Hi all
(for "jack" cylinder connected by hose to hand-pump)
Dismantled cylinder with blown seal and got new seal on-order.
When I "mantle" the cylinder with the new seal in-place, I'd have to
ensure no air trapped in it? When ready for use?
I think it's infeasible to assemble the cylinder with oil in it. You
have to invert it to make some assembly (the return spring?) hang
centrally so you can push the piston in and catch the central "thing"
with its screw through the head of the piston. Plus then push piston
to bottom of travel.
Assemble piston with smear of oil left, piston to bottom of cylinder,
then pump oil in, disconnect, put cyl. on side with connector
uppermost, push on seal-on-disconnect ball in fitting and push piston
along cylinder expelling air? Until oil starts to emerge?
Shake and tap cylinder, back to same position of connector uppermost
and repeat "bleed" - see oil coming out free of bubbles?

Regards,
Rich S

"Richard Smith" wrote in message ...

Hi all
(for "jack" cylinder connected by hose to hand-pump)
Dismantled cylinder with blown seal and got new seal on-order.
When I "mantle" the cylinder with the new seal in-place, I'd have to
ensure no air trapped in it? When ready for use?
I think it's infeasible to assemble the cylinder with oil in it. You
have to invert it to make some assembly (the return spring?) hang
centrally so you can push the piston in and catch the central "thing"
with its screw through the head of the piston. Plus then push piston
to bottom of travel.
Assemble piston with smear of oil left, piston to bottom of cylinder,
then pump oil in, disconnect, put cyl. on side with connector
uppermost, push on seal-on-disconnect ball in fitting and push piston
along cylinder expelling air? Until oil starts to emerge?
Shake and tap cylinder, back to same position of connector uppermost
and repeat "bleed" - see oil coming out free of bubbles?

Regards,
Rich S

---------

I just positioned the cylinder with its in/out port upwards and ran the
piston out and back a few times. You can tell if there's air left by the
solid or mushy feel of the pump handle when the piston reaches full travel.

"Jim Wilkins" writes:

"Richard Smith" wrote in message ...

Hi all
(for "jack" cylinder connected by hose to hand-pump)
Dismantled cylinder with blown seal and got new seal on-order.
When I "mantle" the cylinder with the new seal in-place, I'd have to
ensure no air trapped in it? When ready for use?
I think it's infeasible to assemble the cylinder with oil in it. You
have to invert it to make some assembly (the return spring?) hang
centrally so you can push the piston in and catch the central "thing"
with its screw through the head of the piston. Plus then push piston
to bottom of travel.
Assemble piston with smear of oil left, piston to bottom of cylinder,
then pump oil in, disconnect, put cyl. on side with connector
uppermost, push on seal-on-disconnect ball in fitting and push piston
along cylinder expelling air? Until oil starts to emerge?
Shake and tap cylinder, back to same position of connector uppermost
and repeat "bleed" - see oil coming out free of bubbles?

Regards,
Rich S

---------

I just positioned the cylinder with its in/out port upwards and ran
the piston out and back a few times. You can tell if there's air left
by the solid or mushy feel of the pump handle when the piston reaches
full travel.

Does the pump have some mechanism to throw out air in the system?
Is it "self-bleeding"?

"Richard Smith" wrote in message ...

"Jim Wilkins" writes:

"Richard Smith" wrote in message
...

Hi all
(for "jack" cylinder connected by hose to hand-pump)
Dismantled cylinder with blown seal and got new seal on-order.
When I "mantle" the cylinder with the new seal in-place, I'd have to
ensure no air trapped in it? When ready for use?
I think it's infeasible to assemble the cylinder with oil in it. You
have to invert it to make some assembly (the return spring?) hang
centrally so you can push the piston in and catch the central "thing"
with its screw through the head of the piston. Plus then push piston
to bottom of travel.
Assemble piston with smear of oil left, piston to bottom of cylinder,
then pump oil in, disconnect, put cyl. on side with connector
uppermost, push on seal-on-disconnect ball in fitting and push piston
along cylinder expelling air? Until oil starts to emerge?
Shake and tap cylinder, back to same position of connector uppermost
and repeat "bleed" - see oil coming out free of bubbles?

Regards,
Rich S

---------

I just positioned the cylinder with its in/out port upwards and ran
the piston out and back a few times. You can tell if there's air left
by the solid or mushy feel of the pump handle when the piston reaches
full travel.

Does the pump have some mechanism to throw out air in the system?
Is it "self-bleeding"?

-----------------------------
Oil released from the cylinder to retract the piston flows back into the
pump's reservoir, which needs to be vented to the atmosphere to relieve
pressure or vacuum as oil moves in and out. I have a hand/foot powered
manual hydraulic pump with a hex head reservoir fill and bleeder screw that
the instructions say to slightly open during use.

"Jim Wilkins" writes:

"Richard Smith" wrote in message ...


...

