Abstract: A protection device is provided for a machine which works sheet shaped material to stop the displacement of the machine when the protection device encounters an obstacle. The machine includes clamps which are displaced by the machine and which hold the material. The protection device includes two blades arranged parallel to each other and disposed on the machine in a loop shape surrounding each clamp. The two blades form a pair of normally open contacts of which at least the outer blade is flexible and resiliently deformable to allow the blades to be brought into contact with each other and close the contacts when the outer blade encounters the obstacle. A stop device is coupled to the normally open contacts to stop the displacement of the machine when the contacts are closed.

Abstract: A method and system for monitoring brake performance in part-revolution clutch presses and the like comprising an overrun cam coupled to a switch for indicating passage of the press die beyond the nominal desired stop position and entry into a danger range indicative of impending brake failure. A control relay is coupled to the overrun cam switch for inhibiting press operation when impending brake failure is sensed. A time delay relay is coupled to a press operator responsive switch for inhibiting operation of the monitoring circuitry and permitting passage of the press die through the danger zone during normal press operation.

Abstract: An arrangement for protecting tools in a hydraulic press against overloading if a foreign object or body is present in a tool space of the hydraulic press. A displacement or travel switch monitors at least a portion of a path of movement of a press ram with a control member providing an output signal during a predetermined movement of the press ram. A control circuit evaluates a sequence of the output signals of the displacement or travel switch and the control member in such a manner that a fault signal is formed when the additional switching device provides an output signal prior to an output signal of the displacement or travel switch. The control member is arranged in a path of force of at least one component of the hydraulic press and is constructed as a signal transducer operating virtually stationarily as a function of pressure.

Abstract: A sewing machine is provided with a safety device which protects an operator's fingers from the needle and includes a ring suspended over the presser foot of the machine. The suspended member is movable by finger pressure applied thereto in any direction and when so moved, completes an electric circuit to shut off the machine.

Abstract: A back-up safety system stops the engine of a machine such as a power mower upon failure of a main safety system whereby release of a dead man control normally declutches a work performing member from the engine and brakes it to a stop while the engine continues to run. The back-up safety system comprises a switch that is closed upon release of the dead man control, in series with an SCR in a magneto grounding circuit. The SCR is gated on by a sensor comprising a biasing coil connected with the SCR, a ferromagnetic rotor constrained to rotate with the work performing member and having circumferentially spaced pole projections, a permanent magnet, and a core with which the coil is coupled and which cooperates with the rotor and magnet to define a magnetic circuit wherein flux density varies as rotor projections pass a pole face on the core.

Abstract: A protection arrangement for a tool set in a hydraulic press in which press, a press ram can be moved by at least one rapid- or fast-stroke cylinder piston unit and at least one working stroke pressure unit in a working stroke direction. The protection arrangement protects the tools from an overloading by a foreign object or body situated in the tool space and includes a displacement or path switch monitoring a portion of the path of movement of the ram and a further switching element which responds during movement of the press ram, as well as a control circuit for evaluating the sequence of response of the displacement or path switch and the switching element in such a way that a fault signal is produced if the switching element responds before the path or displacement switch.

Abstract: An energy curtain is formed by exciting high order beam modes in an open resonant cavity. Depending on mode number, the energy resonates in a mathematically determined pattern. A detector senses changes in the resonant condition caused by the presence of an object in the pattern. The apparatus may be used in a variety of applications, including the protection of a machine operator from a hazardous area of a machine, parts counting, and intrusion detection.

Abstract: Fluid links are interposed between manual levers which control the motions of a machine such as a construction crane and associated spool valves which regulate the machine motions. In normal operation within predetermined safe limits of machine motions, pressurized fluid delivery valve means connected with the fluid links is conditioned by a normal signal from a safe machine motion sensing means and delivers pressurized fluid to the fluid links rendering the links "hard" so that the manual levers are enabled to effect safe machine motions. When an unsafe machine motion is sensed by the sensing means, the valve means responds to the interruption of the normal signal from the sensing means and is conditioned to interrupt delivery of pressurized fluid to the fluid links thus rendering the links "soft" and thus disabling the manual levers from causing machine motions beyond safe limits.

Abstract: An emergency system for stopping the endless band blade reeved around a plurality of pulleys rotatably mounted on the base of a cutting apparatus. The system has a bearing rotatably mounted on the base and held in contact with the band blade at all times and an amplifier electrically connected to the band blade by the bearing. When the human body comes into contact with the band blade, the electric charge potantial of the body is amplified by the amplifier and energizes relays which interrupt the current supply to the motor for driving the band blade and, at the same time, actuate an electromagnetic brake and an electromagnetic clamp brake to brake the pulley coupled to the motor and the band blade to immediately stop the band blade.

