps start designing regular lines for 4wd and economy lines with 2wd.
I imagine a lot could be done with specific design to produce lighter, more powerful and durable tractors. However, light trucks started weighing less sometime after '91. Unfortunately, I don't think there was any design goal except to make them lighter. The lightweight light trucks are sometimes though of as the reason tough trucks have become truly lightweights. I hate for that to happen to tractors.
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2002-01-03 34226
There are always trade offs on everything built. It wasn't until new technoligy gave us radar guns on tractors that the industry realized and that means us in the field that we were making tractors to heavy. I remember going out with a fellow and we were plowing on a hill and even going up hill we had 0% wheel slip and the goal is 7%. Here we were on a hill and we had none. We were quick to drain the calcium out of the tires and that still only brought us to 2% well climbing the hill. The customer stated that by eliminating the weight it was as if we just gave the tractor 15 more horsepower which we didn't. The tractor rode better and the performance was definitly noticeable while climbing the hill and he couldn't tell that he had gained wheel slip without looking at the gauge. Today I say if you don't need it don't carry it. Tom you don't think that tires will make a difference but I'll tell you it does. I was so into the big tires and no calcium that I actually went to far for the hills here and ordered such big rubberon one tractor looking for the ultimate that the tractor didn't have enough power to run at full throttle going down the rode. Traction; while before he drove it down the rode was the buz word in his neighborhood, just couldn't believe it! Better than any of his other four wheel drives and yet the smallest. There are catches to everything. Tires do make the difference. There are tractors built out there today that have to heavy of a chassis to be a top performer much less satisfactory. You can't take the weight off if they build it in, but you can add it if it is light and needed. Tires are also critical, as long as the tractors are built right from the start with the metal where they need it thats what counts, I see the engines in these overweight tractors needing rebuilding all to soon. There is a sweet spot of around 110 to 120 lbs per horsepower that we have found and it does make a difference. ....
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 | Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-01-03 34238
I had written a full response to this but lost it on the computer. In short Iron castings are more ridgid than steel. Older tractors used only casting for simplicity and ease of repair.
Old technology the heavier the casting the more ridgid the tractor the less wear due to flexing of the structure underload.
Weight cost money, in iron, in parts handling and in shipping costs. Weight reduction in tractor has not traditionally been a engineering goal, as weight is needed for traction.
Iron casting is difficult. Modern alumium casting reduce weight using ribbing in the areas where the stress is applied. One needs computers to do these calculations and modeling.
Kubota seems to be ahead of the curve on this point as their casting are lighter and ribbed. They also are casting iron. Kubota is located away from the other heavy equipment and auto manufacturing areas in Japan (Osaka Prefecture).
Damage of ribbed structures can comprimise the tractors strength.
Steel frames have been around since the beginning. Steel flexes and allows the structure to be more flexable. From what I have seen the welded steel subframes regained popularity with the backhoes where strength without the brittleness is required. Again its use may be due to the computer modeling available. The down side is the difficulty in clutch repair.
The other influence is the hydrostatic drive. The main clutch casting is not needed to link the machine.
Kubotas are lighter, are they any weaker? I doubt it. What they are showing you is more engineering at least in the castings and a shared load between the castings and frame.
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-01-04 34256
Art & Peters: Thanks for the comments. Very interesting stuff. This Board always seems the get a good mix of theoretical, engineering and operational perspectives. Art's comment that less weight equals more power is one of those insightful things that should stick with anybody who has ever has an urge towards tractor hot-rodding (you don't have to turn up the fuel, just take off some ballast).
My tire comment was more about theoretical than practical limits. I was thinking that there probably is a limit to how much tire size and design is capable of coupling power to the ground for given weights. For example, as tractor's power increases, greater traction is needed to be capable of utilizing the power. A light tractor with very wide tires may not have the weight to sink the larger lugs into the ground.
I suspect these conditions produce a limit to how much power a tractor of a particular weight can utilize. What Art pointed out so well is that maybe this limit would never be reached within the range of weights and powers that are realistic for tractors. Perhaps in real tractors, everything can be done with the rear tires.
