Monday, 26 February 2018

Tecalemit Grease Guns

I've seen a few posts recently on Tecalemit grease guns which were often supplied in the toolkits of our bikes. People have problems with them, complaining that they don't work and consequently changing all the grease nipples to more modern types to work with modern snap on grease guns. There's no need for this - these guns work perfectly well if you know what you are doing...

Tecalemit type 7MC toolkit grease gun
There are several different types of grease nipple in the pages of history, but here's the type these guns are used for - The Tecalemit 'Tecazerk' nipple.


Here's one on the girder forks of my Ariel W/NG. Note the cylindrical shape with the rounded end & the tiny ball valve:


These guns are simple to use, but there are a couple of tricks you need to pay attention to to make them work - and keep working. The gun consists of a brass cylinder with spring loaded plunger; the plunger is attached to the piston which pushes greases into a bore (A) in the cap. Grease is contained in the cylinder (B) above a cork seal. The nose of the gun is cast into the cap and a hemi-spherical shape is formed in one end to accept the nipple.


Grease gun anatomy


To fill the gun, the end cap is removed and the volume B is packed with grease, pushing the cork seal down to the bottom of the cylinder. The trick here is to avoid leaving any air bubbles in the body of the gun. Do this with a straw inserted right to the bottom (before filling) and withdraw it carefully, filling as you go and by warming the grease before you start. You can pack the cap with grease before you put it on to prevent air bubbles forming in there too.

Filled with grease
To use the gun, start by cleaning the nipple and making sure you can see the tiny ball valve. You might have noticed there is a check valve in the grease gun and another one in the nipple - they are critical to the operation of the gun. If the ball is stuck and you operate the gun with no nipple on the end, you will get air in the gun and it will only work once. Place the gun over the nipple squarely - it helps to put a cotton rag between the nipple and the gun (old tee-shirts are good for this). This improves the seal between the gun and the nipple and the grease will happily go through the fabric. You can then push the plunger as many times as you want, keeping the gun aligned with the nipple.
Operating the gun
Here's how the gun refills itself. When you release the plunger, the springs close the ball valves and the piston, as it moves back, generates a small vacuum in volume A shown by the white space in the drawing.
Back stroke produces vacuum in Volume A
As the piston emerges from volume A, grease moves forward to fill the void, pulled forward by the vacuum. At the same time, the cork washer moves forward, effectively reducing the volume B until all the grease is used up.
Grease from volume B fills void in volume A

This demonstrates the criticality of the ball valves and the use of the cotton rag - the absence of either prevents formation of the vacuum in the cylinder, which prevents recharging of the gun. Without the vacuum, an air pocket will be left in the cylinder and volume A will not refill and the next stroke will not pump any grease out of the gun.

So the moral of the tale is, carefully fill your gun and take a rag with you in your toolbox!

Lovely period advertisement - courtesy Richard Payne

9 comments:

  1. chris matthews9 March 2018 at 09:21

    Your post was interesting – and timely. Two weeks ago I was wrestling with greasing my bikes - I reckon you have my workshop bugged.

    I have two sizes of Tecalemit Guns – one is the small brass one MC7 (toolbox size) and the other is larger (workshop size).
    In both cases the Gun Connector ends are spherical where they meet the nipples (about 3/16 and 1/4 inch).
    As you know, the usual nipple is P6 and its not spherical like your diagram, its a squared off end - as shown in the Tecalamit literature and on your W/NG.
    This makes it very difficult to actually mate the squared-off and spherical parts to effectively pump the grease.
    I have never had much joy with the Old Chestnut of bits of cloth between the surfaces..

    I wonder if there are any gun connector ends more suited to the P6 nipple ?

    Both sizes of the gun connector ends are same concept with spherical inside ends - but both of mine have ball and spring in the Connectors.
    I wonder if this is Normal ? and if its ‘a good idea’ ?
    What do you think ?
    Regards
    Chris Matthews Tokyo

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  2. I have one of these similar to your photo which has various patent nos and no 715 marked on it. Mine does have a spring loaded valve in the steel tip though.

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  3. Hi can you expand on what you mean by filling with a straw in the gun please?

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  4. Sure. When a gun is empty, put a drinking straw in the main tube down to the bottom, and start filling the barrel of the gun (Volume B) from the top with grease. The air in the barrel will travel up the tube and you should be able to keep most of the air bubbles out of the grease. You can use the straw to push the cork seal back down to the bottom as well.

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    Replies
    1. Graces guide (a great site of interesting info on British Companies has a picture showing how the grease gun is filled https://www.gracesguide.co.uk/images/6/63/Im19270914BNAMR-Tecalemit.jpg
      If the cork is right at the top of the cylinder that method should prevent air bubbles.

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  5. How tight should cork washer fit over the piston as mines missing

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  6. Should cork seal washer fit tight over piston? Mines missing

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  7. I don't get the vacuum at volume "A" bit. My guns will pump grease through in fresh air providing they are filled with no air locks.

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    Replies
    1. that's right - but if the balls don't seal, the volume at 'A' won't refill with grease and you will only get air on the next stroke. You have to make sure that at least one of the ball valves is working - and because we rescue these things from eBay or from autojumbles where they have lain unused for years, the little balls often stick or the springs collapse.

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