Adding gauge to hydraulic press

[Ian Geary]

Hi all

I purchased a new hydraulic bench press from Ebay, which I have assembled (once i had gathered the necessary bolts that were missing)

Zero instructions, but ultimately there's only about 9 bits to it.

Connecting up the hydraulic ram was easy, as it's a self sealing connector.


Next is the gauge port: it seems I need to remove the port plug and screw in the gauge (with washer). Seems simple.


However, the port plug is really tight. Is this normal? Do I just need to give it full force?

This is the thing - I just wanted to check that i am unscrewing the right thing





Fwiw my 27mm crows foot spanner is in a pipe about 60cm long, and i have a breaker bar on the 22m socket.

I am starting to just lift the press of the bench when I push, which is odd as I though gauges etc didn't need to be "over tight"

Thanks,

Ian

[DaveF-SkinnysAutos]

Are you sure it’s not a reverse thread? Have you tried some pressure in the opposite direction, which way is the gauge that screws in threaded? If your happy your applying pressure in the right direction its got to just be tight?

[E-bmw]

I am sure this will be a daft question but I assume you have made 100% certain that there is zero pressure first?

On top of that I think what you are trying to undo there is a bleed port, the gauge point looks to be the bottom part with PTFE thread tape on it.

[Ian Geary]

Thanks for the replies.

I will check for a reverse thread, and see what is on the gauge (ie male).

I haven't checked there is zero pressure yet- in hindsight I should have done e the gauge before the ram.

Still, I've not squeezed the ram yet, and there is a dial/ knob that I have loosened fully, which i assume is the pressure release control for it.


I will also have a closer look at the port - the 27mm larger nut rotates in concert with the entire cylinder mechanism, and so I had assumed i would hold it stationary whilst undoing the bolt screwed into it.


I will do a bit more googling perhaps.

[Belle427]

Cant see it being reverse thread or under pressure, looks like your also taking out the right blanking plug but cant understand why its so tight.

[Novexx]

You look like you are on the right track & the threads visible at the bottom of the dust cap will show which direction you should be turning.

It may well be arsed in some way, possibly overtightened & mangled during assembly.

[E-bmw]

I can't tell exactly the size from the pic but probably 1/4" NPT/BSP tapered thread, which is a standard gauge thread and because it is tapered it needs thread tape.

The "bolt" you are trying to get out is WAY too big for a gauge unless it is 1/2" BSP with a Dowty washer, which is unlikely, although not impossible.

Even having said that if it is 1/2" BSP with a Dowty washer the bolt will be much easier to get out with it in a vice, so remove the full thing would be my advice.

[Ian Geary]

Update/ conclusion - it just needed that slightly longer grunt. Probably similar to a wheel bolt torque.


As the pic shows- the gauge has the bigger thread, so maybe they just prefer bigger in China? (note, not necessarily saying better)

Still for £120, it will save me using the freezer / sledge hammer / bit of wood approach to get bearings seated in future.

[hidetheelephants]

More likely they found a source of gauges cheap and they had the larger thread, so the Happy Dragon Missile and Hydraulic Coupling Manufactury got an order for janky adaptors to step up from 1/4 BSP to 3/8 or whatever it is.

[E-bmw]

Ian Geary said:

Update/ conclusion - it just needed that slightly longer grunt. Probably similar to a wheel bolt torque.

As the pic shows- the gauge has the bigger thread, so maybe they just prefer bigger in China? (note, not necessarily saying better)

So was there any Dowty washer at the bottom?

Or PTFE take/paste on the thread?

Does the "plug" you removed look tapered?

Is the thread-form either "sharp" or "rounded" on the "plug"?

What diameter is the "plug"?