greasable dust caps

I make these for all my implements and trailers

Is there a reason you have the grease fitting off center???

I would rather drill a hole through the side of the hub into the area between the bearings. Then tap the hole for the fitting in the hub.

I have seen where the inside bearing gets very little grease from the dust cap grease fittings style.

Yes you have to make sure uoy have grease at the back seal before you stop greasing I do it this way because its easier to just pop the cap off and bore a hole tap it and stick the cap back on where drilling the hub is probably a better way to get grease to both bearings easier it would also require more time to do also some of my hubs won't allow that . This method is nice when buying equipment take a cordless drill some zerks and taps and you can grease right there and head home. As far as bien offset no real reason though I have had some with a tight clearance between the end of spindle and cap where the offset will let the grease go in easier .
.

I hate being a wet blanket, and I don't want to kill your idea but it has one, possibly two, fatal flaws, depending on how you look at it. What I'm talking about is the fact that when you add enough grease the the cavity in the hub will get full. Once this happens, one of two things is going to happen.

One, the pressure acting on the dust cover is going to push it off. That is the best case scenario. In that case you'll know the second it happens and can put it back on.

Two, and what's more likely to happen, given that the dust cover is installed with a bit of a press fit, is that the pressure of the grease will push past the hub seal. If it causes it to invert then contamination will be able to get into the hub.

If you look at the 'factory' setups, every one I have seen has a low pressure valve to prevent either scenario above from happening. Without that pressure relief the seal is almost always going to be the weak link, and without it working, no matter how much grease the bearings have, their life is going to be shortened by any contaminates that get in to them.

Your better off to just use a good grade of grease, and keep it checked at a regular interval if driving on dry land, and even more frequently if it's on a boat trailer that gets immersed. I work on trailers for a lot of different guys that do landscaping, etc, and the most frequent problem I see is that they let the bearings get loose, and their problems start there, I've seen some that failed, even with grease, simply because the hub got loose on the spindle. Rarely have I seen one, in fact I can't remember one, that crapped out completely from a lack of grease.

Looks like a great way to blow a seal.

I have did this for years and it works. If you do blow back seal the grease will make a dust seal and keep dirt out as well as water. John Deere has used that system for years on the old tractors( 37 F-20 came from factory with grease zerks). All my Farmall & IH tractors have had the caps drilled and tapped for grease zerks and after doing so have never had a wheel bearing failer.

Won't invert the seal because you install the seal with the lip facing out, not in. It has been done that way for years.

I too have greased the front wheels of my two banger Deeres through the end cap for years and have not lost a bearing or seal from over greasing. I pump till a little air and grease starts coming under the seal. I did lose an inside bearing once because I wasn't greasing enough for fear of hurting the rear seal. Jim

I have done the same thing on my equipment for the last 45 years never had a problem, and I have a lot of wheel bearings setup for greasing this way, even my Vermeer baler has them installed from the factory, to me this is a great thing to do, I do it on my tractor hubs as well

I have bearing buddy caps on my boat trailer. Same thing except the bearing buddy caps are also spring loaded.

I filled the center cavity with grease on my trailer and found out how good grease works on the brakes.

I tapped and installed zerks on my gooseneck trailer with brakes I have had no issues in 150,000 miles or more

I guess I"ve been reading too many trade magazines where this stuff has been studied, and personally seen it happen on customers equipment. That said, your right in the fact that a glob of grease will tend to somewhat keep water out, but the problem is that same glob of grease also attracts, and holds dirt/grit. The result is that the dirt and grit tend to basically turn the grease into lapping compound. In turn it will eat the seal, as well as cause the seal to cut into the shaft. The only way to prevent this is to keep the area around the seal grease clean, which pretty much negates the greases ability to seal out water and contaminates. I see the same thing all the time on equipment, and what it works out to is that there is such a thing as over greasing on any type of joint, or bearing. Granted I don"t see this happening in this scenario because most tractor and implement bearings aren't going to see a high enough speed to really get hot, but the rolling resistance in a bearing with to much of a grease load is increased to the point that it can cause it to overheat.

