Tables Relationship Strategy

My db tracks equipment maintenance & repair for estate maintenance. And thanks to contributors on this site, it has proved to be very useful. I have 2 tables now.

Table: ShopWork. Fields: JobID [Pkey]; Ynumber [text, unique number assigned to each machine]; WorkDone; WorkDate; Notes

Table: Equipment. Fields: Pkey; Ynumber; Description; Make; Model; SerialNumber; NewDate; Active [Yes/No]; EquipNotes

I want to begin tracking parts purchases and usage.
Table: Parts (planned, currently a spreadsheet). Fields: Date; Vendor; Mfr.; Part No.; Part Name; Qty; Used On; Cost; Total

My question is the relationship between Equipment & Parts tables

I would like to know what the part is for when it is ordered.

I was thinking of creating a category field in the Equipment table.
Possible category names:
Riding Mower (we have 4 different types)
Walk-Behind Mower
Leaf Blower (2 different types)
String Trimmer (3 different types)
Chain Saw (3 different types)
Back Pack Blower (2 different types)

For example, a fuel filter is used on multiple machines: trimmers, blowers, chainsaws.
I order 12 at a time, and they are used as needed.

I am curious to know how others have approached this problem.