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Converting aux hydraulics to proportional control

1693TA

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Real standard valve used with hydrastatic drive or action. Blocked center with spring return to center, electric solenoid shifted four way valve.

A "soft start" valve would be an easy installation replacing the original valve.
 

materthegreater

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Jul 25, 2012
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VT
Thanks. So you are recommending replacing the whole valve block unit, or just the spools?

Soft start would be better than what I currently have, but I was hoping to convert this valve so that it can be proportionally controlled with slide switches on the joysticks. Are these solenoids capable of holding the valve partially open if connected to a proper controller? I thought about testing it out with a potentiometer to see if I can vary the flow rate with different voltages applied to the solenoids.
 

1693TA

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No, they will not work as you are asking. They receive full voltage for operation from a switch or function, and the full engagement, (spool shift) is slowly actuated. It is not immediate shifting of the spool as your current valve offers. Removal of voltage causes the spool to recenter blocking all ports. Some are dampened in return to center; many are immediate return to center.
 

materthegreater

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Ok, so that helps me understand how soft start valves work. Can you help me understand how proportional valves work?
 

1693TA

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In the "soft start" valve:

The resistance capacitive time constant, (RC) is changed accordingly to the amount of delay desired in the circuit design. This is a design feature not normally adjustable by the end user but can be externally adjusted for application and delay if designed so. This is much the same way your delay feature on windshield wipers operate but slightly altered to slowly apply full voltage to the circuit shifting the spool.

Proportional controls usually utilize a square wave generator circuit and vary the off, and on times of the output voltage on both sides of the "null point" which is felt in the circuit as a varying voltage. This square wave voltage output can be applied to either side of a coil energizing the coil and driving a slug, or a electrical circuit in a given direction.
 

uffex

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Good day Mat
The easy way to understand is to compare it with a florescent light. It uses's less electricity than a lamp that burns power all the time by switching on & off the power, which results in a flicker from the florescent tube. A proportional signal does much the same, mostly with five volts. The period that it remains with power will cause the spool to remain open, the control is by a chip which in turn will be signalled from the slider switch on the control lever. Without going into lengthy text explanation, it is the best I can do.
Kind regards
Uffex
 
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