I'm feeling like taking your approach one step further and connecting the two lines from the motor to each other should get the thing to stop on a dime. But see my response to Tim for more detail. =======
Maybe you could add a normally-closed solenoid valve tripped in advance, in series with an easily accessible throttling valve, to bypass enough of the flow around the hydraulic motor to slow it down before it's stopped.
You could tie it into other solutions, like releasing the valve to help stop the motor, then opening it to free the motor when the locating pin actuates.
If it doesn't work you can just close the valve and leave it there.
It's a big leap from recognizing that the design isn't currently ideal to claiming that someone's an idiot. Seems to me to conclude that you'd have assume that the machine is being used as it was first conceived; that there haven't been changes since it was built; and that the OP's explanation of the machine is complete & correct. The first two are very unlikely if the machine is indeed over 50 years old. The OP has added some info in later posts that belies the third.
Later posts indicate there is a shot pin or similar device on the table.
There was a hydraulic system used on aircraft, and probably in other places, that used a so called "open center" system that worked as you describe. See:
That is certainly true. Unfortunately, the plant has been through a few own ers over the years and documentation has been lax or lost entirely. I haven 't seen this machine run, nor have I seen prints for it - I don't even know that they exist. When I get back there, I will, for sure, pull off a bunch of covers and trace out the hydraulic circuit. I really have no idea what I might find. It's possible that the work I plan to do has already been don e and, as Roger suggested, there are stuck or leaky valves. We'll see next week.
Remember, this is a pre-PLC, pre- contraption. It is entir ely possible that I'll find excessive wear in moving parts (chain drive, by the way) and will have to go back to the idea of an "almost there" sensor to trigger a slow approach and then a "there" sensor to stop. On the face o f it, I have no problem with that, and it may be the easier way overall - a ll electronics, no oil. Right in my wheelhouse.
I certainly could do that, but I don't know what the benefit would be to cu tting the motor power. It's certainly easy enough to do, though, since the controls are already in place.
And that's why I asked here. Even if you know next to nothing about hydraul ics, you still know more than I do :-)
That's certainly one way of making the thing robust in the face of wear.
Someone suggested a proportional hydraulic valve that's actuated by the pallet position -- that would also work, but you might want to back it up with your existing microswitch-and-off.
That's really, really scary, given that most of what I know about hydraulics is what you need to operate forklifts and fix the brakes on your car.
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