Pull Cord Switches

Just wondering if anyone is in the material handling industry and what type of pull cord switch you use. Rees is what we use now, but at $400 quite expensive. I'm looking for a pullcord with pilot light 24v, 120vac, preferrably not a spring type. thanks in advance

Is this an E stop application?

yes estop.....

STI offers a pretty complete line:

http://www.sti.com/switches/ER6022/index.htm

Hope this will help.

I currently use the AB lifeline 4 with the Banner EZ light and Banner Safety controller. You should be using a rated safety controller, do not go to just an ice cube relay or a simple contactor. Also, make sure the rope switch that you pick actuates both when pulled and if there is slack in the rope. This will prevent a cut rope from not actuating the e-stop. And if your risk assesment mandates, use 2 safety contacts from the rope switch to a dual channel controller. Finally, I wire the EZLight so that it is green when powered and flashing red when the e-stop is pulled.


I'm paying around $200 for the lineline 4, $65 for the ezlight and $500 for the Banner safety controller that takes in 11 dual channel inputs (or 22 single channel).

PLC_NEWBIE said:

...preferrably not a spring type...

Click to expand...

Just curious, what else type it may be?

Im using a rees pullcord.....its not a spring type.....its good for 250 ft runs, built like a horse, and you dont need tension....I'm looking for something similiar but cheaper......i highly recommend these but there $$$........spring pull cord in my experience cannot be routed around/under things and still be effective


http://www.reesinc.com/UltraLock/pg2.html

PLC_NEWBIE said:

Im using a rees pullcord.....its not a spring type.....its good for 250 ft runs, built like a horse, and you dont need tension....I'm looking for something similiar but cheaper......i highly recommend these but there $$$........spring pull cord in my experience cannot be routed around/under things and still be effective

Click to expand...

I would highly recommend that you (and anyone else) never use these types of rope switches on an emergency stop situation. These are NOT the best for any e-stop application. The fact that you don't need "tension" tells me if the rope is somehow disconnected from the switch, then you are out of luck. You should always have a tension style switch to detect slack cable. The AB is good for over 400 feet and I've never had any problems going around corners if you use a pulley. I've got miles of conveyors that are protected this way and very rarely have problems (the biggest being extreme temp changes might cause an activation, but I have a tensioner on the rope that easily corrects this problem).

I would also suggest that you do a risk assessment to determine what level of protection you need and the proper way to implement that protection. Imagine what would happen if someone pulled on the cord and the system didn't stop and they got seriously hurt or killed. What would you say to that person's family? What would you say to the lawyer while you are on the stand defending how the system was installed?

Since the subject has been brought up

Does anyone know of a published standard which defines such things as

• how E-stop cords will be installed?
  
• what will be used/not used for hangers
• what color cable will be used/not used
• cable diameter

All the ones I've seen are hung with screw eyes of various sizes - and some are pretty chintzy looking.

Thanks

PLC_NEWBIE said:

Im using a rees pullcord.....its not a spring type.....its good for 250 ft runs, built like a horse, and you dont need tension..

Click to expand...

I got very concerned when I saw this. Then I was that Bruce had addressed the concern. The switch in a pull cord Estop should not only trip if the cord is pulled, it shoud trip if the cord is released. The switch has three positions, two of which are emergency stops.

I use AB pull cord switches. I don't remember how much they are but they are robust and trouble free.

I understand the concern with safety......the lanyard that is used with this is aircraft cable with cannot be cut except with maybe bolt cutters. The maintenance dept is in charge of maintaning safety if something does occur with the cord. We've found that change of weather(temps) cause the spring loaded pull cords to be a nusiance (sp)?

PLC_NEWBIE said:

I understand the concern with safety......the lanyard that is used with this is aircraft cable with cannot be cut except with maybe bolt cutters. The maintenance dept is in charge of maintaning safety if something does occur with the cord. We've found that change of weather(temps) cause the spring loaded pull cords to be a nusiance (sp)?

Click to expand...

OK, still if you see my post, they make tensioners that can be adjusted for the temp changes. They are rarely adjusted more than once a year and that is usually during the regular e-stop checks. By the way, aircraft cable is the best thing to use, but instead of cutting, maybe someone will unbolt the connection for some reason or another. How will the maintenance dept know until there is a problem?