here's a link that might help you http://www.haleproducts.com/_Downloads/hale/product_manuals/Booster%20Pumps%20MANUAL.pdf

the cbp i think stands for centrifical booster pump what the 5 stands for i could'nt decipher that from the download but you should be able to get the idea of how it all works.

is this truck a tanker? any pics?