Bronze Bushes

mardi 24 novembre 2015

A friend of mine asked me if I would make some replacement bushes for his boat winch.The winch had been adapted from a manual to a 12V powered winch by the removal of the handle and replacing it with a large diameter pulley that is connected to a 12V motor.
Otherwise itÂ’s a standard 3 shaft winch, with 2 pairs of gears winch with the gears locked to the shafts by C-pins

The existing bushes were made of hard black plastic but they have not been able to take the powered load and he has had to replace the bushes twice already and they are starting to need replacing again.

He wanted me to replace the bushes with bearings but there was not enough meat on the winch housing to fit bearings so I suggested using Phosphor Bronze.

A 500 mm long, 26.5 mm OD was the least I could buy from the metal merchant and I started turning these up yesterday.


There are 3 shafts, so 6 bushes, 4 @ 16mm ID and 2 @ 20 mm. The bushes are ~15 mm wide.
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The Holes in the galv housing were nominally 24.8mm but were not round and had Galv dribbles inside them - I guess with plastic bushes they are just pushed into the holes and the plastic just flows around any minor irregularities - of course this doesnÂ’t work with bronze.

Just to make things a bit more interesting the bush holes in the housing for the 20 mm shaft were not aligned and had to be squared up.
I started to make each bush specifically to fit each hole but after making the first one I just reamed each hole out to 25mm which made it a bit easier.
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One of the shafts is a slider (slides sideways by about 15 mm) which disconnects the gears between cable drum and drive shaft so the cable can be just pulled out manually.
the bushes have a 2mm lip and are inserted into the holes from the inside of the housing so I could not press fit the bronze bushes into the housing holes - so the bronze bushes are just a neat fit into the holes.

On the sliding shaft, instead of the shaft sliding inside the bushes, the bushes themselves were sometimes sliding in their holes which was not good so I managed to drill a 3mm hole and fit a short (7mm) C- pin through the housing into the bush.
The neat thing about this is the pin provides a small oiling hole.
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All in all a fiddly job, but lots of glorious coloured swarf everywhere.
Now my mate wants a spare set made !!!!
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Bronze Bushes

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