The wheel loader must be improved now

Introduction

After finding how little the excavator has been improved the latest 30 years, the time has come to the wheel loader. Because the wheel loaders are produced by the same manufacturers as the excavators, are bought by the same customers and dig the same gravel, stones and soil, there is no reason for not putting the wheel loaders under equal critical investigation as the excavators in these times with focus on climate changes, use of not renewable resources and CO2-emmision.

History

The history of the wheel loader is very short. The very first was built in 1946 by the Wigren brothers in Järbo in Sweden, built on a Fordson chassis. In the 1950s more companies started to build wheel loaders. The first ones were built as tractors where the cabin and the loading equipment were turned so that the loading equipment was placed over the large wheels. In this way they got larger breaking force on the bucket and the machine became more stabile and maneuverable than using a tractor with a front loader. Then it went on in rapid succession. Wheel loaders with equal sized wheels with four wheel drive were the next step in the development (approx. 1960). Then came the wheel loader with mid-steering in the middle of the 1960s, the number of models increased heavily especially regarding sizes, but then the development almost stopped. In the latest 30 years it has hardly been any further development.

What is wrong with the present wheel loaders?

Why has the development seemingly come to an end? Well, that is a good question when you look at how the developments elsewhere have been the last 30 years. The wheel loaders are about equally heavy compared to the work they are carrying out. The wheel loaders weights nearly 6 times the weight of the mass they can lift and the wheel loader’s efficiency is practically unchanged.
I believe that this also is due to the unfortunate phenomenon that the wheel loaders are compared only by machine weight and engine power. It is therefore very little competition momentum between the producers to increase the efficiencies as long as you buyers evaluate the machine by weight and not from what the machine in fact does, and that are the producers obviously very comfortable with. But once more is the question. Can you wheel loader owners really afford this standstill? And what happens if your competitors suddenly get more optimum wheel loaders? What then? Let us start with looking at some of the biggest weaknesses and limitations with the present wheel loaders. Today all the producers make nearly equal machines.

a. The most crazy is the almost horrible device called torque converter.

This is the very device that steals almost all engine power when you fill the bucket and that demand that the present wheel loaders are equipped with an engine and engine torque that is beyond all common sense. To illustrate this I will use as example one of the present ”30 metric toners”. All the present 30 metric ton wheel loaders are nearly identical, so when no manufacturers are mentioned no one is forgotten. In these wheel loaders there are 285 kW (380 hp) engines. The engines have a 12-13 liter (750-800 cu in.) cylinder volume. This maybe sounds impressing, but not to me. The reason why it does not impress me is due to the following analysis. When the wheel loader start to fill the bucket it is hardly any resistance against the bucket. That will in practice mean almost zero engine power, because used efficient loading power is the speed multiplied by the force you have to push the bucket. Then the bucket is pressed into the heap.
Then the resistance increase while the wheel loader’s speed decrease until the wheel loader has completely stopped after the 2-5 seconds it normally takes to fill the bucket. According to the formula for necessary power, speed multiplied with force, the propulsion power need has dropped to zero. The engine produce at this point 285 kW (380 hp). Where goes all this produced engine power? All this power disappears as heat in the torque converter and is not spent on useful work. “Why use this large engine”, you might ask? It is because the engine has to be that big and needs so large torque to be able to turn the converter pump wheel, or else the engine will stop. “We need the power to lift the bucket”, someone may try to argue. Yes, approximately 50 kW (70 hp), maximum, of the power to lift the mass. The rest of the time you use fairly little power. The wheel loaders have engines that are 4 – 6 times to big, only so that the torque converter shall be able to stall 2-5 seconds while filling the bucket. The result is a too completely fuel hungry, heavy and costly machine that emits all too much CO2. Because of that I therefore think that the description ”crazy device” on the torque converter is deserved.

b. Lack in use of completely continuous gear boxes.

The producers will in the future be forced to take into use better continuous gear boxes between the engine and the wheels also on wheel loaders. Then we can optimize the engines entirely from engine power. The engines will be much more optimal because we can forget all this importunity about the engines torque. With a completely continuous gear box, the torque is without any consequence.
You get considerably lower diesel consumption and engine wear because the engine only rotates with the speed that is necessary to get the power you need at any time. It is bad to hear all the wheel loaders that race the engine at full speed only to push the bucket into the gravel when the same could have been achieved by another gear ratio. It is for sure not good for the engines.
As an extra bonus when using continuous gear boxes, the power will be lead back to the engine so that you do not have to wear out the wheel loader brakes when you use the wheel loaders in steep downhill slopes. Full control without wearing out the brakes.

c. Too heavy machines.

