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SP Maintenance Manual  

SP Maintenance Manual

The following 14 pages were scanned directly out of the original
Southern Pacific wigwag maintenance manual that was
sent out to all of the signal shops in 1949. Outside of a little
 clean-up, I left it in it's original form. Hyperlinked words refer
to any graphics that went with the manual.
Thanks to Denny Dollahon for providing this valuable document.

Page 1


       In the following account refer to Magnetic Signal Company’s Bulletin No. 54 and the accompanying illustrations.

       To obtain the most reliable operation of the wigwag the following features of maintenance and adjustment must be observed.

1.      The mechanism is to be maintained in an approximately level position.

2.      Movable Finger Contact – Ref. 45, P1  J112

The movable finger contact is to fit its pivot pin (Ref. 48) closely so that very little lost motion in a plane parallel to the pivot pin is obtained. Not more than 1/16th inch measured at the lower end of the finger. Excessive play can be corrected only by replacement of worn parts.

When replacing movable finger, pivot pin or bracket be sure that pivot pin is clean and polished and that movable finger swings freely with no tendency to bind. Also be sure that movable finger ribbon is attached as shown in plate J112 and that cotter pin is properly spread. Do not bend or otherwise change shape of new movable finger.

The tension of each leg of the hairpin spring (Ref. 49) shall be equal against the top of the movable finger and when movable finger is in the central position each leg is to rest simultaneously on top of the movable finger and the top of the bracket (Ref. 44a). If properly adjusted the movable finger will definitely return to a central position after movement in either direction.

The position of the movable finger is adjustable by means of oversize holes in the bracket (Ref. 44a) where it is attached to bracket support (Ref. 39). When adjusting be sure that banner is hanging in a perfectly vertical position, not influenced by wind, then locate movable finger diamond so that it rests centrally in relation to the diamond contact guide (Ref. 18) as shown in Fig. 2. 

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