That scenario reminds me of a similar situation. Some of the crimper tools used to put lugs on wire, or other terminals, often have a ratchet mechanism that required the crimpers to go the full crimp before they would release. Even if they were basically an overgrown pair of pliers, it was possible to get you finger caught. No emergency stop button there either.
John Shinn, P.E. From: [email protected] [mailto:[email protected]] On Behalf Of Robert A. Macy Sent: Thursday, January 26, 2006 5:24 PM To: [email protected] Subject: Re: Emergency Stop Switch Please take great care that... 1 Your machine doesn't really need an emergency OFF/STOP switch 2 Place it where it is useful - near to the Operator and near to bystanders. Years ago, I remember seeing one of the most impressive multi-ton presses for bending metal I had ever seen while working at HP in Palo Alto. As rookie engineers we were required to get an understanding of the sheet metal processing to make us better designers. In a "dry run" I activated the press. It moved a shear type of blade downward. When I released the activation, the blade's motion simply ceased, did not retreat. Activate, and the blade continued down. The blade never retreated until the cycle had been completed - down to something like 60 mils clearance into a V notch holder. My first horror was that the machine did not reverse action when the Operator stopped pressure, simply halted where it was positioned. OK, now picture your fingers are captured in this, so where is the emergency STOP/RELEASE button. The machinist pointed to a giant red button mounted on the wall about 15 feet from the machine! When I pointed out the two errors in this scenario, the machinist agreed but said, "What are you going to do? It's what we have to work with." Well what I did was refused to use that equipment. Based upon the vivid images and sensation of potentially having my fingers crushed in a machine whose STOP button couldn't even be reached with your free foot; I stress point 1 & 2 mentioned earlier. - Robert - > To List Members; > > I would appreciate guidance on the subject of emergency stop switches > (buttons). > > When (if every) is an emegency stop switch manditory? > > Must an emegency stop switch be a hardware only function, or can it > operate through the machine's computer and software? > > Does the emergency stop switch have to turn off power to the machine, > or can it just stop the offending action, while leaving power on? > > What sort of responce time should be expected for an emergency stop > switch > (2 part question): > a) How long (realy how short a time) must the operator hold emergency > stop switch in order for it to operate (i.e when I want to hit the > button and run, how long to I need to stand there and hold the button > before it functins)? > b) How long can the machine continue to move/run/function after the > switch is pressed? > > Thank you. > > J. Sandberg > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ________________________________________________________________________ _____ Scanned by Sanmina-SCI eShield ________________________________________________________________________ _____ _____________________________________________________________________________ Scanned by Sanmina-SCI eShield _______ _____________________________________________________________________ - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
