Interesting 4H dial detail

[unbeldi]

I have here a 4H dial that I found on a barn-fresh D1/202 desk set.

The interesting feature of this dial is that the W/BB switch springs are enclosed in a translucent shroud, presumable cellulose acetate.  Please see the pictures.  The dial operates normally.

Has anyone found this feature too?

This dial was originally a #2 dial converted to a #4H. It does not have a date stamp, but the conversion is properly recorded by relabeling the R screw on the casing. It also has a green "Tel.Co. Property" stock stamp, so was refurbished at a WECo center. It has a 150B number plate dated IV 46, which is heavily worn. The finger wheel still is the heavy brass type.

[Kenton K]

Yes I have found some dials with that too.

Kk

[Phonesrfun]

I have never seen that before.

[Dennis Markham]

I too have had at least one #4 with that feature.  It was a few years ago.  It was very dry and brittle.  I think I just removed it from the dial. 

~Dennis

[WEBellSystemChristian]

I have never seen that on a dial, but I have a D1 with hookswitch contacts that has something similar.

[unbeldi]

Dial also came with a nice original number card that was flipped over so it only showed its back in recent years.   That is the ORegon exchange in Inglewood (just SW of Los Angeles). The exchange was built in the 1920s, converted to dial in 1939, and expanded in 1980. It served ORchard 1, 2, 3, 4 and 7, and ORegon 8.  I suspect the card was issued in the early 50s.  Does anyone have a telephone book of Inglewood of the 1950s?

[unbeldi]

There must be a reason for Western Electric to shroud the W-BB switch. I don't think they did this without good reason, as subtle it may be. It is the switch that disconnects the receiver while dialing. The W terminal connects the white receiver lead, and BB is the brown-blue wire from the hook switch.  Since the switch is directly in the audio path one might think that any dirt on this contact pair might create static in the receiver.
Is this the reason?
Was the shroud only present on the conversion switch assemblies for No.2 dials?

[poplar1]

This seems to be an interim solution, perhaps c. 1939-1940. By early 1941, bifurcated BB and W contact springs were used on both updated 4H dials and converted 2A dials.

Perhaps the plastic cover was furnished on converted 2As because it was necessary to change the entire contact spring pileup to add the R contact. On 4H dials as originally furnished, it wasn't necessary to change the pileup, except when twin contacts were added. 

[Contempra]

Never seen that before..

[unbeldi]

This seems to be an interim solution, perhaps c. 1939-1940. By early 1941, bifurcated BB and W contact springs were used on both updated 4H dials and converted 2A dials.

Perhaps the plastic cover was furnished on converted 2As because it was necessary to change the entire contact spring pileup to add the R contact. On 4H dials as originally furnished, it wasn't necessary to change the pileup.

Ah, I always thought of the reason for bifurcated springs being to debounce the springs, but having two contact points certainly would provide simply better contact too and guard against dust problems to some degree.  Good point and this explains the rarity of finding these shrouds.  The shroud is delicate and intricately cut around the hard rubber actuator/post to the R spring.  It probably presents itself a dust magnet and maintenance problems.

[poplar1]

There's another type cover for the BB and W contact springs. This one is made of hard plastic, similar to the one found on some D-1 switch hook contact springs.

Addendum C34.175, Issue 2, 8-15-44 shows this later type contact cover as well as red rope paper gaskets, dial guards, and lock washers (for the finger wheel nut).

----------------------------------------------------------------------------------------------------------------
                            STATION DIALS

                           2, 4 AND 5 TYPES
                               
                             MAINTENANCE

       1.02  This addendum describes the method of applying de-
                vices developed to keep dust, lint, etc., which may cause
    dial failure, out of the 2, 4 and 5 type dials....

      Receiver Contact Cover
      2.03  This cover designated D-156747 and shown in place in
               Fig. 3 fits over the receiver contact springs on all H
    type dials with single contacts. Before applying, contacts to be
    covered should be cleaned by blowing the dust out with Chip
    Syringe No. 23 (with valve) or by brushing the contacts with
    KS-12463 Brush or equivalent and then immediately bur-
    nishing the contacts with the No. 265B Tool. The cover should
    be inserted with the dial springs in off-normal position and so
    that the hole in the cover engages with and is held in place by
    the rubber stud located between the transmitter and receiver
    springs.
-----------------------------------------------------------------------------------------------

[unbeldi]

Thanks. Interesting.  Would be nice to have this in the library.  I only have Issue 1 of this BSP.

So, I guess this provides another time stamp (of many) in the history of the phone, which started in IV 36 (housing) and seems to end in 1953 (HC-5 receiver), without counting the patent dates on the rim of the ex-#2 dial.

[unbeldi]

This seems to be an interim solution, perhaps c. 1939-1940. By early 1941, bifurcated BB and W contact springs were used on both updated 4H dials and converted 2A dials.

Speaking of time stamps.

Inglewood was converted to dial in 1939.  So this correlates with your time estimate of 1939-1941.

It appears this phone was a manual set when it was first installed in 1936 and received a dial for the conversion in 39.
In 46 it got a new dial face and a new handset and new cords in 1952 or so.  In 1954 the receiver was exchanged for an HC-5.

Have to try to date the number card, but since it doesn't have an area code on it may just be from 1952 or so as well.

[poplar1]

Reading between the lines, perhaps the "receiver contact covers" were added in the field, even in 1944 or later, since this is in a BSP for field techs, but "twin contacts" were added only in the distributing houses, from at least early 1941.

1952 seems early for E-4204 number cards.

[unbeldi]

Reading between the lines, perhaps the "receiver contact covers" were added in the field, even in 1944 or later, since this is in a BSP for field techs, but "twin contacts" were added only in the distributing houses, from at least early 1941.

1952 seems early for E-4204 number cards.

Yeah..  may be.  Perhaps it got a new card when the receiver was changed. Certainly by 54 they were in use.