Note: Descriptions are shown in the official language in which they were submitted.
~4~ 9
Descri~tion of Invention
Title: Apparatus for Moving a ~'elicopter Along a Deck
THIS INVr`NTION relates to apparatus for moving a helicopter along
a deck of a ship.
The landing of a helicopter on the deck of a ship, particul~rly in
bad weather conditions, is a very hazardous task and ~everal ~rior
proposals have been made to reduce the risks involved.
One such device in current use 18 the harpoon deck-lock system in
which a harpoon carried by the helicopter is deployed immediately on
touch-down to enga~e in and ~Tip a grid portion flxedly attached to the
deck surface. m e harpoon i~ normally hydraullcally operated end is
arranged to provide a retaining force to pull the helicopter onto the
deck surface. The helicopter is normally fitted with R castorable,
wheeled undercarria~e, and can be rotated about the harpoon fixing by
thrust from the tail rotor to facilitate take-off and to align the
helicopter with a desired direction of Movement acro~s the deck surface.
Another device to facilitate landing of a helicopter i8 the
so-called "bear-trap" device, in which a trap, fixedly attached to the
deck, is arranged to grip a downwardly extending probe carried by the
helicopter when -the helicopter has been brought down under the control
of a cable lowered from the helicopter and attached to a powered winch
usually located beneath the deck. One example of su~ch ~ devi~ce is
'~ disclosed in ~.K. Patent Specification Serial Number ~ t3~ ~nd one
of its disadvantages will be readily apparent from a viewing of Fig~re 1
as constituting~ the significant modification necessary to the ship' B
deck and the extensive bulky equipment that is necessary on the ship to
operate the system.
Raving safely landed the helicopter on the deck, there remains the
problem of moving it for exalDple into a hangar area either to allow
furthe~ helicopter(s) to land or to effeot servicing or maintenance
procedures. q~is also can be an extremely ha~ardous tas~ in bad
weather conditions, since severe motion of the deck can result in loss
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of control of the helicopter durin~ its movement and may result in
complete 108~ of the helicopter into the water. Not surprisingly,
therefore, there `nave been many prior proposale relating specifically
to the movement of a helicopter acros6 a deck, e.g.,the devices and
arrange~ents of ~.K. Patent Specification Serial Nu~ber 1,403,425 and
~nited States Patent Specifications Serial Numbers 3,785,316 and
3,830,452. The main disadvantages of the~a proposals i8 that they
require per~onnel on the deck to secure the helicopter which is
undesirable, and/or they require extensive ~h:Lp-borne equipment.
Another prior proposal for moving a helicopter and which is
designed specifically for use with the aforementioned "bear-trap" deck-
lock device i8 disclosed in U.K. Patent Specification Serial Number
1,285,144. In thi~ arrangement, a movable guided dolly i~ provided
for attachment to the probe in order to move the helicopter, and
embodiments for movine helicopters having either skid or wheeled
underc æriages are described. In both embodiments, personnel are
required on deck to attach the helicopter to the dolly and, in the caae
of the wheeled undercarriage device, precise positioning of the
helicopter i8 necessary in order to facilitate such attachment, and
this may be difficult in extreme weather condition~ rthermore, in
the case of the device for moving a wheeled undercarriage helicopter,
it will be apparent9 since the helicopter is hauled along by the probe
depending from the fuselage, that mo~ent load6 have to be raacted at
the helicopter fuselage, thereby increasing the oomplexity and
structural weight of the probe mounting.
Consequently, there is a need in the art for a simple and
efficient apparatus for moving a helicopter on the deck of a ~hip.
Preferably, such apparatus should nece~sitate minilmum modification to
existing deck ~urfaces, should be operable with existing deck-lock
systems and, preferably, should require no personnel on the deck during
elther landing or manoeuvrine of the helicoptar.
Accordingly, the invention provides apparatus for moving a
helicopter on the deck of a ship, the apparatua includin~ a trackway on
the deck and a movable trolley located on the txackway, wherein the
trolley incluaes a vertically extendable and retractable probe havin~
an upper end arranged for location in en~age~ent means beneath the
helicopter rugelage, the probe mounting means carried by the trolley
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and laterally movable relative thereto, and locking means operative to
lock the ~ounting means and thereby the probe in a central posi-tion on
the trolley.
