To the Gershonites, who had to transport the hangings and coverings of the tabernacle, two wagons are assigned: to the Merarites, who had the charge of the solid parts of the tabernacle, four wagons. The furniture and vessels the Kohathites were to carry on their own shoulders. Compare Numbers 3:25-26, Numbers 3:31, Numbers 3:36-37.
Related Commentaries of Numbers 7:7
Numbers 7:7-9
7 Two wagons and four oxen he gave unto the sons of Gershon, according to their service:
8 And four wagons and eight oxen he gave unto the sons of Merari, according unto their service, under the hand of Ithamar the son of Aaron the priest.
9 But unto the sons of Kohath he gave none: because the service of the sanctuary belonging unto them was that they should bear upon their shoulders.