RINGS, BOLTS AND TELLTALES? by Eric Eaton

Big changes to the ways underground roadways were supported

This picture shows ring supports for roadways which were used up until the 1990s

This photo shows the way coal mine roadways were supported until about the early nineties. The supports you see are what we called rings, rings came in three pieces a bow which is the middle bit you can see in the photo and two legs which attach to the bow with ring plates as you can see in the photo on the right, also attached are struts to tie all the rings together.

This picture shows a roof bolted roadway

The second photograph shows a roof bolted roadway, metal straps in the roof are where the 8 foot roof bolts are put in, the straps come with holes in for the steel bolts to go through and steel mesh is placed over the straps to form coverage of the roof. Bolts are also put in the sides of the roadway, steel mesh is used on one side with steel bolts and plastic mesh used on the other side with wooden bolts. The plastic mesh is used on the side where the coal face will be, the coal face machine can then cut right into the roadway without hitting any steel.

The plastic bags you can see in the bolted roadway are filled with stone dust and are there for safety reasons, if there is an explosion or a fire underground these bags are designed to drop and smother the explosion or the fire. (Although a different design stone dust barriers were also used in the roadways supported by rings).  

Another safety device used in Bolted roadways was what we call a telltale, a five metre hole would be bored in the roof and an a telltale would be inserted with a traffic light system showing just below the end of the hole, these were used to monitor any roof movement, if the roof had moved, remedial work would have to be undertaken at that spot, i.e. more roof bolts inserted or longer roof bolts could be used to make the roof stable again.

As always we are interested in your stories, experience, knowledge and comments regarding our posts.  Let us know what you think.

Eric Eaton.

Categories: News.

Comments

  1. Pete Wood

    Good photo. The earliest rings I used where in two sections, joined in the middle at the top with a fish plate, would have been in the tail gate. The ones you show were used, as well as a three section, with a heavy clip type of fastening, no bolts. The rings had a German sounding name.

    The spacers for the rings went from wood to metal which were bent to fit the flange of the ring.

  2. Frank Nattriss

    I left the industry in Dec. 1973. Walking under a roof with roof bolts would be totally alien to me. I feel this method of support is merely a money saving scheme. I would have felt safer under the old 8 feet rings, two half rings bolted together. I know of one disaster when there was a crack in the strata way above the bolts due to movement towards a old roadway.

  3. Eric Eaton

    You are right Frank it was used to save money, saving on steel rings, sheets, and struts. It was also a lot quicker, were as in a ringed roadway you could at best do about 50 metres in a week, in a bolted roadway in a week 100-200 metres was not uncommon. I also remmber men getting fined for leaving small gaps in between the sheets and then we came to mesh in roof bolted headings, when it fits.

  4. Stuart Fennell

    Bilsthorpe, August 18, 1993. Roadway supported by NATM (new Austrian tunneling method) technology, i.e. roof bolting, collapsed resulting in 3 fatalities. Would it have happened if Hollybank arches had been used instead? I guess no one will ever know for sure..

  5. Billy Walker

    In Monktonhall and Bilston Glen the ‘bow’ centre section was referred to as the ‘crown’ and the completed rings were simply referred tto as ‘girders’
    As early as 1982 I saw small sections supported by a roof bolting system but. I never felt comfortable beneath these
    Really interesting article pity it didn’t explain the mechanism of the telltales
    Given the amount of deformation in most of the roadways I had to go through I think every other bolt would have been a telltale…. I vaguely remember an operator using the roof bolt machine saying the machine wasn’t very reliable…. .or to be truthful the expletive laden pit language equivalent of .,’a right pain in the pinny

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