Page 302 - Ship Construction.DJ Eyres 6Ed

Ch25-H8070.fm Page 291 Wednesday, October 18, 2006 7:00 AM
Cargo Access, Handling and Restraint 291

Hydraulic opening/
closing ram

--- ใช้เพื่อการศึกษาเท่านั้น---
Stern
ramp
Hydraulic securing up
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
cleats

(a) HYDRAULIC STERN DOOR
Stern
door
Stern ramp
down

(b) STERN RAMP
ึ
FIGURE 25.1

Ramps

Ro-ro ships fitted with ramps usually have a stern ramp (see Figure 25.1b),
but some vessels fitted with bow doors may also have a bow ramp which
doubles as the inner weathertight door and is lowered onto a linkspan when
the bow visor or side hinged doors have been opened. Ramps may also be
fitted internally to give access from deck to deck. These can be hydraulically
or mechanically tilted to serve more than one deck and can be fixed in the
horizontal position to serve as decks themselves (see Figure 25.2). In some
ships they can even be raised into the hatch space and serve as weathertight
covers.
Stern ramps can be fixed axial ramps, fixed quarter ramps, slewing ramps
or semi-slewing quarter ramps (see Figure 25.3). The axial stern ramp may
also serve as the stern door and can be lowered or raised hydraulically or by
wire rope arrangements. The quarter ramp was designed for ro-ro ships
using ports which are not provided with right angled quays or link span
connections. The large articulated quarter ramp is raised and lowered by
wire rope purchase arrangements to hydraulic winches. Slewing ramps
serve a similar purpose to the quarter ramp, but are more flexible. The
slewing ramp moves around the stern on a curved guide rail, the movement