The (/a) patent from 1919 is not valid anymore. It cannot be renewed. But it does constitute prior art for new patents.
Starting with the theory:
Everyone can apply for a patent for (almost) everything. The content is analysed only when the grant of the patent is requested. So I could totally apply for a patent for the Pelton wheel right now with exactly the claims from the 1919 patent. But I would not get a grant.
The second patent was granted and the patent office is not stupid, so there probably is something new to the second invention.
How to find out what that is? A patent application normally states prior art, a problem in the prior art and an solution. You can find that in the first paragraphs of a (well written) patent application.
https://patentimages.storage.googleapis.com/pdfs/b298f4abcdec036cc1b7/US4950130.pdf (The patent pdf)
The first sentence of the description is "This invention relates to a Pelton turbine."
Then:
As
is
known,
Pelton
turbines
are
used
for
driving
electricity
generators
or
as
a
direct
drive
for
working
machines.
Generally,
such
Pelton
turbines
include
a
casing
in
which
a
turbine
wheel
with
a
wheel
disc
and
buckets
is
mounted
along
with
a
drive
shaft
which
passes
through
the
casing.
In
addition,
at
least
one
jet
is
provided
for
expelling
fluid
from
a
high
pressure
nozzle
tangentially
of
the
wheel
disc
onto
the
buckets
so
as
to
cause
rotation
of
the
disc
and
drive
shaft.
The
casing
has
also
been
provided
with
a
fluid
outlet
for
removal
of
the
spent
fluid.
Turbines
of
this
type
are
described
in
Ger
man
Pat.
Nos.
12,314;
319,779
and
615,445.
Followed by:
As
is
known,
the
efficiency
of
a
Pelton
turbine
is
closely
dependent
on
the
success
of
keeping
vagrant
spray
water
away
from
the
turbine
wheel
and
the
buckets.
In
some
cases,
the
drive
shaft
has
been
disposed
on
a
hori
zontal
axis
while
the
lower
region
of
the
turbine
wheel
is
acted
upon
by
the
fluid
jets.
In
these
cases,
the
upper
region
of
the
casing
has
been
provided
with
vertical
metal
sheets
parallel
to
the
plane
of
the
turbine
wheel
while
horizontal
sheets
are
disposed
opposite
the
high
pressure
nozzle
in
order
to
prevent
spray
water
from
reaching
the
upper
region
of
the
casing.
In
Pelton
turbines
used
at
variable
speed
for
driving
working
machines,
these
conventional
baffles
do
not
give
satisfactory
results.
On
the
one
hand,
the
outlet
conditions
from
the
buckets
vary
as
a
result
of
the
large
but
necessary
fluctuations
in
speed
and
load.
This,
in
turn,
results
in
considerable
differences
in
spray
fluid
conditions.
On
the
other
hand,
there
are
great
variations
in
the
amounts
of
fluids
and
these
have
to
be
taken
into
account
in
the
construction
by
providing
high
overflow
levels
so
that
large
quantities
of
fluid
can
be
discharged
without
the
turbine
wheel
becoming
immersed
in
the
sump.
Favorable
conditions,
favorable
efficiency,
can
be
obtained
only
within
narrow
limits
and
when
condi
tions
are
approximately
constant.
Accordingly,
it
is
an
object
of
the
invention
to
im
prove
the
efficiency
of
a
Pelton
turbine.
(Emphasis added)
So now we know that the inventors knew about prior art and wanted to patent an improvement.
Lets look at the claims, they define the actual scope of the protection. What is not claimed, is not protected.
The independent claims (the other claims are so called dependent claims, so they have limitations regarding the independent claims - they protect less than the dependent claim (yes, this makes sense ;-) )) are as follows:
- A
Pelton
turbine
comprising
a
casing
having
a
fluid
outlet;
a
transversely
disposed
partition
in
said
casing
separating
a
spray
fluid
and
outlet
region
from
a
ventilation
region
therein;
a
rotatable
drive
shaft
extending
through
said
casing;
a
wheel
disc
mounted
on
said
shaft
within
said
casing
and
passing
through
said
partition;
a
plurality
of
peripherally
mounted
buckets
on
said
disc;
and
at
least
one
high-pressure
nozzle
in
said
spray
fluid
and
outlet
region
below
said
partition
for
expelling
a
fluid
jet
tangentially
of
said
disc
sequentially
onto
said
buckets
for
rotating
said
disc
and
said
shaft.
and
- A
Pelton
turbine
comprising
a
casing
having
a
fluid
outlet;
a
drive
shaft
extending
through
said
casing;
a
wheel
disc
mounted
on
said
shaft
within
said
casing:
a
plurality
of
buckets
peripherally
mounted
on
said
wheel
disc;
at
least
one
nozzle
for
expelling
a
fluid
jet
tangentially
of
a
lower
portion
of
said
disc
and
onto
said
buck
ets
for
rotating
said
disc
and
said
shaft;
and
a
partition
disposed
in
said
casing
to
separate
an
upper
ventilation
region
from
a
lower
spray
fluid
and
outlet
region
thereof,
said
partition
having
an
opening
for
passage
of
said
disc
therethrough
into
,
said
regions.
I don't know enough about Pelton wheels to judge this, but if you read the patent they will probably explain why these claimed limitations constitute an improvement of the prior art.
This way of looking at a patent helps with (almost) every patent and provides a good first intuition as to what to expect from the patent.
