Abstract: A paving breaker for the construction industry of the type having a vibrating moil point or tool steel impacted by a pneumatically reciprocated piston including a double walled cylinder slidably receiving the piston designed so that the space between the inner and outer walls of the cylinder forms a passageway for delivery of piston return air to the lower cylinder chamber and the space also forms an accumulator for air compressed by the piston during the lower part of its power stroke. In one embodiment an outer cylinder sleeve is mounted on an elastomeric member surrounding an inner cylinder sleeve, and is free to reciprocate a limited distance in the housing to partly balance the reaction forces of the piston. This double walled cylinder is surrounded by rectangular polyurethane covers that form an air exhaust space around the cylinder so that exhaust air assists in cooling the cylinder.

Abstract: A pneumatic power tool having a torque sensing control system is disclosed which is capable of consistently applying a precise torque to a fastener so that uniform tightening of any number of fasteners can be obtained. A torsional strain responsive transducer is mounted internally in the tool body and includes a strain gauge network mounted on a torsionally resilient portion of one of the gear cases of the drive train of the tool, the gear case being subject to a reaction component of the torque being transmitted through the drive train. The strain gauge network provides a control signal which effects energization of a solenoid-actuated air shut-off valve in the handle of the tool to automatically terminate the operation of the tool when a predetermined torque is obtained at the output spindle. The control system permits adjustment of the torque output of the tool and provides a visual readout of such output.

Abstract: A pneumatic power tool having a torque sensing control system is disclosed which is capable of consistently applying a precise torque to a fastener so that uniform tightening of any number of fasteners can be obtained. A torsional strain responsive transducer is mounted internally in the tool body and includes a strain gauge network mounted on a torsionally resilient portion of one of the gear cases of the drive train of the tool, the gear case being subject to a reaction component of the torque being transmitted through the drive train. The strain gauge network provides a control signal which effects energization of a solenoid-actuated air shut-off valve in the handle of the tool to automatically terminate the operation of the tool when a predetermined torque is obtained at the output spindle. The control system permits adjustment of the torque output of the tool and provides a visual readout of such output.

Abstract: This disclosure deals with a machine for simultaneously tightening a plurality of threaded fasteners. The machine includes a plurality of torque applying units, one for each fastener, which engage and torque the fasteners. Each unit includes a spindle which engages the fastener and a torque sensing circuit which generates a torque signal representing the magnitude of the torque being applied. A torque control circuit of each unit prevents torquing to above a preset upper limit. A central control circuit receives the torque signals from all of the units, makes a comparison of torque values to identify any unit where the applied torque is greater than that of the other unit or units, and prevents such an identified unit from continuing to apply torque until the other unit or units applies torque essentially equal to that of the identified unit. The torque signals from the units may be averaged and the torque signal of each unit compared with the average.

Abstract: The control circuit receives a signal from a torque measuring device provided on the tool and determines the proper shut off point for the tool. The circuit controls not only the tool shut off but also the rate of application of torque by employing a pulsing circuit. The circuit is capable of detecting the onset of yield and can accurately and repeatedly set a fastener at a desired point in the plastic region. The onset of yield is detected by differentiating torque with respect to time.

Abstract: This disclosure deals with a control circuit for a tool including a motor for turning a rotatable power output shaft of the tool. A torque measuring device is coupled to the shaft and generates a signal which is a function of the torque output. The control circuit responds to the torque output and to a reference signal representing a preselected torque, and automatically turns off the motor when the torque output reaches the preselected torque. Further, the control circuit may cyclically turn the tool on and off at very short time intervals as the preselected torque value is being approached, in order to reduce the reaction torque felt by an operator of the tool. In addition, the lengths of the on times in successive cycles may be gradually decreased as the torque output level increases, with the result that the average reaction torque remains substantially constant even though the peak torque output increases.

Abstract: A pneumatic power tool having a torque sensing control system is disclosed which is capable of consistently applying a precise torque to a fastener so that uniform tightening of any number of fasteners can be obtained. A torsional strain responsive transducer is mounted internally in the tool body and includes a strain gauge network mounted on a torsionally resilient portion of one of the gear cases of the drive train of the tool, the gear case being subject to a reaction component of the torque being transmitted through the drive train. The strain gauge network provides a control signal which effects energization of a solenoid-actuated air shut-off valve in the handle of the tool to automatically terminate the operation of the tool when a predetermined torque is obtained at the output spindle. The control system permits adjustment of the torque output of the tool and provides a visual readout of such output.

Abstract: A pneumatic power tool having a torque sensing control system is disclosd which is capable of consistently applying a precise torque to a fastener so that uniform tightening of any number of fasteners can be obtained. A torsional strain responsive transducer is mounted internally in the tool body and includes a strain gauge network mounted on a torsionally resilient portion of one of the gear cases of the drive train of the tool, the gear case being subject to a reaction component of the torque being transmitted through the drive train. The strain gauge network provides a control signal which effects energization of a solenoid-actuated air shut-off valve in the handle of the tool to automatically terminate the operation of the tool when a predetermined torque is obtained at the output spindle. The control system permits adjustment of the torque output of the tool and provides a visual readout of such output.

Abstract: A throttle valve construction for a pneumatic paving breaker and other types of percussion tools employing a reciprocating piston to impart blows to a work steel or the like is disclosed, wherein partial movement of the control lever of the tool from a fully depressed position to a partially depressed position permits the throttle valve to shift to a position which substantially reduces the quantity of air under pressure being supplied to the operating cylinder of the tool so that the reciprocation frequency and kinetic energy of the piston are reduced. The amplitude and frequency of the vibrations generated by the tool and transmitted to the operator thereof are likewise substantially reduced when the tool is operating in this mode, and a significant reduction in the level of the sound emitted by the tool is also obtained.

Abstract: A safety control means for a portable power tool, such as a pneumatically driven hand grinder, wherein fluid supply and discharge passages are provided in the support handles of the tool and are respectively connected to the fluid inlet and outlet of the motor. First and second fluid control members are mounted in the handles on the upstream and downstream sides, respectively, of the fluid inlet and outlet of the motor. The first control member is movable to a first position preventing motive fluid from flowing through the supply passage and a second position permitting motive fluid to flow through the supply passage. The second control member is likewise movable to a first position preventing motive fluid from flowing through the discharge passage and a second position permitting flow through the discharge passage. A control lever is pivotally mounted on each of the tool support handles for effecting movement of the respective control members between their first and second positions.