the auxiliary blade to enter, latch, and finally, to release
d. Check the following while operating switch
the auxiliary blade at the proper time. While operating
Refer all malfunctions to organizational
switch slowly rotating contact blade ( 12, fig. 3-4).
Check the entry of the auxiliary blade (7) into arc chute (
1). The blade should enter smoothly and be in center of
(1) Operating rod (8, fig. 3-31 fully closes
the opening. It should travel the full length without
primary contact blades ( I 1, fig. 3-4).
binding or heavy scraping. Insure that the auxiliary
blade (3, fig 3-6) contacts enter the chute properly
(2) Watch the primary contact blades (12, fig.
positioned and latch the auxiliary blade. Note the
3-51 and note the engagement of the primary contacts
position of the primary blades (11, fig. 3-4) is released
(4), arcing contacts (6 and 8), and the guide block (10).
by the auxiliary blade release hook (14). The release
The blades (12) should center around the guide block
hook should hold the blade out of arc chute until with a
(10) without bearing heavily on either side. They should
1/ 2 inch before arcing contacts touch.
also be centered in the primary contact (4) and arcing
contact fingers (6).
(3) The arc chute must be positioned to allow
Auxiliary blade spring
Auxiliary blade release hook
Release hook spring
Operating rod crank
Main crank shaft
Figure 3-3. Switch blade