High torque

Hi
i want to slow down a 12 DC Vactuator to achieve highest possible torque.Do you know any potentiometers for the purpose ?how do i wire it to operate back and forth smoothly?

Do you mean a 12 VDC Actuator? If so exactly what make, model and type do you have? They make different actuators for different applications and sometimes an actuator is not the best choice for an application where a linear motor would be a better choice. What is your application?

Ron

Kwame,
Putting a resistor in series with a DC motor will greatly reduce the torque. The best way to slow the shaft down and INCREASE the torque is to put a reduction gear on it. Slowing it down using a PID PWM controller is the only way of retaining most of the torque.

A regulated DC voltge will do a pretty good job. I have a specialised pump here with a 12v DC gearmotor, that I run from a 1.0v to 1.8v regulated DC SMPS and it turns very slowly with excellent torque. For a simple open loop system it works very well at least in my application where the pump load is through a fairly narrow range.

Without any detailed specifications on exactly what type of actuator it is, I can only generalize.

Torque, given most every DC actuator I've worked with, will be directly proportional to amperage.

So, replace the 12V 4A power supply (guessing here) that current limits or shuts down under maximal load with a 4V 12A power supply (same power) that tolerates a stall condition for as long or longer than the actuator can. If the actuator is likely to fry if left in that condition for too long, protect it with a self-resetting thermal cutoff.

Yes was refering to 12 VDC!
I am thinking of using progressive Automation linear actuator the following specs:Linear Actuator (Stroke Size 9", Force 400 Lbs, Speed 0.59"/sec) .Does anyone know of any other brands which can be slowed very easily to increase using a variable resistor to increase torque.

HI RB
how did you do it?Which hardware did use and how about the wiring?

kwame said:

slowed very easily to increase using a variable resistor to increase torque.

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MikeMl said:

Putting a resistor in series with a DC motor will greatly reduce the torque.

Click to expand...

cachehiker said:

Torque, given most every DC actuator I've worked with, will be directly proportional to amperage.

Click to expand...

What part of resistor in series did you not understand? A resistor will decrease amperage which will in turn, given the typical DC motors used in actuators, decrease torque. You most likely need more amps, not less. Is the current actuator stalling with 12VDC applied to it?

Like MikeMl said, a reduction gear is an option. I'd say the best. But then you'd have to be good with mechanical stuff. I paired a motor to an external gearing system scavenged from CD-drives by using rubber belts.. might work for you.

I am guessing this is the linear actuator that you are looking at. Should that be true:

Voltage: 12V DC
Load Capacity: 200 lbs, 400 lbs
Type of Duty: 10%
Operation Temperature: -25ºC~+65ºC
Protection class: IP54
Low Noise Design: db<45 (A)
Certification: CE

You have the 400 lb version I assume which has a travel speed of .59 inch per second (no load) and about .31 inch per second under full load.

They do offer a controller for the unit but it looks to be a pair of momentary push buttons for in and out movement. However, and this is a guess, the motor is likely a permanent magnet type motor and obviously from their images geared. Should that be true I would think about just using a good little MOSFET H Bridge and PWM it for your speed control forward and reverse.

I would use their contact us link and give them a call to inquire if their motors can use PWM for speed control. That is how I would likely go about it.

Ron

kwame said:

HI RB
how did you do it?Which hardware did use and how about the wiring?

Click to expand...

I used a cheap SMPS control IC; part number M34063 and a TO220 drive transistor and good sized toroid inductor. It was wired as a standard buck voltage regulator as per the IC datasheet. The IC limits the lowest output voltage to about 1.2v which was fine as the correct motor speed was in a range from about 1v to 2v.

If you use a regulated voltage with the ability to provide plenty of current it gives a acceptable regulation of motor speed provided (as I said before) the mechanical load does not swing through too large a range.