Data on PTC Optimus 80s & Primus 71Ls

Discussion in 'Stove Models' started by kaw550red, Mar 22, 2011.

  1. kaw550red

    kaw550red RIP

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    BACKGROUND

    1962 Optimus bought the Primus brand name for liquid fueled stoves from A B Bahco who continued to use the Primus brand name for gas (lpg) appliances. They also got Bahcos stock of parts, tanks and partly completed stoves. Optimus rebranded some of their own models as the equivalent Primus model. They created the Primus Trading Company (PTC) to sell the Primus brand stoves. This existed until 1976

    1964 Optimus bought the Radius brand name together with the firm’s stock of parts. Optimus never used the brand name but used some of the parts on both Optimus and Primus stoves

    1969 Optimus bought the Svea brand name together with the firms stock of parts from Primus Sievert. Optimus rebranded some of their own models as the equivalent Svea model. They created the Svea Trading Company (STC) to sell the Svea brand stoves. This existed until 1976

    APOLOGIES

    The photos are taken from my archived photos. Some have been cropped to show the necessary information. Unfortunately this means that they may not be as clear as purpose taken photos. Unfortunately I do not now have the stoves to produce better photos

    PRE PTC STOVES

    1300811124-80_stove_opt.jpg 1300811145-71L_stove_opt.jpg


    The left stove is the Optimus 80 The right stove is the Primus 71.

    Theoretically parts from either stove could appear on any 71 or 80 made during the PTC period. However I have never seen a Bahco made tin, tank lid or regulating key on any of the stoves made in the PTC period

    PTC PERIOD STOVES

    Stove Fittings

    The fittings are given in the order that they were produced. However they were not necessarily fitted to the tanks in the order that they were produced.

    Burner Plate

    1300811372-Opt_burner_plate_opt.jpg
    1300811665-Prim_burner_plate_opt.jpg

    The Optimus burner plate at the top is a dished brass plate which was used before during and after the PTC.

    The Primus burner plate below it was made of white metal with a conically shaped centre.

    The Radius burner plate was very similar to the Optimus brass plate and I do not have a photo of one

    I do not have a photo of a Svea burner plate

    The next section follows

    Regards Bryan
     
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  2. kaw550red

    kaw550red RIP

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    Burner

    1300811898-Early_80_burner_opt.jpg 1300811917-Bahco_71_burner_opt.jpg 1300811930-Rad_Burner_opt.jpg 1300811943-123_burner_opt.jpg 1300811981-Leaded_burner_opt.jpg

    The pre and early PTC Optimus burner is first.

    The Bahco 71 burner is next.

    The Radius burner is next. It could not be fitted as original equipment to any PTC stove made before 1964

    The Svea 123 burner is next. It could not be fitted as original equipment to any PTC stove made before 1969. Whilst that burner could be fitted to a 71 or 80 the 71 and 80 burners could not be fitted to a 123 because the regulating spindle would not have coincided with the hole through the 123 windshield.

    The last burner is the Optimus burner modified to burn leaded petrol. I have not been able to verify this but I think that it was introduced around 1970. This opinion is contradicted by the 1972 catalogue and parts list which still shows the original Optimus burner however catalogues often used out of date drawings or photos.

    Tank Lids

    1300812203-Petrol_tank_lids_opt.jpg

    On this photo the lids are numbered 1, 2, 5 & 6 starting at the left
    1300812233-3_lid_opt.jpg 1300812257-4_tank_lid_opt.jpg

    These two lids are numbered 3 & 4 starting at the left

    1 This is a pre and early PTC Optimus tank lid. It appears to have been made up until the late 1960s.

    2 This is a Sieverts (Svea) tank lid first used by Optimus in 1969.

    3 This is a later Optimus tank lid fitted with the early valve gear.

    4 This tank lid is later and is fitted with a five sided valve gear which appears to be from a later period.

    5 This tank lid appears to have been introduced after 1976. The valve gear has a square hole.

    6 This is the last petrol tank lid used by Optimus. It appears to have been introduced towards the end of the 1970s so should not appear on stoves made in the PTC period

    I do not have a photo of the Radius tank lid in use in the 1960s but it should fit in between 1 & 2 if they were used on the PTC 71s & 80s

    More Follows

    Regards Bryan
     
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  3. kaw550red

    kaw550red RIP

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    Tank Markings

    1300812744-Pre_PTC_Opt_tank.JPG

    1300812773-71_Tank_marking_opt.jpg

    These are the markings on the 80s and 71s immediately prior to the PTC so they could appear on early PTC stoves.

