בנסוע המחנה, after the cloud above it had already withdrawn, for prior to that they were forbidden to enter the Tabernacle.

ונתנו על המוט; after that the Levites were permitted to carry all these parts.

ופקדת אלעזר, to issue orders who was to do what; i.e. who was to carry which parts of the Tabernacle.

פקדת כל המשכן; responsibility for the whole Tabernacle at the time when they broke camp to start their journeys and again when it came time to make camp.

אל תכריתו, do not allow the procedure of carrying parts of the Tabernacle to be a free for all, the one first on the spot carrying the part he chooses to, for if you do this the resulting chaos will lead to destruction, to death. Such chaotic conditions will inevitably lead to desecration of holy things, holy objects, with tragic results, i.e. loss of life. Our sages illustrated what is meant when describing the race between priests to be the first to carry out the cleaning of the ashes off the top of the altar. (compare Yuma 23-24).

ושמו איש איש על עבודתו ואל משאו, assign to each of them his specific duty in order to avoid a free for all. By doing this, you will insure that each Levite will wait patiently until his turn comes to carry out his assigned duty.

ולא יבאו לראות, by having a previously assigned roster of individual duties you will avoid that someone will see things forbidden to be seen by him, as a result of which he would have to die. He will avoid watching the priests covering the holy vessels, something which would cause their death.

לעבוד ולמשא. The former, לעבוד, while the people were encamped; the latter while the people were journeying. ולמשא, at the time of the journeys. Seeing that earlier when the Torah said:ומשמרת בני גרשון באהל מועד, (3,25) it spoke about their carrying out their function at the time of the people being encamped, the Torah also stated that everything which was under their control while the people were encamped remained under their control during the journeys.

ועבדו, during the periods when the Israelites were encamped their duties consisted of watching over all the vessels which formed part of the auxiliary equipment of the Tabernacle, i.e. אשר יעשה להם, “watching over all that would be done with them or to them.” For instance, seeing to it that the tools enabling the pegs to be firmly implanted in the earth so that the wind could not blow away the carpets forming the roof of the Tabernacle would be in good shape and position.

לכל משאם, at the time of the journey,

ולכל עבודתם, when the people would be encamped.

EACH ONE TO HIS WORK AND HIS PORTERAGE AND HIS RESPONSIBILITY. He appointed each one to the work that he would do at the time of encampment AND HIS PORTERAGE at the time of traveling, that he would know the weight of his burden and he would know his responsibility, i.e., that he would know the names of the names of the items that he would carry that were designated by name, as it is said (v.32), "you shall list by name the objects that are their porterage tasks."