Electricity: circuit makers and breakers – Switch activation inhibitor – Removable actuator
Reexamination Certificate
2000-05-01
2001-07-31
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Switch activation inhibitor
Removable actuator
C200S043050, C200S061660, C200S334000
Reexamination Certificate
active
06268574
ABSTRACT:
TECHNICAL FIELD
The invention relates to electrical shut-off devices, and more particularly relates to an electrical and pneumatic lock-out device for gates and machinery frames generally in the automotive assembly art.
BACKGROUND OF THE INVENTION
Maintenance crews and automotive assembly plants and other manufacturing operations have a long felt need for more safety equipment in order to electrically and/or pneumatically shut off equipment that they are working on. The men and women performing the maintenance need to make sure that neither the electricity nor the pneumatics are operational on the machine which they are maintaining. Prior art methods of shutting off electricity have included walking over to the electrical control panel and turning off all the electricity to a particular part of the room in which the maintenance is being performed, or if wired properly, shutting off the electrical circuits to the machine being worked on. Many times these control panels are not in sight of the maintenance workers. Needless to say, third parties who do not know about the maintenance operation can turn the electricity back on without the knowledge of the maintenance crew, yielding an unsafe situation. As can be imagined, maintenance crew workers would have more confidence in their safety if they knew that they had the control and only they could turn off the electrical circuits that were shut off to the area in which they are working, and that there was not an ability for a third person to turn the electricity back on. The maintenance crew needs to know that both the electrical system and the pneumatic system have been shut off in the case of lifter machines and other equipment which utilize both electrical and pneumatic devices.
Moreover, maintenance crews are subject to placing themselves in danger to save a little time by turning off the electricity within a certain area, and then returning to attempt to only turn on the electricity to a certain portion, while still being within the area of danger. It is necessary for the electricity to be shut off to the entire area in order for a maintenance person to perform his or her task in a totally safe manner. The temptation may always be there for trying to partially operate a machine while hoping that they do not get caught in the mechanics of another portion which should be shut off. In normal assembly plants, there are work cell safety gates which separate various machines in order to create safety zones, and it would be most prudent if the electrical and pneumatic shut off could occur even at the gate entering the safety zone which incorporates the manufacturing equipment. For instance, a gate entering into a lifting machine could have all the electricity shut off the minute that the gate is opened up. Furthermore, safety lock-out devices could be utilized on the lifter to render the pneumatics immobile, thereby giving the maintenance person a green light to perform their expected duties.
OSHA regulations have attempted to provide safety mechanisms for the maintenance crews in order to reduce injuries and down time. Many times, maintenance crews and machine operators have figured out how to electrically “jumper”, tamper, override or bypass the safety equipment. This has resulted in numerous injuries and expense to companies for repairs. It would be most desirable to have a failsafe system for rendering the machine within a gated area to be non-operational during the maintenance period.
Therefore, it would be an advantage to the art to provide an electrical and pneumatic lock-out device for rendering machines completely free of the possibility of them being turned on or moved while the maintenance person is performing his or her tasks.
It would be yet a further advantage to provide a complete electrical and pneumatic lock-out device which cannot be manually overridden or bypassed.
SUMMARY OF THE INVENTION
In seeking to provide the advantages noted above, there is an electrical and pneumatic lock-out device constructed in accordance with the present invention that will achieve all of the advantages desired. The electrical and pneumatic lock-out device of the present invention is as simple as possible, while still utilizing safety interlock switches known in the prior art and regularly accepted in the industry.
In one embodiment of the present invention, an electrical gate lock-out device is disclosed which includes a safety interlock switch mounted to the work cell gate frame by a mounting bracket which further includes a locking mechanism to be activated by either a key or an actuator button for the engagement and disengagement of a switch key and a lock-out safety pin which holds the door shut and turns on the electricity. Once the key and lock-out safety pin combination has been removed, then a mechanical shut-out device is opened up. The interesting aspect of the invention is that the lock-out safety pin is permanently attached, i.e. welded, to the electrical shutoff key which is pulled out of the safety interlock switch. In essence, if the welded lock-out safety pin/key combination is removed from its engaged position, the electricity is shut off once the gate has an opportunity to be opened. As long as the gate is locked shut, the electricity may be turned on. However, for the gate to be opened, even a few centimeters, the electricity must be shut off as the opening device for the gate is welded to the key that turns off the electricity.
In yet a second embodiment, the same lock-out safety pin is welded to a key that is mated to the same type of safety interlock switch, but in this embodiment, the lock-out safety pin is also welded to a safety pin to be inserted into a stroke bar in order to pneumatically render a lifting machine inoperable.
REFERENCES:
patent: 4189692 (1980-02-01), Bonnar
patent: 4262180 (1981-04-01), Walter
patent: 4359615 (1982-11-01), Meyerhoefer et al.
patent: 4511771 (1985-04-01), Rossell
patent: 5432309 (1995-07-01), Takeuchi et al.
patent: 6049276 (2000-04-01), Agozzino
Cargill Lynn E.
Friedhofer Michael
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