Two Hydraulic Cylinders to be Synchronized by Arduino

I have a brake press for folding sheet metal 60 tone bending force. Originally press had CNC control system but its become obsolete because its 30 years old.

The press has 2 hydraulic cylinders pushing down a punch. The 2 cylinders need to be synchronised electronically so they are coming down level.

So, the plan is to have encoders readers on each site sending signal to Arduino. The Arduino will control relay connected to hydraulic proportional solenoid valves.

Do you think its achievable?

I have electrical hydraulic knowledge but only starting to learn Arduino for the first time.
Any advice would be appreciated

Once designing heavy fork lift trucks, let's see if I can contribute.
I guess that both the position and the preasure on both cylinders might be interesting. Equal postions but different forces applied or equal preasure but different positions.....

What is the stroke of the cylinders? What preasure range do You use? That will direct You finding sensors.

Good luck avoiding oscillations!


Did you already choose a test model for combing out initial software bugs, before you risk to kill the press?

Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.,148850.0.html . Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

How did the original setup achieve parallel operation?
How did it monitor each cylinders position?

Tom... :slight_smile:

A hydraulic flow divider can do that. Why complicate it?

Thanks you for all your replay. The stroke on the HACO press is about 200mm. The pressure is 200 bars.

I did by pass old CNC controller and its working fine up and down but no precision. I did install limit switches on each side so, they control the depth position.
At the moment some ram move little bit faster compared to second one.
The reason why I don’t want to use hydraulic flow divider because its more costly and more work.

If you think it about the press has everything to control level electronically. Originally was cnc press.
It still has 2 sliding encoders on each side and it has proportional solenoids valves control.
Just need little brain to take signal from 2 side encoders and then control via relay proportional solenoids valves.

Do You have dokumentation, manuals, to the sliding encoders?

Thank you for your replay.

that kind of encoder is out of production, but here are some details available:

Code: 732365600010
Encoder MSA 322.23
resolution : 5 µm
grating pitch 20 µm
accuracy ±10 µm/m
reference index: 85 mm from left
supply: +5 V
output: square wave signals 5 V
cable: K1, 3 m cable, connector L70
measuring length 170 mm
Encoders made in Austria- RSF Elektronik Ges.m.b.H

Ok. What protocool, how does the communication work between the sensors and the system? If the system is obsolete it ought to be possible to get answers from the manufatorer.

If not, is Your old system working regarding the measuring part? Can You get hold of some analyzing equipment and crack the signal?

Of the 175 results - one might have some good info - also check with the manufacture - many have old sheets online and will send you a link - the info is also needed if someone wants to update or replace an old control part -

Encoder "MSA 322." - Google Search......0....1..gws-wiz.efB_ZRysBek

The company looks to be foreign to the US but they should have English speaking people

Since it is a square wave output I would expect some sort of PWM - even my old Fluke 87 meter would probably give you some good info.

I would expect a quadrature encoder inside, with A, B and index signals.

you are correct An encoder would make more sense - how many output leads ?

I have about 9 output on the encoder cable.

I tried to get some more info from the manufacturer about the encoder but without success.

Please see below replay text from manufacturer of the encoder:

so you should have two encoders (one left and one right) and both have a reference index for re-initialisation.
The encoder is just counting (up/down) the exact synchronization (presetting) you need to do by software (controller)

reference index: 85 mm from left

And ..... did the old system include safety interlocks for the system ( to stop you bending fingers ) , that may need care in implementing .

My guess would be it used LVDC type position sensors , need to power them up and look at the output.

The press did not have safety interlock system. But I agree with you hammy safety is first…

I can buy new encoder suitable for Arduino brake press synchronization project if needed.

I’ve got my starter Arduino kit last week doing self-study on the lesson:

I can imagine that 2 potentiometer about 10K ohm with sliding 200mm should do the job as encoders.

The programming part is bit difficult for me but I will try to learn new things…

See the attachment electrical schematic of the balancing controller.

Basically I need to write a program to compare 2 analog inputs from 2 potentiometers connected to a Arduino and show me the difference on one LED (relay) also connected to the same arduino.

There is the logic plan how that should works

P1 is the main master potentiometer
P2 potentiometer should always match resistance to P1 by switching off and on LED 1 and LED2.
LED1 and LED2 its relay which control proportional solenoid valves.

When is no difference in resistance between the 2 analog plus minus 5% two LED should be ON
When is the difference in resistance on P2 is < then 5% to P1 switch LED2 and LED1 is off
When is the difference in resistance on P2 is > then 5% to P1 switch LED1 and LED2 is off
Have you any advice about the code please?

Arduino Uno can write or read 6 pins in 1 cycle using Port registers.

How slow can you make the press move?

The speed of the movement on the press is already set up.
What I need just switch on and switch off servo control solenoid (left side right side) if difference 0-10% on potentiometers was detected. I will attach linear potentiometer to each cylinder to read there position. I have a dual pedal switch for up and down.
For now I also have installed limit switches for depth controls.
The press has original Linear encoders but not sure how to connect to Arduino.
I attached picture how cnc press works.