more arresting engine and retractable sheave is
bypassed, the deckedge indicator light will display
the green and amber lights.
SEQUENCE OF OPERATION
Energizing the motor to raise the retractable
sheave, by pressing the RAISE push button, causes
the motor to rotate a helical gear keyed to its shaft.
This transmits the motor force to another helical
gear on the wormshaft. The wormshaft turns the
worm and drives the worm gear on the sleeve. The
worm gear rotates freely on the sleeve for part of
the rotation, thus permitting the motor to gain
speed before full loading.
As the worm gear
rotates, the lugs on its face engage the lugs on the
face of the clutch bevel gear. Rotation of the clutch
bevel gear, which is splined to the sleeve, rotates the
sleeve, which is directly connected to the screw of
the retractable sheave, thus raising the sheave.
When the sleeve rotates, the limit bevel gear, keyed
to the sleeve, rotates to turn the pinion of the
geared limit switch. This is the only function of the
limit bevel gear. When a predetermined point is
reached by the rotor of the geared limit switch, the
RAISE circuit is broken and the raising operation
ceases. As the geared limit switch is actuated, the
green lamp (sheave UP lamp) will light in the
deckedge light box.
Energizing the motor to lower the retractable
sheave, by depressing the LOWER push button,
causes the motor and the drive system to operate in
the reverse direction. Again there is free rotation
until the lugs on the worm gear make a complete
revolution before striking the other side of the lugs
on the clutch bevel gear. The sheave lowers until it
is completely seated and opens the torque limit
switch to break the motor circuit. If an obstruction
prevents the sheave from descending, the worm,
which is still rotating because of the force of the
motor, does not turn the worm gear. The worm is
driven axially along the wormshaft until the torque
limit switch is opened by the tripping plate washer.
The torque limit switch may be adjusted to permit
the sheave to seal with a predetermined force before
the circuit is interrupted. The torque spring then
absorbs the remaining inertia of the system after the
circuit is broken. During the time the sheave is
lowered and raised up until the time the RAISE
geared limit switch is tripped, the red (sheave NOT
UP) lamp glows on the deckedge light box.
For manual operation, the handwheel must be
mounted on its shaft and secured to the shaft with
a setscrew. The declutch lever must then be thrown
in a counterclockwise direction. This movement will
slide the clutch bevel gear along the splined section
of the sleeve to engage a gear on the handcrank
shaft. When the handcrank is turned, the sleeve
turns, rotating the sheave screw to raise or lower the
sheave. The declutch lever remains in the clutch
position until operation under motor power is
at which time the handwheel is
disconnected automatically by the clutch trippers.
There is no danger to an operator if he or she is
turning the handwheel when the motor is started,
because the handwheel is disengaged instantly
without shock or jolt.
The following are instructions for removing parts
in order to gain access to the unit when it needs
servicing or inspecting:
1. Shut off the power.
2. Remove the limit switch cover.
3. Disconnect the power and control wires from
the operating unit.
4. Remove the entire operating unit from the
5. Remove the electric motor.
6. Remove the mounting screws and take out
the geared limit switch.
7. Remove the pipe flange (end opposite
mounting pad), and take out the gland thrust ring.
8. Remove the housing cover from the end
opposite the mounting pad. Remove the gland
follower and packing cover.
9. Remove the lubricant from the housing.
10. Loosen the setscrew in the declutch lever
hub and remove the declutch lever.
11. Remove the three capscrews from the
handwheel through the cap and pull out the entire
handwheel pinion assembly.
12. Loosen the jamnut and setscrew in the
clutch fork and remove the declutch lever.