HF Trailer # 90154 Grease fitting on back of hub

[AceMan]

Does the fitting allow you to grease the seal and the bearing? HF manual is pretty bare bones on the subject.

[48Rob]

Ace man,

I don't own a HF trailer, so can't speak for their design, but generally if there is a grease zerk on the nose of the spindle, it is designed to carry grease to the rear or inner bearing.
(not to be confused with bearing buddy add on caps)
The "grease seal" isn't designed to be lubricated, but it does serve to contain the grease in the hub.

The front or outer bearing can be accessed by removing the hub, for regreasing.
The rear or inner bearing requires that the grease seal be removed for access.
The grease seal is usually destroyed during removal, so having a way to grease it for a few years before removal is needed (to clean and inspect) is a nice feature.

Here is a picture.
<img src="http://im1.shutterfly.com/media/47a0cf09b3127ccefbed7f20825f00000030O02AbNGjdu5bMge3nww/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/">


I looked up the manual, and it does suggest "greasing the seal".
Odd, as since the seals purpose is to prevent grease from coming out, the wear surface will always be exposed to grease.
Nowhere in the instructions does it say to use the zerk to lube the bearings.
It does say to remove, clean, and repack the bearings by hand every 2-3 thousand miles.
Maybe a call to their technical assistance line would get you a better answer.

Rob

HF manual
http://manuals.harborfreight.com/manual ... /90154.pdf

[Dale M.]

Actually this type of spindle (with zerk) is design for easy greasing of BOTH bearings... IN theory all the grease pumped in at inside bearing (between bearing and seal) is forced through both bearings and excess is allowed to ooze out through "opening" in dust cap... Excess is simple wiped off and rubber plug replaced in "dust cap".... Whole chamber in hub plus space in bearing should be filled with grease when done (in theory)... Seems to work well on most trailers I have serviced that are equipped so...



http://l.b5z.net/i/u/6149609/f/product_ ... e_7-11.pdf

IF bearings are "clean" this simply regreases them and you should be good to go...

Dale

[Larry C]

Actually this type of spindle (with zerk) is design for easy greasing of BOTH bearings... IN theory all the grease pumped in at inside bearing (between bearing and seal) is forced through both bearings and excess is allowed to ooze out through "opening" in dust cap... Excess is simple wiped off and rubber plug replaced in "dust cap".... Whole chamber in hub plus space in bearing should be filled with grease when done (in theory)... Seems to work well on most trailers I have serviced that are equipped so...



http://l.b5z.net/i/u/6149609/f/product_ ... e_7-11.pdf

IF bearings are "clean" this simply regreases them and you should be good to go...

Dale

The Dexter spindle looks like a good engineered product. I don't think the caps with grease zerk on the outside are that great. I have seen where they have pushed the inner seal out of the hub.
Also, I was always taught way back that you don't want to fill the hub with grease, just the bearings. It supposedly creates more heat. I believe I have even read this somewhere recently.
I do think the Dexter set-up looks pretty good though, especially if the hub and spindle are designed for this purpose.

Larry C

[Dale M.]

Do not confuse Dexter "spindles" with Zerks with "Bearing Buddies" that were first attempt to pack boat trailer spindles fully with grease to keep water out.....

Incidentally Volkswagen recommends (in early aircooled beetles and what not) to full packing front hub and rear rear axle carriers (on IRS cars) with grease.....

Think filling hub completely with grease and causing it to heat up or whatever is either myth or old wives tales....

Dale

[bobhenry]

Think filling hub completely with grease and causing it to heat up or whatever is either myth or old wives tales....

Dale

Here is what one old wife said.....

Lubrication Technology / Jul 2010
A Review on Grease Lubrication in Rolling Bearings
by Lugt, Piet M, Zabawski, Evan


As a rule of thumb approximately 30% of the free volume of the bearing should be initially filled with grease. It will be clear that this is much more than required to provide the bearing with a (fully flooded) lubricant film. In the beginning, excessive grease churning, or grease flow, takes place, which is responsible for the high temperature peak caused by the churning component of the friction torque. The initially thick lubricant films in the beginning indicate that at least during this initial bearing operation thickener enters the contact.

Single contact measurements by Aström, et. al.40, Williamson, et al.41, and Kaneta, et al.42* using a scoop to ensure fully flooded conditions, have shown that the film thickness is indeed higher than the fully flooded oil film thickness. The optical setup also made it possible to show that grease thickener lumps were entering the contact. The literature does not reveal if Ulis is really restricted to the initial phase of bearing operation. It might be that this is very pronounced in the beginning and diminishes slowly over time.

The most widely used model to describe grease lubrication is that the grease acts as an oil reservoir where the oil is slowly released into the running track (Booser and WiIcock43). Lubrication guidelines are then formulated according to this ability to bleed (Baker44). There is definitely no consensus here. Already in 1967 Scarlett9 referred to an alternative mechanism of a high viscosity layer retained within the rolling track.

And he is a registered tribologist .


Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, ...

The term is churning . Basically what is being said is if the thickening agent has no where to go it is forced thru the bearing also. The grease is designed to bleed oil as needed into the friction path and provide an oil film cushion. If there is no place for the thickner to hide it to gets ran thru the bearing. It's kinda like using 140 weight rear end oil in your crankcase!