Bearings 101

[Sea Wind]

Hey Guys,
I bought a tandem axle trailer last year and after two seasons it has about 7000 miles. I usually check the bearing every 250 miles on long trips and they never get warm.
My questions are, how do I know when the bearings need grease? Also what type of gun/grease should I get?
Here are a couple of pictures:





Thanks,
Pedro

[seahouse]

Hi Pedro-

From the picture it looks like you have a button-type grease fitting. I’ve seen this type of fitting on European industrial machinery requiring high volumes of grease, but until now I had not seen it used on trailer bearings. It requires a dedicated fitting on the grease gun that slides onto it from the side (hence, I presume, its being offset from the centre). You’ll need to buy one of those.

Most hub greasers allow the pressure from the gun to compress a spring-tensioned piston that over time continuously forces the fresh grease through the bearing and out the rear, or axel, side.

For these types, of which yours may or may not be, checking the degree of release by visual inspection of the piston position is usually done every 6 months or so, and grease added if needed.

I would try and find out the manufacturer of your particular hub and get their recommendation on frequency, if you want to be safe. Maybe some else on the forum will recognize and be more familiar with this arrangement than I am. Until then (after 2 seasons you just might be on borrowed time now) I would give a couple of (slow- so as to not risk blowing out a seal that might be vulnerable) pumps with the gun every few months, depending on mileage and number of submersions, and keep checking for heat buildup, just as you’ve wisely done.

It’s VERY important (as with any grease fitting leading into a precision bearing) to carefully wipe the surface of the nipple clean before you connect the gun to it. A single grain of sand (and button fittings have a larger opening in them than regular nipples, so the risk is greater) in the opening will get pumped into the bearing by the gun and in the wrong place it will toast your bearing.

- Brian.

[seahouse]

It’s hard to tell, but looking at the picture it’s also possible that the fitting might lead into drilled holes that terminate at the interior of the bearings, feeding them directly, so no piston feeding them. In that case a couple of pumps at regular intervals should keep fresh grease on the bearing. The grease oozing out in the picture looks pretty fresh for being 2 years old, though. You might find that, if you have trouble attaching the grease gun, that you'll have to bend the cotter pin out of the way to give you more clearance.

[Catigale]

..and remember your tandem axle trailer is running those bearings <50% of rating, compared to 95% load rating of the ingle axle trailer, so the lifetime will be much, much, longer.....

[Hamin' X]

What he has is a SuperLube spindle and hub unit from Tie Down Engineering. Different from and not to be confused with Bearing Buddies. The hub only version puts grease in from the rear and does not have the grease passage down the spindle. I have never seen one the the button head grease fitting before. It makes sense though, because they are typically used for high volume applications and here, you are applying new grease until all the old grease is displaced. More info:

http://www.tiedown.com/pdf/c718.pdf

~Rich

[Sea Wind]

thanks guys! Rich, I think that you are spot on. I knew that they were not bearng buddies but was not sure what they were.
Good to know that all I need is a regular grease gun.
Pedro

[Oskar 26M]

What he has is a SuperLube spindle and hub unit from Tie Down Engineering. Different from and not to be confused with Bearing Buddies. The hub only version puts grease in from the rear and does not have the grease passage down the spindle. I have never seen one the the button head grease fitting before. It makes sense though, because they are typically used for high volume applications and here, you are applying new grease until all the old grease is displaced. More info:

http://www.tiedown.com/pdf/c718.pdf

I have Tie Down Engineering Supelube hubs on the Venture trailer I bought two years ago for my . I store the boat mast up on the trailer at my marina, so the trailer usually travels no more than a few hundred metres and the bearing never get warm. I periodically 'top up' the grease in the bearings just to make sure no water accumulates in the hub.

I recently planned an 8000 km trip with a heavily loaded boat so before leaving I undertook a 200km 'test run'. One of the bearings got quite hot quite hot during the test run so I replaced the grease in all the wheels. It is easy to do with a standard grease gun following the directions in Hamin' X's link. I also added more grease a couple of times along the way. I checked the bearing temp by hand every few hundred km, and they stayed cool the whole way.

