Abstract: The specification sets forth a hammerspring for a dot matrix printer having a plurality of such hammersprings spaced along a hammerbank with permanent magnetics to draw said hammersprings into a retracted and uniformly stressed mode through a spring portion which are released by overcoming the magnetic retention, the hammerspring formed with a base portion connected to the hammerbank with a spring portion extending from said base portion having a decreasing transverse cross sectional area extending to an enlarged end portion for improved magnetic retention against said permanent magnets.

Abstract: In measuring a selected parameter of a test gas in isolation from gas pressure fluctuations, a pump draws the test gas through a storage capacitor into a sensor, storing the gas in the storage capacitor. A valve closes a fluid flow path which admits the test gas to the storage capacitor and opens a fluid flow path between the storage capacitor and a constant pressure alternate gas source, isolating the storage capacitor and the sensor from pressure fluctuations in the test gas. The storage capacitor prevents any mixing of the test gas with the alternate gas until measurement of the selected parameter has been accomplished.

Abstract: A dot impact type serial printer is provided with a print head which has a plurality of print wires for printing an image. The print wires required to print a particular image are thrust toward a platen successively upon receiving a print timing signal, where each print timing signal is delayed from the previous print timing signal by a predetermined time interval t. The delay of each print timing signal is based on the time required for a surface wave, caused by the impact of print wires on the platen, to pass lengthwise across the platen and is selected to be less than one-half the surface wave travel time.

Abstract: Sheet-guiding drum for a printing machine convertible from first form to perfector printing and in reverse, including at least two sheet-guiding surfaces formed at a circumference of segments of an outer drum part which are adjustable in circumferential direction with respect to an axial support member for journalling the sheet-guiding drum, and a clamping device for locking together the segments of the outer drum part and the journalling axial support member, the clamping device having radially directed friction surfaces disposed on the segments of the outer drum part and on the journalling axial support member and being pressable with a clamping force against one another in axial direction, and a tension rod movable in axial direction of the journalling axial support member for pressing the friction surfaces on the segments and on the journalling member against one another, includes lamellar, interengaging friction elements alternately connected to one of the segments of the outer drum part and to the journ