How to link comb boxes in excel ???

I'm trying to find a way to build combo box for several tables. Attached is an example of the problem I'm facing. In a nutshell, I have three major categories (W. Loaders, T. Loaders, Excavators) and for each one there are a number of equipments with their data. Anyway, I was able to make a combo box for each category but I'm trying to have in cell one the three categories. Once I select the category in cell one the related data will be available in cell 2, 3, 4 because I have three available data for each category. If you have the chance to see the attached file which is just an example, you will have better understanding of what I'm trying to say here.

Your help is greatly appreciated

Take a look at the attached and see if this is what you meant.

See sheet2. You can use Data Validation with the list option and eliminate the need for a combobox.

That's exactly what I meant thank you so much.