TABLE OF CONTENTS The function of the safety circuit is to react to the entry into, or the presence in, a danger zone of a person and initiate a signal to the machine controls that causes them to bring the machine to a safe state. This part deals with some typical safety circuits and the techniques employed covering the different media mechanical, electrical, hydraulic and pneumatic that can be used.
The object of a guard is to prevent a person or parts of a person from coming into contact with dangerous parts of machinery. This can be achieved by either providing a physical barrier, such as a guard or fence, between the person and the dangerous part or by other safeguarding arrangement that ensures that when a person reaches a part of the machinery it is no longer dangerous, i.e. it is not moving. This chapter deals with the design of mechanical guards and related devices. The designs of safeguarding arrangements for electrical, hydraulic and pneumatic circuits are dealt with in Chapters 9 , 10 and 11 respectively.
Guards provide a physical barrier between the operator and the dangerous parts of a machine. They can take the form of either enclosing guards or distance fencing.
Enclosing guards completely block all access to dangerous zones. They must be robustly constructed to...
