Rockford Systems, LLC
1-800-922-7533 (U.S.A. only)
10
The formula found in the ANSI B11.1 Standard (Mechanical Power Presses) uses the stopping time measured during the
hazardous portion of the stroke, plus the reaction time of ergonomic touch palm buttons or the existing presence sensing
device (if either or both exist), plus the additional time or distance allowed by the brake monitor (stopping performance
monitor). If a presence sensing device is the safeguard used, its minimum object sensitivity is also used to add additional
distance to the calculated safety distance.
Components of the STM Device
The device consists of three major components:
1. the meter which is the processor containing the electronics and displays.
2. the position and velocity sensor which detects motion.
3. the hand-held actuator which automatically releases or pushes a button or other device on the machine. This actuator
is preassembled for use with two-hand controls (see Figure 3.1 on page 14).It can also be used to operate the flag
when presence sensing devices are used as the safeguarding method. If the hand-held actuator will be used with
presence sensing devices, the push button plate and foot pad must be removed and the flag added (see photo 2.5
on page 13).
Other STM components and literature provided with this device are the presence sensing flag, wall transformer, hard and
soft carrying case, and instruction manual. Optional equipment available includes a wheel encoder (for machines that
stop beyond bottom or top dead center and for rotating machines), and a printer with cord for permanently recording
measurements.
Operation of the STM Device
Prior to using the STM device, the battery should be fully charged. Open the carrying case and plug the hand-held actuator
and sensor into the labeled receptacles on the meter. Set the sensor on the bed of the machine and attach the magnet
and cable to the slide or other reciprocating machine component. With power to the meter, inch the machine to a point
in the cycle where the stop signal is to be given and program this position. Bring the machine back to its start position
and cock the hand-held actuator. Using the hand-held actuator,on one two-hand control and your free hand on the other,
push down on the machine’s actuating means(palm buttons) to start the machine cycle. When the machine cycle reaches
the programmed stop point, the hand-held actuator releases the palm button, generating a stop signal. After the machine
stops, the meter displays the stopping time in milliseconds and the safety distance in inches or millimeters. For complete
step-by-step instructions, please refer to page 20.
When using the cable-operated sensor, the STM stops timing just before bottom dead center or top dead center (depending
upon selection of measurement for downstroke or upstroke) on mechanical power presses and press brakes. This happens
because of the linear motion of the slide. If the machine coasts beyond bottom or top dead center, the stop signal must be
given sooner in the cycle or a tachometer must be used. Most machines that have high torque and fast-acting brakes will
stop in time to provide accurate readings. To improve a machine’s stopping ability, numerous improvements can be made
to a mechanical power pressor press brake to provide faster stopping times such as:
• installing new brake lining(s)
• installing new brake spring(s)
• relocating the dual valve closer to the clutch and brake to exhaust air quicker
• having a properly sized dual valve for the application
• having properly sized air piping or hoses
• making sure the dual valve muffler is clean, unclogged, and working properly
• making proper air counterbalance adjustments based on the upper die weight.
(Continued on next page.)
SECTION 1—TABLE OF CONTENT
Stop-Time Measurement Device
