Blaw Knox 95 Layout

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Blaw Knox Layout with a fixed screed.

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I believe a skilled operator should understand there machine and all its adjustments.

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This is a BK95 by this time the screws were hydraulic but still a skilled job (just less physical)

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All important stuff when you were setting up, simple things like this could make all the difference to a good mat finish.
( but then the roller driver could stuff that up for you )

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Hello all,
Here are some more diagrams to mull over which might interest some of you.
The last diagram shows a built up fixed screed which I think would have measured 24ft.
You can see the the various types of extension boxes available which are bolted together, the larger 2ft ones could also have burners on if required. (Note the burners on this screed are fueled by diesel) I could be asked to change the width of the screed several times a day on some jobs if cut off shoes were not practical.(This was a very laborious task sometimes, a loader and lifting chains were used if available).

The diagram shows various components, the drive motors, drive shafts, carrier bearings and V belts for the tampers etc. Some of these parts needed greasing or oiling at regular intervals during the day, you would constantly be checking fuel and hydraulic pipes for leaks and fireboxes for cracks and loose bolts. This was time consuming but better than a failure with a thousand tons in front of you!.( I used to get an extra 2 hours pay per day for this task, that showed the importance i think!)

All the various turnbuckles are shown (but not the shims in between the boxes) which would be used to set the screed up in conjunction with a good straightedge to lay the perfect mat, they're not just for support when in the raised position.

When the day was finished you would switch off the the burners but leave the fans running to keep a constant air flow whilst the screed was cooling down, you were best to leave the tampers running with screed in the raised position for a while( usually whilst you where cleaning the rest of the machine down) so the bitumen that had got in between the tampers and the tampershields would drip out and then you would wash it down with diesel.

Care had to be taken on how you supported the screed when you parked the machine up after the shift because of distortion whilst it was cooling down, so you would use blocks at intervals along the sole plates (like shown in the diagram) , you would never rest it straight onto the ground.

Most Pavor drivers didn't get much spare time, if you weren't laying, you would be maintaining to minimize breakdowns etc, we could get very possessive of our machines because of the work we put into them

[Ian Fletcher1970]

Hello all,
Here are some more diagrams to mull over which might interest some of you.
The last diagram shows a built up fixed screed which I think would have measured 24ft.
You can see the the various types of extension boxes available which are bolted together, the larger 2ft ones could also have burners on if required. (Note the burners on this screed are fueled by diesel) I could be asked to change the width of the screed several times a day on some jobs if cut off shoes were not practical.(This was a very laborious task sometimes, a loader and lifting chains were used if available).

The diagram shows various components, the drive motors, drive shafts, carrier bearings and V belts for the tampers etc. Some of these parts needed greasing or oiling at regular intervals during the day, you would constantly be checking fuel and hydraulic pipes for leaks and fireboxes for cracks and loose bolts. This was time consuming but better than a failure with a thousand tons in front of you!.( I used to get an extra 2 hours pay per day for this task, that showed the importance i think!)

All the various turnbuckles are shown (but not the shims in between the boxes) which would be used to set the screed up in conjunction with a good straightedge to lay the perfect mat, they're not just for support when in the raised position.

When the day was finished you would switch off the the burners but leave the fans running to keep a constant air flow whilst the screed was cooling down, you were best to leave the tampers running with screed in the raised position for a while( usually whilst you where cleaning the rest of the machine down) so the bitumen that had got in between the tampers and the tampershields would drip out and then you would wash it down with diesel.

Care had to be taken on how you supported the screed when you parked the machine up after the shift because of distortion whilst it was cooling down, so you would use blocks at intervals along the sole plates (like shown in the diagram) , you would never rest it straight onto the ground.

Most Pavor drivers didn't get much spare time, if you weren't laying, you would be maintaining to minimize breakdowns etc, we could get very possessive of our machines because of the work we put into them

Hi Richard,
Sounds a very time consuming job - I suppose the advent of the hydraulically extending screed made life a lot simpler?

[Hutch]

still have nightmares about fitting those 3/4 metre extension boxes.those prop shafts connecting to the main screed were a right pain to fit either you had to sand the shaft to get it to slide on or the key would drop out as you slide it on.Even though the tamper frame had holes in it for bolts you never bolted the 3/4 extension to the main screed, one gang done this and snapped the bearing housing on the extension tamper and after this fitting 3/4 boxes became a fitters job.When we done a screed overhaul my old boss would try to have us shim the extensions to the nearest thou and weld packers to the top bolt holes to force the extensions down as the screed frame had distorted. In his mind near enough was never good enough.The extensions would then have the machine number and fitting order welded to them.Building up a wide screed could take a day as once you had fitted the extensions you then had all the auger extensions, baffles and bracing to fit.Even extending screeds still need boxes fitting on wider jobs having fitted two 250mm ones to a Vogele screed last night and still seem fiddly with bolts in akward places and cams to set the sole plate to the main screed.

