Please give me examples of old machines that are still in use - not because of nostalgic value but because they are still doing their job so well they don’t need to be replaced or redesigned. For example the tractor of my family soon turns 60 but it still does its job adequately. But I have heard there are much older tractors still in use. You can name both old designs that are still in production and machines that were built long time ago.
With a machine I mean somewhat complex mechanical or electrical system. I can’t define that any better.
Has to have an old design that is still in use unchanged in any way. For example, my flathead screwdriver here is pretty much the same design as a similar tool a century ago, but the metal of the blade is different and the handle is plastic. Those changes mean it’s not the same as the wood handled screwdrivers my grandfather used.
Is the same physical machine, with absolutely no upgrades or changes that affect the way it works.
Is the same physical hardware that was made a century ago? Is that necessary? Big clocks like the famous big ben have had large sections of them rebuilt. Also, they probably have various bits of modern equipment retrofitted on.
B-52’s were first put in service 60 years ago. Not sure if any specific B-52 from then is still flying, but unlike tractors, there’s no real replacement. We’re still using the old thing.
Are any of the original hydroturbines at Niagara Falls still connected to the grid?
How about some of the canal locks in Europe? Any really old ones still in use?
Hammersheads dug up from Roman Republic days are all but indistinguishable from today’s … but that’s not really a “machine” the way the OP defines it. Hammers in the general sense go back 2,600,000 years
The Tyne Swing Bridge has been in operation since 1876. The pumps feeding the hydraulic accumulator have been modernised, but the swing mechanism is original.
This brings us to Theseus’ paradox. "whether an object which has had all of its components replaced remains fundamentally the same object."Ship of Theseus - Wikipedia
If you go to Salisbury Cathedral you can see what is “Probably the oldest working [mechanical] clock in existence, made of hand-wrought iron in or before 1386.” Some parts have been replaced or restored but it is still largely the original clock.
This doesn’t really fit the OP’s criteria though because it exists as a curiosity rather than the apogee of clock design.
In general terms the internal combustion engine has been around for a while - lots of improvements over the years but still essentially a set of pistons driving a crankshaft and powered by exploding fuel.
In terms of old machines that Dopers are more likely to have I suggest metalworking (lathes…) and woodworking (table saws…) from their shops as well as manual typewriters.
I’ve been in a number of factories here in the northeast that are using huge things like rolling presses that bear 1800’s dates on their frames. No absolute candidates, but paging through photos, I find one calendaring press (produces rolls of thin rubber compounds from batch mixing) with an artistic 1873 on the frame. Real monster, about ten feet high and wide, three or four feet thick, and with a drive gear about eight feet across (which sits in a well of its own, with nameless sludge in the bottom that is one drop of blood from summoning Cthulhu). For safety, the gear and well are surrounded by plastic garden fencing in poor repair.
There are examples of 19th century factory machinery that are still being used as originally intended. I can’t think of any links off the top of my head, but it’s not that uncommon.
The Panama Canal Locks, which opened in 1914, still use the original gates and other parts of the mechanism, although the machinery that opens and closes the gates was changed to a hydraulic system in 1998.