Does the pump have some mechanism to throw out air in the system?
Is it "self-bleeding"?

-----------------------------
Oil released from the cylinder to retract the piston flows back into
the pump's reservoir, which needs to be vented to the atmosphere to
relieve pressure or vacuum as oil moves in and out. I have a hand/foot
powered manual hydraulic pump with a hex head reservoir fill and
bleeder screw that the instructions say to slightly open during use.

Ah... The oil separates to the top in the pump's oil reservoir and
can be expelled / displaced with additional oil...

"Richard Smith" wrote in message ...

"Jim Wilkins" writes:

"Richard Smith" wrote in message
...


...

Does the pump have some mechanism to throw out air in the system?
Is it "self-bleeding"?

-----------------------------
Oil released from the cylinder to retract the piston flows back into
the pump's reservoir, which needs to be vented to the atmosphere to
relieve pressure or vacuum as oil moves in and out. I have a hand/foot
powered manual hydraulic pump with a hex head reservoir fill and
bleeder screw that the instructions say to slightly open during use.

Ah... The oil separates to the top in the pump's oil reservoir and
can be expelled / displaced with additional oil...

------------------------

I just finished reading this book;
https://www.amazon.com/Secret-Horsep.../dp/1911658506
The author is a racing engineer familiar with the technical difficulties of
high horsepower engines which he describes in detail, such as the problem of
separating the highly agitated oil and air froth that comes back from the
scavenger pumps in the dry sump Merlin, so that air bubbles won't be pumped
into highly loaded crankshaft bearings which would allow them to rub and
wear rapidly. The problem is worse in a fighter where "down" can be in any
direction.

"Jim Wilkins" wrote in message ...

.... The problem [of liquids vs gravity] is worse in a fighter where "down"
can be in any direction.

-------------------------
https://www.inventricity.com/tilly-shilling

"Jim Wilkins" writes:

"Jim Wilkins" wrote in message ...

... The problem [of liquids vs gravity] is worse in a fighter where
"down" can be in any direction.

-------------------------
https://www.inventricity.com/tilly-shilling

One of my main heroes.
Her story is how you learn technical things.
Book "Negative Gravity".
She spawned through her war work a generation of engineers who came of
age in the 1960's.
Apparently she was a demanding taskmaster. It was said that if things
didn't work out, you'd better have a good account of yourself - but if
you could, that was just experience for moving onwards (or something
like that).

I like the strength of personality and identity in taking on the then
ultimate machine (the Rolls-Royce Merlin engine), unfazed, and being
its master.

"Richard Smith" wrote in message ...

"Jim Wilkins" writes:

"Jim Wilkins" wrote in message ...

... The problem [of liquids vs gravity] is worse in a fighter where
"down" can be in any direction.

-------------------------
https://www.inventricity.com/tilly-shilling

One of my main heroes.
Her story is how you learn technical things.
Book "Negative Gravity".
She spawned through her war work a generation of engineers who came of
age in the 1960's.
Apparently she was a demanding taskmaster. It was said that if things
didn't work out, you'd better have a good account of yourself - but if
you could, that was just experience for moving onwards (or something
like that).

I like the strength of personality and identity in taking on the then
ultimate machine (the Rolls-Royce Merlin engine), unfazed, and being
its master.

----------------------------

I'm impressed by Sir Stanley Hooker's contributions, despite his being
"Not Much of an Engineer"

On Monday, January 11, 2021 at 6:01:08 PM UTC-5, Richard Smith wrote:
"Jim Wilkins" writes:

"Jim Wilkins" wrote in message ...

... The problem [of liquids vs gravity] is worse in a fighter where
"down" can be in any direction.

-------------------------
https://www.inventricity.com/tilly-shilling
One of my main heroes.
Her story is how you learn technical things.
Book "Negative Gravity".
She spawned through her war work a generation of engineers who came of
age in the 1960's.
Apparently she was a demanding taskmaster. It was said that if things
didn't work out, you'd better have a good account of yourself - but if
you could, that was just experience for moving onwards (or something
like that).

I like the strength of personality and identity in taking on the then
ultimate machine (the Rolls-Royce Merlin engine), unfazed, and being
its master.

And Frank Whittle was credited for inventing the turbo jet (1930-37). Small military aircraft constantly get engine design changes. I like at the end of an episode of Hogan's Heroes - 'Easy come, easy go' (1971), they stole a P-51 as a decoy and it crashed and they later joked that it had been refitted with a Messerschmitt engine.

"bruce bowser" wrote in message
...


And Frank Whittle was credited for inventing the turbo jet (1930-37). ...

---------------------------------------------

He was -one- of the inventors.

https://www.airforcemag.com/article/0182engine/

https://en.wikipedia.org/wiki/Hans_von_Ohain

https://en.wikipedia.org/wiki/Nathan_C._Price

https://en.wikipedia.org/wiki/Vladimir_Pavlecka