The following patent was issued in 1919. I believe that the original patent was not renewed. I am trying to understand if the the original patent in all of its definitions was reissued to the new owners and is now locked.


The above is a water driven motor called the Pelton Wheel. Did the second pair of people reapply for the same patent?


So, the former patent of the Pelton Wheel from 1919 cannot be touched anymore? Basically, not one thing new was added.


2 Answers 2


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."


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:

  1. 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.


  1. 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.

  • This is a brilliant reply, Don! You really know the laws.
    – Owlitz
    Dec 21, 2016 at 0:25

It looks like the '130 patent is an improvement to the '893 patent. It cites the older patent and describes improvements. Did you carefully read the specifications and claims. Just because you don't see anything obviously different in the drawing doesn't mean that "not one thing new was added". Figure 3 in particular shows a different arrangement for baffles around the impeller.

  • Thank you, Eric. So, could I design my own Pelton Wheel?
    – Owlitz
    Dec 17, 2016 at 7:00
  • So, all I need to do is add something that has not been tried yet?
    – Owlitz
    Dec 17, 2016 at 7:01
  • @Owlitz. Both of these patents have expired by now so neither keeps you from making a Pelton Wheel. This doesn't mean there aren't other patents. If you just want to make one for yourself and not sell it, then even active patents wouldn't be a problem. If you like my answer, please accept it by checking the accept control.
    – Eric S
    Dec 17, 2016 at 17:29
  • By adding something not obvious you could create a patentable invention. Notmally that might infringe older patents when build (sold), but as they are expired. There might be others though.
    – user18033
    Dec 17, 2016 at 18:28

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