{{Techniques infobox
|image           = 
|designers       = [[User:Tim|Timothy Schmidt]]
|date            = 2021
|vitamins        = 
|materials       = 
|transformations = 
|lifecycles      = 
|tools           = [[Wrenches]]
|parts           = [[Frames]], [[Nuts]], [[Bolts]], [[End caps]], [[Plates]]
|techniques      = [[Tri joints]]
|files           = 
|suppliers       = 
|git             = 
|reversible      = true
}}

[[Category:Techniques]]

=Introduction=
The three-point hitch is a widely used type of hitch for attaching [[Ploughs|ploughs]] and other implements to an agricultural or industrial [[Tractors|tractor]]. The three points resemble either a triangle, or the letter A. Three-point attachment is the simplest and the only statically determinate way of joining two bodies in engineering. 

=Challenges=
==Size categories==
There are five different hitch sizes, called categories.  The higher category hitches have sturdier lift arms and larger connector pins.

{| class="wikitable" border="1"
|-
! style="text-align: left; padding-left: 1em; padding-right: 1em;" | Category
! style="text-align: left; padding-left: 1em; padding-right: 3em;" | Tractor power
! style="text-align: left; padding-left: 1em; padding-right: 3em;" | Top link pin diameter*
! style="text-align: left; padding-left: 1em; padding-right: 3em;" | Lift arm pin diameter
! style="text-align: left; padding-left: 1em; padding-right: 3em;" | Lower hitch spacing
|-
| style="text-align: center;" | 0
| style="padding-left: 1em;" | Up to 20hp
| style="padding-left: 1em;" | 5/8 in
| style="padding-left: 1em;" | 5/8 in
| style="padding-left: 1em;" | 20 in
|-
| style="text-align: center;" | 1
| style="padding-left: 1em;" | 20 to 45hp
| style="padding-left: 1em;" | 3/4 in
| style="padding-left: 1em;" | 7/8 in
| style="padding-left: 1em;" | 28 in
|-
| style="text-align: center;" | 2
| style="padding-left: 1em;" | 40 to 100hp
| style="padding-left: 1em;" | 1 in
| style="padding-left: 1em;" | 1+1/8 in
| style="padding-left: 1em;" | 34 in
|-
| style="text-align: center;" | 3
| style="padding-left: 1em;" | 80 to 225hp
| style="padding-left: 1em;" | 1+1/4 in
| style="padding-left: 1em;" | 1+7/16 in
| style="padding-left: 1em;" | 40 in
|-
| style="text-align: center;" | 4
| style="padding-left: 1em;" | More than 180hp
| style="padding-left: 1em;" | 1+3/4 in
| style="padding-left: 1em;" | 2 in
| style="padding-left: 1em;" | 48 in
|}
There are also variants to the above categories denoted by N, (narrow). These utilize the pin sizes of the listed category, but the width of a category one step lower. The N variations are common in "quick hitches" and allow larger tractors to easily hook onto smaller utility implements.

:<nowiki>*</nowiki> refers to implement end; tractor end not specified

=Approaches=
<gallery>
File:Plate-three-point-hitch.scad.png|Three point hitch plate adapts to 5/8 inch, 3/4 inch, 7/8 inch 
</gallery>


=References=
* [https://en.wikipedia.org/wiki/Three-point_hitch Wikipedia: Three-point hitch]