Help with zirk fittings
Question: (I hope this makes sense....here goes) When pumping grease through the wheel zirk fittings, is it fair to say that as long as grease is flowing back out through the front seals that you hav...
Forum Discussion
Sjm9911 wrote:
Im not a mechanic, but are those closed systems? The zerk fitting isnt. One side is open. I can see in a closed system adding grease or anything for that matter make something give. In an open system the path of least resistance is followed. And i will agree , the people that probably have problems are those that do not do it correctly, or dont use it at all for a long period. The latter could make a blockage with hardened grease, making it a closed system.
It is both "open" and "closed" system.
Take a look at the diagram below.
The axle stub has a long hole bored through the center.
That bore goes all the way to right before the inside of the grease seal where their is a cross bored hole.
Grease must be pushed all the way through that bore and cross bore, into the outside of the inner bearing that is against the inner seal.
Grease then must travel in to the hub cavity, filling the cavity completely before reaching the inside of the outer bearing.
The grease must be pushed through the outside bearing and the outside of the outer bearing is "open" to atmosphere.
The grease must travel that long skinny bore then make a hard 90 degree turn into the cross bore, push through not one but two bearings..
There is going to be resistance the entire route the grease must travel.
Resistance = pressure build up.
It is critical that one turns the drum or hub while using this system as that helps reduce the pressure buildup.
