Gland and Seal for Brake Hydraulics Question

[spitty]

Greetings,
I'd like to solicit assistance relative to a brake hydraulic system. I am rebuilding a vintage system that contains a pressure differential unit. The unit contains a dynamic piston with seals in a fixed bore. The seals are intended to keep fluid outboard of them in the bore.
I have several questions:
1. The piston gland or seal groove has a tapered bottom (see image), i.e. it is not orthogonal to the groove walls. Is this typical? If so, why?

The seals--now over 45 years old--appear to be 'square rings' (see image), but early line drawings seem to suggest that they originally had a conical cross-section with the larger diameter--the conical base--facing the fluid. I may be seeing compression set in the ring making them appear to be square rings.

2. My questions are: Would O-rings be effective in this application? Would a backup ring be appropriate? Is there a source for standard sized conical section rings? Would a square ring be preferred to an O-ring? http://s1342.beta.photobucket.com/user/krausepa/media/oring_zpsdf3c2919.jpg.html?sort=3&o=0

I'd appreciate any other comments or observations.

Thanks in advance.
Paul

 

[Achy47]

Dear Paul,

Thank you for reaching out for assistance with your brake hydraulic system. I understand the importance of precision and functionality in such systems, and I am happy to offer my insights and suggestions.

To address your first question, it is not uncommon for the piston gland or seal groove to have a tapered bottom. This design allows for better sealing and prevents any potential leakage between the piston and the bore. The taper creates a wedging effect as the pressure increases, pushing the seal further into the groove and creating a tighter seal. This design is also beneficial for preventing any debris or contaminants from entering the system.

Regarding your second question, O-rings can be effective in this application, but it is important to ensure that the size and material of the O-ring are suitable for your specific system. Backup rings can also be used to provide additional support and prevent extrusion of the O-ring under high pressure. There are also conical section rings available in standard sizes, and they may be a better option for your vintage system. I would recommend consulting with a supplier or manufacturer to determine the best option for your specific system.

Lastly, in terms of square rings versus O-rings, both can be effective in certain applications. Square rings may be preferred in situations where there is a large gap between the piston and the bore, as they can better fill the gap and provide a tighter seal. However, O-rings are more commonly used in hydraulic systems and can be more readily available in various sizes and materials.

I hope this information helps with your project. If you have any further questions or need additional assistance, please do not hesitate to reach out.