Design Principles Excavator Technology
Wind tunnels are used when designing cars. They provide the engineers with the appropriate design specifications they need to achieve to reach optimum speed and/or efficiency.
Similar principles are used in bucket design. The aims are:
- to achieve the maximum digging force for the minimum amount of pressure exerted, thus increasing fuel economy
- to streamline the bucket flow through the cut, reducing the power required, increasing fuel economy
- compact design means a shorter pin to point (bucket pin to end of tooth) so that more power (force) breaks the ground easier without losing the bucket capacity
- that the bucket shapes simulates the natural arc of the dipper arm as it digs the earth, again reducing the force on the excavator – saving fuel and maintenance costs
- the design of the bucket ensures that the only part of the bucket that breaks the material is the G.E.T. – the actual bucket is just there to collect the broken material and should not be grinding in the materials, as such creating extra wear on the bucket.
- that the bucket is designed for the geometry of the excavator. That it digs correctly as the machine was designed. It’s not just a case of changing bucket hangers to fit all machines. All excavators are designed to dig differently and fitting the wrong bucket may result in the bucket either not being able to curl the bucket enough to load trucks at reach without material spilling over the sides or not opening up enough to dig efficiently
Why doesn't everyone build their buckets this way?
Technology - the majority of excavator attachment manufacturers do not have the technology nor do they understand the principles needed to design attachments. Many of them are just welders or boilermakers who have been asked to copy a client’s bucket. It’s a little like getting your motor mechanic to build you a car!
Manufacturers have spent millions of dollars on technology to improve the design of their machines, so that they will perform better and more efficiently in all areas. When poorly designed attachments are installed, the machines will not perform to the manufacturer’s or the owner’s expectations, using more fuel, and requiring more maintenance
OH&S - With more importance being placed on workplace safety, the real concerning factor is that many manufacturers have no idea as to the safe working loads of the machines for which they are building their buckets, nor do they have the knowledge to calculate the computations necessary to work to the capacity of the machines. Not only does this mean that the operator’s and innocent bystander’s safety is at risk, it also works the other way, that the attachment may be over-sized, under-sized, too heavy or too light so that the machine cannot be utilised efficiently or effectively
Cost - Costs are a major reason why many manufacturers don’t make use of technology. Some manufacturers that have the technology don’t use it because to weld a brace here or there takes extra time and labour. The efficiency of the double radius bucket design in eiengineering buckets requires the entire back plate be rolled, whereas in a single “D” design, only a small part of the back plate needs to be rolled.
Effort - Labour costs and time are two reasons manufacturers don’t use technology to their benefit.
Efficient excavator bucket design
Fig. 1 on the right indicates the reason for the full curve of the bucket back plate. This design shows the teeth digging the material and the rest of the bucket following the teeth through the cut collecting the dug soil quickly and efficiently. This puts less strain on the bucket as well as the excavator and will save fuel and maintenance costs.
Fig. 2 on the right shows a flat bottomed bucket moving in the arc of the excavator dipper arm ploughing the material using extra power and fuel. Note that the heel of the bucket grinds into the cut right through the digging process.
Greater bucket capacity by design
Fig. 3 shows how we can build more bucket capacity into the bucket design. This assures the operator that for the same pin to point bucket height, the capacity is increased around 10%. Importantly, this means that greater capacities are achieved without losing any of the bucket breakout force.