Setting up multiple hydraulic pressure settings

  • Thread starter Mike Piotrowski
  • Start date

Thread Starter

Mike Piotrowski

Currently, when the operator presses the palm buttons, the cylinder begings its stroke and when it "feels" resistance it builds up pressure to a setpoint (controlled by an adjustable screw in the pump) until the operator releases the buttons. The problem is, with different products, the pressure is sometimes too much or not enough. It is tedious/time consuming for a qualified tech to adjust the pressure screw on the pump each time we switch products. Is there a way of creating a 4 position switch so that an operator can choose from 4 different pressure settings? (Of course, I would like the ability to change these settings if new products come along). Has anyone seen a similar application?
I've done it with four pots, an amplifier card, and a proportional valve. I used a Nachi valve, as other inexpensive proportional valves (I won't mention any brands ;^) have worse hysteresis and repeatability. The amplifier should have a dither signal and it will need to be set to a fairly high amplitude for repeatability. The selector feeds one of four voltages from the pots into the amplifier. I didn't do the hydraulic circuit, but I think it was a pressure relief type of circuit, so the pump screw was set to the max pressure desired. If you see jerky response as the switch is thrown and the amplifier doesn't have any ramps, you can add a series resistor and a small electrolytic cap to ground on the signal from the switch to the amp. Willy Smith

Harry Wilson

M-System of Dallas has a device with four output alarms. The alarm setpoint can be adjusted from the front of the din rail mounted unit. The device displays PV or Pressure continuously. See attached or call M-System at 800/544-3181 Regards, Harry