Abstract: An improved welding apparatus and method of use including a pair of opposed electrodes mounted on arms which are fixed against outward displacement during the application of the welding current. One of the arms includes a cylinder for moving an electrode to and away from the work piece. The cylinder includes a pilot operated check valve which permits a one-way flow of hydraulic fluid while the weld current is applied. The check valve prevents movement of the electrode away from the work piece during expansion of the weld nugget, however, permits inward movement of the electrode after the nugget is softened.

Abstract: An improved welding apparatus and method of use including a pair of opposed electrodes mounted on arms which are fixed against outward displacement during the application of the welding current. One of the arms includes a pneumatic cylinder for moving an electrode to and away from the work piece. The cylinder includes a piston rod attached to a clutch by a ball screw mechanism. A brake assembly is connected to the unidirectional clutch to prevent outward displacement of the electrodes during expansion of a weld nugget and permitting inward movement of the electrodes to provide indentation of the weld after the nugget softens.

Abstract: Electrical resistance spot welding is controlled by stopping the welding current upon detection of indentation of the work pieces by the electrodes. Indentation is detected indirectly by monitoring the deformation on at least one arm supporting an electrode. The piston of the welding gun cylinder is prevented from displacing in direct proportion to displacements of the electrodes during formation of the weld so that the squeezing force applied by the electrodes to the work piece, and therefore the deformation in the electrode holders, varies as a function of electrode displacements.

Abstract: Electrical resistance spot welding is controlled by stopping the welding current upon detection of indentation of the work pieces by the electrodes. Indentation is detected indirectly by monitoring the deformation in one or both electrode holders. The piston of the welding gun cylinder is prevented from displacing in direct proportion to displacements of the electrodes during formation of the weld so that the squeezing force applied by the electrodes to the work piece, and therefore the deformation in the electrode holders, varies as a function of electrode displacements.

Abstract: An apparatus and method for detecting disturbance in a protected area or perimeter by scanning the area or perimeter with a rotating beam of radiating energy, such as light, infrared, ultraviolet and the like, and counting the number of pulses at the output of a detector or sensor upon impingement on the detector or sensor of the beam reflected by each one of a plurality of reflectors disposed in the protected area or perimeter. Upon turning on the apparatus, a first pulse count corresponding to each complete revolution of the beam is stored as a pulse reference number for a "normal" state in the protected area or perimeter. In operation, the number of pulses for each revolution of the beam is continuously counted and compared to the stored reference number and an alarm is triggered as soon as the stored reference number and the counted number are unequal.

Abstract: The quality of an electrical resistance spot weld is determined by monitoring the squeezing force applied through the electrodes to the workpieces by a force-transmitting device that exerts a squeezing force that varies when indentation of the workpieces occurs.

Abstract: A control for controlling load on a tire undergoing testing while rotating in a loaded condition against a test road wheel. As the tire temperature increases during the warm up period of the tire and inflation pressure and load consequently also increase, the control will automatically decrease the load applied to the tire to maintain a preset load on the tire. During equilibrium temperature and pressure conditions of the tire, the control will effectuate decreases in load only and will not permit the tire load applicator to oscillate the load about the reset load point. The load applicator is maintained in an inactive condition by the control means except when a load decrease is necessary. During equilibrium temperature and load conditions on the tire, a relatively fast increase in temperature and a correspondingly fast load increase indicating incipient failure of the tire can be detected by the control.

Abstract: A particle detector, such as for detecting the passage of seeds through a mechanical seeder, comprising an angled-over impact resounding tubular conduit disposed in the flow of particles such that each particle is caused to impact and be deflected by the wall of the angled-over conduit. An impact detecting transducer, such as a crystal, is attached to the exterior wall of the angled-over conduit at, or proximate to, the area of particle impact. The angled-over conduit is connected between a pair of inlet and outlet conduits made of substantially impact absorbing material. The transducer feeds into a utilization circuit permitting to simply detect whether particles are present or not in the conduit, or, in the alternative, capable of counting the number of particles passing through the conduit.