The three-point linkage, or hitch, system is a standard system designed in the 1920s by Harry Ferguson for attaching farm implements to tractors. The basic system is comprised of 2 lower arms or connection points and one upper arm used to help stabilise the attached farm equipment. For more information on the three-point system, watch our slide show on top link assemblies.
The category of your linkage system is typically governed by the size of your tractor's engine measured in horse power. Ensuring that your tractor is fitted with the correct linkage fittings to enable your implements to be attached securely is critical and can result in costly repairs if not carried out correctly. The first point to note is to find out what category your tractor's three-point linkage system is.
Linkage Categories
| Category |
Description |
| 0 |
Normally used on the smallest garden tractors where lightweight implements are attached to some sub-compact tractors and ride on mowers. |
| 1 |
Compact tractors - this is probably the most common category found on tractors under 50 horsepower. There is a sub level to this category and that is with tractors that are classed as limited category 1. The limited part means that you will not have the full range of movement that a category 1 has as the hitch is lower to the ground. This means that implements may not be able to lifted as high or open as wide as a full category 1. |
| 2 |
Utility tractors - This is typically used on tractors between 50 and 140 horsepower. If you compare a category 1 to a category 2 you'll notice that the linkage has much bigger arms and pin holes to support larger and heavier implements on a category 2 machine. |
| 3 |
Large tractors ranging from 110-220 horse power. The linkage connection type changes here from a ball and pin to a hook which is easier to connect to large implements. |
| 4 |
Heavy duty tractors with engines larger than 180 hp |
Top Links
The rigid top link is responsible for setting and maintaining the correct tilt alignment of the implement for normal operation, any incorrect setting of this will result in the inefficiency of the implement being used.
Lower Lift Arms
The two lower hitch lifting arms are powered by the tractor's hydraulic system, and controlled by the driver/operator. The lower arms provide lifting, lowering, and even tilting of the attached implement.
Selecting the Correct Size Pins
You must have the correct size and type of pins to attach everything relating to the three-point system, these include linch pins and the pins for both ends of the top link assembly. The main lesson here is not to use substandard hardware such as using old bolts, nails, or anything else that you may think is suitable to hitch the implement, this is how accidents can happen when your implement falls off the tractor at the most inconvenient time. Some common mistakes are to use incorrectly sized or broken pins for a particular category of linkage as each category has its own size of pins as displayed below.
| Category |
Top link pin diameter |
Lift arm pin diameter |
| 0 |
5/8 in (16 mm) |
5/8 in (16 mm) |
| 1 |
3/4 in (19 mm) |
7/8 in (22 mm) |
| 2 |
1 in (25 mm) |
1 1/8 in (29 mm) |
| 3 |
1 1/4 in (32 mm) |
1 7/16 in (37 mm) |
| 4 |
1 3/4 in (44 mm) |
2 in (51 mm) |
FAQ
Can you attach a category 2 implement to a category 1 tractor?
You can attach a different category implement to a different category of top link assembly, for example fitting a category 2 implement with a 1 1/8 inch arm pin to a category 1 tractor with a 7/8 inch hole. To overcome this problem, you can purchase a category one pin and swap out the implement pins. Care should be taken to ensure that your category 1 tractor is powerful enough to operate the category 2 implement.
What if you have a category 2 tractor but a category 1 implement, can you attach the implement?
You can easily fix this in one of two ways depending on your lower link equipment. The quickest way would be to use a specially made sleeve to slide over the existing category 1 pin on the implement to make it into a category 2 implement. The second way, and this depends on your lower link arms, is to change out the ball on the arms for a category 1 size hole. This isn't a common piece of equipment but if your tractor it fitted with this feature then it can be really useful.
You can view our full range of Linkage Components or filter your search by selecting a parts category below:
How to Select Tractor Top Links...
Manual Top Links
Manual top links consist of adjustable tubes with a "ball end" at each end. One end of the ball-end is used to attach to the tractor the other to an implement such as a plough or hay tine.With manual top links, all length adjustments to it are done manually by placing a top link pin into the shaft locking collar.
Not all top links fit to every type of tractor. To select the correct top link to do the job, firstly you need to decide if your top link is going to be used for a specific tractor make. If not, a standard or heavy duty top link can be used. Next, the type of ball end that fits on to the tractor needs to be specified. Finally, the ball end that attaches to the implement parts needs to be chosen.
To make this task easier, you can use our Manual Top Link Wizard which guides you through the process of selecting the correct top link. . Alternatively, please contact us to discuss your requirements.
Hydraulic Top Links
Hydraulic top links as the name suggests enables the top link to be adjusted hydraulically rather than manually. This provides much greater control when adjusting the angle of the attached implement.
As with manual top links, hydraulic top links can have ball ends to attach to the tractor and implement. Additionally for Hydraulic top links on the tractor end a knuckle-type fitting can be used and on the implement end a hook fitting can be specified. As with manual top links, a ball attachment is also available.
Use our Hydraulic Top Link Wizard to make it easier to select the correct top link. Alternatively, please contact us to discuss your requirements
.