Eventually you'll need some sort of parts. Open this link to the FNH Construction site, for the 4500.
New Holland Construction | 4500 - 3 Cyl Industrial Tractor | MyCNHi US Store A lot easier to navigate using a personal computer.
Pretty well covers all of the function groups on the tractor. Just select a function group in menu to the left. Then drill down through the particular section you want, and select that particular exploded view. You'll see an exploded view, then to the right a description and OEM part number. A red or green dot shows availability through a dealer, many show red, so N/A. But the important thing is, it shows the OEM part number. I found many years ago the secret to finding parts is to use the OEM part number. Copy and paste that OEM part number to a good search engine. Google works best for me.
Many salvage yards, aftermarket dealers, ebay sellers, etc. list many parts using the OEM part number. Much better than just using a generic term when looking for parts, and you know you have the correct one.