On my trailer the grease hub caps have yellow "Bullfrog" rubber plugs (not the black Tie Down plugs shown in Sea Wind's photo). The yellow rubber becomes brittle over time and split, so they have to be replaced regularly.

[seahouse]

Thanks Rich-
Good system, that. Nice and simple. I see (from the link) why it is not as widespread as Bearing Buddies. It requires a factory-dedicated axel (or hub) with a spindle that’s been drilled and tapped. And cannot be retro-fitted as simply on any trailer the way the Bearing Buddy can (by swapping the hub cap).

So they recommend an annual greasing.

-B.

[Tomfoolery]

Here's a pic of button head grease fittings. Not real common these days, especially in automotive, but you can get a fitting for your grease gun if you want. Or just change them out for standard Zerks.



Dexter EZ Lube is a similar system, but what's puzzling is that the fitting is off-set from the spindle center. Normally you'd drill the center because it weakens the spindle the least that way. That fitting is far off center.

Perhaps you could wipe that area clean and take another pic, for the knowledge base here. Any pitch that's not a fastball over the plate is an opportunity for us to learn something, after all.

[seahouse]

The mating fitting on the grease gun has a straight section that slides on from the side, so I don't think you'd have enough clearance to attach the gun fitting to the button if the button were centred on the spindle. I wasn't clear, but that's the offset I was alluding to in my post above.

They did drill the "grease gallery" holes to the side, and not above or below the centre line of the spindle - so it looks like there was some consideration for the loss of strength from having a hole there.

-Brian.

[Ormonddude]

lol I may be a stubborn old sob but I think I would simply pull all that junk out of there-put in normal stuff and new bearing buddies because if I never seen it I dont like it and dont want it and I have no IDEA why they did that. (actually I do know its to wrangle you into expensive replacement bearings grease and fittings) I will have none of it I say NONE!!!! lol

[RobertB]

lol I may be a stubborn old sob but I think I would simply pull all that junk out of there-put in normal stuff and new bearing buddies because if I never seen it I dont like it and dont want it and I have no IDEA why they did that. (actually I do know its to wrangle you into expensive replacement bearings grease and fittings) I will have none of it I say NONE!!!! lol

Why spend alot of money replacing something that works when all that is needed is a grease gun adapter?

[Default User]

Pedro,

With the kind of luck I have seen you have, you should consider installing an active temperature monitoring system, with automatic grease injection.

Interresting thread tho, I believe that I may go thru my bearings again.

Hope to see you in the '13 sailing season somewhere.

FairWinds,
Dave

[Ormonddude]

Why spend alot of money replacing something that works when all that is needed is a grease gun adapter?

Okay first of all I have never seen a grease stud sticking out of a bearing, second a bearing buddy is self monitoring (you load it until grease comes out the full hole and refill it when the spring is relaxed and the squash plate is receded) Third bearings and bearing buddies are pretty cheap about $50.00 a Axel. Forth I seen a on Ebay where the bearing failed and the wheel went through the fender and the Hull. Fifth unless the trailer was new its a good idea to take the old bearings out and inspect them. Sixth its almost silly to reinstall technology that is somewhat unseen by me or this forum. Seventh Most people Including me would replace the bearings upon inspection regardless of condition and keep the old bearings as Spares. If you need more reasons I may could squeeze out a few more but I think you get the point.

[seahouse]

After two years (and who knows how many more) without attention, the system as it is has proven itself without failure. It’s only going to get better when routine maintenance is done.

I think going to the trouble of replacing something because some people are unfamiliar with it is not a good reason to do so. In fact, while it may or may not be the case here, very often the best systems are the ones that are not so common in the mass market. But we are in internet land, and what is a normal best practise in one region, might be unheard of in another.

If there will be sufficient clearance under the rubber dust cap, replacing the buttons with standard grease nipples, as suggeted, is a viable solution, but I suspect that the reason the button fittings are there in the first place is because of their low profile under the caps.

- B.