Fun With Hydraulics - Auto-Cycle Valves

Auto-Cycle valves can be a real time saver... and they are pretty neat, to boot. The concept is that one operation starts and ends the whole cycle. In the typical system, you have to hold the valve in position on the extend stroke, and then reverse the flow to retract your cylinder. With an auto-cycle valve, the extend works just like the retract AND it automatically starts the retract phase.

Prince Manufacturing makes a darn good RD5000 Series Auto-Cycle valve. Here's how it works:

1. Pull both handles and the cylinder begins to extend.
2. When the cylinder reaches full extension, the pressure builds to the point of engaging the pressure-release detent (also found on standard logsplitter valves) which springs the first handle back to neutral.
3. The second handle still being engaged forces fluid to the retract side of the cylinder, causing the cylinder to return itself to the closed position.
4. When the cylinder reaches fully closed, the pressure build-up engages the aforementioned pressure-release detent, which disengages the second handle. Cycle done.
   

I recently discovered that this can also be done in circuits using hydraulic solenoid valves, simply by using pressure switches and relays. Using one pressure switch on the extend and one on the retract (using relays to lock-in the signal) you can alternately engage the opposite sides of the valve.

1. Engage the cycle by starting the Extend function
   
2. When pressure builds to the pre-determined level, the pressure switch will output a signal, which disengages the relay and engages the retract function (and it's relay)
   
3. When the cylinder fully retracts, pressure is builds to the second preset level, and the second pressure switch sends the signal to disengage the relay. The cycle is over.

This is remarkably useful on splitters, crushers and anything else that can be left alone to do its job.

Using Solenoid-Actuated Hydraulic Valves

Solenoid-Actuated Hydraulic Directional Control Valves

It sounds like a ridiculously long and complicated name, but its actually a very simple concept and even easier to implement. Solenoid valves simply take the place of other hand control valves, using an electrical current to control the valve. Instead of having to physically push or pull a handle which moves the spool into the desired direction, solenoid valves can be used with an array of switches, automated programmable controls, or operated with wireless transmitters.These valves (also known as D03, D05 or D08's) depending on the the flow rating) are extremely reliable, easy to setup and easy to maintain. They have been used for years in industrial and commercial environments and are now becoming commonplace in the agricultural, mobile, and end-user markets.

Solenoid Control Valves Must be attached to a subplate or manifold in order to be used. The subplate/manifold is drilled with porting, mounting points and, often, cavities for a gauge and relief valves. Multi-Station Manifolds can be used to bank multiple valves together in one compact unit. The manifolds can also be ordered in custom configurations for those who are looking to pack as much functionality into as little space as possible. It is also possbile to sandwich other types of valves with these, such as pressure reducing valves, flow controls, and pressure switches.

• D03 Valves - Up to 20 GPM (12 GPM for Tandem Center)
  
• D05 Valves - Up to 40 GPM (25 GPM for Tandem Center)
• D08 Valves - Up to 75 GPM (65 GPM for Tandem Center)

Available in Tandem Center, Closed Center, Float, and Motor Spools, 12VDC, 24VDC and 115VAC.