We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
382 RICHARDSON'S BLUEBOOK OF PROJECTION
(83) The tension should be enough to insure certainty of feeding when the current-carrying contacts are smooth and in good condition.
(84) Too much tension wears the parts unnecessarily. It may even cause roughening of the carbon's outer surface, which would weaken the current-carrying contact. Excessive tension may cause "sticking" when bits of carbon, adhering to the outer surface, are forced into the contact. On the other hand too little tension makes for unevenness, or may even stop the feeding completely.
(85) In case the positive carbon ceases to rotate and feed forward, ease up on the contact pressure and try to finish the run. Then carefully examine the contacts for roughness. If they are rough remedy that at the earliest moment or the contact blocks will be ruined quickly.
(86) To make a quick test for roughness, place the lamp in re-trim position, release the feed mechanism and shove the positive carbon backward and forward several times through the current-carrying contact. With the front end of the carbon extending out in normal operating position, and with the feeding mechanism released, you should be able to move the carbon backward and forward easily. If it binds more than it should, then one of two things or both, is the trouble. Either the pressure of the contact blocks is too heavy or the contact surface is roughened. Smooth the contacts and (or) adjust the contact pressure.
High Intensity Carbon Contact Pressure
(87) Too little contact pressure causes arcing and quickly-roughened, burned contact surfaces. Too much pressure places undue strain on the feeding mechanism and may cause the carbon to stick — to fail to rotate and feed. (88) There must be good electrical contact between the rotating carbon and its contacts or trouble will result.
(89) Always have spare feeding mechanism parts in stock, ready for use. Ordinarily the controlling spring and parts that contact the carbon are sufficient to have on hand for an emergency.