AMETEK 1025 Foot & Palm Switches - Manual (Page 6)

Chapter 1: Overview
Operating Manual 2
TIME UP/TIME DOWN This switch determines the direction of the test. In the
TIME DOWN position you are performing a standard test
according to OSHA requirements. The switch should be in
the TIME UP position when checking press top stop.
STOP TIME (mSEC)/ This switch is used to select the display mode, either time or
SAFETY DISTANCE (IN) distance. Time is measured in milliseconds and distance is
measured in inches.
FULL REV/PART REV This switch is used to determine the press clutch operation
mode, either full or part revolution. The majority of tests
are run in the part revolution mode.
CONTROL START Known as CSP, this dial is used to set the point in the
POINT (IN) stroke at which the command to start timing and fi res
the Auto-Hand is g iven. When the CSP dial is turned
clockwise, the dial will increment and de-increment when
turned counterclockwise. The CSP dial reads in tenths of
an inch. Example: 123 equals 12.3”.
MANUAL START This jack is used with the optional manual start switches.
AUTO-HAND This connector is used to connect the Auto-Hand to the
Safetimeter.
1.2: Theory of Operation
The P/V transducer measures the open height of a press. When this measurement
coincides with the preset CSP position, and the ram is traveling in the direction
selected on the TIME UP/TIME DOWN switch, the Auto-Hand will release one of the
two run controls or press an E-STOP control to initiate the press stop. When the
ram stops, the P/V transducer sends a stop signal to the Safetimeter and the meter
displays either stop time or safety distance, whichever display mode was selected
prior to the test.
NOTE: No OSHA standard exists for defi ning when a press has stopped (at what
ram velocity). The Safetimeter ends its measurement when the ram velocity
is approximately .17 inches per second (10 inches per minute). When
measuring stop time, you must take into account all elements and devices
used to bring the ram to rest. These include the “fl ight time” of the run and
E-STOP buttons (time for switch to activate), control relays, solenoids valves
and clutch and brake mechanical elements. Where an electronic guard (light
curtain) is used, response time of the device and the depth penetration factor
must be added to that measured by the Safetimeter before calculating safety
distance. Response time is generally stated by manufacturers of electronic
guards. However, to verify systems, the Auto-Flag can be used.