However, if a tractor is designed to put power on the ground through its rear tires, then as much weight as possible would be on the rear axles with only enough on the front for balance. Some weight has to remain on the front so there is a possible source of traction in 4wd machine. Of course, 4wd robs power as do all rotating gears. Shifting weight forward would increase potential for traction from the front wheels, and at some point the gain is positive I imagine.
My curiosity is whether a tractor that was designed strictly as a 4wd machine would be any different from one that is as designed as 2wd with 4wd as an option. If so, perhaps it could be lighter. Don’t know it’s just a curiosity.
Dang this is getting too long. Hope this thread carries on ‘cause I’m interested in castings too. My impression is that given cross-sections of cast may stronger than steel. It’s just that cast isn’t very forgiving since it breaks rather than bends. Of course, cast doesn’t deflect either, which makes it good for machine tool beds.
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-01-04 34263
O boy;
Here comes the physics.
Cast iron vs Steel Rigidity
The question is ridgidity versus flexability. Steel depending on the structure can be harded to provide material that is as hard and as brittle as cast iron. Consider a file, how many have you broken?
In general as you harden steel you loose ductility and flexability. If you want to create a ridgid structure like the bed of a milling machine, engine block etc. then cast iron is better than steel for construction. To create the same structure out of steel would require considerable addtional welded components to provide the same ridgidity. New modern structures can be made lighter using composite structures but mass production is difficult and costly.
Steel can be given better qualities by forging. Consider the sword blade masters that would forge together hard and soft steel in thin layers, like good french pastery. This gave the blade the hardness and flexibility needed.
Maximum traction will be a dependent on the ground on which the tractor is moving. Farmers use different tire set ups depending on where they are farming. As you and Art stated to be most versitile it is best to be able to add and subtract weight depending on the conditions.
Depending on the system 4 wheel drive costs you nothing. For example I owned a Jeep Cherokee with full time 4x. The truck had a 360 CID and averaged 16 MPG US or 20 MPG Imperial. Why? Because a driven wheel uses less energy than a non-driven wheel. Most of the field work is done in this country with 4x.
Your 4x friction loss penalty comes in acceleration. Without the 4x the field laviothans would be much bigger and heavier. Many of these are full time 4x. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2002-01-04 34264
just for some additional things on proper ballasting. Two wheel drive tractors are ideally 25% front and 75% rear. Four wheel assist as they call it on the front of two wheel add on to four and they should be 40% front and 60% rear. The bigger tractors or articulates are normally at 55% on the front and 45% on the rears for proper weight transfer. Now the problem enter's in with a loader and to find the proper ballast. There we throw the books away and over load the rear. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-01-05 34283
There sure are a bunch of things going on in this thread. I guess I can see now that a 4wd only design may not be much different from a general design. The difference between good weight distribution for 2wd & 4wd should adjustable by ballasting techniques. Maybe a simple design goal of just making them lighter and using better tires is straight to the point.
I have the belief that detachable weight is good, and I haven't loaded my turfs for that reason. I depend on a heavy implement like a box blade for ballast, but there's a problem. When the blade is in use on the ground, the weight no longer acts as ballast, and of course that's when more rear traction is needed. Weight in the bucket adds to front traction and helps but also stresses the front drive train. Maybe I should give up and buy wheel weights. They are sure expensive, although I did hear of somebody making some from lead filled brake drums.
I guess it would be ideal to make cases from alloy steel that could be forged and hardened--sure would cost though. I seem to recall small cast iron bridges etc. I think the idea is that the cast supports more load per weight than mild steel, but maybe they were just simpler cheaper to build.
It is curious to think about designs that mix elements the load by deflecting with those that don't. I wonder how much load the steel actually takes off cast cases in tractors with frames and loader and hoe sub-frames. In terms of weight, my '69 Honda 750 had sand-cast cases. The cases changed next year to die castings, and I believe there was some ribbing. I'm guessing that the die cast cases were lighter, but die-casting is more expensive. Ribbing probably can't be done very well with sand casting. Thanks. I never know exactly what was being folded in the descriptions of sword blade making I've read.
I left out 4wd. There are several archived discussions about full time 4wd. Generally, it isn't exactly in a turn except if there's a differential in the front drive shaft.
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