The Craftmans Shop > New from Old
Thwaites 2 Ton Two Cylinder Dumper Running On One Cylinder
Spurry:
Another brilliant job, Andrew. Thanks for sharing.
Pete
awemawson:
Thanks Pete for the kind words.
.... but a bit of thinking has left me deciding that that centre pivot definitely needs sorting - there is at least 1/4" play in the bearings - perhaps more, with the result that the thing clanks all over the place.
The front of the machine is hinged to the rear by three self aligning spherical bearings arranged at two levels. The lower pivot, which seems to have very little play in it, is just a single bearing. Whereas the upper arrangement is a bit more complicated - it has a 'fish plate' of 1" thick 3" wide steel 17" long, each end of which has bearings inset into the thickness. There are grease seals jammed above and below the bearings which are lubricated by co-axially drilled grease runs in the pivot bolts
The whole upper bearing assembly is available as a repair kit, but at £293 it's rather pricey :bugeye:
awemawson:
Now I've rather ignored this problem for a long time, as it's not the easiest of things to get off and work on.
Firstly, undo it, and the dumper falls into two bits :bugeye:
Secondly, the rear fixing of the 'fishplate' is very badly obscured by the hydraulic steering orbitor.
Now in a flash of inspiration I've decided that, so long as I leave the lower bearing intact, and suitably weigh down the bucket so it tends to collapse backwards (weight at the moment empty tips it forwards) I can support it on axle stands if I can somehow get at that rear fixing.
Now here comes the clever bit - slice the entire steering support assembly off with an angle grinder and put it to one side - finish the pivot repair, then weld it back on :ddb:
This has the advantage of killing two birds with one stone. When we moved here, the very helpful hi-ab driver LeRoy foolishly tried to lift the dumper off his lorry using this steering support assembly, and pulled it entirely off the machine :bang:
It had to be quickly welded back so the machine could be moved as it was obstructing everything else, and the only welder to hand was my old MIG BUT NO GAS :( It didn't help that it was pouring down as well. So it got glued on as a temporary fix eight years ago, and has never been re-done :palm:
They must be the grottiest welds I've ever made, but they have at least lasted, so this gives the opportunity to cut them off and hide the evidence :ddb:
awemawson:
I bit the bullet at the weekend and ordered that expensive top link kit. I'd intended to pull out the old and see if I could re-manufacture it, but realistically I don't have the time as I can't measure the bearing until it's out, then several days waiting for bits, meantime machine cannot be moved. Costly but I think probably expedient.
The kit won't arrive until Tuesday or Wednesday so I've been giving some thought how to control the two halves of the dumper when I remove the original. I had thought that to weld a temporary strap between the two halves would be the way, but in practise I'll need to adjust their spacing in order to get the large pivot bolts installed. Just relying on axle stands is a bit dodgy, as they tend to slip as you strain on things balanced on them.
So I came up with the idea of taut lifting strops arranged so I can adjust the tension as I install the bits. The 'skip' has suitably tough handles welded to it in convenient places that will take shackles, and on the rear half a pair of 10 mm deck hold down bolts were in just the right place to mount brackets. It was a simple job of boring holes in a bit of 6 mm thick 50x50 angle iron and bolting them, on :ddb:
With a tourniquet rod put through the lifting strops and turned, I can fine tune the relative position of the front and rear halves of the machine, all the while keeping the lower pivot assembly in place
smiffy:
Hi I have enjoyed reading you posts ,for many years I worked on all manor of plant both large and small .When changing the centre pivot bearing I would tip the skip onto a block of wood and lock the ram of with a length of angle ,them place a jack in front of the pivot,place a trolley behind the pivot ,remove the bolts through the pivot and wheel the rear end backwards .If i remember correctly this can be done without removing an of the pipe work , usually took about 2 hours from start to finish.
On a completely different note many years ago i was the mechanic for the coastal defence work near you at Fairlight cove which involved unloading 250,000 tons of stone shipped in from Norway on barges each carrying 10.000 to 15,000 tons. The barges were floated in at high tide the bilges pumped full of water so they settled on the sea bed them the stones ,each weighting a minimum of 10 tones pushed over the side and at low tide they were loaded onto dumptrucks run up the beach and unloaded and positioned using 5 tine grabs on 75 ton excavators. Very punishing work for both men and machines ,if i can find some pictures I will try to post them .Over a 6 month period we had 3 machines break down and go and get a swamped by the tide , a real recover problem as one was a D8 The other 2 both 75 ton excavators . Happy day
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