    1300812931-Early_PTC_80_opt.jpg 1300812954-Early_PTC_71_opt.jpg

    After those tanks were used up. Optimus used these two foil labels to indicate the brands on the early PTC stoves

    1300813075-Late_PTC_71_opt.jpg

    This was the label used on the later PTC 71s. It is probable that Optimus used a similar coloured label for the 80s produced in the same period

    1300813092-Post_PTC_80_opt.jpg

    This was the label used by Optimus after the PTC ceased to exist. Basically it has a silver background with blue and red printing on it.

    More Follows

    Regards Bryan
     
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  4. kaw550red

    kaw550red RIP

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    Tins

    1300813453-Pre_PTC_Opt_cas_opt.jpg 1300813516-71L_case_opt.jpg

    These two tins were in use before the PTC and were probably used on very early PTC 71s and 80s

    1300813562-80_box_opt.jpg

    This tin is from a post PTC 80 but is the same tin that was used for the PTC 71s and 80s. Optimus used paper labels stuck to the top to show the brand of the stove. Optimus used foil stickers on the tanks but paper labels on the tins.

    Tin Damage

    1300813676-Typical_flame_damage_opt.jpg 1300813698-Typical_pan_supps_opt.jpg

    This sort of damage is typical of a used stove. The tank supports projected above the tin top so the flame could be blown sideways damaging the paintwork around the tin sides and back.

    The pan supports and top shelf were very prone to rusting. Sometimes the pan supports could become detached from the top shelf because of rusting. Sometimes the top shelf could simply disappear through rust. This tin was the second tin used on the stove that it contained.

    I have now finished

    Regards Bryan
     
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  5. hikin_jim

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    Excellent, Bryan. A veritable compendium. I have a late Primus 71 (1962) and an Optimus 80 from some time thereafter, so this post was particularly interesting.

    HJ
     
  6. kaw550red

    kaw550red RIP

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    Hi Jim

    The pre PTC Primus tin was a heavier tin than the 80 and I have never seen an unusable one.

    The pre PTC Primus regulating key also looked to be a better design than the 80 key which overheated if left on the spindle whilst the stove was lit. The 71 key looked long enough to lose the heat before it got to the end of the key suggesting that it could be left in place when cooking

    Regards Bryan
     
  7. hikin_jim

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    Well, I'm wrong about this. At least partly anyway. I've been calling the 2nd stove I inherited from my uncle an Optimus 80 even though it said Primus 71 on the box and on the tin. I assumed it was just an Optimus 80 with a Primus sticker on it.

    Bryan's excellent post made me take another look at it. It has an engraved tank with Primus 71 on it. I assume that if the tank is engraved then at least the tank is a "real" Primus part. The box says "Primus Trading Company" on it, and the tin is clearly the Optimus tin.

    I suppose it's really something of a Frankenstove although mostly (I think) an Optimus 80. It's hard to tell about the burner though.

    HJ
     
  8. hikin_jim

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    "Primus Sievert?" Is that a typo or was there really such a thing?

    HJ
     
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  9. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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  10. kaw550red

    kaw550red RIP

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    Hi Jim

    As George said Primus Sievert did exist.

    One of our problems is that we are inclined to think of Primus, Optimus, Svea and the other brand names as being stove makers. They were not. They were brands that were owned by various companies during their existence.

    Despite what it says on the pre 1919 stove tanks Primus stoves only started to be made by Hjorth in 1919. Prior to that the tanks were marked AB B A HJORTH & CO STOCKHOLM, SWEDEN. SOLE MAKER. The first maker of Primus stoves was F V Svensons Fotogenkoksfabric. That company changed its name to include Primus in the title probably when Svenson left the company in 1904. Hjorth was the marketing agent until 1919 when he bought the Primus company. Hjorths continued to make the Primus stoves until 1955 when they changed the stove maker's name to AB Bahco.

    In 1962 Bahco sold the Primus brand name for liquid fuelled stoves to Optimus. However they continued to make Primus lpg products. Two firms were using the same brand name at the same time.In 1964 Svenska Esso bought AB Max Sieverts which became AB Sievert Apparater which included Svea stoves amongst their products. In 1966 AB Sievert Apparater bought the the Primus division of Bahco and became Primus Sievert AB. They continued to make Svea stoves until 1969 when they sold the Svea brand name to Optimus.

