Powell PowlVac ARG 4 Series, Instruction Bulletin

Page: 19 / 52

Powered by Safety
®
11 Equipment Description
01.4IB.50023A
When the close latch is released by the closing
coil, the closing spring pulls the camshaft
around and the main closing cam moves
the main linkage into the closed position.
The main linkage rotates the drive levers
of the jackshaft, which is supported by the
mechanism side sheets, where it is clamped by
hook plates and by the ground and test device
side panels. The jackshaft has three (3) upward
pointing levers to which the operating rods are
attached. The operating rods, approximately
horizontal, are moved to the rear of the device
by the rotation of the jackshaft.
The end of the operating rods remote from the
jackshaft levers is connected to the movable
contacts of the ground making switch. The
stationary contacts of the ground making
switch are mounted on the center insulating
barrier. Directly beneath the stationary
contacts are the movable contact kickoff
springs. When the moving contacts of the
ground making switch make contact with the
stationary contacts, the springs are loaded by a
force sufficient to assist their separation during
opening of the ground making switch.
In the linkage position shown in Figure 5 , the
kickoff springs and the main opening spring
are both acting to compress the three (3) main
mechanism links. The linkage is restrained
from movement by the secondary trip prop
acting on the primary trip prop roller. The
component of force tends to make the primary
trip prop move downward, but it is restrained
by the secondary trip prop face acting on the
primary trip prop roller. The clearance between
the primary trip prop roller and the secondary
trip prop is controlled by the primary trip prop
adjusting screw. When the trip shaft is rotated
by the action of the manual trip plate or the
optional electric trip solenoid (when furnished),
the secondary trip prop moves forward and
permits the primary trip prop to move down,
thus permitting the main linkage to move
down and the jackshaft to rotate, opening the
ground making switch. The left had of the
jackshaft has a connection for the opening
spring. A projection of the left hand operating
lever also operates the auxiliary switch
(Figure 3, c) .
With the standard electrical control scheme
(Figure 9) , the closing spring is not charged
until a closing operation is called for by an
external signal. As soon as the spring is fully
charged, the tripped linkage can reset under
the action of the reset spring (Figure 5, l) and
the primary and secondary trip props can
fall into the reset position. The reset spring
stretches between an extension on the main
cam roller pin and a spring support pin located
on the right mechanism side sheet. The trip
latch check switch operated by a lever on the
trip shaft will now close. This allows the closing
coil to energize, closing the ground making
switch. The closing spring remains discharged
after a closing operation.