Firstly i am new to hydraulics, i want to build a hydraulic circuit that powers 4 cylinders at each leg of a Quad-Wheeled-Robot. The idea is to move the Chassis of the Robot up and down in all possible ways to avoid obstacles. I did design a system but i am not sure if it has everything i need is there anything that i need to add to it?.

Below is a picture of the simple design using only one actuator cylinder.

It has the following specs:

  • Dynamic Load: 4000 N bis 6000 N
  • Motor: 12V BLDC 1000W (Feedback)
  • Pump: min 80 to max 150 Bar @ 3 to 5 L/min
  • Tank: 5 l
  • Control Valve: 4x Proportional 4/3 Servo-Control Valves (closed Center)
  • Zylinder: Stroke 200mm (Piston/Bore 32mm; Rod:16mm)
  • Check Valve and Unloading valve (if i need one)? Also i have added a Cooling and Filter.

Updated Version all return lines going through Cooler

enter image description here

  • 1
    $\begingroup$ Any pressure relief valves? If the ram / chassis is stuck for example? $\endgroup$
    – Solar Mike
    Commented Aug 27, 2019 at 15:36
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    $\begingroup$ I only see one solenoid and one cylinder - with 4 cylinders, will you multiply the other components also? or how is the final circuit supposed to look? What are the purposes of T2, T3 and T4, is there any connection to T1? $\endgroup$
    – mart
    Commented Aug 27, 2019 at 16:09
  • $\begingroup$ @SolarMike oh ok thanks, only on the piston side or both? $\endgroup$
    – user200509
    Commented Aug 28, 2019 at 17:45
  • $\begingroup$ @mart yep, its just with one actuator as the rest will just be split with a hose to the CETOP config. All the T1 T2 etc are just one tank. The pipes will be connected to the Tank. $\endgroup$
    – user200509
    Commented Aug 28, 2019 at 17:47
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    $\begingroup$ All your tank returns should pass through your radiator, you'll introduce heat into your oil passing through those valves. Id add a dump valve as well or turn the pump off when not actuating any cylinders, you'll get a lot of built up heat when not doing any work. Also, whats the center positions on your solenoids, P to T or P and T blocked? $\endgroup$
    – Corey
    Commented Aug 29, 2019 at 12:26

1 Answer 1


If the first VMA 1.025 is acting as your pressure relief valve, you might be OK, depending on duty cycles/pressures/flowrates/etc...You do still build some heat flowing over that relief valve, but like above, depends on your system. I had a similar issue in a design recently so I feel the need to mention it. If you go with a dump, put the valve right after the pump, dump into a T/Y fitting before the radiator, just add a check valve before the T/Y on the other incoming side of the T/Y. With a center position, P and T blocked, you'll be building pressure/heat upstream of that valve with nowhere to go,not so much an issue in constant operation, but may be evident when the machine idles. If intermittent a great deal between operation and not, I would maybe cycle off the pump.

I like the updated diagram, watch your filter though....you can filter your return oil coming out of your radiator into the tank, but your pump should not be puling oil through a filter, your going to want a strainer for that. I know, pretty similar names, but your strainer has much larger holes, never want to starve a pump for oil.

  • $\begingroup$ Firstly the motor is operated using a Raspberry Pi, so when the center position on the control valve is blocked/closed. The motor automatically stops too. So i think the Dump valve isn't required. Hm, can i put the filter on the return line as the last part of the circuit just before the tank? That will leave the motor and the Tank direct to one another like you mentioned. The VMA 1.025 (0140) looks dicey though. Feel like the oil could escape through the check valve going through the drain line? $\endgroup$
    – user200509
    Commented Aug 31, 2019 at 8:16
  • $\begingroup$ also can i replace the relief valves on Port A and B for the cylinders with check valves? $\endgroup$
    – user200509
    Commented Aug 31, 2019 at 16:22

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