29
Leaf Spring
8
Groove for
Leaf Spring
Inner Facing
32
4
8
8
Figure 73. Overall view of the concep-
Figure 75. Details of the leaf spring and its T-groove on
tual crushable plastic cushion. (Dimen-
the inner facing.
sions are in inches.)
74) mounted directly above the cylin-
Cap
Cap Gasket
Cushion
drical body cushion will allow exces-
Hinge
sive snow and water to drain, and will
Shoulder Gasket
protect the crushable foam from exces-
sive moisture and dirt. The cap cush-
H-Section
Rubber Gasket
ion would be made of two hubs joined
by a hinge. The cutout grooves in the
foam surface of both the body cushion
and the cap cushion will allow a spe-
Reflective
cially profiled shoulder gasket to seal
Decal Sheet
the cap cushion onto the body cushion
(Fig. 72). The annulus between the
inner facing and the pole will provide
the dripping path for melted snow or
Leaf Spring
rainwater. A specially molded polyure-
Body Cushion
Figure 74. Illustration of the two halves of the crushable plastic
thane cap gasket configured with appro-
cushion split open.
priate grooves and lips, and slit from
the center, will serve as the top end-cap
of the conical cap cushion. The bottom end-cap
hubs of rigid high-density closed-cell polypropy-
(Fig. 76) will also be made of molded polyurethane
lene foam sandwiched between two FRP facings
in two halves. The outer facing of the body cush-
(Fig. 74). Both the outer facing and inner facing
ion will fit into the recess of the bottom end-cap,
will be made of vinyl-ester-impregnated, chopped-
which will be clamped together with a stainless-
glass-reinforced molded product. The outer fac-
steel band clamp. Another stainless-steel band
ings of the two hubs will be joined with a full-
clamp of smaller diameter will tightly clamp the
length hinge to allow the two hubs to close around
neck portion of the bottom end-cap onto the pole.
the rigid pole. A longitudinal groove in the foam
The bottom end-cap will provide openings
on each hub will allow an H-section rubber gas-
between the radial ribs through which water drip-
ket to seal the longitudinal open joint of the outer
ping from the pole can pass down. The outer sur-
facings. Along the length of the inner facing, lon-
face of the outer FRP facing will have a bonded
gitudinal T-grooves, molded in during casting,
reflective decal sheet for easy recognition of the
will receive a series of three stainless-steel leaf
crush cushion at night or low lighting. Special care
springs (Fig. 75). The leaf springs in four such
has been taken in this design to make it adapt-
slots, spaced at 90 apart, will hold the cushion in
able not only to fixed posts, but also to small or
place against the pole. A conical cap cushion (Fig.
53
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