Turret traverse data _ Allied v German

[Charles Markuss]

This is from my ASL article on the British, and may be of interest...


…Perhaps the most significant British advantage lay in turret traverse systems, and this has now been recognised in ASL following extensive research by this writer long after WoA was released, and explains why the Challenger and Comet have now been given fast turret traverse in ASL. Britain developed an hydraulic turret traverse system based on power turrets fitted to RAF bombers, and later also an electrical system, both having a specification demanding 360º traverse in 20 seconds (though this time varied, depending on the size and weight of the turret). The hydraulic system was first tested on an A9 cruiser in 1938 but the War Office specification of a full rotation in only 8 seconds proved to be over-ambitious and a slower speed had to be accepted - after a lot of worki. These systems gave a range of creep speeds so that power could actually be used for the fine laying of the gun, which speeded-up the firing process in situations where a split second could mean the difference between life and death. In comparison German, Soviet and early US systems were less effective, the former being dismissed in a British post-war report as “exceedingly cumbersome and inefficient. Training by power was never attempted, possibly because German turrets were usually wildly out of balance”ii. Hydraulic traverse systems in the British army (at least) gave way to electric gear because of the wish to avoid oil leakageiii, and to lessen the fire risk if a vehicle was penetratediv.

In short, German, Soviet and early US turrets were slued round in the general direction of the target and sighting adjustments were then made by hand. Britain sent a sample of the hydraulic version to the USA in 1940, and from this with considerable British pressure and inputv the Oilgear system was developed, along with the inferior Loganport hydraulic and Westinghouse electrical systems (both of which suffered from tight spots and variations in friction, especially the Loganport gear)vi. It is no wonder that US crewmen tried to get into a Sherman with an Oilgear mechanismvii. The systems used on vehicles like the T-34s, Valentines, Lee / Grants and those (later) versions of the Stuart that had power traverse suffered from considerable ‘back-lash’ in the mechanisms; even after British modifications the hand traverse and elevating gear on the early Stuarts was so poor that crew were reluctant to traverse the turret in actionviii. When the Lee / Grant’s 37mm gun was used at all, crews also preferred to use manual rather than power traverseix. The Italian L6/40 and M11/39, the first batches of Soviet T-34/85sx, the German PzKfw III family, the US M 10 and Staghound had only hand traverse; the PzKfw III needed 88 hand turns in high gear to traverse 360º, and 132 in low gear for fine layingxi while the M 10 gun crew needed about 80 seconds to turn the turret just 180ºxii. The German hydraulic systems were directly dependent on engine speed, while the PzKfw IV used a crude electrical system. Another German disadvantage was that their better but more complicated sighting equipmentxiii took a little longer to operate and this could give allied vehicles an edge in a gun duel. One advantage of US traverse systems over British equipment was that they were run from batteries, and so could be used ‘silently’ with the tank’s engine turned offxiv. Yet according to a report by a US Tank Destroyer officer, his M36 crews used power traverse only in training, and preferred manual traverse in combat (which was far smoother than the M 10’s manual system)xv. Little data on Italian systems seems to have survived, but Italian sources state that their hydraulic systems turned the turrets only slowly, were badly sited in the centre of turrets, were large and cumbersome (especially the earlier of two versions) and often removed by crews who regarded them as “almost useless”xvi.

The superiority of the British systems (with some exceptions) can be seen in the following table, gleaned from numerous published and unpublished sourcesxvii:

Vehicle Fastest traverse time (seconds) 360º Control Quality (and
using power type)

Tiger II <10 @3000 engine rpm** Poor (H)
A 13 10 Good (H)
Crusader 10 Good (H)
Valentine 2-pdr 10 left / 12 right Poor (E)
AEC I 10 left / 12 right Poor (E)
AEC II and III 11 Poor (E)
Challenger 12 @ 2700 engine rpm Good (E)
T-34/76 13.8 left / 13.6 right* Poor (E)
Matilda II 14 Good (H)
Stuart M5A1 14.4 left / 14 right Poor (H)
Cromwell 14-15 Good (H)
A9 15 Good (H)
A10 15 Good (H)
Churchill 15 Good (E)
Sherman 15 Oilgear type Good (H)
Sherman 15 Loganport type Poor (H)
Sherman 15 Westinghouse type Poor (E)
M 18 TD 15 Oilgear Good (H)
M 36 TD 15 Oilgear Good (H)
M 24 Chaffee 15 Oilgear Good (H)
T 26 / M 26 15 Good (H)
Panther A 15 @> 2500 engine rpm (forbidden 11/44 >)** Poor (H)
Stuart M3A3 15.4 left / 15.92 right Poor (H)
Valentine 6-pdr 16.9 Poor (E)
Panther G 18 left / 17 right Poor (H)
Panther A 18 @< 2500 max engine rpm (max from 11/44)** Poor (H)
Tiger II 19 left / 18 right @ 2000 engine rpm Poor (H)
Lee / Grant 20 Poor (H)
Ram 20 Poor (E)
T-34/85 21.1 Poor (E)
Comet 24 Good (E)
PzKfw IV 25.07 Poor (E)
S35 Somua 36 Poor (E)
Char B bis 36 Poor (E)
Char D2 36 Poor (E)
Panther D 60 Poor (H)
Tiger I 60 Poor (H)
KV 1 60-70 Poor (E)

(H) = hydraulic mechanism, (E) = electric motor.

* One source gives 10 seconds for all T-34/76 versions, which does not seem to take increasing turret weights of successive versions into account; this figure probably therefore only applies to the earlier M 1940 version with smaller and lighter turret. ** To preserve engine life German crews were eventually restricted to 2500 rpm when traversing; whether they obeyed this official edict is another matter.

The British also insisted that only the Oilgear traverse gear was used in Fireflies for reasons already explained and because, of the three otherwise interchangeable types used in Shermans, it was also the most compactxviii. Because only late-production 105mm Shermans had power traverse, and it was a minority type in British service anyway, they were not used for conversions…

...The generous assistance, over the years, of the staff at the Tank Museum, Bovington, the Badley Library at the Royal School of Artillery, Larkhill, and the School of Infantry, Warminster, is gratefully and humbly acknowledged.

[Freightshaker]

Interesting stuff, thanks!

[Exorcist]

ASL was a damned complicated system to learn and use, but I always thought that I could get back into it if I had to.

Now, Im not so sure. If they are getting into this kind of nonsense, Im hanging back!

[Charles Markuss]

Worry not, Freightshaker.

The stuff above merely explains to gamers why some tanks have fast turret traverse, some slow and some restricted, or are even classed as SP guns.

The different types of system are identified on the counter with a circle around the vehicle, or a square, broken square or no outline at all - respectively.

Use the force and have faith!!

[koreaboy]

hmmm. interesting. that turret traverse data goes against something i had thought for a long time. one of the strengths i had seen attributed to the T-34 was it's very good turret traverse speed, especially vs. the heavier german tanks. i can't recall exactly where i read it, but it was something i thought was true. your numbers look pretty solid so i guess i have to change my preconception! thanks.