Rail Express – September 2019

Weekend project: ‘Rudd’

coupling cams

The secondweekend

projectforthis month

finishes offtheLima

Mk.2f projectfeatured

inREM184 ,byfi tting

close coupling cams

taken from Hornby‘Rudd’

ballastwagons.Theycan

be used on manyother

models too!

H

ORNBY’S mini-rangeofmodern

ballastwagons which comprises

of the ‘Rudd’, ‘Tope’ and ‘Clam’ is a

very useful collection forlate1980s and

1990s modellers, with manyexamples

of the full-sizewagons survivingwell

into the Privatisation period. Like many

infrastructurevehicles of the time,

theyare re builds ofredundantrevenue

wagons, this time, the HTV coal hopper

fleet being thewagons concerned.

The models producedby Hornbyare

generallywell receiv ed by modellers,

despite theoverlythick sides of the

Rudd and Clam models. Theyare

equipped with the samewell mo delled

HTV derived underframe and close

coupling cams which come fitted

with quiteafierce spring. In practice,

models with short underframes do

not need close coupling cams and

experience with the Hornbymodels

has demonstrated this time and again

with thewagons workin gthrough tight

curves without the close coupling cams

actually doing anything useful.

So, can theyberemovedand putto

better use?Some tinkering has shown

that theywillfitc oaching stockwell,

with thehandful of Lima Mk.2f coaches

being used to test the idea. Theycan

be adapted to suit almost anyproject

including EMUs and

bogiewagons too. In the

second of twoweekend

projectsforthis issue

of REM, some tinkering

with close coupling cams taken from

HornbyRudd wagons produced some

interestingresults.

Couplingcam considerations

Each couplingcamassemblyisfi tted

to thewagons with three cross-

headscrews making them simple to

remove.The underside of thewagon

underframe secures the moving

coupling arm moulding in place, so care

is needed toavoid losing the arm when

removing the assembly. It is fitted to

the wagons immediatelybehind the

headstockswith the NEM coupling

pocket correctlypositionedrelativ eto

theheadstocks. The arm is short as

aresult, which means that theymust

also be fitted to therecipient model as

tight to therear of theheadstocksas

possible.

When used on longervehicles such

as coaches,bea ware that therelatively

short arm means that the coupling

camswill not be effectiveoncurves

of less than secondradius. Alonger

coupling bar or other couplings maybe

needed to prevent buffers from locking.

Having said that, thegapbetween the

gangwaysstill closesup dramatically

compared to using the original

couplings.In commonwith projects like

this one, someexperi mentationsoon

establishes what can be achieved.

Preparing the underframe

With the Lima coach underframe

separated from the coach body,use

the coupling cam assemblytowork

out wherethe hole to accommodate

the moving coupling arm needs to

TOOLSAND

MATERIALS:

■Sharpscalpel.

■Various tweezers.

■Cross-head jeweller’sscrewdriver.

■Steel ruler.

■Pin-vice and micro-drill set.

■Steel rule.

■Solvent cement.

■CAglue.

■ 20 -thou black styrene card.

■ 60 -thou black styrene card.

■Parkside ModelsPA 34 pocket

mounts.

■NEM-362 coupling pockets.

What does the Hornby‘Rudd’ and

Lima Mk.2 air-con coaches havein

common?Close coupling cams!

Rudd, Clam andTopewagons have

short underframes, making close coupling

cam mechanisms unnecessary.

The cams areeasily removedbyreleasing the cross-headscrews(A). Note the NEM

coupling box(B); coupling arm moulding and its finsreferred to in the article (C) and

centring spring (D).

The coupling cam assemblies shown

removedfromthewagons. Note howthe

underside of the floor is shaped toretain

the moving coupling arm moulding.

Acoupling cam assemblyisplaced

on theunderframe to see howitwill

fit behind the headstocksand the

modifications needed to fit it.

M14 RAIL EXPRESS Modeller September 2019 Supplement No. 185

MODELLING