OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

203
exceeds the requirements of control circuit
operation and main system replenishment.
(j) The replenishing check valves function to supply
fluid to the suction side of the main system
to compensate for internal leakage.
(k) The timing and control mechanisms are semiautomatic
cycle control devices which operate
by response drive from the B-end when the control
action is manually ini tia ted. The mechanisms
include timing and control cams, (dr ,
271712) keyed to a cam shaft and directly coupled
to the B-end worm wheel. These cams make
one revolution for every thirty degrees· of
projectile ring movement. Separate timing
cams control each direction of offset of the
A-end pump. Whenthe pumpis centered (neutral)
clearance exists between the timing cams and
cam link rollers. This clearance limits the
pump offset at the beginning of a cycle and
is sufficient to allow the 'pump to overcome
normal internal leakage and to' start projectile
ring rotation when the manual lever is
movedfrom neutral. That lever movement (150 0
for each direction) controls the starting cam
and control link gearing movement. In conjunction
with the timing cams the manual control
also controls the movements of .the 'control
link, yoke and cam links, and the interlock
switch cam. All of these elements follow
the manual control, when starting, until all
clearance is taken up between a cam roller and
its respective timing cam. Thereafter the
starting cam, control link gearing and the
centering spring follow the manual control
lever until it has moved through its full arc
of 150 degrees. The arrangement operates at
starting to give gradual acceleration up to
full speed of the drive output. A,t the start
of a cycle th e cam roller, held against the
timing cam by the offset centering spring, is
in contact with the highest point of the cam.
It follows the cam contour (as the camrotates)
and permits the centering spring to expand and
to gradually increase pump offset (and drive
speed) until maximum velocity is attained.
Deceleration at the end of the cycle is similar
and is similarly controlled when the cam
roller approaches the high point. Then the
centering spring offset again gradually increases
until the pumpyoke returns to neutral.