    Whilst Primus Sievert had sold their Svea brand name they continued to make the Primus and Sievert lpg products however it appears to have changed its name at some time after the Svea sale. I have a Primus commercial lpg catalogue from the 1990s and it states that Primus and Sievert are registered trademarks owned by Primus AB.

    It appears that either the use of the Primus brand name by Optimus was for a fixed number of years or Primus AB bought the brand name back from Optimus.

    I will comment on your stove on the Primus 71 topic.

    Regards Bryan
     
  11. Spiritburner

    Spiritburner Admin SotM Winner Subscriber

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    As the guys have pointed out & as touched on in several articles on the main protaganists throughout this article section they certainly did!

    I believe it was until relatively recently too.

    Once the Svea brand was divested to Optimus, the Sievert side of the group concentrated on the industrial market & Primus on leisure. That is still the case but now independently of each other.
     
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  12. hikin_jim

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    Clear as mud! ;)

    OK, thank you for that explanation. A bit confusing, but it can be picked apart.

    HJ
     
  13. Spiritburner

    Spiritburner Admin SotM Winner Subscriber

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    You think that's bad? At least it's accurate - you should have heard some of the myths being bandied about before CCS! ;)
     
  14. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi Bryan, You have produced a great piece of research with this study.
    I have posted photos of a couple of Op.80s which I have, in the Gallery. The positioning of the engraved lettering is slightly different on the two tanks.
    On the stove which I believe dates from the mid-1950s the Optimus lettering is fairly low, near the bottom flange on the tank:

    1301075526-Op.80.-St-289-9.jpg


    On a slightly later Op.80, dating from mid-1950s/early 1960s, the lettering is higher relative to the bottom flange:

    1301075963-St.288.-Op.80-11.jpg

    Are these observations significant I wonder?
    Best Regards,
    George.
     
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  15. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi Bryan, you have a pair of the Optimus 80 stoves shown together in the Gallery as "1950s Op.80s":

    https://classiccampstoves.com/threads/10610

    I reckon both of these have the Optimus engraving in the lower of the positions I describe.


    On the other hand, the Archivist, Phil Masters c1960s Optimus 80 shown in the Gallery:
    appears to have the Optimus engraving in the higher position that I describe.

    https://classiccampstoves.com/threads/711

    Best Regards,
    George.
     
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  16. kaw550red

    kaw550red RIP

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    Hi George

    During the PTC period there were various events which had a consequence on the stoves.

    During the pre PTC period there are no datable events so dates given for stoves in that period are virtually meaningless unless they are justified by the reason for the date. Unless the stove has been owned from new the date is an opinion not a proven fact.

    You appear to have got the dating of your stoves reversed. Did you have a specific reason for your dating?

    In the case of my two 80s my dating was based on when I bought them. I think two of the three stoves that I owned were bought in 1958. As near as I can remember one of my tins fell apart in 1960. The other tin was also suspect so I ordered two new tins. They took some time to arrive so I bought another stove to use until the replacement tins arrived. That allowed me to continue to use 2 stoves for camping. I replaced the defunct tin and continued to use the other tin until it failed and then replaced it. I think that the last stove and tins were bought around the end of 1960.

    I sold one of my 80s to Base Camp for their museum which left me two out of my original three stoves

    I have no idea which of the stoves that I kept only that they were bought between 1958 and probably the end of 1960.

    Both of the stoves that I still own have the lettering near the bottom of the tank so it looks as though that was the last version of the pre PTC 80s.

    The 1958 is when the first stoves were bought however that does not necessarily mean that they were made in 1958 only that they could not have been made later than 1958.

    I do not know of any way to date the higher lettering and can only say that it appears to have ended by at least 1958.

    The 1958 is a positive date. I attended the Outward Bound School in December 1957 and our instructor told us that petrol stoves were better than paraffin stoves. He did not say why they were better and I believed him. Using leaded petrol in a petrol stove was like playing Russian Roulette. I had no idea when the stoves would decide to take a rest.

    Regards Bryan
     
  17. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi Bryan, Thanks for replying.

    I am afraid that I have no firm dates for these two Op.80 stoves, and ascribed suggested dates from looking at the price of one of them, catalogues, and other Op.80s included in the Gallery.

    https://classiccampstoves.com/threads/10876

    https://classiccampstoves.com/threads/10881

    The only things I am sure about is that they are both clearly Optimus 80 stoves and pre-PTC. There is also the difference in the position of the Optimus engraving, relative to the bottom flange, on the tank.