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Your right Ian, when i started machine driving I had a fixed screed on my pavor so i loved the extending screeds, they made my life a great deal easier, you didn't have to be as accurate when operating because you could move the screed in or out as you were laying, so things like joints were easier to match up or you didn't have to change your drive line as you approached iron work etc, just slide the screed in around the gulley and as you went passed slide it back out. A little bit of hand laying and the manouvre would be done with hardly any fuss. (that's the simple version ) And best of all no building up and knocking down (only extension boxes when required).

You still had to keep good control of the flow of material and speeds and not mess about too much because it would affect your levels dramatically. The art was to communicate well with your screwmen and give them the heads up if you were changing anything.

Pavor driving is an art, like i said earlier, any change can have a dramatic effect on the levels, speed, flow control, moving the screed in and out, temperature of material the list is endless (That could be another thread).

On major jobs we could could use extending screeds on roadbase and base course but not on wearing course. For that we could only use a fixed screed. It was believed that you got the best finish with a fixed screed which from experience i do agree (that statement could start some arguments here )

On major jobs in the eighties we used to either have one machine with two screeds (a Blaw Knox) and just carry out a screed change. Or two machines on the job, one with a fixed and one with an extending, a Blaw Knox would would do all the lower layers with an omniscreed and a Dynapac with a fixed screed to lay the wearing course.

As time went on the use of extending screeds on all types of asphalt became more common, and fixed screeds were only used on major jobs such as motorways and runways. I'm not sure what the standard now ( i haven't driven a machine for quite a few years ) but im sure some one will comment.

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still have nightmares about fitting those 3/4 metre extension boxes.those prop shafts connecting to the main screed were a right pain to fit either you had to sand the shaft to get it to slide on or the key would drop out as you slide it on.Even though the tamper frame had holes in it for bolts you never bolted the 3/4 extension to the main screed, one gang done this and snapped the bearing housing on the extension tamper and after this fitting 3/4 boxes became a fitters job.When we done a screed overhaul my old boss would try to have us shim the extensions to the nearest thou and weld packers to the top bolt holes to force the extensions down as the screed frame had distorted. In his mind near enough was never good enough.The extensions would then have the machine number and fitting order welded to them.Building up a wide screed could take a day as once you had fitted the extensions you then had all the auger extensions, baffles and bracing to fit.Even extending screeds still need boxes fitting on wider jobs having fitted two 250mm ones to a Vogele screed last night and still seem fiddly with bolts in akward places and cams to set the sole plate to the main screed.

Looks like things haven't changed too much then Paul We ended up having boxes welded with numbers and what order they went together and what machine they went with to make life easier ( which it did ). I'm glad you mentioned the augers and baffle plates and all the other hassles! I think we could write a book between us just on this subject!

Do you still get people trying to knock off iron work with the side plates (by extending the screed and pushing the iron work off)?
We used to end up using helecoils just so we could mount the side plates because they had broken them off so many times, or on the machines with extending baffles they would forget they were out in slide the screed in and damage the side plate that way!


I remember once i had a Blaw Knox which had had its flight chain carriers bent up under the machine on a manhole which had jammed up the flight chains, so in my wisdom i went down a manhole, they drove the machine over the top of me and i carried out the work to get them unjammed and straightened out. while i was down the man hole the gits went to the pub and didn't come back for 2 hours and i couldnt get out I wasnt a happy bunny LOL

[Hutch]

Hi Richard
Extending screeds were around for a long time before they became accepted in the uk with Demag building the first one in 1979. But due to the two leading uk paver manufacturers Blaw Knox and Barber Greene struggling to develop a decent extending screed councils would not allow them to be used on tolerance work.I remember one of Blaw Knox's development engineers saying he watched a Hoes 12000 with extending screed and thought how can the Germans design a good screed and we can not.Barber Greene eventually gave up and fitted a Danish Partner Tecnic screed while Blaw Knox developed the Omni 5 screed which was a copy of the Vogele screed for which they had to pay a royalty to use the guide system. Then theres high compaction screeds but thats another story.

[70's steve]

"councils would not allow them to be used on tolerance work"
yep remember my dad saying exactly the same thing , i'd suspect my dad wishes that he had telescopic screed/boxes on he's bk 90 back then , he's told me a good few story /many times about how he had to blot on the boxes / travel to the next job with the boxes still bolted on , 1 time on the old connaught bridge (A406 ) he got stuck /wedged with them on lol , but he's poor backsuffered lifting fitting them ,

[70's steve]

please remove this post , double posted , thank you