That said, it is the seals job to keep out water and contaminates, not the job of the grease. At the same time, it's the greases job to lubricate the bearings, not seal them. IF you have the seal backwards then it can't do it's job. IF you have gobs of grease pushing past the seal, then the grease can't do it's job. Basically what you have then is a situation where you have to keep greasing the part to insure that the grease stays where it's supposed to be to seal the joint, because the seal is no longer doing it. When done properly, the seal does it's job, with no help, and with good quality grease, it does it's job with no help.

Think about it like this. The wheel bearings in your tractor, or on your trailer, are no different than the wheel bearings on your car or truck. Who would even think of doing something like this to the wheel bearings on either of those types of vehicles. In reality you really shouldn't simply because the gobs of grease pushing past the seal will get on the brake shoes. At the same time, those bearings are the very ones that see way more abuse than the ones on your tractor, or implement. First they are spinning a lot faster with a load on them all the time. Then, the shock loads to them when you hit a pot hole, etc at 60 MPH are as great or greater than anything your tractor, or implement, is going to experience. Still they work just fine day in, and day out just as they were designed to do.

As a mechanic, I can see the value in using one of them on something like a boat trailer where the wheels get submerged, and water has the potential to get in the bearing housing. On the other hand, in general use, I have seen just as many bearings fail that used the "bearing buddy" or some variation thereof, as I have those that had nothing but a plain dust cover. Like I said originally, most wheel bearing failures, at least that I have seen, come from not keeping them tight/preloaded, not from a lack of lubrication. So, if your doing proper preventative maintenance, your going to have to take the dust cover off to check the preload now and then anyways. So, why not go ahead and pack in a little grease when your there, and let both it, and the seal do their jobs...........Instead of wasting a lot of time and grease where it"s not really needed?

Ultimately, what I see in most of these type things (at least on the commercial side) is just another 'better mousetrap' that someone is getting rich off of, but really isn't doing much good for the folks that buy them, in most cases, because nothing beats proper preventative maintenance. But that"s just my opinion based on 30 plus years of working on machines, trailers, vehicles, and all types of bearings, in many different applications.

As along as you keep them greased its not an issue. The contaminated grease is in the seal area keeps getting pushed out of the bearing area and replaced with clean grease. The only issue is the inside of the rim gets really messy as the grease leaks out.

If you fail to grease them for a long time while seeing lots of road or field use it might create a problem - but that could happen anyway.

I will agree with you, NCWayne. Also I cannot see gun grease as being a proper wheel bearing grease.

I have one grease gun loaded with wheel bearing grease.

I've got those on a Knowles wagon here and I took a pair of caps off an Oliver 70 and put them on my 1600 that has a loader on it because they have zerks in them. Running that thing in the mud feeding cattle in the spring,it's nice to be able to pump some grease in until the moisture starts crackling out of them now and again.

My stock trailer came with these from the factory. No problems after almost 10 years. I believe you can buy them, I think called "bearing buddies".

You guys must be out of touch because there is wheel bearing that can be used in a grease gun. Since we went to doing this we have not replaced any seals or bearings. You do clean it off from time to time. My John Deere D,L and Farmall F-20 have grease caps and if greased properly the bearings last for ever.

My issue isn"t with the grease coming out of a tube/grease gun -vs- a tub, as they do make good quality wheel bearing grease in tubes. My issue with the whole deal is that if the seal, and the correct type of grease are used, and both are doing their job, there is no need to keep adding to what is essentially a sealed area.

That said, I can see the benefits in certain situations, but nothing will ever take the place of proper, preventative, maintenance.

Bearing Buddies are quite different. They are spring-loaded and originally intended for boat trailers. Greasing the Bearing Buddy pressurizes the hub so water can't get past the seal.

The other system is the "E-Z Lube" axle, and is pretty common on utility trailers. The E-Z Lube axle has a passageway drilled through its center with outlets between the inner bearing and seal. Grease flows towards the dust cap, so in theory it won't be pushed out the seal. See the link below for a picture.
E Z Lube axle