The probe may be power operated so as to provide a downward force
on the helicopter, tending to hold the helicopter onto the deck when
the probe is located in the enga~ment means. Preferably, the probe
is hydraulioally operated.
~ he probe ~ounting me.~ns may comprise a be~m stI~Icture slidably
mounted on spaced-apart parallel guide bars c~rried by the trolley.
Conveniently, the locking means may be located on the beam structure
and may be operatively associated with a laterally extending locking
bar carried by the trolley so as to be capable of locking the mounting
means in any position relative the trolley. ~he locking means may
comprise a hydraulically operated sprag lock mechanism.
Said engagement means on the helicopter may comprise a trap and
~uide rails arranged to guide the upper end of the probe into the trap
as a result of relative movement between the helicopter and the trolley.
~he trap may include a vertically extendin aperture for en~a~ement by
a lock plunger oarried by the probe and, preferably, the lock plun~er
is spring loaded 80 as to protrude from 2n upper end of the probe and
is selectively movable by hydraulic presaure into a retrac-ted position
within the probe.
In one embodiment ~f the invention adapted for uæe with a so-called
harpoon deck-lock system, the trolley may be provided with a
longitudin lly movable portion remote from the probe mounting means
and having an upper surface configured for operative asaociation with
the deck-lock system. Preferably, the movable portion iB power
operated by any suitable means such as a hydraulic jack fDr movernent
between extended and retracted positions.
A plurality of ~uide roller~ may be provided on the trolley and may
be located in parallel longitudinally extending slots. Preferably the
~lots have an inverted T-shape in cross-section, in order to react the
downward force applied to the helicopter through the probe.
In one form of the invention suitable for u~e in modifyin6~ an
existin~ deck surface, the slots may be provided in a track~ay having
an upper surface raised from and substantially parallel to the deck
surface and longitudinally extending ramp portions alon~ each side
thcreof, Conveniently, the trolley may be provided with a plurality
of ~heel~ arran~ed to run along the upper ~urface of the track-way.
Power means are provided to move the trolley along the trackway
and may comprise remotely located winch means attached to the trolley
by one or more cables. Conveniently the cable(s) may be routed along
the T-shaped slot.
rrhe invention will now be described by way of ex~ple only and
with reference to the accompanyin~r drawings in which:-
Fi~ure 1 is a fragmentary side elevation of a helicopter on a
ship's deck and illustrating apparatus according to one embodiment ofthe invention,
~ igures 2 and 3 are view~ similar to Figure 1 and illustrating
apparatus according to a sacond embodimantg
Figure 4 is a plan view of part of the apparatus of the
embodiment of ~igures 2 and 3,
~igure 5 i8 a side elevation taken in the direction of arrow A on
~igure 4,
~igure 6 is an end elevation taken in the direction of arrow ~ on
Figure 5,
Figure 7 is a fra~mentaI~ sectioned elevation taken on lin0s C-C
on Figure 4,
~igure 8 is a siae elevation of part of the apparatus taken in the
direction of arrow D on ~igure 4 and includes details of interfaca
apparatus on the h01icopter,
Figure 9 is a sectioned view taken on lines E-E of ~igure 8 and
showing the apparatus engaged beneath the helicopter9
Figure 10 is a fragmentary bottom plan elevation taken in -the
direction of arrow F on Figure 8,~ L~c~ P~ ~661 ~r ~a~.
Figures llA to llH inclusive ~re schemstic illustrations of a
seguence of operations of apparatus according to the invention to move
a helicopter having a particular type of undercarriage configuration,
Figures 12A to 12H are schematic illustrations of a sequence of
operations for moving a helicopter having a further type of
Imdercarria~ge .
Referring now to ~igure 1, a helicopter 21 is shown on the deck 22
of a ship.
The helicopter 21 has a tricycle undercarriage comprisin6 a
5~g
-- 5 --
castorable no6ewheel 23 located centrally beneath a fusela~e and two
castorable rear wheels 21l (~hown in broken line) located l~terally one
on each side Or a longitudinal centreline. The helicopter 21 iB
sho~m secured to the deck 22 by a deck-lock syntem generally indicated
at 79 which, for illustrative pu~o6e~ is shown as a harpoon dec~-lock
system conprising a harpoon 25 carried by the helicopter 21 eng.~ed in
a ~rid 26 permanently fixed in the surface of the deck 22.
