Diff breathers

[grandsons]

Sure... but it's my understanding that only the portal axles are designed as pressurized axles. The beam axles in the Grenadier is not a pressurized design.

I don't agree, because the breather cap is a valve type . To humble knowldge a valve is not designed to balance pressure, the pschhhhht you should hear when depressing the cap means that there was some remaining pressure..

Here is an accessory reseller, describing the famous pschhhhht

It's not a lot of volume, the audibility of the pschhhht is function of subtle parameters like the escape channel geometry.

 

[Tazzieman]

Mine goes pfsst

 

[parb]

I'm pretty sure, without having looked at it, that this is a check valve whose purpose is to provide unidirection.
Generally check valves are not considered to be part of a pressure management system, although it may seem that way when gas exchange take place. I'm not sure if the sound is due to gas escape through a narrow opening or something else.

In industrial engineering it's generally a type of device avoided in critical system because it's relative high failure rate when contaminated by fluids. If you have 2 of them independently on a system (like we do in a car) then the probability of failure doubles.

I'm sure that probability lies within acceptable levels at the Ineos fleet level for their design and cost objective. But you can make a different decision. Of course that requires you to design something with less risk and in case of relocating the thermal expansion of fluid feature to a different location you need to pay close attention to materials and routing.

The calculus ultimately becomes a estimation of which risk presents with the lower probability. The inputs are severity multiplied by probability.

I estimate the severity to be medium and probability to be low for me personally. I think the cost is small and the probability becomes very low by avoiding a check valve in that location and that is worth it to me.

I suspect that relocation that check valve further away from fluids likely offers the same benefit as the arb breather. This is mostly an analysis of risk of malfunction of the unidirection, which doesn't matter so much if it's located further away from where fluids can enter the valve.

Maybe an even better design would have been a thermal expansion chamber like typically done in boilers. But I think that is hard to get right in a vehicle that moves in 3 dimensions, and it's space consuming.

great discussion btw. I rarely get to talk systems risk and analysis anymore. I'm trying to push some of these ideas, practices and formal analysis methods into the world of AI.

 

[NQ94]

Agile Off Road has another good short video showing how the seal operates.
Cut the seal open and depending on the seals design there can be multiple sealing edges onto a polished surface or have a internal vertical face that seals. The issues with these type of seals occur at installation. Some seals can be separated and installed in two pieces with normal tools but there is a good chance the seal will leak after installation and leak worse if the sealing surfaces have been lubricated during reassembly. Some of these type of seals will have a special tool and or special instructions for installation to avoid distortion of the seal. The inner and outer surface that press onto the yoke and into the case may need sealant like Locktite 567 or 641 retaining compound to seal the two mounting surfaces to stop fluid weeping around the outside of the seal.
Depending on the internal sealing surface design these type of seals can handle pressure, they are used on some large engines accessory drives, industrial powertrains and compressors and in most cases are a better seal then a normal lip seal because when replaced the dynamic sealing surface is also replaced.

View: https://youtube.com/shorts/BxnC3pbznWc?si=3QuhMPtGOh_czJL9