Abstract: In a protective device for controlling a sewing machine at a predetermined number of revolutions by a motor equipped with a clutch mechanism and a brake mechanism which are electromagnetically actuated, a protective device is constructed comprising a detector to detect substantially the rotation of the driving shaft of the sewing machine, and a detector to detect the voltage of a control circuit with an output from the detectors being compared with a reference value representative of a predetermined driving state for the sewing machine, so that when the output of the detector becomes lower than the reference value, the operation of the control circuit is terminated, whereby safe operation is provided for the apparatus and an operator.

Abstract: A collapsible electric foot-toe guard is employed with a loading platform having electric controlled lift and descent movements, functioning as a safety device in the protection against unwitting protrusion of human limbs into the path of descent of the platform lift, said collapsible foot-toe guard being comprised of an outwardly depended contact plate moveably engaging a base support plate through hinge means to permit said contact plate with contact thereof to fold toward the base support plate, such folding movement effective to break a normally open, held closed electric limit switch circuit to arrest descent of the platform lift.

Abstract: The disclosure is directed to a perimeter safety switch for machines that require an operator. The safety switch comprises a longitudinal support member that extends around the permimeter of the machine at approximately waist level, and is spaced outwardly therefrom by a plurality of brackets. The support member carries a longitudinal switching element that is actuatable at any point over its length, and which forms part of an electrical circuit for interrupting power to the machine in response to actuation of the switch.

Abstract: A system for producing a control signal upon intrusion of a human part into a protected area, for example the area about the needle of a sewing machine, whereby radio frequency signals at a predetermined frequency are coupled to the human machine operator from a plate on which he sits or stands. As the operator's fingers or other body part approaches the protected area, an antenna receives the rf signal and applies it to an rf phase lock loop receiver which produces an output pulse when the received signal is at the predetermined frequency and is above a predetermined amplitude to operate solenoids which prevent or terminate machine operation. Preferably, withdrawal of the body part triggers a timer which produces a signal permitting the machine to operate for a given time which is greater than the normal time between intrusions, thus continuously checking that the system is working properly.

Abstract: A defecting or cut off saw inludes a support for boards and a transversely movable rotating saw blade for cutting the boards to length or cutting away defects therein. The transverse movement of the saw blade is controlled by an electrical circuit, the operation of which is acutated by the simultaneous depression of a pair of spaced cycle switches. The control circuit includes a timing circuit permitting movement of the saw across a board only when both of the cycle switches have been operator actuated within a predetermined period of time of one another. The circuit provides infinite stroke control for returning the saw blade to its start position at any time when one of the cycle switches is released.

Abstract: A combined mechanical and electrical control for the traction drive and collector-impeller drive of a snowblower is provided which operates to disconnect the traction drive when the operator loosens his grip on a traction drive control lever to an extreme drive-disengage position to which it is constantly biased. Further, the control operates to stop the engine in the event that the operator loosens his grip on the level when the collector-impeller drive is engaged. However, the control is arranged such that the operator may manually hold the traction drive control lever in an intermediate drive-disengage position, while leaving the collector-impeller drive engaged without the engine stopping.

Abstract: A pair of battery-powered radio transmitters are individually worn on the wrists of a machine operator, and two radio receivers are tuned to receive the signals broadcast by the radio transmitters, the first radio receiver being a proximity-sensitive device switching off the driving power to the machine whenever either radio transmitter comes within a preselected safe distance limit from the work-accomplishing region of the machine whereas the second radio receiver is a radio transmitter operating state-verifying device switching off the driving power to the machine whenever either or both of the radio transmitters fails to transmit its characteristic broadcast signal.

Abstract: A piezoelectric transducer is positioned on a member of a power press subject to stress under dynamic conditions. A ball joint bracket means fixes and maintains the transducer on the member parallel with the direction of force and with the faces of the piezoelectric ceramic plate perpendicular thereto. The high voltage signal generated by the transducer is transmitted to a signal conditioning circuit and impressed upon the grid of a grid-controlled vacuum tube. If the conditioned signal is sufficient to overcome the biasing grid voltage, it activates an electric circuit for the performance of one or more functions, including stopping the power press in the case of an overload, counting the number of times the press is overloaded or the number of times a workpiece is produced, and measuring the press load during a work cycle.

Abstract: A safety device is provided for the operation of small presses, spot welding machines, etc. The device is characterized by the use of a probe or sensor whose movement, if obstructed, prevents closing of an electrical circuit which activates the punch or ram of the press. Means are provided for minimizing or eliminating bounce or vibration of the sensor to avoid erratic operation of the device and the press. Provision is also made for rendering the device "fail-safe" under certain conditions, including failure of internal parts of the device or improper usage of the device by the operator. Economies in manufacture of the device are effected by the improvement of certain parts and elimination of other parts of previously used devices of a similar nature and construction.