A trolley 27 is positioned beneath the fuselage of the helicopter
21 and is movable along a trackway 28 fixed to the surface of the deck
22. The trolley 27 includes a vertically extenda~le probe 29 having
an upper end adapted for location in engagement means 30 prcvided on the
lower surface of the fuselage of the helicopter 21. Guide rail~ 45 ~are
associated with the engagement ~ean~ 30 beneath the fuselage for a
purpose to be hereinafter described.
The embodiment of ~igures 2 and 3 i8 similar to that of Fi~re 1
except that the trolley 27 iB particularly adapted ~or use with the
harpoon deck-lock system 79. ~o this end, the trolley 27 includes a
generally hori~ontally extendable portion 31 shown in its retracted
position in Figure 2. An upper surface of the portion 31 has a grid
configuration compatible with the grid 26 in the deck 22.
Rsferxing now to Figure 3, it will be seen that the probe 29 i~
located and locked in the engagement mean~ 30 and that the harpoon 25
has been disengaged from the grid 26 in the deck 22 and re-engaged in
the grid provided at the outer end of the extended portion 31 of the
trolley 27.
~ igure~ 4 to 6 inclusive show detailc of the trolley 27 used in the
embodiment of ~igures 2 and 3.
The trolley 27 compri~e~ a generally rectan6~1ar body 32 having
guide rollers 47 attached beneath each corner and intermediate the
len~th of side frames 1~8. The rollers 47 are located in parallel
longitudinally extending slots 33 of inverted T-shape provided in the
low profile trackway 28 which has an upper surfaoe rai~ed from and
parallel to the deck ~urface and longitudinally extending ramp portion~
46 alon~ each side. Winch cables (not shown) extend along the ~lots 33
from re~ovely located winch means and are attached to each end of the
trolley 27.
Two wheels 78, having ~olid rubber tyres, are located externally of
side frames 48 to run ~long the upper surface of trackway 28.
The probe 29 comprise~ a hydraulic ~ack having a ca~ing 34 housing
a ram 35, the ram 35 havlng an upper end 36 arranged for location in the
en6a~ement me~ns 30 provided beneath the helicopter fuselage 21. The
5 casin~ 34 ic attached at one end of a horizont~lly longitud1nally
extending strut 37 pivotally located for rotation about its axis on
mounting mean~ comprislng a laterally slidable beam ~tl~lcture 38.
The structure 38 is located at one end of the body 32 and is slidably
mounted on spaced~apart parc~llel ~ide bar~ 49 extending between the
~ide frames 48. A hydraulically operated sprag lock m0cilanism 50 is
carried by the structure 38 c~nd is operatively a~sociated with a
toothed surface of a laterally extending locking bar 51. A pin 52
located adjacent a lower end of casing 34 (see also ~igure~ 8 and 9) is
arranged for location in a hydraulically operated locking device 53
which i6 spring loaded for enga~ement as the probe 29 moves into its
vertical operational position.
An angled strut 39 extendH between an upper end of the ca~in6 31~
and the strut 37 to support the probe 29 in one plane, and a hydraulic
~ack 40 extendJ between the casing 34 and the structure 38 in a plane
perpendicular to the plane of the strut 39.
It will be apparent, therefore, that extension and retraction of
the hydraulic jack 40 æerves to move the probe 29 between a generally
horizontal stowed position shown in broken outline in Figures 4 and 6
and a vertical operational position shown in full outline in Figures 4
to 6 inclusive, and that lateral movement of ~tructure 38 assi6ts in
correctly locating the probe 29 in respect of the engagement means 30
on the helicopter. Also, when the probe 29 is in itE vertical
operational position, the strut 39 and locking device 53 combine to
rigidly support the probe 2g in any lateral direction.
In the illustrated embodiment, the trackway 28 te~ninates in
proximity with the grid 26 fixedly attached to the deck of the 6hip
(Fi~lres 2 and 3) which fo~ns the shipborne part of a harpoon deck-lock
~y~te~. The longitudin~lly extendable portion 31 of trolley 27 is
located at an end of the ~vdy 32 remote from the laterally ~ovable beam
35 st~lcture 38, the portion 31 being operable by a hydraulic jack 41
between a retractea pogition sho~n in ~igures 4 and 5 ~nd the extended
po~ition illu~trated in ~ re 3. The upper surface of an outer end of
-- 7 --
portion 31 is provided with a &rrid 44 compatible with the ~rid 26 in
the deck 22.
