Saturday, 5 July 2014

T-34 Tires

"To member of the State Committee of Defense, comrade Beria

At this time, the T-34 has rubber tires with ventilation openings (made from rubber gr.80). These tires do not provide reliable service due to the destruction of the rubber, and limit the top speed of the tank.

From August 1st to September 10th, the NIBT proving grounds and NII of tire manufacturing tested T-34 tires made from various types of rubber. As a result of the trials, it was shown that 210 km of runtime with production tires caused damage to 43% of the tires, while tires without ventilation openings made from 120s rubber did not have damage after 2000 kilometers. The average speed of movement was 25.5 kph and the external air temperature reached 33.5 degrees.

Wheels with smooth tires made of 120s type rubber without ventilation openings easily last the warranty period of the T-34. In connection to this, I ask for your order to the People's Commissariat of Rubber Production (comrade Mitrokhin) to supply tank factories with 120s rubber tires without ventilation openings starting from November 1st, 1943. Attached are the summary of trials and the conclusions made by the NIBT proving grounds and NII of tire production.

Malyshev.
Fedorenko
October 12, 1943

Summary and Conclusions on the trials of T-34 tank tires, conducted by the NIBT proving grounds.

1. The following is data on trials of tire damage as a result of motion with the average speeds of 25-35 kph.

Rubber type
With ventilation openings
Without ventilation openings

Distance (km)
Air temperature
Percent damaged
Distance (km)
Air temperature
Percent damaged
gr.80
210
20-22
43%
2001
15-27.5
30.8%
gr.81
525
14-22
25%
2034
14-33.5
17.7%
120s
502
14-22
10%
2001
14-33.5
0%

The presence of openings weakens the rubber mass, as a result of which it is deformed more easily, generates more heat, and, as a result, damages the rubber wheel due to the rubber melting (gr.80 and gr.81) or cracking (120s). 

2. The most heat resistant tires are ventless tires made from 120s rubber.

3. Tires without openings suffer from damage at speeds 40-45 kph, more so tires made from gr.80 and gr.81 rubber than tires made from 120s rubber.

Conclusions:
  1. Rubber tires for T-34 road wheels (size 830x150) without ventilation openings are much more robust compared to tires with ventilation openings. Tires without openings survived trials 2315 km long with the average movement speed of 25.5 kph with external temperature ranging from 14 to 33.5 degrees.
  2. Out of the trialled rubbers, gr.80, gr.81, and 120s, 120s type rubber demonstrated the greatest heat resistance and lowest heat generation properties.
  3. Tires with 120s rubber, without ventilation openings, and with a smooth surface are recommended for production.
Lieutenant-General of Tank Forces, Vershinin.
October 11th, 1943"

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