Posted for Adam Molny <Adam@ValidationPartners.com>:

Hi Brent - Thanks for the info. As you may have guessed, I am new to hydraulics.
The lock valves are a good idea to ensure positive sequencing. I just
have to work out the logic. However, I'm not sure what to do about the
spool valve. Is there another type of directional control valve that
would be more suitable?

Thanks,
Adam