Exclusive Trimline Cord
Richard Gerber #4231
the early Trimline phones (AD1 base and AC1 wall base; 220A, 1220A and
2220B handsets) are the cords used by it. The cord made for the Trimline
telephone had large snap in plugs that made it quicker and easier to
replace or change the cord—using the proper tool—KS 16750.
cords can’t be used on the Princess, the 500 sets, the 2500 sets or for
most other types of phones. A few exceptions were brought to my
attention by Arthur Bloom. These would include the “cuckoo clock”, the
851 and 2851 wall key phones and the 830/831 and 2830/2831 series of
desk key phones. Some sets were retro-fitted to hardwire. There were
also some special service central office sets and test equipment using
the Trimline cord. This came about after the Trimline cord had been
manufactured for 10 years.
invention at the time, the Trimline cord was the first and only plug-in
spring and line residential and business telephone cord. There were
operator plug type cords and 4 prong wall plugs to make the phone
“portable”, and other cords of this type, but the Trimline cord had a
different use and look. The cord started with a large plastic plug until
it evolved into the small modular plug on the phones today. Soon the
modular plug cord replaced the Trimline cord. When the modular cord
first appeared we differentiated between them by calling them maxi and
mini plugs. Only the large plug cords used on the Trimline phones (and
the small number of previously mentioned sets) are rightly and properly
called Trimline Cords.
cord had its own exclusive department at Western Electric where it was
manufactured. No other cords were made in the Trimline department.
There is only
one Trimline cord but it has several evolving stages or types leading
towards the modular cord of today. Once it became modular it was no
longer an exclusive Trimline Cord. Ergo, all Trimline cords so named are
large plug cords that fit only the Trimline telephones and the few
Trimline cords were the H5AA and the D5AL, spring and straight (line) in
that order. They have a five conductor cord in a four conductor jacket
(body) and hailed as a major breakthrough by the Western Electric
engineers. Usually with added conductors a cord would increase in
circumference. The Trimline phone itself had to wait until the problem
of squeezing five conductors and a string into a four conductor body was
solved. Once accomplished, production on the Trimline cord proceeded in
earnest in April of 1965AD at the Western Electric Baltimore Works.
helped hold the cords round shape. The paper surrounding the conductors
kept the inner part of the jacket from sticking to the conductors when
the ends were stripped. Later the paper was deleted, a cost savings, and
the conductors were coated with silicon powder. Each step in the
evolution of the Trimline Cord resulted in a cost savings with no
diminishing quality or function to the cord. Soon came the H4DB four
conductor cord as another option.
evolutionary period of the Trimline cord covered roughly the years 1965
to 1974. Production lasted a few years longer (around three?). In that
span there were at least 9 distinct types of ends or plugs on the
Trimline spring cord and two types of bodies (jackets). This makes well
for a collection in Trimline Cords. Add the colors and a person would
have a variety of collectable cords. Be aware that some of the older
cords might have weakened or cracked plastic shells.
The first type
of jacket (body) is a round cord about the size that was already in use
on the H4CJ cord. The second kind is a flat smaller size that is still
in use today.
flat cord with the large one piece plug was used on the Trimline (Type
#9). The modular 2 piece plug was added almost at the same time (maybe I
should have made that Type #9A). The modular cord then became the
standard cord for all the phones in the Bell System and other companies
as well. Start up production for the mod cord began in March or April
people call the Trimline a Princess also. There is NO such thing. The
Trimline is a Trimline and the Princess is a Princess. Western Electric
never confused the two. I don’t know how that started. Yes, the later
Princess phones has the mod cord as does the later Trimline. Maybe that
brought about the confusion of the public between Trimline and Princess.
On all round
Trimline cords with the color coded conductors, the red and green
conductors had to be diagonal from each other. Otherwise there would be
a feedback problem. (Likewise on the four conductor D-Station wire.)
manufacturing of anything there are, at times, problems that crop up in
the process. A serious problem arose after two or three years of
Trimline cord production. On one end of the cord the plastic shells were
cracking as they were riveted. I think it was the square end of the
spring cord; both the H5AA and H4DB’s were cracking. The beveled or
notched end appeared okay. Supervisors, engineers, material handlers,
set-up men, and women production workers spent at least two days trying
to find the problem with the shells. They checked the shells, the
machines, the manufacturing and other things and couldn’t find the
cause. An hour after a temporary material handler came on the job of day
three he noticed that the short and long rivets which were suppose to be
in different bins were mixed in all of the holding bins. From the bins
they were put into the riveting machines. The material handler showed
the supervisor the holding bins and what caused the shell cracking
problem and saved the company from further expense. I know this incident
is true because I was that material handler.
incident that I don’t remember being involved in happened when the new
one piece plug was delivered and assembled on the cord. After hundreds,
maybe thousands of cords were produced with the new plugs it was
discovered in the field that they wouldn’t fit into the phones. The plug
design was too large for the opening. The Trimline department shut down
for two days and with its three shifts cut off the completed plugs on
every cord. They re-plugged the cords with a newly designed one piece
cord started out as a replacement cord for the Trimline cord but it soon
branched out to become the mainstay cord for all types of telephones,
computers and other electronic equipment as well.
cord had two variations, starting with a two piece plug that was
sonic welded or heat sealed. The clip did not have WE on it. Then came
the one piece plugs the color of the cord; soon it was changed to
clear. Any telephones with dates before March 1974 that have modular
cords have been modified and refurbished. An exception might be field
test phones sent to certain cities by Bell Labs.
modular cords from Western Electric had color conductors, black, red,
green, and white. Soon they went to all black and then all silver. The
flat cord made color coding unnecessary.
