TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
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4. When the key is normal the tip of the spring K1 must be approximately in the<br />
centre of the gap in the wheel and clear the wheel by 0.015 inch minimum.<br />
5. The inner spring when at the bottom of a tooth shall exert a pressure of 10<br />
grams minimum on the wheel and when at the top of a tooth 175 grams<br />
maximum, including the pressure of the outer spring. When at the top of a<br />
tooth the inner spring shall have a pressure of 15 grams minimum exerted<br />
upon it by the outer spring.<br />
6. The nickel silver contact spring shall be adjusted to give a 50/50 make to<br />
break ratio, as previously described. The permissible variation being between<br />
53/47 and 47/53. To give this there should be a clearance of 0.030 inch<br />
minimum 0.034 inch maximum between the inner and outer spring contacts<br />
when the operating spring occupies a midway position between any two<br />
teeth. This dimension is to ensure a good contact gap and also checks the set<br />
of the tip of the steel impulsing spring.<br />
7. When a bent-up segment is used the bent-up portion shall engage the insulator,<br />
on the tip of the outer spring, approximately on either side of the centre<br />
line of the insulator.<br />
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