(Mechanical Project) Automatic Trimmerhead

Automatic trimmerhead is an examination project for making an automatic trimmerhead for grass trimmers with the user and functionality in focus. Our perception is that a happy user is a user who can pick up his or her trimmer, use it and put it back to its place when the job is done. It should not be necessary to interrupt work and perform maintenance on the machine just to make it work as promised.

The project has been made in collaboration with the company Husqvarna, which is one of the biggest actors dealing with garden machinery on the market. Together we determined the project goal, “To invent, construct and test a brand new concept for how an automatic trimmerhead can look and function”.

At this day there are several different automatic trimmerheads on the market, both semi and fully automatic. After having seen and tested many of these trimmerheads, we have come to the following conclusion. They are either difficult for users to handle or has unreliable functions, sometimes both. We have, with this kept in mind, tested and analyzed the different models to find the problem. We found one, and maybe the only, reason to why these trimmerheads does not function as promised. All the trimmerheads functions are based on the increased rotation speed that will occur when the cord breaks off.

In our product we have therefore designed a mechanical solution that feed cord based on not only the force affecting the cord but also on the length of the cord. A trimmerhead with a cord feeding function which can activate based on the length of the cord does not exist on the market and is according to Husqvarna, who has much knowledge on the subject, a new and very interesting way of solving the problem.

Since the beginning of the project we have had many ideas and surely we have encountered even more problems, but this is what has given us the knowledge we needed to make it to where we are today. The result of this is a brand new concept with good patent possibilities on several parts and functions which have given Husqvarna everything they need to continue the work and to turn our solution into a high quality product.
Source: Halmstad University
Author: Axenskär, Christian | Winde, David

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