The "Grabenspiegel-P" - P 38 231 na ja...

The "Grabenspiegel-P" (means something like "trench-mirror" - a periscope) was determined for observation by pioneer troops
These devices had been made in early 60ies and were still in army-store until 1990 - and are mentioned in latest issues of "Handbuch fuer Pioniere" (Handbook for pioneers). There were some of these handbooks which were no real regulations but a summary of many regulations to give an overview.
These handbooks are interesting sources for my investigations.

Below three overall views from P-38231.
P- rechte Seite Gesamtansicht - Ausblickseite Gesamtansicht - Okularseite  
Gesamtansicht - linke Seite Gesamtansicht ;-)) Scenario how I took the photographs....


Now let´s have a look at some details:

Umschaltung  Umschaltung-2  
A closeup of the eyepieces of which we find two: One for 20x magnification (see the german expression "Vergrößerung" engraved into the housing) which means an angle of view of 2°30". Using the the silverish lever, you turn a big prism into the housing to change the eyepiece. 40x magnificatin means an angle of view of 1°.
These two magnifications had been decided as the maximum magnification, which is useful in terrestric daylight-oservation (lit: compare with König and Köhler: Die Fernrohre und Entfernungsmesser).

It is quite interesting that the units are "degrees of angle" an not the 1/6000 Mil-Strich (60-00) as are used with the horizontal and vertical gears.
Each eyepiece has its own marking:

Strichplatte 40x  Strichplatte 20x  
The picture on the left shows the marking for the 40x eyepiece; on the right you see the marking for the 20x magnification. The interval between the large vertical lines is 10-00. These markings enable a good chance to estimate distances: If there are objects of known size (in meters) you multiply this size by 1000 and then devide by the numbers of "Mil-Strich".
Example: a VW-Golf - in the US better known as "Rabbit" (in Germany you may find it almost next to each tree ;-)) - appears within two big lines. It has a breadth of approximately 1,70 m. Calculate: 1,70 x 1000 : 10 = 170 m. - A real short distance to meet with a Golf - take care!!!!  (OK - I am kidding...)

To use the "P" in darkness, 20x markings can be illuminated by a torch - if you have one. Therefore there is a little window into the right side of the housing.
A quite primitive way as we are used to find those typical illumination devices like we know from the Scherenfernrohr.

Strichplattenbeleuchtung The little window for illumination of 20x markings.

By aid of  "P" you can determine horizontal and vertical angles:
Desiccant Trockenpatronen - Umkehrsystem
With the lever upon the scale (left picture) you can loosen the horizontal gear for free turning of the periscope. Scale is devided by 60-00. Above you see the two little windows for the desiccant cartridges on the opposite side of the housing There is also the typeand serialnumber of this device engraved. Additionally there are some kyrillic letters to see: "PBU" between "P38231" and "1747".
As English is the standard language in NATO-use, it was Russian into all Warsow-Contract-Countries. I presently do not know the meaning of "PBU" but it is certain, that it is an abbreviation beginning with "Periskop......". If I find more information, I will let you know.

But let´s continue discovering our peiscope.

To derive the beam from vertical to horizontal there is a swivelling optical mirror in the head of our periscope.

Ausblickkopf - Seitenansicht
This picture shows a view from the right side. The front glas is opened. Under the round covers (each side with 6 screws) there are the (ball) bearings for the mirror wich is driven by a cardan shaft.
Ausblickkopf - geschlossen Ausblickkopf - Rueckseite
Same view as above with front glass closed.- At the right the white sign "just to be opened in case of observation" below the third desiccant cartridge.
This was to prevent the valuable optical system from damages and foggy layers due to air-humidity.

Vertikaltrieb Umkehrsystem - linke Seite
The begin of the cardan shaft to drive the mirror for vertical swivel. "Fix up direction +/- before observation".
The scale indicates the vertical angle.

Ausblickkopf - Objektseite Front glass opened.

Objektiv - 1

Objektiv - 2  
A view through the front glass right into the periscope. We see the objective lens with a diameter of 80 mm (focusing width is 500 mm).

 
Protokoll Document of last (medium) maintenace in 1989.
trockenmittelbehaelter Surface of the transportbox for a spare desiccant cartridge "Desiccant cartridge  just to be opened before inserting into the device". There were three of these belonging to each device - unfortunately two are missing.....

Zubehoer Backside of the upper document with some accessories: the big screw to mount the periscope on wood (trees), a flat screwdriver to chnge desiccant cartridges and the last little box ....

Verpackung  

This picture shows the way the periscope is stored into its transport box - upside down.

Zapfenmontierung  The mounting onto the tripod.
P38231 uses the same tripod as SF-14.

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