Glossary entry (derived from question below)
Spanish term or phrase:
eje triple rodado simple
English translation:
Tri-axle, single wheel / Tri-axle, single wheeled
Spanish term
Translator
Native in: Spanish 
Works in: English to Spanish, Spanish to English, Portuguese to Spanish, and 2 more.
eje triple rodado simple
Cálculo de momento por carga especial
Camiones
Gracias!
Proposed translations
United Kingdom
Freelance Medical Translator, MA (Hons)
Native in: English (Variants: British, Scottish)
Works in: French to English, Spanish to English, English
Tri-axle, single wheel / Tri-axle, single wheeled
http://cbi-mfg.com/catwalk
Another reference with a photo at
https://ps-af.facebook.com/marketplace/item/3831975796829403...
And another here
https://www.marketbook.co.za/listings/trailers/auction-resul...
32 foot long tri-axle single wheel, deck tail with ramps trailer.
2007 TN Trailers 52' Enclosed Trailer Tri Axle, Single Wheel, New Brakes Last Fall
worked for int. orgs (IMF, OAS, IDB)
Native in: English
Works in: Spanish to English, German to English
one/single-wheeled triple-axled (vehicles)
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Note added at 32 mins (2020-10-01 04:17:45 GMT)
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or just say: one/single wheel triple-axle
United Kingdom
experienced and well qualified linguist
Native in: English (Variant: UK)
Works in: Spanish to English, English, Spanish, and 3 more.
single triple-axle wheel
"study or survey of a bridge's resistance
current measurements or calculations by specific charge
lorries, trailers or trucks"
Chile
Business communication and health
Native in: Spanish
Works in: English to Spanish, Spanish to English, Spanish, and 1 more.
tri axle/3 axle, single tire
Yo traduciría el rodado simple como single tire/tyre. Tambien he visto que se refieren a este término como super single tire.
https://rjrlaw.com/practice-areas/sc-accident/tractor-traile...
Triple eje en inglés para mi sería: tri axle o 3 axle
https://engineering.stackexchange.com/questions/29514/why-ar...
Discussion