What is the best plain bearing for agricultural machinery?

There must be an answer to this question. After all, there are a limited number of "best Italian restaurants", "best frozen pizzas" and "best TV shows". We don't even have to narrow it down. Such is the case with the question of the best plain bearing for agricultural machinery. At the end of the day, there is no "best" of anything. You know that as well as I do. But the question keeps coming up. Who should I order a pizza from? Should I bake one myself? Or should I go out to dinner? When all is said and done, I wonder if I should modify the beef stew recipe I've made a million times. You may be wondering what this has to do with sliding bearings. Very much.

The first question has to be, "What do I need this for?"

Let's move away from the cooking example. Before we ask what kind of plain bearing is best for agricultural machinery, it might be helpful to elaborate on the question. What do we mean by "agricultural machinery"? Technically speaking, the plain bearing in the cockpit lever of a combine harvester is part of the agricultural machinery. But its technical requirements are very different from those of a seeding plow blade depth limiter. There are many differences of this type: pressure rollers, parallelograms, metering devices and additional components such as track loosers, track markers, folding mechanisms, etc. Various forces are applied everywhere to the sliding bearings, which have a wide range of motion profiles and different sealing requirements to protect against dust and moisture.

This is just the seeding plow blade bearing point. A tractor is a completely different machine. One has a gearbox and electric lift, the other has a variety of adjustable seats and armrests, control elements and displays. The range of applications and needs is enormous.

Is there a "best" plain bearing for agricultural machinery?

Sure, it would be nice if there was only one slide bearing that could do everything, or at least most things. But is there any food you've always liked? Maybe French fries and ice cream? But they usually cause stomach pain and weight gain, so they don't always help. But before we eat, we ask ourselves, "What do I need this for right now?" At least subconsciously. If I'm out for a walk and want something to eat, french fries are great. On a laid-back Sunday, I might prefer beef stew. To get the day off to a healthy start, low-sugar cereal is better.

In the technical field, this means that the most important parameters of use should be defined.

◬ How much force is applied to the sliding bearing?

◬ What is the kinematic curve and how fast do the shaft and the plain bearing move with respect to each other?

◬ What rod body will be used as a counter partner?

◬ How high is the ambient temperature?

◬ Are there other environmental conditions, such as dirt, moisture or weathering?

◬ How good is the necessary operating performance?

A path through the jungle of choices

Just as there are many different types of food, each with many recipes, there are countless types of plain bearings. Just as there are hundreds of good and common recipes for beef stew, the range of products from manufacturers specializing in plastic bearings varies greatly: there are reinforced fibers, PTFE, silicone-free resins, chemical resistance, heavy-duty, and more. But when should I use which bearing?

The problem with plain bearings is that while the technical literature provides various methods for calculating the durability of various bearings, they turn out to be only rough approximations. Many influencing factors, such as dust ingress, shaft surface and material, shock and impact, are difficult or impossible to consider, but have a significant effect on the service life of a plain bearing.