solenoid needed

[dmehling]

I am looking for an inexpensive solenoid.  It needs to be a pull type with a stroke distance of about 3 inches.  I am open to other actuators, but I need linear movement and a spring to hold an object in place after current has been shut off.

[Admin]

It needs to be a pull type with a stroke distance of about 3 inches.

I dont think you will find any above about 1 inch. I think what you want is a motor that uses a worm gear and a linear rod.

otherwise . . .

Check the google ads on this page:
http://www.societyofrobots.com/actuators_solenoids.shtml

Some of the places on this page has solenoids:
http://www.societyofrobots.com/robot_parts_list_motors_servos.shtml

[dmehling]

If I can't use a solenoid, then what are some other ways of using an actuator with a spring mechanism?  I am trying to build a clamp and need an actuator to hold it open, so that when electrical current is not applied to the actuator the clamp will automatically close.

[Admin]

Again, use a worm gear. When power is off, the worm gear still holds. It will hold better than any spring, too.

For example:
http://www.linearmotion.skf.com/en/8/fam-cat2106fid311-Magforce.html

Basically a worm gear drives a normal gear, and this normal gear drives a linear rod with teeth in it. This page has a good animated example, but it takes forever to load:
http://www.li-xiang.com.tw/new_page_88.htm