Grease fittings for valves

[mOHMo]

Can someone help me to point out some doubts I have about grease fittings for valve?

1- where does the designations "Button Head" and "Giant Button Head" are from? The only standard stating "Button Head" that I found is DIN 3404.
2- is it correct to consider "Button Head" for 5/8" (16mm) fitting size?
3- is it correct to consider "Giant Button Head" for 7/8" (22mm) fitting size?
4- is there any limit in the pressure that each of these fitting size can hold? (how can I rate pressure for them?)
5- comparing DIN 3404 with some grease fittings I have bought I find that fitting size are not exactly the same: is there any other applicable standard?

Thank you in advance

 

[MikeHalloran]

Before our producers discovered the virtues of permananently lubricated joints, the USA was awash in small grease fittings, typically with a 1/4" hex body, and a tapered 1/4-28 male thread screwed into a part (ball joint or whatever) with 1/4-28 straight female threads. I assume there are standards for them at sae.org.

Since the fittings are pretty small, and steel, they can withstand whatever pressure you can generate with a grease gun, colloquially alleged to be 10,000 psi.


<tangent>
Around 1972, I designed a flight simulator motion base that used custom universal joints comprising big steel pins rotating in greased plastic bushings. The pins were lightly pressed and mechanically secured into blind holes in 'crosses' flame cut from heavy steel plate.

When the design hit the shop, the super called up; "I know what the grease fitting holes leading to the bushings are for, but why are there grease fitting holes connecting to the cavities at the blind end of the pivot pins?" I said, when you need to remove the pivot pins, you put grease fittings in those holes and pump out the pins with a grease gun. He scoffed. ... a lot.

A few weeks later, he called to apologize. The first pin they had tried to insert had gotten stuck halfway in, and after trying everything else, they jacked it out with a grease gun, effortlessly.

</tangent>


Mike Halloran
Pembroke Pines, FL, USA