The portion 31 is Gupport~d by two laterally spaced-apart ~lide
bars 54 ~lidably mounted in cro~s beams on the body 32, and 80 that
upper side surfaces of the portion 31 engage at 55 with surfaces of a
support ~tructure 56 provided on the body 32 (~igure 7).
. The individ~ l areas 57 of the trolley 27 house operating
equipment ~uch as hydraulic and electric equipment and an elec-trical
control syste~, and are covered by individual access panels (not shown).
Conveniently, winch cables and electric power and control cables arc
routed along the slots 33.
Figures 8 to 10 inclusive illustrate details of the construction
of the probe 29 and the interface equipment carried by the helicopter.
Referring now to Figure 8, the probe 29 is shown in its vertical
operational position with its upper end 36 retracted into the casin~ 34,
and in alignment with the trap 30 attached to the undexsi~ of the
helicopter ~uselagre 21. A~ illustrated in ~iguxes 8 and 10, the trap
30 is supported by a spherical ela~tomeric mount 57 having a central
vertically extending aperture 58, and comprises a ~-shaped structure
having an inwardly extending flange 59 around three ~ides thereof
located with its open non-flanged side ~li~ned with the 0nd~ of
converging ~uide rails 45 that are al60 provided with inwardly extending
flanges. The front of the helicopter is in the direction of arrow G
on ~igures 8 and 10.
Fib~re 9 illustrates constructional details of the probe 29 which
is illustrated in its oxtended position with its upper end 36 engaged in
the trap 30. ~he casing 34 has ~n open upper end housing the hollow
ram 35 which has a piston head 60 at its lower end. The upper end 36
of the ram 35 ha~ a dome-shaped ùpper surface carrying a guide roller 61
~upported by a ball bearing 62.
An upper end of a centrally located hollow lock plungrer 63 is
slidably mo~ted 1n a bore in the upper end 36, and a lower end of the
plunger 63 is slidably mounted in a bore in the rc~m 35. An
intermediats ~lange 64 on the plunger 63 is located in a chamber 65 ln
the ram 35 and is provided with an ori~ ce 66. A ~pring 67, located
in chamber 65, act6 on the flange 64 to urge the lock plunger 63 into
the position illustrated in ~i~ure 9 in which it protrudes from the
-- 8 --
domed upper surface of upper end 36. A rounded cap 68 provided ~ith
a vent orifica 69 iB provided at the upper end of lock plung~r 63.
A lower end o~ lock plunger 63 i8 slidably located around the
circu~ference of a hollow pintle 70 supported from the body 34. The
5 pintle 70 has a piston head 71 located in the bore of the lock plun~er
63 and spaced-apart from the lower end thereof to fo~n .~n ar~ular
chamber 72.
'rhree threaded connections 73, 74 and 75 are provided in the body
34 for connection to a controlled supply of pres~urised hydraulic fluid.
Connection 73 is connected through the bore of pintle 70 to the chamber
72, connection 74 is connected to a chamber 76 in the body 34 at one
side of the piston head 60 on the ram 35, and connection 75 is
connected to an annular chamber 77 on the other side of the piston
head 60.
'rhe sequence of operation of apparatus const~lcted in accordance
with the invention and for a helicopter having a tricycle
, undercarriage with castorable nosewheel and mainwheels will now be
de~cribed with reference to Figures llA en~ llH inclusive,
Referrin&~ now to Figure llA, the helicopter is s~howr; on the deck
of a ship and with the harpoon 25 en~aged in the grid 22. It will be
noted that the harpoon 25 is not centr.lly located in the grid 22 so
that the helicopter is not alignea with the trackwa~ 28. 'rhe trolley
27 is shown at one end of the traclcway 28 re~note from the grid 22.