Sequence for the H5AA Trimline Cord
reversing and washing the cords were sent to the Trimline Department.
to both ends
and pick paper
4…Add tips to
plastic shells were added to both ends
were added and riveted, different operator for each end (now it’s a
and tested 100%
Production Sequence Before Modular Cord
piece shell and tie a knot in the conductors
in slots on shell (now it’s a plug)
H5AA cost cuts
elimination of the string and
elimination of gold content
elimination of two different grommets
elimination of the different shell
pieces for one
elimination of the rivets (5 per
The first gold
tips had a high karat content of gold and locked in a safe when not
used-like during the weekend. They are worth their weight in gold.
Cost cuts for
gold tips went from high content gold to gold plated then to base metal.
Care of the
Trimline cords began like the other cords. When it reached the coiling
department—nicknamed boys town for an obvious reason—it joined the other
coded cords to be coiled, then heated, then cooled. This put the spring
in the cords. Here’s an important piece of information for the collector
who may want to get the spring and shape back into their cords. Do NOT
boil them in a pan of water! One reason is that the plugs are not to get
wet, corrosion and deterioration of the contacts. The second and third
is the treatment doesn’t last very long and could cause color fading.
Instead put them on a 3/8 inch wood dowel (metal or fiber glass if you
have it) and tighten the cord then put twist ties at both ends to hold
it in place. Bake it in the oven at 105 degrees. Leave for 10 to 15
minutes, times might vary. Make sure the wood doesn’t catch on fire.
After baking, put them in the refrigerator—not freezer—for 10 to 15
minutes. Your cords should be like new for a good while. (All of the
Western Electric cords have gone through this process at the factory
once, so it shouldn’t take as long. The aged plastic plugs of the
Trimline cords were never subject to the heat and cold. It would be good
to experiment and start at a lower temp and shorter time. The extreme
temperatures might crack the older plastic plugs, therefore don’t go
over the recommended temps and times.) For the non-Trimline cords
(spade ends) the temps and times can be increased to 120 degrees and
baked for 20 minutes. Refrigeration time can be increased to 20 minutes
twisted, tangled and backward describe Trimline and other types of
Western Electric spring cords that have been abused. Although the main
focus of this article is the manufacture and evolution of the Trimline
cord, the abuse of all spring cords needs to be addressed. The sight of
an abused cord not only looks ugly but its function could be weakened
First off all
WE spring cords made in the US have the coils lean to the right when
relaxed. The coils are tight and firm. If any WE cord leans to the left
and are loose they need to be re-twisted (reversed) back into shape.
your phone looking good and the cord looks like nine miles of bad road.
For modular cords there are detangle adapters for sale.
observations most people don’t notice that the cords are an important
part of the natural look of the telephone. Also a clean cord enhances
the overall appearance of the telephone. A plastic cord cleaner
suggested to me, “Arrow-Magnolia”, works well. I haven’t tried it yet.
Soap, water and elbow grease works too. The spade tips may get wet but
not the Trimline plugs or the modular plugs for the above reasons.
Cord as a new innovation played a part in the versatility of the
telephone. As stated before it made possible the modular cord which
replaced all of the different cords in use including the Trimline cord.
I am thankful to have had the opportunity to have been at the start of
the residential and business telephone plug era. The last corded phones
H4DB cord Types
Cord Type #1—Two piece clear plastic riveted shells;
grommets, one tapered (angled), one square, both the color of the cord;
gold tips; stamped code, length, the quarter and year on metal clips.
#2—Two piece clear plastic riveted shells; grommets, one tapered, one
square, both the color of the cord; gold plated tips; stamped code,
length, year on metal clips.
#3—Two piece clear plastic riveted shells; grommets, one tapered, one
square, both the color of the cord; base metal tips; stamped code,
length, year on metal clips. (Later no stamping on metal clips)
#4—Two piece clear plastic riveted shells; grommets, both tapered
(error), both the color of the cord; base metal tips; no stamping on
#5—Two piece color plastic riveted shells; grommets?; base metal tips;
stamped metal clips. *
#6—Two piece plastic sonic welded shells; one colored tapered, one clear
square; base metal long blades; plastic clips, no ID molding on clips;
flat cord-Modular type. **
#7—One piece tapered color plastic shell, clip and grommet; one piece
square clear plastic shell, clip and grommet; base metal tips; no
stamping on clips.
#8—One piece tapered clear plastic shell, clip and grommet; one piece
square clear plastic shell, clip and grommet; base metal tips; no
stamping on clips.
#10-One piece small color plastic plug same on both ends; small copper
blades; WE molded on plastic clips; Modular cord, code changed to H4DU.
#11—One piece small clear plastic plug same on both ends; small copper
blades; WE molded on plastic clips; a) color conductors, b) black
conductors, c) silver conductors; Modular cord, code changed to H4DU.
* This cord
might have been experimental, not sure if it was manufactured.
of this cord was discontinued in a short time as it led to the small
plug Modular cord.
Trimline cord H5AA & H4DB – 5’6”, 9’, 13’, 25’?
Trimline cord H5AD – 5’6” only (equipped with Message Waiting Lamp)
modular cords H4DU – short & standard, long, extra long
Trimline cord D5AL – 5’6”, 9’, 13’
Trimline cord D5AN - 5’6”, 9’, 13’ (retractable)
conductors ran left to right- yellow, green, red, black, white
conductors ran left to right- green, red, black, white
H4DU - no
(Tapered) Trimline plug fits in the handset.
Trimline plugs fits in the base. (spring and straight)
BSP Trimline cord colors as of January, 1973
I’d like to
hear from anyone who has other information, corrections or stories about
the Trimline Cord.
Gerber, former Western Electric, AT&T Technologies, Lucent Technologies,
and Celestica employee. Retired Lucent; ACTA #4231