be located.Markinacentreline first
and then drawround the fins of the
coupling armmoulding to determine the
minimum sizeofthe opening.
Usinga2mmdrillinapin-vice, drill
arowof holes around the inside of the
lines and then push through using a
modelling knife. File the hole to shape,
using the arm moulding to achievethe
same curved sided shape as seen on
the underside of the donorwagons.
Whilstfiling and cleaning up the hole,
checkprogress withacompletely
assembled coupling cam untilitfits
neatlyand with its leading edgeup
against therear ofthe headstocks.
Installation
On theupper surface of the coach
underframe,apiece of 20-thou black
styrene cardwas fittedoverthe
opening to hold the arm moulding
in place.Afilling pieceofthe same
material isrequired to pack out
the space to ensurethe armworks
smoothly.Once completed, the coupling
camassemblyispositioned on the
underside of the underframe moulding,
centredasaccuratelyaspossible and
threescrewholes drilled in place with a
0.7mm diameter drill to match those in
the cam assembly.The threeretaining
screws are‘self-tapped’ into thescrew
holes to secureeverything.
Thecam is testedbymoving it to
one side and then the other,allowing
it to spring back into place. If it is
too slack in the frame,removethe
assemblyand pack theoversizearea
of the opening with strips of styrene.
If thearmmoulding catches andwon’t
return to the straight position, check
the openingsfortight spots or burring,
including the packing piece.
Tosmooth the action, useadry
lubricant such asKadee‘Grease-em’
sparinglyinthe cam mechanism.
Interestinglyenough,thespring centres
the cam armwell,but isalittle fierce
in its actionforthe originalwagons.
Itworksbetter in heavier long frame
vehicles such as coaches and it should
beretained as it holds the arm in place
in the cam assembly.Fixed coupling bars
Oncehappywith the action of the cams
nowtheyarelocatedintheir newhome,
choosing couplings comes next.
The NEM coupling pocket happened
to be positioned at the correct height
when used on Lima coaches with the
particular wheel andReplicaRailway
bogie combination used in the original
coachrebuilding project. Thereisno
doubt that some adjustments to the
positioning of the cams mayberequired
formost projects to achievethe correct
heightforthe NEM-362 pockets as
stated in theMOROPstandard. It's
necessaryforacompatible coupling
system and to makethe close coupling
cam installation compatible with any
collection.
If thecoaches aretobecoupled in
afixedrakeorportions ofarake; or the
inner ends of EMU trailers, the height
of the coupling pockets maynot be
asvitalfor the inner couplings as long
as theyarethe sameheight as each
other.However,aproprietary NEM-362
uncouplingsystem cannot then be
used because theyrequirethe coupling
boxestomeet theMOROPspecification
forheight from therail,makingbar
couplingsabetteroption.
Youcan makeyourowntomeet
your needs, of course. Simple bar
couplings of 60-thou black styrene
wereused on thefeatured models, cut
toawidth of 4mm–slightlywider than
the inside dimensions of the NEM-362
coupling boxes. Coupling bar length
depends on the minimum trackradius
of thelayout on which theyareto
operate. Once the minimum lengthwas
determined toavoid buffer lock and
with 8mm allowedateachend to slot
into the coupling pockets, the coupling
bar endswerechamferedtoabout 3mm
in widthforapush-fit firm enough to
keep the coaches coupled together.Finishing off
Tocompletetheproject, the donor
Rudd, Clam andTopewagonswere
fitted with newcouplingmounts.
The underframewaspackedtothe
correctheight with pads of 20-thou
black styrene cardand newcouplingsfittedusingreplacement NEM-362
pocketsfitted toParkside ModelsPA 34
mounting blocks. Alternatively,one
cansecurethe original tension lock
couplingsdirectlytothe underframe
withscrews wheretheyshouldwork
perfectlywell.Asforthe modified
stock, the newcammechanisms and
couplings will haveto beweathered
in to suit therest ofthecoach
underframe.Afinalthought
Whatwouldasuitable alternativetothe
Hornbywagon couplingcams be ifyou
do not haveacollection ofRudd,Tope
andClamwagons?Thereisanexcellent
closecoupling camsystem which will
work just aswell, producedbySymoba
(alsoavailable underthe Gützold name).
Thesystem is complete with coupling
bars,adjustableNEMpockets and
closecoupling (kinematic) assemblies.
Symoba products areavailable through
DCCSupplies (www.dccsupplies.com).An opening to accommodate the
moving coupling arm moulding has to be
cut into the underframe.The opening is shaped to allowthe fins
on the coupling arm to movefreely.The assemblyisoffered up to the
underframe and centred as accuratelyas
possible to allowthescrewholes (A and
B) to be drilled.
Dry graphite lubricant is used to ease the side to side action of the moving coupling
arms in the cam assembly.The stiffcentring spring does therest.
Asimple bar coupling can be made up of 60-thou styreneforfixedrakes, tapered at
the endsforafirm push fit to the coupling boxes.Thegapbetweenthegangwaysisclosed up on straight track. Note the NEM
coupling pocket (A) and coupling bar (B).The finishedresult is both neat andreasonablyunobtrusivewhen used on the Lima
air-conditioned coach models.Rudd coupling camsworkwell, spacing thegangways
apart to prevent buffer andgangwaylocking when the coaches run through curves.
Supplement No. 185 September 2019 RAIL EXPRESS Modeller M15
MODELLING