'~he no~ewheel 23 i8 shown located cn the trackway 28 so that the
first manoeuvre, depicted in ~igure 11~, iE to castor the nosewheels 23
and rotate the helicopter about the harpoon 25 and in a clock~ e
direction viewed from above until the nosewheel 23 is ,just clear of the
trackway 28. It will be understood that at this sta.~,re, the helicopter
engines and rotors are ~till operatin~ 80 that rotation about the
harpoon 25 is accomplished by lateral thrust from the tail rotor. The
ram 35 Or probe 29 i8 in its retracted position, and pressurised
hydraulic fluid is supplied throu~h connection 73 (~ ure 9) into
chamber 72 to retract the lock plunger 63 against the force of spring 67
into the position shown in ~i~re 8. The trolley 27 is then moved
towards the helicopter until the probe 29 is located beneath the
fuselage. Pressurised hydraulic fluid is supplied throu~h cor~ection
74 into chamber 76 (Figure 9) to extend the ral~ 35 90 t~t the do;ned
- 9 ~-
surface of upper end 36 bears on the underside of the fuselage with a
positive pressure of ~etween 30 and 50 lbs. The pressure at
cor~ection 73 is released 90 that the cap 68 OD lock plunger 63 i~
al~o urged against the underside of the helicopter by the forcs of
sprin~ 67.
Further movement of the trolley 27 towards the helicopter engages
the ~uide roller 61 at the upper end 36 of probe 29 in one of the
~u;de rails 45 thus guiding the probe 29 into the trap 30 ~Figure llC).
Thi6 is permitted by lateral movement of the beam structure 38 on the
trolley 27 on which the probe 29 is mounted as shown in Figure llC.
As the upper end 36 enter6 the trap 30, the pressure of spring 67
forces the lock plunger 63 upwardly into the aperture 58 in the trap 30
thereby locking the probe 29 to the helicopter. The hydraulic supply
to the chambar 76 is released.
Ae shown in Figure llD, the helicopter i8 now rotated about the
harpoon 25 in a counterclockwise direction viewed from above, which
serves to mova the beam structure 38 laterally on the trolley 27. AB
the beam structure 38 reaches it~ centralised positiont the sprag lock
50 i8 actuated to locX structure 38 to the body 32 of trolley 27.
The mainwheels 24 are now castored as shown in Figure llE and the
harpoon 25 is released from the grid. Lateral thrust from the tail
rotor of the helicopter is now utili~ed to rotate the helicopter about
the probe attachment in a counterclockwisa direction viewed from above
until the nosewheel 23 i8 located centrally of the trackway 28. It
will be apparent that this ~anoeuvre automatically aligns the mainwheels
24 with the trac~ay 28 as shown in Figure llF.
Portion 31 of the trolley 27 iB now extended by hydra~lc jack 41
as shown in Figure 3, and the harpoon 25 is re-en~aged in the grid 44
formed in the upper surface of the portion 31, to provide a dual
attachment of the helicopter to the trolley 27, 'rhe hcld-down force
exerted by the harpoon 25 is reacted through enga~rement of side
surfaces 55 of portion 31 with mating surfaces on the body 32 (Fi~ure 7).
AB shown in Fi~ure llG, the nosewheel 23 and mainwheel~ 24 are now
castored to the fore-a~d-~ft position, The helicopter rotor is now
~topped and the en~ine(s) shut do~m, lf the helicopter iB fitted with
a foldable tail cone, this is now moved to the stowed position,
The trolley 27 iB now ~oved along the trackway 28 to move the
helicopter, through the attachment of the probe 29, into the hangar
or stowa~e area on the deck.
It will be apparent that manoeuvres following en6a~e~ent o~ the
lock ~lun~er 63 in the trap 30 are accomplished with the probe 29
unpressurised. ~o~ever, in an smergency such as a move~ent of the
deck beyond predetermined limits, pre~surlsed hyaraulic fluid i8
supplied to chamber 77 through connection 75 to exert a tension on the
fusela~e of about 5000 lbs. in order to positively retain the
helicopter on the deck. ~his re~trainin~ force i9 reacted at the
flan~e 59 on tha trap 30 and at the rollerc 47 in the slots 33 in
trackway 28. Additionally, the ~prag lock 50 can be actuated with the
beam struct~re 38 in any laterally offset position to provide further
restrain in an e~er6ency. Preferably, the spra~ lock is arranged to
automatically engage when unpressurised so as to provide efficient
locking of the beam structure 38 in the event of a failure of the
hydraulic 6upply .