    You are lucky in having the provenance of your two Op.80s, because as you say it gives a date before which they must have been made.

    We need more information....

    Best Regards,
    George.
     
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  18. kaw550red

    kaw550red RIP

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    Hi George

    We always need more information but sadly have to draw conclusions from incomplete facts

    I have looked at your mid 1950s 80 and I can see your problem.

    I suspect that the clipping has nothing to do with the original purchase of the stove but has been added later. The original buyer would have got a hand written receipt stating the date, the item bought and the price paid for the item. If he had been interested in the provenance of the stove he could have put that in the box. The clipping could have been included by a subsequent owner as an indication of when it might have been bought. The price would have been more indicative of age if it had been marked on the cardboard box rather than on a clipping. I was under the impression that an 80 tank was 1/3 pint capacity not the 1/2 pint shown on the clipping.

    Whilst the stove shown on the clipping is an earlier version it coincides with that shown on the cardboard box. The price shown coincides with the price on Nottingham Camp & Sport Supplies 1956 advert. That advert also shows the earlier stove. Unfortunately out of date illustrations were often used in adverts in those days.

    Until 1964 we had Retail Price Maintenance (RPM) in the UK. I think that it was introduced at the beginning of WW2. That law meant that the manufacturers set the price of their goods and all retailers had to charge that price. During the 40s and 50s goods were in short supply in the UK. In that situation people are prepared to pay extra to buy difficult to obtain goods. By fixing the price of the goods the government limited inflation and there was very little increase in price from year to year. The 1956 price could have been applicable before and after that year. In 1962 an Optimus 80 cost the equivalent of £1.975 when bought anywhere in the UK. Between 1956 and 1962 the price of the stove only increased 3.9%.

    It was interesting that the clipping mentioned best value. The price stated applied to every 80 sold in the UK so you got an identical value from all retailers although people who were unaware of RPM would not realise that.

    The location of the lettering on the tank could be a red herring. Whilst we often refer to it as being engraved it is actually impressed into the surface. I presume that the tank top was rolled over a former with the printing on it. If this is correct the inside of the tank top would need to be on a tight fitting plug to stop it being crushed by the pressure on the lettering. Constant use would wear the plug where the lettering was forced into the tank metal if the lettering was always in the same position on the tank.

    It may be that they varied the position of the lettering in all periods to extend the life of the plugs. This would mean that the position of the lettering was misleading as an indication of age.

    From the appearance point of view the higher lettering is centrally in the height which suggests that it was probably the first location for the lettering if it is actually an indication of age and if the positions were constant during a particular period. The lower lettering looks unbalanced for position. My two stoves have the lower lettering which suggests that this was the later lettering position but unfortunately this is not conclusive proof of this theory.

    The cardboard box suggests that yours is an early stove in the new case as it shows the earlier case but again this could be misleading as I doubt whether the cardboard boxes were used in the order that they were produced. People are inclined to do things the "easy" way. Later boxes could have been stacked on top of early boxes so the early boxes could have surfaced to be used at a much later date than they were produced. This comment also applies to stove tanks which may have been used in a different order to their order of making.

    I thought that the 80s that I bought always had the tank lid 60º to the left of the regulating valve when it was facing you. In other words it imitated the position of the tank lid in relation to the pump on a paraffin stove. I always assumed that the burner had been replaced if it was in any other position. I have noticed that a large number of the 80s have the tank lid on the right of the regulating valve so either my memory is faulty or a lot of stoves have replacement burners

    Sorry that I cannot be of more help

    Regards Bryan
     
  19. Rick b

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    Hi Bryan, thanks for all the interesting information. Is there a reason that you know of why a self cleaning needle wasnt added to the newer 80 like the 123?
     
  20. kaw550red

    kaw550red RIP

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    Hi Rick

    They produced a No 7 stove as you describe for the UK military. I think that it was for special forces use. They never produced a civilian version of the stove.

    The case was much more substantial than an 80 case. It had riveted on pan supports so that they could be replaced if they rusted away. The stove was supplied separately to the case so either could be replaced if necessary. All of the cases that I have seen have been dated 1978 so the model was in existence then but I have no idea how long the model existed after 1978

    1301159847-7_Open.JPG 1301159865-7_stove.JPG 1301159892-7_Insts.JPG 1301159905-7_case.JPG

    Regards Bryan
     
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