Linear actuator control - speed vs torque

Hi,

We want to buy a linear actuator 24VDC. We want to control this with a circuit board fro electromen http://electromen.com/files/3513/7811/0071/EN_em-174a.pdf

I wan't do decrease speed with this but I have one question I wan't to verify. The sales person of the actuator tells me that if I use the card and put the speed down I won't loose torque. Is this correct? And how is this achieved?

/Tim

The linear actuators we use have a nominal speed and torque. If we want lower speed (or higher torque), we choose a different model actuator. Most of the time lower speed in the same model range goes with higher torque and vice versa.

Yes this line of actuators also have diffrent models with diffrent speed but we need two speeds for our actuator, hence the curcuit board for controlling the speed.

When ordering diffrent models I assume that the gearbox is what makes it slower and stronger.

I would put that question to the supplier. If he can't give a good technically based answer have him put the question to the next level up. "Trust me" doesn't cut it.

I don't know much about DC motors, but I think torque is a function of current. I have used AUMA valve operators in the past, and they use a DC motor and control operating speed without losing torque. I don't know the internal details of their system.

I just got done putting 10 linear actuators on a damper system. The spec'ed rotary actuators weren't strong enough.
We went with a simple 100lb, 24 volt, no-position-feed back. ($125.00 each)
Temperature too cold in room, PLC sent .5 pulse to close. Temperature too hot, .5 pulse to open. Actuators automatically shut down at end of stroke, but will wake up when asked to reverse.....so no worries there.
I did have to put "cycling bits" on them, so they couldn't fire at the same time and over-amp the power supply.
Looking forward to seeing them work here in Wisconsin when it is -20 degrees outside.
As far as torque goes, the gear-reduction is the same whether you run them fast or slow. (Voltage controlled?)
So I am leery of what the salesman told you.

I sure will ask my salesperson again, but it is always nice to know how people in "the real world" answer and have experienced. I will let you know

That company also sells DC servo controller boards. To be used with a linear actuator with position feedback. Think of those as a long linear pot, attached to the linear piston moving in/out.

The board is fed from the PLC with an analog 0..10V signal. The higher the voltage from the PLC, the further the actuator extends. Giving a slow ramp up on the analog PLC output would make the linear actuator move out slowly. Faster ramp up makes the actuator move faster (up to its nominal speed).

Does that sound similar to what you intend to do?

The board is essentially a normal DC drive. It has IR Compensation to maintain a pretty good speed regulation with variable torque loads. It should do fine for what you are looking for.

rQx said:

I sure will ask my salesperson again

Click to expand...

Ask the guys in the technical department. My experience is that salespersons, say their products do many things, some of which they don't.