====== three point hitches ======

^ Projects infobox ^^
| Image | {{:archive:three-point-hitch.scad.png?240}} |
| designers | [[:user:tim|Timothy Schmidt]] |
| date | 2021 |
| vitamins |  |
| materials |  |
| transformations |  |
| lifecycles |  |
| tools |  |
| parts | [[:frames|Frames]], [[:nuts|Nuts]], [[:bolts|Bolts]], [[:end_caps|End caps]], [[:plates|Plates]] |
| techniques | [[:tri_joints|Tri joints]], [[:space_frames|Space frames]], [[:trusses|Trusses]], [[:bolting|Bolting]] |
| files |  |
| suppliers |  |
| git |  |

[[:category:projects|Category:Projects]]

[[:category:agriculture|Category:Agriculture]]

==== 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 ====

How to match industry standard sizes using as few [[:category:parts|parts]] and [[:vitamins|vitamins]] as possible.

==== Size categories ====

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

^ Category ^  ^  ^  ^  ^
^ Tractor power ^  ^  ^  ^  ^
^ Top link pin diameter* ^  ^  ^  ^  ^
^ Lift arm pin diameter ^  ^  ^  ^  ^
^ Lower hitch spacing ^  ^  ^  ^  ^
| 0 | Up to 20hp | 5/8 in | 5/8 in | 20 in |
| 1 | 20 to 45hp | 3/4 in | 7/8 in | 28 in |
| 2 | 40 to 100hp | 1 in | 1+1/8 in | 34 in |
| 3 | 80 to 225hp | 1+1/4 in | 1+7/16 in | 40 in |
| 4 | More than 180hp | 1+3/4 in | 2 in | 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.

:* refers to implement end; tractor end not specified

==== Approaches ====

''{{:archive:plate-three-point-hitch.scad.png?600|Plate adapts to 5/8 inch, 3/4 inch, 7/8 inch pins for category 0 and 1}}''

{{:archive:three-point-hitch.scad.png?600|Category 0 hitch}}

{{:archive:three-point-hitch-category1.scad.png?600|Category 1 hitch}}

==== Attachments ====

{{:archive:pxl_20210531_000317977.jpg?600|Planter}}

  * Backhoes
  * Cement mixers
  * PTO stump grinders
  * Trenchers
  * Scoop pans
  * Wood chippers
  * Post drivers
  * Chain harrows
  * Cultipackers
  * Land levelers
  * Soil pulverizers
  * Cultivators
  * Subsoilers
  * Harley rakes
  * Finishing mowers
  * Flail mowers
  * Sickle bar mowers
  * PTO fertilizer spreader
  * Pine needle rakes
  * Sprayers
  * Straw blowers
  * Seed planters
  * Potato plows
  * Booms
  * Carry alls
  * Sweepers

==== References ====

  * [[https://en.wikipedia.org/wiki/Three-point_hitch|Wikipedia: Three-point hitch]]
  * [[https://wiki.opensourceecology.org/wiki/Bobcat_Standard_Quick_Attach|OpenSourceEcology: Bobcat Standard Quick Attach]]

----
[[https://github.com/timschmidt/replimat/blob/e0bc0b855bb946bab00c75ca0d8b002ae0dc0172/wiki/three_point_hitches.html|Original archived page]] — revision 8374, 2021-09-25T14:11:08+00:00, by Tim.