What do you actually check on a pre-trip inspection?

Sounds like grease. Oil hubs have the plug. It’s vented by the little hole in the center. If it has the clear window, and if it’s old and foggy or if there isn’t any window at all, you can remove the plug, and visually inspect the oil. Also should sure the vent hole isn’t plugged. A plugged vent can cause the seal to fail. You can also stick your finger in the oil and feel around for any metal. Be careful if the hubcap and plug are old and brittle. The rubber plug gets hard like plastic, and the plastic windows get brittle and can break when removing or re-installing the old plug. The grease caps aren’t vented, and don’t have any access plug. Typically if an oil seals leaking badly, you can easily see oil all over the backside of the shoes, sometimes a stream runs down the tire after sitting a while. Especially after 2-3 days in the hot summer. Often that’s when an old seal will leak. Sometimes it will stop leaking for a while. Good idea to look for a steam of oil running down the backside of a tire as part of a pre trip. Also can look at backside of shoes/hub from opposite side fairly easy. Crawling around underneath on the ground isn’t practical. Ideally seals will be checked for seepage by looking inside the drum/hub area and if seeping be changed before it completely blows out and makes a big oily mess of everything. Grease seals usually just seep a little bit. They usually don’t blow out and make a big mess. There’s different grease. Some of the first used were a thinner semi fluid, they all act like oil when warm in operation, and thickening up like grease when cooled or parked. Usually it’s a OO weight grease. Very thin, yet it stays in place amazingly well, and lasts a long time. So if the hub cap doesn’t have a vent or removable cap, it’s probably filled with grease, and probably won’t ever give you any problems.

 

Wow. It took 55 posts to see one that I could identify myself with.

Almost 16 years under my belt in NA. No matter what the weather is, at least I take that walk around check every morning.
I go under every trailer when I hook up to it. If it's too muddy right there, find a more convenient spot. Even if it's the next truck stop.

Running in winter conditions, make sure your wheels are turning. I had a few frozen shoes but never ruined the tires. I found them all.

 

Agreed -- I'm sure every maintenance department that's dealt with me gets sick of me calling, but it is what it is lol. I'll be realistic about the actual risks involved and will run it to where they want it fixed, at least.

Really doesn't add any time if done right. If anything, one could argue it saves time when factoring in the chance of a road service call being avoided. Customers, 30 minute breaks, right after parking for the night on the way into the bathroom, etc.

Just a couple weeks ago, I picked up a trailer, went two miles down the road to scale it and grab a coffee, and an old, dry rotted air bag started leaking in those few minutes of driving. Seems like every time you think "there's no way", it finds a way to break lol. Wasn't bad enough to hear without a walk around. Wasn't a big "catch" in St. Louis, but it could've been a bigger problem if someone picked up that same trailer and ran it west out of Fargo and didn't notice it til the next morning if it had blown completely.

 

If you need to add oil you
Add the oil through the valve stem

 

I think he has auto inflaters. That’s a whole different ballgame!

 

Yeah your right then he shouldn't worry cause the auto inflater will keep the hubs automaticaly full

 

Those autoflates move the fresh oil that is stored in the outside tire thru the hubs and then the used oil flows from hub into the inside tire were it is stored until it can be rotated back to the outside tire.