Rastra de tiro excéntrico, para facilidad de operación ajustándose a la comodidad del operador y, requerimiento del terreno. Se puede ajustar para ir directamente detrás del tractor o hacia un lado.

https://www.deere.com/es_LA/products/equipment/tillage/harro...

425
Offset Disk
Offset Disks provide reliable strength

https://www.deere.com/en/tillage/disks/425-offset-disk/

New offset disc harrow. Used for the second stage of cultivation after ploughing and before planting. It is essential that you use a disc harrow (or other type of harrow) to break down the soil to a fine tilth before planting. Atempting to plant directly into soil that has been ploughed but not adequately harrowed is likely to result in damage to your planter.

http://www.dumelow.co.uk/offset-disc-harrow.html

Mounted Offset Disc Harrow
ADVANTAGE
The FARMKING MOUNTED OFFSET DISC HARROW is used in open farm workings for the superficial ploughing, for the shattering of clods, preparation of soil for sowing, burial of organic substances & remains.
To air the soil and to eliminate the weeds.
For breaking the roots.

http://www.agro-implements.com/mounted-offset-disc-harrow.ht...

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Note added at 1 hr (2017-10-10 22:05:34 GMT)
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Here's a definition of a 'rastra de tiro'.

Las Rastras de Tiro son aquellas que se enganchan a la barra de tiro del tractor, y se acoplan las mangueras con el sistema hidráulico del tractor que hace que las llantas bajen para transportase y que se suban al iniciar la labor en el campo. Se recomienda su uso en parcelas planas y grandes que le permitan al operador maniobrar.

http://www.agromaquinarias.net/rastras-de-tiro-2/

There are four general types of harrows: disc harrows, tine harrows (including spring-tooth harrows, drag harrows, and spike harrows), chain harrows, and chain-disk harrows. Harrows were originally drawn by draft animals, such as horses, mules, or oxen, or in some times and places by manual labourers. In modern practice they are almost always tractor-mounted implements, either trailed after the tractor by a drawbar or mounted on the three-point hitch.

https://en.wikipedia.org/wiki/Harrow_(tool)

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Note added at 1 hr (2017-10-10 22:09:13 GMT)
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I've compared photographs of disk and drag harrows, and 'rastras de tiro' all have disks.

https://www.google.co.uk/search?q=rastra de tiro&source=lnms...

https://www.google.co.uk/search?q=disk harrow&source=lnms&tb...

I think it's probably better not to include 'offset'.

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Note added at 22 hrs (2017-10-11 20:04:40 GMT)
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Las rastras de discos son equipos de labor secundaria principalmente. Aunque en algunos lugares y ocasiones también se utilizan como equipos de labor primaria.

Tipos de las rastras de discos

Por el tipo de enganche al tractor y según la disposición de los cuerpos:

Enganche al tractor.

Integrales. Son aquellas que enganchan al tractor por tres puntos. Van suspendidas en el transporte. Equipadas con discos de 50 kg. y su peso es relativamente pequeño.
De arrastre. Enganchan al tiro del tractor por medio de una barra de tiro. Estas rastras de discos son mucho más pesadas y van equipadas con ruedas que sirven para el transporte y dar la profundidad de labor. Las ruedas son controladas por medio de un cilindro hidráulico.

https://www.reparatucultivador.com/rastras-de-discos/

If you're not sure what type of harrow it is, you could use 'trailed harrow'.

All trailed machines fold hydraulically for transport and a rear drawbar is offered as an option on models up to 6.6m.

http://www.greatplainsmfg.co.uk/en-gb/products/727/simba-x-p...