In order to illu~trate the ~ersatility of the apparatus of the
invention, the sequence of operations shown in Figures 12A to 12H
inclusive is in respect of a helicopter ha~ing a tricycle
undercarriage in which the mainwheels 24 are non-castorable. In such
a case it i8 necessary for the nosewheel 23 to be movable within a range
between 90 degrees of the fore-and-a~t position ~nd a smallar an~le on
either side of the fore-and-aft position. Conveniently, this may be
achieved by a castorable facility into the extreme 90 degree~ position
and a steerable facility throughout the restricted range and operable
by the pilot.
~ he sequence of operations ~ho~n in Fi~ure~ 12A to 12C inclusive is
identical to that previously described in relation to Fib~res llA to llC
inclusive. At this stage in the sequence of Figure 12, the rotors are
stopped, the engine(s) shut down, and the tail cone folded toit6 stowed
po~ition.
As shown in Figure 12D, the nosewheels 23 are moved to an
intermediate position. The harpoon 25 is then relea~ed from the grid
26 and the helicopter is retained in position by the ~robe 29.
~e~errin~ now to Figure 12E, the'trolley 27 is mo~ed ~long the trackway
away from the grid 26 th~rebv movin~ the helicopter throu h the attached
probe 29 from the position indicated by the broken line to that
~4~
11 --
indicated in full line, this being permltted by lateral movement of
the beam structura 38.
The nosewheel 23 is moved to the position shown in ~igure 12F and
the trolley 27 ~nd attached helicopter iB moved further alon6 the
trackway 28. As illustrated in Fi~ure 12F, this manoeuvre moves the
trolley 27 ana heliconter from the position shown irl broken outline to
that shown in full outline in which the beam structllre 38 i9 moved b~ck
to its centralised position, and the helicopter i~ eorrectly al~ned
with the trackway 28. It will be apparent that at this stage, the
harpoon 25 can be re-en~aged in the grid pro~ided In the portion 31 of
the trolley 27 if desired. The nosewheel 23 is then moved back to its
fore-and-aft position (Fi~re 12G) and the trolley 27 and attached
helicopter are moved along the trackway 28 into the storage area
provided.
For take-off, the helicopter is moved out onto the deck by the
trolley 27. The guide roller 61 at the u~per end of the probe 29
enables the helicopter to be rotated ~bout the probe 29 into a desired
heading. The deok-lock sy~tem 79 is then re-engaged in the grid 26,
the trolley 27 moved clear, and the helicopter la~nched from the deck-
lock in a conventional manner.
~ hus, in apparatus accordin~ to this invention, ths trolley 279
probe 29, lock plun~er 63 and extendable portion 31 of the embodiment
of Figures 2 and 3 are operable from a remote control console on the
ship so that personnel are not required in the exposed deck area at any
time durin~ either landing, traversing or taking off. This is a very
important consideration especially when operating in a hostile
environment or in extreme weather conditions. Fur-thermore, it will be
apparent that operation of the apparatus of the invention is controlled
entirely from the ship's deck thereby relievin~ the pilot of any
re~ponaibility during this dangerous manoeuvre.
The ri~id mounting of tha probe 29 on the trolley 27 ensures that
moment reaotions do not occur at the helicopter structure which is
required to react shear forces only, thereby minimising the etructural
wei~ht of fittin~s requlred on the helicopter. The embodiMent of
~igures 2 and 3 for use with a ha~poon deck-lock syste~ en~ures a
positive two-point attachment of the helicopter during deck
manoeuvres.
- 12 -
Whilst embodiments Or the apparatus have been described for use
with a harpoon or other type of dcck-lock system, it will be apparent
that other modifications may be made without departine from the scope
of the invention as defined in the appended claims. For instance, the
interface ~ay be modifi~d so as to comprise lockin~ meQnæ, such as a
jaw-type locking means, that may be operable by the pilot 80 as to
enable the helicopter to t~Xe-off from the probe 29 without having
first to engage the deck-lock syste~. The apparatus can be used with
other types of deck-lock sys~ems and, whilst operation has been
described in relation to two different tricycle undercarriage
configurations, it is not limited thereto and can be adapted to operate
with other confi~rations such as a tricycle undercarriage having a
central tail wheel or a quadrupedal undercarria~e. ~he rais~d
trackway 28 is suitable for use in modifying an existin~ deck
structure, however, it will be apparent that the trackway can also be
fo~,ed by providing the inverted T-shaped slots 33 beneath a deck
surface 22 during construction.
