but #158s are even more critical. My plan is to use Sergents
on my home switching layout, but I would not consider them
or the #158 for use on the modular club layout setups. The
dips and bumps that seem to be standard with modular lay-
outs that are set up and taken down repeatedly seem to
invite nuisance-uncoupling without adding to the problem
with small coupler heads.”
Mixing Kadees:
Signals
Q.
What’s the difference between an absolute block system
and a permissive block system? I’ve been trying to read up on
signals, but can’t find the answer.
A.
An absolute block system allows only one train in a block at
a time. A permissive block system allows more than one train in
a block at a time. Using rules and signals, a permissive system
allows one train to follow another in the same block.
Just to throw in another confusing term, a common system in
use in the U.S. today is absolute permissive block, which pro-
vides full signal protection for opposing trains in addition to the
protection for following trains that an automatic block system
gives. (Most single track ABS systems provide some protection
against opposing trains but the protection is not complete, and a
track occupation authority system like timetable & train order or
track warrant control is needed.)
Here’s good web page that tells the basics of railroad signals:
Jay S. Bogguss wrote a series of five articles that started in
the November 1991
Model Railroader
that will tell you about
everything you need to know about absolute permissive block
Questions, Answers & Tips - 4
signaling. Bill Reid, Rich Pistello and Rich Weyand did similar
articles for
Mainline Modeler
late in 1994. Back issues should
be available. Andy Sperandeo frequently writes about signals
in his “The Operators” column that appears on the final page
of each month’s
MR
.
Simmons-Boardman publishes “Railroad Operation and Rail-
way Signaling” by Edmund J. Phillips Jr. It’s available from:
and:
TIPS
Taking notes
When starting a kit that will need to be painted, put a 3 x 5
file card [4, next page] in the box to note the name, number,
and/or manufacturer of the various colors used. A couple
seconds of note-taking will save a lot of time if the project
gets shelved for whatever reason. When I started on a wood
kit that I had not worked on for quite a while, the card was
in the box and I was touching up in a couple of minutes. (The
same trick works with paint colors and detail part numbers
for car and locomotive projects.)
– Terry Roberts
MRH-May 2014
