(1), according to the image, the inventory increased by 4 tons in 2 hours, so it needs to increase by 2 tons 1 hour since I started working in the morning.

(2) From the OA section, it can be seen that the warehousing capacity per hour is 4÷2=2 tons, because only Party A and Party C work, so: one party of Party A and Party C has warehousing and the other party has warehousing, and the warehousing capacity per hour-warehousing capacity per hour =2 tons. Also, from "each car is only responsible for the purchase or shipment, and the traffic volume per hour is the most in car C, the least in car B, and the traffic volume of car B is 6 tons per hour", we can know that the traffic volume of car C > car A > car B =6 tons.

Therefore, car C is an inbound car, car A is an outbound car, and the traffic volume of car C- car A =2 tons. Also: only B and C are working in section AB, and the storage capacity is more than 6 tons; Only Party A and Party B work in the BC section, and the outbound volume in (8-3) hours is small, so: the B train is an inbound train.

So the incoming bus is B and C, and A is the outgoing bus.

Solution 2:

(1), according to the image, the inventory increased by 4 tons in 2 hours, so it needs to increase by 2 tons 1 hour since I started working in the morning.

(2) Assume that the hourly purchases of three cars, A, B and C, are a ton, B ton and C ton respectively, which can be obtained according to the image information.

2a+2c=4，

4+b+c+5a+5b= 10

After sorting, 2a+3b=2.

When b=6 (when car B is an inventory car), a=-8 and C =10;

When b=-6 (when B gets out of the truck), a= 10 and c=-8 (the contradiction is abandoned);

Therefore, the inbound cars are B cars and C cars, A car is an outbound car, and the transportation volume of A car is 8 tons, so the transportation volume of C car is 10 tons.