There is no old definition.
(new)
A horn press is a special type of gap-frame press where a heavy cylindrical shaft or "horn" appears in place of the usual bed. Curved or cylindrical work pieces can be placed over the horn for such operations as seaming, punching, and riveting. On some presses, both a horn and a bed arc provided, with provision for swinging the horn a side when not needed.
(J. T. Black,Ronald A. Kohser, DeGarmo's Materials and Processes in Manufacturing, 2012, page 475)
5) Direct-acting valves (Group: Pneumatic Unit)
(previous)
The direct-acting valve, is the simplest and least costly design.A reduction in pressure at the inlet acts on the underside of the diaphragm, which in turn, opposes the pressure exerted by the main spring, allowing the closure member to open, thereby increasing pressure.This type of valve is suitable where accurate control is not essential and where the steam flow rate is small and reasonably constant.İt has some fluctuation of steam pressure and a relatively low capacity for its size.
(Facility piping systems handbook 2nd edition Michael Frnkel p.11.16)
(new)- Better
When the solenoid is energised in a
direct-acting valve, the core directly opens the oriiicc of a normally-closed
valve or closes the orifice of a normally-open valve.
The force needed 10 open the valves is
proportional to the orifice size and fluid pressure. As the orifice size
increases, so does the force required. To open large orifices while keeping the
solenoid size small, internal pilots are used.
(T. Christopher Dickenson, Valves, Piping, and Pipelines Handbook,1999,page 151)
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