EARLY OPTIMUS 11

Discussion in 'Optimus No:11' started by kaw550red, Feb 14, 2009.

  1. kaw550red

    kaw550red RIP

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    I was given this stove by a work colleague in 1972 as a reward for a favour that I had done him.

    At the time it would not work and had been repainted. I then compounded the error by painting it with Hammerite. I eventually found the correct colour from the inside of one of the tank supports and stripped the case and repainted it

    1234636585-11_open_opt.jpg

    I believe that it is from the 1930s for several reasons.

    The case is marked Pat No 71018. This patent was applied for in September 1927 however the patent was not granted until January 1931 and the patent number could not have been known before the patent was granted.

    The tank supports and catch are bolted to the case front.

    The burner is marked OPTIMUS which was the marking used in the 1930s.

    There were import restrictions during the 1940s so the stove is unlikely to have got into this country during that period. In any case if the patent period was 20 years, which is the period now, the patent would have expired in 1947.

    1234639258-11case_top_opt.jpg
    1234639316-11_case_front_opt.jpg
    1234639364-11_catch_and_pump_opt.jpg 1234639404-11_burner_and_key_opt.jpg 1234639459-11_burner_opt.jpg 1234639480-11_wind_and_reg_knob_opt.jpg

    The catch is internal. You press the bottom button and this pushes a plate back inside the case which releases the upper button from the top of the case.

    Does anyone know what fuel the 11s were supposed to use? I have used petrol and paraffin in it but was not certain whether it was meant to be one or the other or multifuel
     
  2. aktopp

    aktopp Subscriber

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    Nice stove.

    According to the 1939 Optimus catalogue it was dualfuel, petrol and paraffin.
     
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  3. Spiritburner

    Spiritburner Admin Subscriber

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    The 11 came out some time between 1935 & 1939. The patented feature was originally seen on the Campingo stoves - the 11 superceded the Campingo No:1.
     
    Last edited by a moderator: Jul 2, 2015
  4. kaw550red

    kaw550red RIP

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    Hi Arne

    Thanks. It has taken 37 years for me to find that out.

    When I got it I had previously used 80s for about 5 years. Petrol stoves have pressure release valves in their tank lids which it had. However the petrol stoves that I was used to did not need pumps. Paraffin stoves had pumps but did not need pressure release valves.

    The burner was very badly blocked when I got it and that could have been caused because it had been used with leaded petrol which was all that you could get until about 1970. That rapidly blocked burners.

    The multifuel 11 may be why the 111 when it first came out in 1952 was designated as being for petrol and paraffin. However there must have been problems with the redesigned burner of the 111 burning both fuels because the 111 was quickly changed to burning paraffin only and a 111B was introduced to burn petrol

    Thanks again

    Regards Bryan
     
  5. nzmike

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    Nice piece of kit!
     
  6. kaw550red

    kaw550red RIP

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    Hi Everyone

    I am currently selling my 11 and thought that I better check what interesting points were not illustrated on my topic before I lost the stove forever

    1253088435-11_tank_lid_opt.jpg

    This is the tank lid with all of the working parts within the tank. It is quite bulky underneath and there does not seem to be the adjustment that you get on later safety valves. You appear to simply screw the locking nut fully down or it does not lock and could fall out

    1253088502-11_pump_rod_opt.jpg

    This is the pump rod. I was curious as to its relative efficiency when compared with the longer stroke 111 assembly. The 11 uses a bigger diameter pump and compresses 80% of the amount of air compressed by a 111 pump which is not as bad as I suspected

    1253088653-11_flame_opt.jpg

    This is the flame when tested with Aspen 4T so it is quite nice for a 70 year old stove which had been using the wrong fuel

    Regards Bryan
     
    Last edited by a moderator: Jun 27, 2015
  7. Doc Mark

    Doc Mark Subscriber

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    Morning, Bryan,

    I wish you outstanding success in selling your nice old Optimus #11! I have one that is a little later in design, and I cherish it. If I had a few coins to rub together right now, I'd try to buy yours, so mine could have a Brother! Nice stove, and a nice restoration, my Friend. Again, best of luck, and God Bless!

    Every Good Wish,
    Doc