Trailer hitch receiver, 1-1/4 in square (SAE J684 classes) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/trailer-hitch-receiver-1-1-4-inch/  (sheet CC BY 4.0)
Basis: Manufacturer specifications (Lippert (CURT))
Catalog version: 2026-10-20

Overall (mm): length 31.75, width 31.75
- A 1-1/4 in receiver takes a 1-1/4 in square shank and a 1/2 in hitch pin, per CURT/Lippert's class and pin guides.
- Rated weights depend on the specific hitch; the class figures are the maker's typical ranges.
- No CAD file: the maker publishes only overall sizes, and a plain box or cylinder is not useful design geometry. The table is the published data; parts with real geometry have their own pages.

dimension  value
Receiver size  1-1/4 × 1-1/4 in (31.75 mm square)
Hitch classes  Class 1 (up to 2,000 lb GTW / 200 lb TW) and Class 2 (up to 3,500 lb / 350 lb)
Hitch pin diameter  1/2 in (12.7 mm)
Minimum usable pin length (excl. handle)  2 in (50.8 mm)

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Lippert (CURT): A Beginner's Guide to Hitch Classes — web — Publisher's page; dimensions are facts — https://www.lippert.com/blog/a-beginners-guide-to-hitch-classes
- Lippert (CURT): Guide to Hitch Pin Sizes — web — Publisher's page; dimensions are facts — https://www.lippert.com/blog/guide-to-hitch-pin-sizes

No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.
API: https://xemstudio.com/api/geometry?object=trailer-hitch-receiver-1-1-4-inch