国机重工 is a Chinese heavy machinery manufacturer. They produce a wide range of construction equipment, including excavators, bulldozers, and concrete pump trucks. Isuzu, on the other hand, is a Japanese automobile manufacturer known for producing commercial vehicles such as trucks. It is possible that the phrase "国机重工Isuzu泵车" refers to a collaboration or partnership between the two companies to produce concrete pump trucks using Isuzu's chassis and engine. However, without further context or information, it is difficult to provide a more detailed explanation.