Whats Happening ?

Working in a chain gang?












Adrian has been talking to John about the problem arising from the snapped drive chain.  John decides to lend a hand to help Trevor and Adrian repair the damage.  After some consideration and discussion it is agreed that the only way to remove the snapped and entangled chain from the main drive sprocket is to reverse it off by using the crane’s engine.  With great trepidation Adrian starts the crane up and engages the track drive levers.  Everything sounds okay so he begins to edge the machine backwards.  With Trevor and John watching carefully for further signs of problems the crane inches backwards but is gently turning to one side.  This is only to be expected since only one track is being driven.  On the other side the damaged chain unwinds itself perfectly and drops to the ground.  Despite now being covered in mud at least the chain is now free and has come off remarkably easily especially when considering how tightly jammed it had got itself.  Trevor, John and Adrian drag the chain from underneath the crane and lay it out on a level surface.  The chain is exceedingly heavy.  Unfortunately one of the links is snapped in half and is irreparable.  Several of the links are very badly twisted and some of the rollers are seized.

John is not at all concerned about the twisted links and sets about straightening them out.  He uses his oxyacetylene torch to heat up the twisted metal.  While the metal is still red hot Trevor and Adrian use crow-bars to apply leverage to bend the twists out  and John encourages the metal to move by applying a very large hammer at the same time.  Within a relatively short time the damaged chain is straightened and the rollers running freely again.  It is then subjected to a thorough cleaning with a wire brush and left to soak in paraffin to lubricate and ease the links, some of which are quite stiff.  It is hoped the it will be unnecessary to replace the broken link since the chain was very slack before coming off.  Being one link shorter may take up the slack and make the chain drive more efficiently.

It is decided that it is sensible to remove the other chain and give it a thorough clean in preparation for the possibility of having to shorten it to the same length as the other. While Trevor and Adrian take up the slack in this chain, John very quickly punches out a link-pin which disconnects it.  It is dragged out from underneath the crane and taken to the shed for inspection and cleaning.  Once on the work bench it is easy to see that this chain is in far better condition then the other and only a small amount of straightening is required which John accomplishes very quickly.   Despite the potential complexity of the problem resulting from the chain break, the repairs have been achieved very easily and with the minimum amount of frustration and effort.

John, Trevor and Adrian next give their attention to the required lengths of chain and come to the conclusion that unfortunately they cannot be used if shortened .  Although both chains were very slack, taking one link out will make them too short to connect the main-drive and track-drive sprockets.  The slack has resulted  from the chains being stretched over the long years in which the crane has been used.  In the design of the crane adjustment was made available to take up slack in the drive chains but this has all been used up.  A replacement link, complete with pins, a roller and side plates, now has to be sourced which shouldn’t be too difficult but that has to be left to another day.  In the meantime the crane isn’t going anywhere.