Editing Tractor (section)

=== Drawbars ===
[[Plows]] and other tillage equipment are most commonly connected to the tractor via a [[Drawbar (haulage)#Agriculture and horse-drawn vehicles|drawbar]].  The classic drawbar is simply a steel bar attached to the tractor (or in some cases, as in the early Fordsons, cast as part of the rear transmission housing) to which the hitch of the implement was attached with a pin or by a loop and [[clevis]].  The implement could be readily attached and removed, allowing the tractor to be used for other purposes on a daily basis.  If the tractor was equipped with a swinging drawbar, then it could be set at the center or offset from center to allow the tractor to run outside the path of the implement.

The drawbar system necessitated the implement having its own running gear (usually wheels) and in the case of a plow, chisel cultivator or harrow, some sort of lift mechanism to raise it out of the ground at turns or for transport.  Drawbars necessarily posed a rollover risk depending on how the tractive torque was applied.<ref>{{Cite journal|last1=Irwin|first1=Amy|last2=Poots|first2=Jill|date=12 Apr 2018|title=Investigation of UK Farmer Go/No-Go Decisions in Response to Tractor-Based Risk Scenarios|journal=Journal of Agromedicine|volume=23|issue=2|pages=154–165|doi=10.1080/1059924X.2017.1423000|pmid=29648955|url=http://aura.abdn.ac.uk/bitstream/2164/12160/1/JAg_tractorpaper_revision.pdf|hdl=2164/12160|s2cid=4783478|hdl-access=free}}</ref> The Fordson tractor was prone to roll backward due to an excessively short wheelbase.  The linkage between the implement and the tractor usually had some slack which could lead to jerky starts and greater wear and tear on the tractor and the equipment.

[[File:Modern John Deere Tractor IMG 0401.JPG|thumb|left|A large, modern John Deere model 9400 four-wheel drive tractor with tripled wheels and a drawbar-towed tool chain, including one-pass tillage equipment, planter and fertilizer applicator with tanks]]

Drawbars were appropriate to the dawn of mechanization, because they were very simple in concept and because as the tractor replaced the horse, existing horse-drawn implements usually already had running gear. As the history of mechanization progressed, the advantages of other hitching systems became apparent, leading to new developments (see below).  Depending on the function for which a tractor is used, though, the drawbar is still one of the usual means of attaching an implement to a tractor (see photo at left).