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

247
The arrangement of each control handle is such that the total
arc of movement (161 degrees) is unequally divided from neutral
to lIHoistlJ and from neutral to "Lower u • Full lever movement
to "Lower" is 116 degrees and is equivalent to 20 degree inclina
tion of the tilting box. The control handle however cannot
be manipulated to give high speed lowering with load by
reason of handle limits top which limits handle movement to
seven degrees. This device, actuated by lever IICII, is shown
on drawing 236523. Full lever movement to IIHoistll is 45 degrees
and is equivalent to 7.5 degree inclination of the
tilting box. These factors limit the acceleration and speed
of rack upward movement and permi t full speed retraction of the
unloaded rack. Conversely, when projectiles are being lowered,
the arrangement prevents movement of the handle toward high
speed lowering. This device permits manipulation to throttle
the pump deli very and thus t-o check descent of the load.
The bracket arrangements which provide these limi ting movements
of the control handle are the safety stop and mechanical interlock
devices described in the next paragraph.
37. Can t.r o L hand Le Zim it stops. - Both control handles
are mounted, wi th free bearing on a coupled vertical control
shaft with a positive clutch element arranged with each to
provide engagement of the handle with the shaft. Each clutch
is inanually operated and is provided with a locking pin for
securing in both open and closed positions.. In addition to
this facility for engaging or disengaging the handle from the
control the bracket contains the following elements of. the indicator
mechanism which operate to restrain control handle
movement or to free the handle from mechanical interlock.
(a) Safety stop. - The ilLowerll indicator rod is
arranged with a safety stop lever, bracket and
tongue as shown on drawing 234280 so that when
the direction control (lever lIeI!) is positioned
to IILowerII, the tongue lifts to limit control
handle movement to seven degrees. This is
equivalent to very slow hoist lowering action.
(b) Hoist latch stop. - The IIHoist n indicator rod
is arranged with a latch (pc. 215994-1 or 2)
and a plunger so that when the indica tor moves
from IIHoistll to lIDanger" (see par. 39) the
plunger lifts to prevent moving the control to
IIHoistll. ('The control can be moved however to
retract the empty rack, i. e. Love r in readiness
for another hoist stroke.)