Monday 16 September 2019

Factory #183 Experiments, January-February 1941

"Report on the execution of experimental work on armoured vehicles from January 1st to February 20th, 1941

Tractor "42" on the T-34 chassis
Due date: September 1940
2x prototypes were built in November of 1940. Factory trials were supposed to complete in December 1940. A number of gearbox, tracks, winch, etc. defects were discovered during trials. Presently, the defects are being corrected, after which trials will resume.

T-34 tank modernization
The design bureau is developing a modernized T-34 with a new hull, turret, gearbox, main clutch, and suspension. A draft project is being worked on. Individual components are being built. A model is being built.

Information on correcting defects in prototypes from January 1st to February 18th:

Corrections applied
Tractor “42”
Produced November 1940
1.       The gearbox is not appropriate for a tractor. The difference in speed between 2nd and 3rd gears is high. It is impossible to shift from 2nd to 3rd gear on in very difficult terrain.
2.       The gear hubs of the 1-2 and 3-4 gears get jammed in their slots.
3.       Gear teeth of the 2nd and 3rd gears have chipped.
4.       11 teeth on the immobile gear for the 3rd gear have chipped.
5.       The immobile gear for the 1st gear was destroyed.
The gearbox has been redesigned. The case, rollers, gear and pinion, 1st gear gears and reverse gear gears have been left the same.
The gears of the 2nd, 3rd, and 4th gears are now constantly engaged.
The 3rd gear speed was lowered from 29.5 kph to 23 kph.
The 4th gear speed was lowered from 47 kph to 42.5 kph.
Gear shifts happen via a crab clutch.
The gears of the 1st and 3rd gears have been reinforced.

Hadfield steel tracks:
1.       Do not allow driving in mud with a load in tow due to slipping.
2.       Track pins lose their splints and fall out during motion.
3.       The track pin eyes get worn out quickly and the tracks break.
A new design was developed. The material is the same. The track shape and width have changed. The eye diameter increased. Quick-install grousers have been produced.

1.       The worm gear jams. The worm gear is cast iron, the worm is steel.
2.       The cable unrolls slowly. It is only possible to unroll it with the engine working by pulling it out by hand.
The worm gear has been changed to bronze. A device for disconnecting the winch from the link has been developed, which allows quick unrolling of the cable.
T-34 tank
Produced January 1941
Main clutch (disk deformation).
Three variants of disks have been tried.
1.       The driving disks are cast iron instead of steel.
2.       11 thick steel disks instead of 22.
3.       Steel disks with cutouts.
So far the third variant shows the best results. They were put into production, but so far the problem of deformation has not been entirely resolved. Development of new variants is underway.

The fan does not last for the lifepan of the vehicle. The blades and rim break.
Three new fans have been developed, one with two blade supports and two with a friction clutch attachment on the flywheel. The results have not been promising. A new clutch with a new flywheel and a friction clutch for the fan has been developed.

1.       Big difference in speed from 2nd to 3rd gear (15-29.5 kph), making it impossible to switch from 2nd to 3rd gear in very difficult terrain.
2.       The gear hubs get jammed in their slots.
Gearboxes with reduced 3-1 gear ratios are being tested.

Trials of a gearbox with constant engagement of the 2nd, 3rd, and 4th gears and reduced 3rd and 4th gear ratios are underway.

Ammunition rack:
1.       The rack does not allow an aimed rate of fire of 6 rounds per minute.
2.       The capacity of 77 rounds is insufficient.
A new ammunition rack that allows for an aimed rate of fire of 5 RPM has been developed.
To increase the amount of ammunition carried, extra ammunition will be carried along the sides of the hull after redesigned fuel tanks are installed. The overall amount of fuel carried will not change, but ammunition capacity will increase to 100 L.

The driver’s observation devices and the observation devices in the turret do not allow for sufficient vision.
A driver’s hatch with two “triplex” glass observation devices has been tested and gives improved vision compared to the production version. It is necessary to improve its resistance to shells, at which point it will be put into production. New observation devices with prisms instead of mirrors are being developed.

Tracks do not last the warranty period. Links break and track pin eyes wear out quickly.
Trials of reinforced tracks with reinforcement ribs and thicker pins did not give required results. A number of variants have been developed and are in production.

Flamethrower trials show that:
1.       The range with an oil-kerosene mixture is no more than 65-70 meters.
2.       The amount of fuel carried is enough for 3-4 shots.
3.       The fuel leaks.
4.       The ignition system is unreliable.
5.       The stream lasts too long.
Blueprints for a briefer stream and increase of the amount of shots have been sent to production.


  1. Having driven a tank using a clutch. I think most drivers have a natural tendency to drive the vehicle flat out and keep it in first gear and then slam it into second. But the gap between 2nd and 3rd gear ratios is wide enough that it can be hard to instinctively know when to shift.

  2. I love these reports, it really shows how much work and effort went in working out design. Thanks.