Rockford Systems, LLC
1-800-922-7533 (U.S.A. only)
9
OSHA REGULATIONS AND ANSI STANDARDS
(continued)
On part revolution clutch presses, the clutch/brake control must have control reliability and brake monitoring (stop-performance
monitor). The following are the requirements of OSHA:
(b)(13) Control reliability. When required by paragraph (c)(5), the control system shall be constructed so that a failure within
the system does not prevent the normal stopping action from being applied to the press when required, but does prevent
initiation of a successive stroke until the failure is corrected. The failure shall be detectable by a simple test, or indicated by the
control system. This requirement does not apply to those elements of the control system which have no effect on the protection
against point of operation injuries.
(b)(14) Brake monitoring. When required, the brake monitor shall meet the following requirements:
(i) Be so constructed as to automatically prevent the activation of a successive stroke if the stopping time or braking distance
deteriorates to a point where the safety distance being utilized does not meet the requirements set forth in paragraph (c)(3)(iii)(e)
or (c)(3)(vii)(c) of this section. The brake monitor when used with the Type “B”gate or movable barrier must detect slide top-stop
overrun beyond the normal limit reasonably established by the employer.
(ii) Be installed on a press so that it indicates when the performance of the braking system has deteriorated to the extent
described in paragraph (b)(14)(i) of this section; and
(iii) Be constructed and installed in a manner to monitor brake system performance on each stroke.
DESCRIPTION OF THE STM DEVICE
Preliminary Steps to Follow Before Using The Device
Before using the enclosed equipment, make sure to follow these preliminary steps.
1.
Read and make sure you understand this entire Instruction Manual. Refer to the various photos and line drawings found
throughout the manual, if necessary.
2.
This STM (stop-time measuring) device has been carefully inspected and tested before shipment. Unpack the instrument and
perform a visual inspection. After this inspection, open the instrument case and remove the accessories stored inside.
General Description and Overview
The STM (stop-time measurement) device measures the time it takes a machine to stop after a signal is given. It is mainly used on
reciprocating (stroking or cycling) machines, such as mechanical and hydraulic presses or press brakes. With optional accessories, it
can also be used on machines that rotate, such as lathes, mills, and drills.
Industry uses this type of device to find the stopping time of a machine before installing safeguarding devices such as a two-hand
control or a presence sensing device (light curtain or radio frequency). It can also be used to determine the safety distance when
installing and maintaining safety mats, emergency-stop devices and guard interlocks. The stopping time measured by the STM device
during the hazardous portion of the cycle is used in the OSHA(Occupational Safety and Health Administration) or ANSI (American
National Standards Institute) formulas to calculate the safety distance. The safety distance is then used to establish the location of the
safeguarding device in relation to the nearest hazard. This device can also be used to periodically check the machine’s stopping time
to ensure that the current safety distance corresponds to the current condition of the machine’s stopping ability.
This STM device is also used by Federal and State OSHA compliance officers, insurance company loss control engineers,and safety
training personnel to determine if proper safety distances are being used for the existing safeguarding method.
The portable design makes the STM very easy to use. A stop signal must be provided, which releases or actuates a button or other
operator controlled device on the machine during the hazardous portion of the cycle. If a machine has a presence sensing device, the
“plane of light” can be interrupted with the furnished flag, which sends a signal to stop the machine.
When using this STM device, the display gives both the stopping time of the machine in milliseconds (thousandths of a second),
and the calculated safety distance in inches or millimeters. The safety distance is usually based on the hand-speed constant of 63
inches(1.6 meters)/second. For mechanical power presses, the OSHA formula multiplies the hand-speed constant (63 inches/second)
x the stopping time of the machine at 90°of crankshaft rotation. When using this formula, the reaction time of either ergonomic touch
palm buttons or a presence sensing device should be added to the stopping time to calculate the proper safety distance.
(Continued on next page.)
SECTION 1—IN GENERAL
Stop-Time Measurement Device