Comparing the wheel loaders by weight is also from my point of view a misfortune for the entire construction business. It makes it quite uninteresting for the manufacturers to produce efficient machines. If only the wheel loaders are heavy and have large engine power everything is fine. The manufacturers do not exert themselves at all and that marks also the machines. It looks like they get away with using brand names as an argument for you to buy their machines. This has obviously functioned excellent for many years and as long as you users think this is plain sailing they will continue doing so. That should be something to think about the next time you buy a 30 tons wheel loader, which if it had been optimized correctly, you could have done the very same loading job with a wheel loader that weights 10-15 tons. You could have saved 0 000 of the 0 000 you must pay when purchasing. You could have saved more than 0 each day in fuel cost (almost the entire driver’s salary). You could save lots of expenses when you want to move the machine from one place to another and you could have reduced the CO2-emmisions to the nature extensively. Or is it really that huge profit margin in the construction business that this does not mean anything to you?

d. Lack of springing.

Another problem with the present wheel loaders is that they do not have springing on all wheels. This is a typical heritage from the tractor when people were marvelously satisfied with 4-8 km/h working speeds. We do not need to drive fast someone will of course argue. Yes, you need that or else you must have much larger machines. Subsequently the wheel loaders have resulted in some kind of dinosaurs in comparison to what can be loaded with them. To illustrate what this means in the construction we can do the following consideration. Let us as an example use that the springing in the tires when running over a given dip with the present wheel loaders is 2 cm. If we increase the springing length to 10 cm on a wheel loader with springs the strain will be reduced to 1/5 of what it is today with the same weight. If we then halve the size by doubling the speed the strain will be reduced to 1/10 in both bucket arms and wheel loader. We can then more than halving the weight. Because the prices for such machines almost are in proportion with the weight, you could reduce the machine investments with 50-60 % in comparison to what you have today. Money that you could save.

Reflections

Global warming. UN’s climate panel’s depressing predictions about the problems that the emissions can cause like the one where 30 % of the species on the planet can die out, that several hundred millions people can become climate refugees because of floods and drought etc. These are the headlines that will dominate the headlines until something has been done about it. The politicians will all the time try to find ways to reduce CO2-emissions. All the way down to the kindergarten and schools the children are indoctrinated how important it is to save the environment. While I have worked with this article I have often pondered on how such a huge business as the construction machine business almost has got away from the focus on reducing their emissions and excess consumption of not renewable resources. That must be because the construction business has managed to pretend that they have optimum machines and refused any attempt focusing on this by trying to be silent or be rejecting comments, telling everything is perfect. By application to several of the large manufacturers, one machine manufacturer answered that to take in use this new continuous gear box that saves 50-80 % fuel consumption and CO2-emissions ”is not consistent with -----‘s product policy”. The other ones didn’t answer at all. I find it fairly naive that they think they in the long run can slip away the focus in this way. Therefore, maybe it is the time for you customers to think thoroughly through if you want it to be this way. I have lately also read what the chairmen and CEOs write about the products they deliver. I think it maybe is time to show a little bit of professional modesty because of all these suboptimal machines they deliver to you as customers, but no, bragging, bragging, bragging. Either they are not aware of how ineffective their machines are or they know and brag loudly so that no one shall discover. The larger I therefore believe that the shock will be when it appears how poor efficiency their construction equipment are because then the producers will be forced to a radical change in a very short period of time. If they instead had calculated and optimized on the way, they could have avoided the shock they now will get, but then they would have to do something more than just copying each other. I also believe that the construction firms that continues to buy old fashion machines that use far to much fuel and that emit several times too much CO2 will get large problems with politicians and customers, especially the government like road authorities and similar. I am convinced that the politicians will demand that the construction firms have to use equipment with low consumption and low CO2-emission to get jobs in the future and then other customers will do the same. Then it maybe is not that profitable to own these old fashion machines any more.

What now?

We have become more and more tempted to start production of this new generation wheel loaders ourselves because we then can build the new production from the basic. Wheel loaders are in the reality very simple machines from a construction and calculating point of view. Therefore we have started with the development of the new generation construction machines. We are convinced that it will oust the present construction machines, because if not the construction business themselves take care of these problems very fast, I am convinced that they will get good help to change their way of using resources and reducing their emissions by the politicians that wishes to reduce the emissions. New laws, directives and taxes will then for sure be the means.
If you are interested or have views, please contact us on email:flaco@fladby.com. Flaco’s internet site is: http://flaco.fladby.com

© Tron-Halvard Fladby/ 2007.06.26