Deliveries

 "Table of arrivals of tanks at the front lines in 1941, by type

Type	Domestic				British			American		Total
Month	KV	T-34	T-60	T-70	Mk.II	Mk.III	Mk.IV	M3 S	M3 L
Total 1941										20,740
Jan	126	206	348	-	-	16	-	-	-	696
Feb	165	420	260	-	-	-	-	-	-	845
Mar	105	338	84	-	-	-	-	-	-	527
Apr	320	702	576	-	134	144	-	14	32	1922
May	350	1003	898	-	255	171	-	30	16	2723
Jun	199	698	657	103	-	74	-	144	222	2091
Jul	299	1177	746	371	86	44	-	66	91	2880
Aug	178	1378	250	583	10	63	-	35	98	2595
Sep	45	598	-	439	-	72	-	54	43	1251
Oct	160	1100	75	640	-	10	-	24	5	2024
Nov	215	1312	-	838	85	163	-	187	61	2861
Dec	239	1678	48	1026	-	-	42	23	16	3072
Total 1942	Total domestic:  20,957				Total foreign: 2530					23,487

"

Via Alexey Isayev

This data is interesting on its own, but it's also interesting to compare to deliveries of foreign tanks. The first Matilda and Valentine tanks began arriving during the Battle for Moscow and were thrown into battle with little preparation. As you can see in the above table, once the situation stabilized a little bit it took some time before new units with British tanks could be properly outfitted. Large deployments of Matildas and Valentines only take place in April, four months after deliveries began.

A similar picture can be seen with American tanks. The first shipments arrived in January of 1942 and we start seeing a small number of these tanks on the battlefield in April-May, 4-5 months later. Once the pipeline was set up, it was not as hard to deploy new tanks. A bump shipments that came in May hits the front lines in June. A lot of tanks were tied up in delivery by the end of the year: 3875 foreign tanks were delivered to the USSR in 1941-1942, but only 2530 were actually fielded before the end of 1942.

You can see the same pattern with Soviet tanks. Evacuation of factory #183, the USSR's largest producer of the T-34 tank, began in September of 1941. The factory began to set up in the Urals in December-January, and by May of 1941 you see a spike in deliveries of T-34 tanks. Similarly, production of the T-70 was authorized in March of 1942 and we see these tanks begin to arrive on the front lines in July.