Passenger Stairway PS-813B/E Boeing | 9
SECTION 1 - PROCEDURES, SPECS & CAPABILITIES
2. The outer A-frame is the upper A-frame section. This section slides
up and down over the inner section. Two hydraulic cylinders raise or
lower the outer A-frame. The top of the outer A-frame is attached to
the lower stairs section.
3. NOTE: The A-Frame ratchet does not have to be locked in ratchet
stop for normal operation. It is intended as a safety device in the
event of cylinder failure. The ratchet assembly (dogs) must operate
freely into any position on the ratchet stops on the A-Frame.
The A-frame ratchet assembly mechanically locks the A-frame at
various positions. The ratchet assembly consists of a ratchet shaft
equipped with ratchet dogs and a hand lever for engaging the ratchet
dogs to ratchet stops on the A-frame. The ratchet is secured in the
engaged position by the o-center weight of the handle.
1�1�2�2 | Lower Stairs Section
The lower stairs section consists of fteen aluminum steps with tread
surfaces and two side panels, which incorporate handrails. The stairs may
be illuminated by lights installed in the side panels.
The base of the lower stairs section is mounted to the stairway chassis
by means of a shaft, which enables the lower section to pivot when the
A-frame is extended.
The upper portion of the lower stairs section is supported by the
A-frame. Rollers at the upper end support the upper stairs and permit it
to slide freely.
A stair ratchet assembly is attached to the underside of the lower stairs
section. This assembly consists of a ratchet shaft, ratchet dogs and a
manually-operated lever. The ratchet dogs lock the upper stairs section
in position by engaging stops welded to the bottom of the upper stairs
section. The stairs ratchet is released manually by operating the hand
lever.
1�1�2�3 | Upper Stairs Section
The upper stairs section consists of fourteen aluminum steps with tread
surfaces, two side panels with handrail and the service platform. The
upper section is attached to the lower section through a channel on each
side of the lower stairs section. Two rollers are installed on each side at
the lower end of the upper section, enabling the upper section to move
up and down smoothly.
The upper section is raised and lowered by the stairway hydraulic cylinder.
The upper end of this long, slender cylinder is attached to the platform. The
lower end of the cylinder is secured at the base of the lower stair section.
NOTE:
The A-Frame ratchet does not
have to be locked in ratchet
stop for normal operation. It
is intended as a safety device
in the event of cylinder failure.
The ratchet assembly (dogs)
must operate freely into any
position on the ratchet stops
on the A-Frame.
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